Field of Science

Lyme disease and autism: the echo chamber of woo


In the "this isn't science or news" category, a local Fox station story out of Sacramento. Let's take this short steaming pile bit by bit, shall we?

Headline: "Doctors find link between Lyme disease, autism"
Problem 1: The story isn't about "doctors" finding "links." It's about one doctor claiming to have seen children in her practice (more on that later) who are "cured" of their autism after treatment for Lyme disease after testing positive for it. In reality, the story presents only one example to support the claim.

Problem 2: The story doesn't show any "link" in the scientific sense of the word, at all. In fact, it produces no science whatsoever. Yet, the headline sounds so very, very sciencey, does it not?

Lede:
Although the mystery of autism continues to puzzle the medical community, some doctors are finding a link between autism and Lyme disease, which is called "Lyme-Induced Autism," FOX40 Sacramento reported.
See above. "Some doctors" appears to be "one doctor." And yet, they've named it "Lyme-induced autism." A search of PubMed for this new disease turned up exactly no hits.

Exposition:
Mary Hendricks, 19, was diagnosed with a severe case of autism at the age of 2, but also showed symptoms of digestive problems, skin infections and pain.

After 17 years of constant doctors' visits to diagnose the problem, a specialist told Mary's mother, Tina, that the key to diagnosing her daughter would be to diagnose her first.

In the past, Tina had suffered from colitis, fibromyalgia and flu-like symptoms.

The mother has a history of vague, non-specific symptoms. The child was diagnosed with autism at age 2.

Bring in the specialist:
Doctors ordered a Lyme disease test, which came back positive. Then, the same test showed that Mary also suffered from Lyme disease. After receiving the results, Tina recalled that before getting pregnant with Mary, she had two ticks removed from her skin and hadn't thought about it since.

"If a child has autism from birth, many times it's because the child inherited an infection from the mother. I do think that Lyme disease, especially congenital Lyme is a cause of autism ," autism specialist Dr. Lynn Mielke told FOX40.

What? Where are the data showing that "if a child has autism from birth, many times (italics mine) it's because the child inherited an infection from the mother"? This is an etiology that is absent from most scientific discussions of autism I've seen. It's not that people haven't looked into it. They have. And they found no link between maternal infections throughout pregnancy and autism diagnosis. "No association was found between any maternal infection and diagnosis of ASDs in the child when looking at the total period of pregnancy: adjusted hazard ratio = 1.14 (CI: 0.96-1.34)."

That study did find that hospital admissions specifically for viral infections in the first trimester or bacterial infection in the second trimester were associated with an increased risk for an autism diagnosis. But nothing that fits the alleged pattern of a pre-pregnancy Lyme infection and autism.

In fact, as noted, there are no hits combining Lyme infection and autism as an entity in the literature, and there are only four hits on the two terms combined at all. Only one of these directly addresses it. This paper is from the journal of questionable questionableness, Medical Hypotheses. I was curious about the authors on this paper in this questionable journal, so I looked them up. The first author, Robert Bransfield, is president of the International Lyme and Associated Diseases Society, which is weird, because he's a psychiatrist. This association aligns itself with the viewpoint that current diagnostic testing for Lyme disease is faulty and encouraging people not to rely on test results for Lyme's (see point 5). In some courts, this insistence that the microbial presence of the causative agent in Lyme's is elusive enough to evade all testing and that some people thus suffer chronic, undetected Lyme is considered woo. He's referred to as a "Lyme warrior" by some (warriors are big in the woo world). There is a bit of a cottage industry around this one.

I also looked into the other authors. What I found is something that I've seen again and again: the hypothesis echo chamber, in which the only people who continue to talk about the hypothesis are the ones who devised it in the first place. And offer "tea recipes" as a cure. Or are allied with non-standard practices and have also published in Medical Hypotheses. Alt-Med conferences on chronic Lyme and/or autism, papers in Medical Hypotheses, LLCs. Does not impart confidence.

The rest:
Mielke said she thinks that Mary contracted Lyme disease from her mother during the pregnancy, which played a big role in Mary's development of autism. He started intense treatment on Mary's Lyme disease, and the outcome was successful beyond their expectations.

"As we treat Mary for her Lyme, some of her check list autism symptoms are disappearing," Tina said.

"For her to wake up, smile and giggle and laugh .. we haven't heard that for years," added her father, Danny.

Miekle told FOX40 the severity of Mary's autism may mean she'll only improve minimally, but for the Hendricks even small improvements translate to huge miracles.

"I have had patients in my practice with autism, who when we treated their Lyme disease, their autism improved so much that they were no longer autistic," Mielke said.

Again, where are the data on these patients? Is it actually possible to become "no longer autistic" as a result of a treatment in the years beyond early childhood? A search of PubMed on various term combinations yields no such evidence, although some people do appear to develop out of the diagnosis.

And finally, the selected expert: The expert selected for this story is Dr. Lynne R. Mielke. This Dr. Lynne R. Mielke. This Dr. Lynne R. Mielke lists biomedical "treatments" for autism on her Website that include hyperbaric oxygen and detoxification, which includes intravenous infusions of chelators ("heavy metal detoxification agents"), and both treatments may actually do harm. Oh, and there's a page labeled "vaccine issues" which offers up equivocation about vaccines, against the evidence-based guidelines of the American Academy of Pediatrics. Based on what she writes on the site, she is a DAN! (Defeat Autism Now!) practitioner. In other words, this is wall-to-wall non-evidence-based therapies for autism. Is Lyme mentioned on the site? Why, yes, it is. From the page:
In general, at this time Dr. Mielke will not be the prescribing doctor for the complex antibiotic and herbal protocols that chronic and acute Lyme patients need. She will refer patients to the appropriate ILADS physician for that. However, she will work closely with those doctors, making sure that the Lyme patients have all of the additional therapies that they need for an optimal treatment outcome.
Echo chamber and logrolling in our time, anyone? The choice of this "expert" with a clear dog in the hunt for input about a putative Lyme-autism link was a massive fail.

The bottom line: This "news" story with its sciencey headline misses the science entirely because there is none. It uses an "expert" with a clear dog in the hunt--her clinic offering non-evidence-based autism "treatments." It cites "doctors" when only one is quoted. It uses a single case to illustrate a broad, unsupported statement. It offers zero counterpoint or information from anyone about (a) whether chronic/undetected Lyme exists or (b) whether there is any science supporting the link asserted in the headline. It offers nothing in the way of a scientific study to support what it says.

In other words, "fair and balanced"? Um, no. More like False and Bullshit.

[Photo credit: Classic Lyme target-shaped rash. Via monkeypuzzle on Flickr]

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ETA: And this old-news no-news tries to go viral:

All courtesy of Fox"News," bringing you anti-science stories since, oh...inception?

Environmental sex determination: a huge gamble?


Turtles: An old love

It's hard to shake off an old love, right? One of my oldest loves as an adult scientist is the turtle. More specifically, it's any turtle that uses temperature-dependent sex determination (TSD). Sex determination refers to that decision point during (usually) early development when an organism's developmental pathway shifts toward female or toward male. In humans, the decision point is (usually) at fertilization: if the winning sperm carries an X, it joins up with the X from the egg, et viola! Females. If the winning sperm carries a Y, then the outcome is an XY zygote that, all things moving forward as anticipated, will develop as male.

Sounds so straightforward, doesn't it? But even in humans, the next step in the process--differentiation as one sex or the other--hangs fire for awhile, as steroid hormones and other chemicals help the body get rid of sex structures that aren't needed and work to build up sex-related structures that are. That's right: Both sets are there, meaning that a vertebrate embryo's all ready to move forward when the determination of which path to choose has been made.

We're a human-centric bunch, and if we bother to think a little further outside of our species, maybe we consider other primates, or when really pushing the envelope, we'll take a look at interesting creatures that have fur, all of which appear to use chromosomes to determine sex. But when it comes to sex determination, the natural world offers a dizzying mix of possibilities: mammals with 10 sex chromosomes, fish that switch from male to female in adulthood, worms that are true hermaphrodites and can self fertilize, and a few organisms still using an ancient mechanism to delay the decision about male or female until the last possible moment. The factors that help make that last-moment decision are environmental--which makes sense, as the decision is inferred to relate to which sex might be better for the way things are at the moment. These factors can include crowding, chemical signaling from specific tissues, location, or the best-known of these, temperature.

I just wrote that environmental determination makes sense because the delay might be related to choosing the better sex for the current environment. But no one really knows what underlies the selection processes for environmental determination. Even more intriguing, it's unclear why chromosomal determination seems to be so widespread, with its instantaneous decision regardless of environment. I've got some ideas about that. Having left research, I am not, however, able to do anything any more to investigate it, so I'm laying it out briefly here for any of the army of dedicated sex determination researchers who, like me, just can't stop thinking about this stuff.

Environmental sex determination
A lot of species across all kinds of organisms use the environment for determining sex, including plants, a lot of vertebrates, and invertebrates. But the reptiles get a lot of the focus, as TSD occurs in some turtles, all crocodilia and tuatara, and some lizards like geckos and agamids.

The focus of research to explain the persistence of TSD or environmental determination has been the Charnov-Bull model (Bull was on my prelim doctoral committee, woohoo!), which is based on the concept of differential fitness: that environmentally determined sex prevails in patchy environments where males may fare best in one patch type, whereas females may fare well in a different patch type. In other words, with this explanation, the features of where they live have some kind of influence on choosing the better sex for success among those features.

Within a reptilian focus, others have proposed models based on a similar concept to explain temperature-dependent sex determination; however, research published in the past few years places these ideas in a new context. My idea is that environmental sex determination is about the gamble. As long as gambling works out for the species, it persists. When the negatives of gambling on sex overwhelm the positives, chromosomal determination gains ground. That doesn't mean, however, the the environment isn't still at work on other parameters, even as chromosomes set the pathways in motion.

I propose that patchy environments are a common experience from embryonic development onward and that the environment can exert sex-based differential effects regardless of whether sex is determined by environment or by a specific sex chromosome. Environmental sex determination is not a requirement for sex-by-environment effects on phenotype. These effects can range from the timing and length of embryonic development to size to swiftness in the chase or being chased to differences in metabolic rates.

So what is the real distinction between chromosomes for determining sex and the environment? The difference between the two mechanisms lies in simple probability: sexual species can still respond to environmental variability via a suite of traits under environmental influence to produce at least some offspring with the most-adaptive combination of sex and other phenotypes. But environmental determination of sex is a riskily advantageous mechanism that can expand the number of individuals of a specific sex with this suite of traits. It can increase the probability of producing offspring with the most adaptive combination of sex and phenotype for the season and place.

The risk that environmentally determined species run is that their reliance on an environmental cue to determine sex, and thus, their population’s primary sex ratios, leaves them more vulnerable in the short term to the greater or more sudden vagaries of the environment, including global climate change or endocrine-disrupting contaminants in the case of the temperature cue. For vertebrates, the effect of temperature is ultimately the same as the effect of a chromosomal combination: production of sex-specific steroids and other molecules that push the organism down the pathway of developing as one sex or the other. Thus, temperature changes would obviously influence the outcome, and as many studies have shown, interference with that steroid signaling from compounds that act like hormones can change the outcome, too.

Although I developed this idea using reptiles and temperature-dependent sex determination, it applies also to other groups, including invertebrates. Additionally, it is possible that environmental and chromosomal sex determination exist simultaneously in some species, with environmental determination serving as a vestigial or redundant pathway.

The enhanced probability model

I suggest that patchiness is essentially a universal experience among organisms, and that regardless of sex-determining mechanisms, organisms may experience sex-specific predation or local mate competition or differential resource use between males and females. These experiences are certainly not confined only to organisms that exhibit environmental sex determination.

Patchiness can be spatial (how much room?), temporal (how much daylight time?), physical (look at all these rocks!), biotic (prey), or abiotic (water, air, shade, aforementioned rocks), but above all, it is complicated. In the spatial context, an acre of habitat can be divided into patches based on biotic (living) factors, such as plant growth. The plant growth itself can result from patchiness of abiotic (nonliving) factors, such as rock distribution, soil availability, or photoperiod (daily exposure to light). Times of year or month or day provide temporal factors that affect environmental conditions. In other words, any environment is patchy because biotic and abiotic influences in that environment will not all be uniform. Even in what appear to be uniform distributions, clumps occur. Even when a single factor appears to be uniform, such as soil type over a particular area, the soil itself may vary in levels of nutrients or contaminants present.

The Difference Is in the Numbers

The fundamental question is: Why has environmental sex determination been maintained and why has it not been replaced with a mechanism that determines sex at conception? The answer, or course, lies in the costs and benefits of each approach, and in the model proposed here, the benefits are strictly in the numbers.

It is costly to reproduce, not just in human dollars, but in energy investments. Thus, in making this investment, an organism’s best approach is to produce as many of the better-than-average offspring as it can. Most organisms, regardless of their sex-determining mechanism, will encounter a patchy environment, and in many situations, being a female in one type of patch may be better than being a male in that same patch. Organisms with chromosomal sex determination take the safe approach of having about 50 percent of their offspring develop as the better sex for a given patch. With this approach, they do not run the risk of rapidly skewed sex ratios in response to variations in environmental cues; however, they also invest a great deal of resources in the 50 percent of their offspring that will not be the better sex for the patch.

Organisms that use environmental cues to determine sex, often at a time well beyond conception, also have a tradeoff. Their approach is riskier in that they are highly susceptible to sudden sex ratio fluctuations if environmental cues alter, but their approach is also a better initial investment because of the enhanced probability that they will produce a greater percentage of offspring that are the better sex for a given patch. In reptilia, environmental sex determination is most prevalent in long-lived species (turtles, crocodilia); this longevity may allow for adjustments to sex ratio that are not as correctible in shorter-lived species.

Two Predictions

If environmental cues affect phenotypes with differential fitness results for the sexes, then an organism with chromosomal sex determination will have a 0.5 chance of producing offspring with the better combination of phenotype and sex with every offspring produced. In the same situation, an organism with environmental sex determination can use environmental cues to create a >0.5 chance of producing offspring with that better combination of sex and phenotype with each offspring produced.

The upshot of this scenario is that in situations where environmental cues during development can produce adaptive sex-by-phenotype effects, the presence of environmental sex determination should provide an advantage by aiding production of more offspring that are successful relative to an organism with chromosomal sex determination. This proposal has not been directly tested, but some work provides indirect support for the idea. Chelydra serpentina (snapping turtle) hatchlings in the field have experienced enhanced first-year survivorship if they emerged from nests that produced single sexes compared to the survivorship of mixed-sex nests (which may still exhibit a sex ratio skew); in this scenario, those females who produced single-sex nests may experience enhanced fitness (how much your genes are represented in the population) relative to turtles of the same species that produce mixed-sex nests. In the same Chelydra serpentina study, hatchlings from mixed-sex nests showed a propensity for running, even though hatchlings that remained immobile had a higher rate of survivorship. The outcome of a similar study in a species with chromosomal sex determination could be quite informative in terms of the survivability of hatchlings from throughout the season.

Another prediction of the enhanced probability model is that species with temperature-dependent sex determination will most often produce nests with biased sex ratios. In fact, empirical and theoretical studies demonstrate that reptile species with temperature-dependent sex determination are prone to producing nests with a strong sex-ratio bias, often near 100 percent, although the skew in either direction appears to be species specific. This skew has also been seen in nonreptilian species with environmental sex determination. With this added temperature-influenced phenotype of gonadal sex, the nest can produce a greater percentage of offspring with a suite of these phenotypes—including sex—that may be the best for a particular patch. In this way, temperature-dependent sex determination could be maintained because of this adaptive advantage with its potential for enhanced parental fitness. Chromosomally determined species can produce “better” males or “better” females for a patch, but they will also simultaneously produce not-so-great members of the opposite sex, thus obtaining lower returns on their investment.

Scenarios

The Benefits of Delay

In a simple scenario, the above prediction might hold true and could be tested using similar and rapidly maturing species occupying the same habitat area but employing different sex determining mechanisms. As a hypothetical example using lizards, two species live in the same habitat and breed at the same time. One species exhibits environmental sex determination with temperature as the trigger, with low temperatures producing males and higher temperatures producing females; the other species exhibits chromosomal sex determination. Both species respond developmentally to temperature, and different incubation temperatures result in different phenotypes; e.g., high-incubation-temperature hatchlings from either species run faster than their low-temperature counterparts. Male hatchlings require greater resource input. Predator presence increases as the laying season progresses. The females of which species will exhibit the greater relative fitness?

The females from the environmentally determined species may produce male-skewed sex ratios from eggs they lay early in the season when temperatures are lowest, predators have yet to emerge in full force, and food is abundant. Females with chromosomal sex determination are expected to produce a close to 50:50 ratio. Females with environmental sex determination who lay their eggs later in the season will produce high-temperature offspring that are both female and faster runners. The females with chromosomal sex determination who lay their eggs in the late season will produce fast-running males and females in an expected 50:50 ratio. The mother with environmental sex determination has produced low-temperature, slower, metabolically needy males at a time when predator presence is low and resource availability is high, and has produced faster, less-needy, high-temperature females when predator presence is high and resources have declined.

The mother with chromosomal sex determination has produced slower females and males simultaneously early in the season, and has produced faster females and males late in the season. If being a fast male hatchling with big metabolic needs is not adaptive late in the season, and being a fast-running female with lower metabolic requirements is, the mother with chromosomal sex determination has expended half of her resources producing offspring without the better combination of phenotype and sex. The success of her offspring should be less than that of the female with environmental sex determination who produced slow males early on and fast females later in the season, and therefore has overall produced more offspring with the most-adaptive combination of sex and phenotype.

This basic scenario of increased success for the offspring of organisms with environmental sex determination could be examined in situations where similar species inhabit similar habitats, but employ different sex determining mechanisms, a relatively common occurrence. At least some data support to idea that reptile species with environmental sex determination live longer—and thus can reproduce longer and enhance fitness—compared to their chromosomally determined counterparts. The question that arises is: do they live longer because they are the better-than-average male or female?

The Costs of Delay

In the same scenario above lie hidden costs to the environmentally determined species. Unusually warm early seasons could result in overproduction of less-adaptive females and underproduction of better-than-average males, thus reducing the relative fitness of the mother with environmental sex determination. Indeed, the relationship between global warming/climate change and sex ratios has been mentioned in some studies. There is also the suggestion that this subjection to environmental change, which weakens the advantage of environmental sex determination, might be less notable in long-lived species that have the opportunity over many breeding seasons to readjust sex ratios, a potential explanation for its prevalence in the longer-lived reptilian species and absence in snakes.

Sex determination appears to have made many transitions between environment and chromosomes as sex determinants, and it may be that over long periods of time, the steady conservative approach of chromosomal sex determination wins the race as populations of organisms with environmental sex determination adapt via a shift to a chromosomal pathway or succumb to the unpredictability of environmental change.

Applies to other groups, too

Environmental cues affect phenotypes in taxa other than reptiles, and invertebrates may provide a gold mine of opportunities for examining the effects of environmental cues on phenotypes and their interaction with sex. The sex of some invertebrates is subject to environmental cues; for example, temperature determines the sex of the copepod Tigriopus californicus, and this species also produces a male-biased sex ratio, supporting one of the predictions of the enhanced probability model. The cuttlefish Sepia officinalis demonstrates temperature-influenced differences in predatory pursuit behavior, and incubation temperature has been shown to affect the locomotor activity of the wolf spider Hogna carolinensis, although these studies do not report any assessments based on sex.

Some invertebrate research has uncovered sex-specific developmental responses to environmental cues like temperature; the aquatic insect (spp Diptera) often exhibits a decreased female size in warmer temperatures, although male size does not decrease at the same temperature. An amphipod, Gammarus duebeni, provides an interesting invertebrate example of environmental sex determination and the interaction of environment and sex in phenotype. Research involving a population of G . duebeni, in which males are produced earlier in the season, shows that there is a sex-by-size advantage to being male, and that both sex and size result from the environmental cue.

Conclusion

A number of studies that have been done on effects of environmental cues—including temperature—during development in many species have not included analyses of sex-by-temperature effects on phenotype. From invertebrates to vertebrates, many questions about the effects of these cues on sex in species with environmental sex determination, chromosomal sex determination, or both, remain to be answered. These species provide ready models to examine the main predictions of the model proposed here: a species with environmental sex determination will produce biased sex ratios with each reproductive event and offspring from environmentally determined species will have enhanced success when compared to similar species with chromosomal sex determination. These effects will manifest as differential phenotypes in males and females—or as phenotypes with differential adaptive value in males and female—as a result of the interaction of environmental cues and sex.

The Bears of Texas - Chapter 8: The Bears and the People Today

Chapter 8

The Bears and the People Today

“This could be the start of a beautiful friendship.” Casablanca

"Bears are soulless, godless, rampaging killing machines." Stephen Colbert

For centuries, we have lived in a state of war with bears, killing them out of fear, or for food, or for fun. In today’s more conservation-conscious society, bears are protected in Texas and cannot be killed for fun or food. But what about the fear?

We certainly have little reason to fear the bears on our own account. Since 1900, 63 people have been killed by black bears in North America, few of them in recent memory, and you are far more likely to be struck by lightning or killed by a dog than to be killed or injured by a bear. So what do we really fear?

The lingering sense of bear as foe can be traced to our long past of viewing the bear as competition and to visions of maddened bears tearing at cabins trying to get at the pig fat. In areas where the bear is coming back—especially in West Texas—some of the factors that led to its extirpation still exist, including ranching. But ranchers’ attitudes definitely have changed somewhat over the last century, and the black bears appear to live peacefully and co-exist with the ranchers for the most part.

The very fact that the bears returned and established a population reflects a change in land stewardship approaches on the part of private landowners and government in the area. They have cared for the land well enough that there is food, shelter, and water for the bears to enjoy. Unless private landowners cooperated, no comeback in Big Bend would have been possible. Bears do not care about boundaries, borders, or property lines, and they often wander where they are not “allowed.” If property owners in the area had not tolerated these wanderings, the Big Bend bears would not have made a comeback since the loss of even a single bear could have had such a devastating effect on the population.

Education has been part of the key to this change in outcome. Landowners know more about bears; they understand that these largely vegetarian animals are not really that much of a threat to their livelihood. According to the Texas Parks and Wildlife Department, many landowners in West Texas find themselves living in bear country and managing it with few conflicts. Not only do the landowners co-exist peacefully, but they aid in tracking bears, providing information to the parks department about bear sightings and indirectly helping bears by providing water for livestock during drought that the bears also have access to.

In fact, in the recent years of drought, the West Texas bear population might have disappeared entirely without this water assistance from property owners. Nevertheless, a 2006 Texas Parks and Wildlife survey of residents of the Trans-Pecos found that landowners remain divided on the issue, with 40% favoring bear recolonization and 46% not favoring it.

The odd thing is that the idea of bears not really presenting a threat to livestock is not a new one. In 1905, Bailey wrote about bears in West Texas that “at present the black bears do no serious damage to stock, and it is greatly to be hoped that their numbers will not be materially reduced.” Of course, the reduction was so material that bears virtually disappeared.

But ranchers today seem to have absorbed the attitudes of their counterparts to the south, where Mexican ranchers even in the 1930s tolerated bears and viewed them as a status symbol, an approach that seems to getting a foothold among landowners in West Texas today. One Trans-Pecos rancher of a few years back refused to kill bears even when they did attack livestock; a cowboy who raised pigs on the rancher’s land lost all of his stock to bears, and the rancher paid the cowboy for the loss rather than letting the cowboy kill the bears. The attitude that bears conferred status and were not a threat preserved the population in Mexico through the 20th century, and it may help preserved the recolonization of West Texas today.

This assistance from people is not just a bonus for the bears, it is a requirement. A friendship between bears and humans must be maintained if recolonization is to become permanent. Animal populations rarely re-establish themselves in old territories without human help, and certainly not in the absence of controls on human behavior. Wolves in Yellowstone would never have returned had not people transported them there and maintained the necessary vigilance to ensure their survival. Although the bears in West Texas are an anomaly because they initiated their own recolonization, success requires human support.

The black bear populations in West Texas have undergone phases of success and retreat. During one phase, Mexico served as a source of bears, but the Trans-Pecos region was the sink; bears disappeared from the area and the population numbers sank almost to zero. But as records indicate, bears maintained their contact with the “sink,” with males especially making occasional forays north of the border and warding off the finality of extinction.

What West Texas really is for the bears is, as naturalist Frederick Gehlbach put it, a series of mountain islands in desert seas, with the populations in northern Mexico serving as a sort of continental repository of bears, some of whom venture onto the desert sea and find their way to the sky islands in the mountains of the Trans-Pecos. As each sky island builds its population, it can serve as a stepping stone to nearby habitats, a way-station for the wandering bear searching for more habitat and resources.

Our new-found friendship with the black bear will probably not extend itself to the grizzly. What serves as a series of way stations for a black bear would not suffice for the grizzly. A recolonization of grizzly bears anywhere in the Southwest is highly unlikely because no reservoir of the great bears remains. As the extirpation of the grizzly moved inexorably to its empty end, populations became more and more isolated and were too small to serve as reservoirs for distant habitats. Each isolated population eventually disappeared and the grizzly vanished from the Southwestern edifice, never to return. There is no northern Mexico for the luckless grizzly bear.

Our new friend, the black bear, has had better luck. The arrival a small population of bears in the Black Gap National Wildlife Management Area and the subsequent increase in bear sightings throughout West Texas spurred the Texas Parks and Wildlife Department to begin researching ways to create a beautiful friendship with the bears through careful management of both people and bears. They have sought data on the food habits, denning ecology, and movements of desert bears for information that will lead to better management of bears with minimal bear–human conflicts.

By the spring of 2001, officials had captured 19 bears, fitting 13 of them with collars for radio tracking and monitoring their moves by ground and air. Research has involved analyzing bear scat for information on diet and monitoring their preferred scavenging grounds for food availability. Early results demonstrated an established population that, as we have learned, may be quite closely related. On the upside is the fact that the project also documented migratory subadults moving in from Mexico, a good sign because these wanderers bring with them their own individual sets of genes, adding to the variation of the population. Researchers from federal and state government and from universities continue their work with the bears in West Texas, closely watching this small population that has brought so much hope to the future for bears in Texas.

One reason bears or other animals find it difficult to recolonize an area is that human activity has fractured or erased their former habitats. Unless the niche opens for a bear to settle into, the bear has no role to fill in a particular area. Humans, with our buildings and freeways and reservoirs and dams, alter the landscape and render incapable of supporting the original wildlife. This insuperable obstacle to recolonization is especially powerful in the case of large carnivores, which typically need lots of territory and comparatively more resources than other organisms.

Bears are no exception to the large-carnivore rule; they do best with a range of contiguous forest or riparian corridors rather than a quilt of farmland, desert, and population centers. However, they can adapt to human encroachment, as seen in New Jersey and other eastern states with high human populations and bear populations that are flourishing.

A quilt of varying human activity is exactly what bears find in East Texas, so different from the well-preserved, scarcely populated West Texas habitat. Just across our borders, in Oklahoma, Louisiana, and especially Arkansas, bears have what they need to flourish: miles and miles of unbroken, preserved forest land. For this reason, although East Texas attitudes toward the bear are definitely friendlier since oil replaced the piney woods rooter as a basis for the economy, the bears need more than the human hand of friendship to flourish. The East Texas economy also increasingly relies on tourism and eco-tourism, and some part of this boom is because people want to see the bears.

The bears do try. They cross over from neighboring states fairly frequently, with about 12 reliable sightings in 2006 alone, according to Nathan Garner, Texas Parks and Wildlife’s resident East Texas bear expert. Some of these events over the years have been more than sightings—a small male met his death in the teeth of a car grill on Interstate 30 west of Mt. Vernon on the Hopkins/Franklin county line in May 1999. Others encounters were more positive and scattered over several counties throughout East Texas. The most common source of black bears currently appears to be Oklahoma, although Arkansas and Louisiana also serve as a bear repository.

As the bears enjoy continued success in the nearby states, we may see more of them lumbering into East Texas, looking for more food and shelter. Although long-existing human settlement stands in the way of recolonization, a study done by the Texas Parks and Wildlife Department indicates that there is enough suitable habitat to support a small black bear population in the area. Research from 2005 indicates that East Texas could sustain a population of as many as 2,200 bears.

Human attitudes also must be suitable, and in East Texas, the evolution has been slow. While land in East Texas has reverted from tilled fields back into forest, and the people have flowed from rural to urban centers, bears still suffered from the long, mutual history of distrust. In the late 1950s, a bear rumored to be the last black bear in the Big Thicket—although it may have simply been a wandering visitor from out of state—met its fate at the end of a gun in Livingston. The citizens responsible then barbecued the 450-pound animal and ate it, reporting disappointedly that it tasted “gamey.”

It may take awhile for bears to get a foothold in East Texas comparable to that they have gained in West Texas. As Pete A.Y. Gunter said in his book, The Big Thicket: An Ecological Reevaluation, “Big meat-eaters are spectacular; they are dramatic; and their existence in a habitat attests to its character as a real wilderness. It takes more than a remnant panther or bear, however, to constitute a wilderness ecology.”

Even in the 1940s, hope existed that bears could return to and thrive in East Texas. In 1937, four pet bears gained their freedom in the Big Thicket, but as might be expected, they quickly disappeared. Even with the Thicket under federal protection today, a permanent bear population remains a distant dream.

One suggestion made in the 1940s for bear recolonization was to rely on human introduction of animals from other areas. Rumors that the park service was doing just this in West Texas surfaced in the 1950s, but they had no basis. Although no bears have entered Texas with human assistance, they have been reintroduced in neighboring states. The reintroduction of the black bear to Arkansas has been described as one of the most successful translocations of a large carnivore; bears eventually recolonized areas of forest far from the original reintroduction sites, and there is no doubt that some Texas wanderers came from Arkansas’s woods. One female was captured near Dangerfield, Tex., in 1980 and had Arkansas tags in her ears.

Bears had disappeared from Arkansas in the early 20th century, and in 1958, the state’s Game and Fish Commission started the reintroduction process, moving 254 bears from Minnesota into the Ozark and Ouchita mountains over a period of 11 years. Today, there are well over 3000 bears in the region. Why did the reintroduction work? Lots of great habitat that was bear habitat in the first place, translocated animals were wild, many release sites were used, and the service released mostly males to establish territory before releasing females. Our extended hand of friendship resulted in great success on both sides.

Why can’t Texas do it too? Consider the reaction of East Texas residents to the simple idea of establishing federally protected lands in the Big Thicket in the later 20th century:

The sudden appearance of a new drive to create a park was accompanied by the equally sudden appearance of fantastic rumors spread by park opponents. Local people were warned that all local schools would be closed; that millions of visitors would come and take over their homes; that their children would be eaten by government-sponsored bears and panthers. The old bogey of economic disaster was dragged out and refurbished. A park would drive out the lumber industry and destroy all jobs; loss of tax revenue from lands taken over by “the feds” would drive small towns into bankruptcy. No one seemed to heed the argument that a park would bring in a new industry (tourism) to complement an old one (timber). That, of course, might undermine the monolithic control of lumber interests in the region.

The national preserve was established eventually in the 1970s, in spite of leaders in the area like Congressman John Dowdy, who once referred to the Big Thicket as a “mosquito-infested swamp” and referred to the Sierra Club as the “Sahara Club.” It was the work of another congressman, Senator Ralph Yarbrough, that helped make the Big Thicket Preserve a reality. But the people of the Big Thicket find themselves in a situation similar to that of the great bear hunters: They love the Thicket, but they rely on the industries that destroy it, and economic realities always trump conservationist desire.

Nevertheless, there is a place for the bear in East Texas, if the bears can find it and the people can tolerate their presence. A 1998 Texas Parks and Wildlife study showed that a corridor along the middle Neches River, running through Angelina, Jasper, Polk, and Tyler counties, offers the best place for a bear to live. One attractive feature of the corridor is that it runs through the Angelina National Forest, made up of bottomland oak and upland pine.

Whether the black bear will return and prosper in East Texas lies in the hands of the Fates, the residents, and the lumber companies. While there is growing support among East Texas residents for bear re-introduction, the support is not overwhelming enough to convince the state park service, and people still voice concerns that their children will be attacked by bears at school bus stops. Nevertheless, 70 percent of all comments received via email, letter, and public hearings in 2004 and 2005 indicated support for the new East Texas Black Bear Conservation and Management Plan that will restore bears to East Texas. The ending year of the plan is 2015, and only time will tell.

***************

Watching bears recolonize can tell us about much more than bears in Texas. We can monitor conservation genetics and find out what happens in a population with low variability when it returns to its old stomping grounds. We can find out what stops bears from dispersing and what encourages them. By monitoring how the bears respond to their fragmented habitat, we can gain knowledge about how other large mammals might be similarly affected. And because bears are what scientists call “sexy”—anything that appeals to the public in spite of its esoteric nature—the public may be more interested in learning about conservation through efforts to help and support the bears.

The last question to consider is, Why do we care whether bears make it back to Texas or not? How many of us, in our daily lives, walking down the sidewalk or driving home from work, pause to think, “Gee, it would be great to see a bear right about now”?

And that is the point. We don’t think about it much in our daily lives because the bears have disappeared from our daily lives. For settlers and ranchers, the bears’ disappearance helped the people survive and relieved them from a certain measure of hardship. But today, when we want to leave our daily lives behind, we want to find something different out there, something that says, “This is not part of my day-to-day existence; this is something special.” Traveling to a national park like Big Bend or a preserve like the Big Thicket and having the chance to see the tenacious, secretive, shy black bear can top the list of the most interesting things you’ll ever do in your life, much as hunting bears topped Teddy Roosevelt’s list.

I’ll never forget my first wild bear sighting. It was outside of Jasper National Park in Canada, and we saw the black bear as we blew past it going about 55 miles per hour. Literally rendered speechless in that moment, I gestured wildly to my husband to turn around. There it was, by the roadside, smaller than I expected and blithely snipping the heads off yellow flowers with its carnivorous teeth. Blue-black, smooth, shiny, and wild, standing in contrast against the green and gold background—it is something I will never forget, and I’ve seen many wild bears since then. My only regret is that I didn’t see my first bear in my homeland of Texas. Thanks to efforts in Big Bend and East Texas, others may have that chance.

References

Bailey, Vernon. 1905. Biological Survey of Texas. USDA Biological Survey, No. 25. Washington Gov’t Printing Office.

Caputo, Robert. 2002. Mother Bear Man. National Geographic, March. pp. 88-101.

Gehlbach, Frederick R. .1993. Mountain Islands and Desert Seas: A Natural History of the U.S.-Mexican Borderlands (The Louise Merrick Natural Environment, No 15) Texas A&M University Press: Bryan, TX.

Garner, Nathan, personal communication.

Gunter, Pete A.Y. 1993. The Big Thicket: An Ecological Reevaluation. University of North Texas Press: Denton, TX.

Morzillo, A. T., L. J. Jianguo, and A. G. Mertig. 2005. Attitudes about and opinions toward black bears in east Texas. Technical Report, Department of Fisheries and Wildlife, Michigan State University. 69 pp.

Onorato, David P. and Hellgren, Eric C. 2001. Black Bear at the Border: Natural Recolonization of the Trans-Pecos. In Large Mammal Restoration: Ecological and Sociological Challenges in the 21st Century. Maehr, David S., Noss, Reed F., and Larkin, Jeffery L., Eds. Island Press: Washington, D.C.

Patoski, Joe Nick. 2006. “Back in black: with or without a stocking program, the black bear is returning to East Texas.” Texas Parks and Wildlife Magazine, February.

Powell, R.A., Zimmerman, J.W., and Seaman, D.E. 1997. Ecology and Behavior of North American Black Bears: home ranges, habitat, and social organization. Chapman & Hall: NY.

Smith, K.G. and Clark J.D. 1994. Black bears in Arkansas: Characteristics of a successful translocation. Journal of Mammalogy 75(2):309-320.

Texas Game, Fish and Oyster Commission. 1945. Principal Game Birds and Mammals of Texas: Their Distribution and Management. Press of Von Boeckmann-Jones:Austin.

Willingham, Emily. 2001. Return of the Bears. Texas Parks and Wildlife Magazine, August. pp. 46-51.

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The complete book, When Worlds Collide: The Troubled History of Bears and People in Texas, is now available as a Kindle download on Amazon. Thanks for reading.

The Bears of Texas: Chapter 7 - The Comeback Bears of Big Bend?



Big Bend: El Despoblado, or “the uninhabited land.”

“A carpet of interacting plants and animals deftly woven on a geologic loom.” Frederick Gehlbach, Mountain Islands, Desert Seas: A Natural History of the U.S.-Mexican Borderlands.

Big Bend National Park is one of the largest and least-visited national parks in the country. It encompasses 800,000 acres and an entire mountain range (the Chisos) that reaches elevations of up to 8000 feet. The Chihuahuan Desert harbors almost 25 percent of the world’s cactus species, and the World Wildlife Fund gives it third place in overall desert species diversity. Lots of land, high level of diversity, sky islands of subalpine habitat, few people...sounds like a good place for a bear to live.

In 2000, I wrote a piece for Texas Parks and Wildlife Magazine about the bears coming back to Big Bend NP, and much of that story has found its way into this chapter, which also includes updates from a sidebar to a story on East Texas bears in the same magazine published in February 2006 and from a recent peer-reviewed publication.

As I researched the piece and visited the park, talking to the people there who worked day in and day out with bears, I became even more enamored of the idea that bears would come back to stay. I envisioned an idyllic scene where people adopted laid-back attitudes about the bears, allowing a live-and-let-live feeling to overtake the acrimony of earlier times. But as it turns out, the people aren’t the problem, nature is. I had forgotten that our best laid plans can be swept off the table by the unpredictable caprice of a nature we still struggle to understand. The edifice stands, but whether or not the bears will adorn it remains to be seen, even several years after I visited the park for that first interview about the bears.

Before all this worry about who was at fault, the clear enemy of the bear was man. Bears in the Big Bend had a bad reputation in the early 1900s. In 1937, a black bear allegedly stampeded 19 goats over a 3,000-foot cliff in what would one day become the national park. It was unfortunate timing for the bear because the National Park Service (NPS) had just convinced the Texas Parks and Wildlife Department to add the black bear to its protected game animal list. When newspapers reported the “Goat Tragedy,” the Park Service regretted that the story had been given to the press since it “will not be appreciated by local ranchmen.”

In the thirties and forties, black bears and other predators—including coyotes, bobcats, and golden eagles—were hunted for sport and much despised among local ranchers, except when they served as tourist attractions. One Marathon saloon, open in 1910, kept a pet bear so customers would buy it a beer. Apparently, the only bears allowed to live in those rough days were the pet bears—at least until they became too “cross.”

Some idea of conservation—and allowing wild bears to live, too—arose within a few decades. One suggestion was to create areas as refuge for bears—its primary feature would be that sheep would be excluded. The establishment of Big Bend NP accomplished this to some extent, but advocates suggested further preservation in areas outside the park where bears still lived.

The birth of the national park began in 1935 when legislation to create Big Bend NP was passed, but it wasn’t until June 1944 that the NPS took over its 27th national park. In the interim, a great deal of preserved natural history was lost forever when a fire destroyed the museum in the Basin, incinerating hundreds of locally collected specimens, leaving to the imagination any possibility that grizzly specimens may have been among them.

By the time Big Bend NP was established in 1944, few resident bears remained in the area. Biological surveys did a good job of documenting the organisms still in the park, and heavy land use during 1942–1944 coupled with several severe drought years totally wiped out any remaining bear population in the area. Shooting and trapping by ranchers, hunters, and federal predator control agents had also decimated the population, and habitat lost to development may have provided the coup de grace. Despite the notable absence, rumors abounded in the 1950s that the park service was secretly importing bears into the park, but the rumors had no basis and probably sprang from the hostility local ranchers felt for the park service, which has yet to import any bears to any part of Texas.

The bears started to import themselves back into the park in the 1980s. The preceding decades saw only the occasional individual bear—usually male—making its way across the border from Mexico. But sightings became common enough that at as the 1980s faded into the 1990s, the park had its first “bear jam” or traffic backup (example at left) because of a bear sighting.

Today, the park has an established population of black bears, but their existence remains tenuous. The park service must manage the people–bear relationship, and the forces of nature remain potential threats to the population’s stability.

One force of nature that seems to guide so much of how animals interact is hunger. In my original article, I described a story related to me by bear biologist and then-graduate student Dave Onorato: Hunger drove Candy the bear from the mountains of northern Mexico, spurred her across huge stretches of uncharitable desert, compelled her to swim the Rio Grande, and pushed her across more rugged ground before she finally reached the promised land of the Chisos Basin in the Big Bend. One day in the 1984, she did what no other female Mexican black bear had done in 50 years. She made the Big Bend her home.

Eventually, fanciful humans named her Candy, although scientifically, she was known as Bear #7.

Onorato, one of a handful of serious bear researchers monitoring bear activity in Texas, was a doctoral student in 2000, earning his Ph.D. from Oklahoma State University, but doing his work in Big Bend NP and surrounding areas. Candy, he told me, was the matriarch of the Big Bend population. When I went to talk to him, it was one of his few days off, and I had interrupted a rare visit from his father, but he graciously served as my guide to all things bear in Big Bend.

The day we took our tour, viewing a bear trap (general ex., right) and observing his use of locator devices, was not your typical Big Bend early October day. Fog and mist lingered long into the late afternoon, obscuring the deep blues and soft sandstone reds of the mountains. It was freezing cold, a harbinger of the storm that would lock the desert country in snow and ice that evening. Onorato took me in his truck to a trap site and explained to me the various attractants used to lure the bears into the traps. These traps were simply for capture and release, and the baits were harmless fish-scented lures; things had changed a lot since the days of deadly snares, self-triggered shotguns, and strychnine-laced snacks.

He told me what they knew at the time about Candy. She arrived in Big Bend in 1984 and began to reproduce in 1988, a banner year because a reproducing female means the population may take root. But the story wasn’t all happy news at the time based on Onorato’s genetic analyses, although the outlook has since improved as more genetic results have come in.

Onorato’s work with the bears originally indicated that Candy (a.k.a., Bear #7) was the Mother of All Big Bend Bears, having contributed her genes to much of the local population. If most of the population were that closely related, there would probably be very little genetic variation among the bears in Big Bend. That kind of relatedness would be similar to a single family’s founding a population on an island where cousins mated with cousins over and over again. The stage in this situation is set for two possible negative effects: interbreeding can result in the surfacing of hidden disorders, and any change—such as the introduction of a new disease—that affects one bear adversely may affect them all that way.

Onoroto’s initial work focused on the DNA found in the bear’s mitochondria, the “powerhouse” organelles of the cell that maintain their own genes and make their own proteins and build most of the cell’s energy-containing molecules. These organelles pass only from mother to offspring, so genetic analyses of mitochondrial DNA tell us about the female lineage.

We expect scientists to be dry and detached in their work, but Onorato had named his bears: Candy, Little Mama, Trixi, Vixen. On the day I visited, we listened on his locator for Hershey’s signal. Hershey was a small yearling male who, at 40 pounds, was about 20 pounds underweight for that time of year, not a good indicator for his survival. As we listened for Hershey and hear his beep, I felt a little buzz of excitement. There were real live bears out there.



The return of the bears sends a frisson of excitement through amateurs and experts. Before the advent of Bear #7, the conspicuous absence of black bears in West Texas engraved itself as a permanent fact in the minds of residents and visitors alike. Bear #7 and the comeback bears that followed surprised west Texans and the National Park Service. Many of us Texans had learned that in Big Bend, bears had gone the way of the wolf. When a friend of mine, known for his tall tales, claimed to have seen a black bear in Big Bend National Park in 1988, I secretly dismissed his story as an exaggerated javelina (left) sighting, even as he described taking a picture and depicted the park service’s excitement about his encounter. But these days, a yellow sign with a bear silhouette warns of a new presence in the park, unmistakable evidence that the bears are indeed back. If that’s not confirmation enough, the bear lockers at the Basin campgrounds should be. The question is, will the bears be able to stay?

The people probably won’t get in their way this time. Raymond Skiles, Big Bend NP wildlife biologist, told me that as the comeback bears have changed attitudes about living in the Big Bend area, the people in the area have changed their attitudes about the bears. “We’ve seen a different feeling of more welcome from society since the bears came back,” he said, “especially compared to what we find in the records from the turn of the century.”

It’s a different Texas from the one the bears left behind decades ago. “There’s a lot of optimism as the bears recolonize west Texas,” Skiles said at the time. “Now we would like to live with them. They enrich our lives, and landowners are willing to consider strategies for managing livestock with bears.” What if bears do become a problem? “Landowners will always have to have some options for dealing with individuals that aren’t compatible,” he says, “but for all parties concerned, we have the attitude that we can get along.”

One thing that may help spur ranchers to alter their attitudes is an alteration in the nature of their livestock. Up to the 1950s, sheep were the mainstay of West Texas, providing wool for war and peace. But by the fifties, the need for wool receded, and a drop in demand combined with drought led ranchers to abandon wool as a commodity. This change set the stage for the bears to return, and allowed to their return to be more welcoming than worrisome for ranchers.

This return of the bear is actually an unusual event in the history of wildlife—animals usually are not successful at recolonizing unless humans step in to help. In the case of the Big Bend bears, however, human intervention has not been necessary; the real key has been a lack of human meddling. In addition to a return to the Big Bend NP area, bears also are setting up territory in the nearby Black Gap Wildlife Management Area, where Courthouse Bear was deposited after his removal from downtown Alpine. Where else might the bear find resources in West Texas? Some possibilities include the Davis, Del Norte, and Glass mountain ranges north of the Chisos. Other potential recolonization sites to watch are the Chinati and Housetop mountains near Amistad National Recreational Area.

What made the bears such a success if humans aren’t responsible? A lucky confluence of factors from the ecological to the sociological made the return a reality. The comeback took a long time, beginning with very occasional sightings in the fifties that increased in frequency in the 1980s. Bears seemed to favor the Chisos Basin area of Big Bend NP, which is much like habitat black bears enjoy in central Arizona. All it took for the population to get its tenuous paw-hold was Candy the female bear making her arduous trek across the mountains and desert—possibly along with a few other members of her population.

Before Candy, sightings in Big Bend NP excited visitors and residents and attracted as much media attention as the arrival of a movie star or a presidential misstep. In 1969, a visitor, Bill Rabenstein, took a picture of a bear near Hot Springs in the park. In 1977, a naturalist and lover of the park wrote of finding fresh scat and overturned stumps and rocks in Juniper Canyon, undeniable evidence a bear had entered the neighborhood. At first, all bear sightings were probably wandering males—up to the 1960s, at least, when several yearling males met their deaths on a ranch northeast of the park. The young bears had probably wandered in from one of the bear reservoirs in northern Mexico, possibly the Sierra del Carmens.

The first sow with cubs sighting occurred in 1978, but it was unverified. By 1988, park employees had recorded 26 sightings, and in the following 10 years, 2,127 observations entered the record. Many of these sightings included females with cubs, the hallmark of permanence in the world of bears. The year 1994 had more than 400 bear sightings within the park.

Not every sighting ended simply in a report and an undisturbed bear. Sightings outside protected lands, even of this protected animal, could end in tragedy, as occurred when the small male lost his life on Sul Ross Hill after causing a stir on the Alpine golf course. In spite of this solemn footnote, by 1997, the bear population in Big Bend had reached about 20 bears, which roamed the canyons and the basin, dining on prickly pear and madrone (right)and acorns. It looked like humans and bears had reached a pretty easy truce. The bears’ preferred habitat might make that truce a little easier to honor. Their best food sources lie in the protection of the park, and the population centers within the park’s boundaries. But how long the bears will stay put in Big Bend is another story.

Onorato told me the early version of the story as I followed him to the bear trap on that unseasonably frigid October morning in Big Bend. Just the week before, highs had hit 100 in nearby Lajitas. “This year, they’ve begun a fall migration,” Onorato said about the bears as we made our way through low-hanging tree limbs and lingering mist. “They’re taking long fall journeys starting around mid-August, and they’re expected to return in mid-November to the natal site. The question is whether or not they’ll come back.” He hoped they would but already he knew that four collared bears had died in Mexico where bears are protected in some areas, but not in others. The year after this trip, I found out that the population had suffered even more losses, threatening the success of the recolonization.

The fall migration caused the population of bears in the Big Bend area to shift in 2000. Estimates early in the year put the number of bears at about 25, but by November, that estimate dropped to 10 or 15. Females trekked back to northern Mexico, covering the kind of acreage usually reserved for the more enterprising males. “One female has migrated 100 kilometers (60 miles),” Onorato told me, “and that’s very far for a female. Usually, 15 to 20 kilometers is a long way for them to go.” The unusual length of these treks did not bode well for the West Texas population, although it was a sign of movement—and the potential for gene movement—between the populations.

Why did the bears leave? Food. Nature seemed unaware of the truce between humans and bears that would smooth the way for bear recolonization. Nature’s representatives in the form of drought and a little caterpillar may have conspired to drive the bears southward, back into Mexico. For two consecutive years, the leaf oakworm caterpillar had decimated oaks in key habitat, depriving the bears of their favorite acorns. Drought decreased other forage, including the juniper and madrone berries the bears particularly target.

As we hiked to a bear trap just off the Basin road, Onorato pointed out the madrones to me. The deep red bark stood out against green leaves, but it was true—no berries were in sight. According to Skiles, when acorns drop, the bears’ failsafe are madrone berries. Without those, the bears must move elsewhere for food or they will starve. Heading southward to Mexico is their way of avoiding starvation. It is just another of Nature’s ironies; the bears probably came from Mexico in the first place because of food shortages that resulted from overpopulation and fires in the Sierra del Carmens.


National Park officials believe that the bear population in the park, which had dropped to no more than 15 female black bears by 2006, might have been on the rise again as the drought-induced conditions finally reversed in the area. Nevertheless, as the vagaries of nature consistently demonstrate, there are no guarantees for these bears, and Texas is now in the midst of a historic drought (left) that will have long-term outcomes for people, bears, and every other living thing in the state.

It’s exciting anyway just to be in a place where bears live. The evening before my tour to the bear trap, a small bear had appeared outside the lodge dining hall, drawing diners from their food to watch him through the window. But the little male was breaking the rules and should not have been so close to civilization. While the park service likes to say that there are no problem bears, only problem people, achieving a balance in a park between the people and the bears can still require a certain amount of finessing of animals intent on becoming a problem.

Luckily, the park has had only a handful of cases where bears entered a campsite in search of food, and Raymond Skiles wants it to stay that way. So far, there have been no serious human–bear encounters in Big Bend NP. Skiles feels that the park staff have an advantage other parks have not had in the past because it was able to manage an animal population before it was even established. “When the bear population started to grow, we decided we wanted to be the first national park in the country to implement cutting-edge technology before we had a problem,” Skiles told me.

The park service has a history of doing things wrong when it came to bears—pictures of grizzlies dining at the garbage dumps in Yellowstone presaged the park’s bear-management difficulties. “The visitors who watched the bears at the garbage dumps didn’t see the aftermath of the ones who got so aggressive that the rangers had to kill them,” Skiles says. “These parks had to go through a painful process to separate people and bears, and they could tell us what we needed to do so we didn’t reinvent the wheel. But no one had ever done this before the problem started.”

What worked in other parks often would not work in Big Bend NP, however, according to Skiles. Bears can’t be relocated easily if they became a problem because the Chisos Basin area is pretty much the only bear habitat available in the park. Destroying renegade bears in such a small population could be devastating—the destruction of even one bear could mean a loss of a significant percentage of the park population. Big Bend NP rangers handled the situation a different way, dealing with potential problems before they happened through education and bear-proofing, much in the way parents keep toddlers out of trouble by locking cabinets and drawers and keeping a constant watch on their activity. Humans had evolved from enemy to nurturer in the world of the bear.

Education is the main ingredient in the nurturing attitude. “We want to teach people how to visit the park without having conflict with the bears,” Skiles told me. Visitors get an eyeful of bear information in every visitor center and in every brochure they see. The park newspaper features a two-page spread on bears, giving advice on how to live safely with wild animals and providing visitors with updates on bear research. The park even offers a special brochure on the return of the black bear.

In addition to education, the park service focused on staff training, research, and facilities that discourage bear-people contact as paramount in keeping the bears wild. Skiles explained: “We train staff to capture and move bears humanely and safely, we’ve changed our waste management from open-top trashcans to bear-proof dumpsters, and we’re using research to develop a scientific basis for our management actions. Our goal is to have a bear population that is wild and is not influenced by human activity.”

Only once have these well-laid management plans gone awry. “We have had one occasion to relocate a bear,” Skiles related. “It was an orphan bear that found a great food source—acorns in a tree near cabins in the park. It was up a tree, drawing a heck of a crowd. People started showing up with picnic baskets, and the fear was that people might feed the bear. So we relocated it to another drainage nearby, hoping it would find another tree. It wasn’t really a problem bear, and the solution seems to have worked.” The picnic baskets brought on shades of Yellowstone NP, where visitors once set up in stands around garbage dumps to watch grizzlies dine. A huge drawback of this entertainment was that grizzlies ceased to fear people and began to associate them with food, making Yellowstone grizzlies among the most dangerous bears in any national park. Staff at Big Bend wanted to avoid just such a situation, and to date, have had great success.

But success is not guaranteed even with all of the careful efforts of the park service. The close of the 20th century saw the loss of one of the park’s most famous bears—Little Mama—and her cubs. Newspaper stories about bears in the park had featured Little Mama’s picture, and she was something of a celebrity. “They died in September (2000),” Onorato said, shaking his head. “She died in the desert in a wash, and there were cub prints behind her. We suspect dehydration.” It’s difficult to maintain detachment with so much invested in a feeble grip on future success.

And success remains important. Little Mama and her kind are considered by some bear experts to be members of a keystone species, anchoring the ecosystem of an area. If they disappear, the ecosystem gets out of whack, and nature’s edifice is undermined. Without the bears, the balance of the system shifts inappropriately—anyone who lives with an urban deer population knows how important a predator population can be; without predators, deer populations increase exponentially and decimate local resources. All the organisms in an equilibrated ecosystem have evolved and existed together in a finely tuned association, providing checks and balances for each other. The removal of a cornerstone like the bear can cause the entire edifice to collapse. Bears are much more than an adornment in Big Bend.

“Black bears eat mostly vegetation, but they are also top predators,” Skiles informed me, “and they have a big effect on the vegetation community and what is growing where. Their return has made a big step forward.”

One step forward, sometimes two steps back. Onorato’s work with the mitochondrial DNA indicated initially that the bears do have close genetic relationships, a fragility in the population not evident to the naked eye. Park officials worried about the lack of genetic variation. “We want to get a handle on what the genetic integrity of this population is so we’ll know if the population is diverse enough to sustain itself,” Skiles said at the time. “Our outlook is positive, but guarded.”

Since my discussion with Skiles, more information about bear genetics in the park has emerged, the most recent published in 2007. In that year, Onorato and colleagues reported in the journal Conservation Genetics that genetic analyses of the Big Bend and north Mexico “metapopulation” revealed a more-promising level of genetic diversity than previously thought. They applied a kind of different kind of genetic analysis in later studies and gained a more complete picture of bear genetics in the south/southwest Texas borderlands.

There is gene flow between the populations, a process in which mating among individuals of different groups keeps genes “flowing” between the groups, potentially keeping levels of genetic diversity higher in a given population. Bears move from northern Mexico and mate with bears in the Texas populations, and bears from the populations in Texas travel to Mexico and mate.

The authors conclude that maintaining this flow is important for the Texas–Mexico borderland bear populations, a key factor in conserving bears in the region. They also observe that it is the relatively “uncommon event” of long-range, female dispersal—a female moving from one place to another over a significant distance, as Candy did—that seems to drive and maintain the diversity of the metapopulation. Interestingly, the authors see hints that a population of bears in the Mogollon Mountains in New Mexico, northwest of Big Bend, may be candidates for classification as another subspecies, based on the results of their analyses. Bears in the Mogollons show little evidence of gene flow between this New Mexico population and bears in Texas.


Skiles made his statement to me about the “positive but guarded” outlook for the bears in 2000. Things can change a lot in just a few years, thanks to the unpredictability of nature. In 2006, he told Joe Nick Patoski that “The population isn’t safe and secure here. It’s a very tenuous existence.” Onorato and colleagues describe the West Texas bear populations as “potentially ephemeral,” and the extreme drought and recent fires in Texas (left, smoke over the Davis Mountains) is disrupting any path to success they may have been treading. Thus, for the black bears of West Texas, the outlook remains tenuously, ephemerally “positive, but guarded.”

References

Airhart, Mark. 2000. Big Bend: Desert Frontier. Earth & Sky Radio Series, September.

Black Bear Update. 1996. Texas Parks and Wildlife Department. Online document: http://www.tpwd.state.tx.us/landwater/land/habitats/trans_pecos/nongame/blackbear/.

Borderland Comeback. 2002. Geographica. National Geographic Magazine, December.

Cox, Mike Cox. 1996. The Grizzly Bear in the Southwest (Book Review). Lone Star Junction, August.

Garner, Nathan, personal communication

Gehlbach, Frederick R. 1993. Mountain Islands and Desert Seas: A Natural History of the U.S.-Mexican Borderlands (The Louise Merrick Natural Environment, No 15) Texas A&M University Press: Bryan, TX.

Jameson, John R. 1945. Big Bend National Park: The Formative Years. TX Western Press: The University of Texas, El Paso.

Jameson, John R. 1996. The Story of Big Bend National Park. Austin.

Langford, J.O, with Gipson, F. 1955. Big Bend: A Homesteader’s Story. UT Press: Austin.

The Mammals of Texas Online Edition. http://www.nsrl.ttu.edu/tmot1/. Texas Parks and Wildlife Department.

Onorato, David P. and Hellgren, Eric C. 2001. Black Bear at the Border: Natural Recolonization of the Trans-Pecos. In Large Mammal Restoration: Ecological and Sociological Challenges in the 21st Century. Maehr, David S., Noss, Reed F., and Larkin, Jeffery L., Eds. Island Press: Washington, D.C.

Onorato, D. P., E. C. Hellgren, R. A. Van Den Bussche, D. L. Doan-Crider, and J. R. Skiles Jr. 2007. Genetic structure of American black bears in the desert Southwest of North America: Conservation implications for recolonization. Conservation Genetics.

Patoski, Joe Nick. 2006. “Back in black: with or without a stocking program, the black bear is returning to East Texas.” Texas Parks and Wildlife Magazine, February.

Skiles, Raymond, personal communication.

Texas Game, Fish and Oyster Commission. 1945. Principal Game Birds and Mammals of Texas: Their Distribution and Management. Press of Von Boeckmann-Jones:Austin.

Tyler, Ronnie C. 1975. The Big Bend: a History of the Last Texas Frontier. National Park Service: US Dept of Interior, Washington, D.C.

Wauer, Roland H. 1997. For All Seasons, a Big Bend Journal. UT Press: Austin.

Willingham, Emily. 2001. Return of the Bears. Texas Parks and Wildlife Magazine, August. pp. 46-51.

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Note: There's one chapter left. For the handful who've been reading the book, my appreciation, and I hope you derived some enjoyment from it. For those who'd rather see regular old blog posts again, I've got a growing list of topics and will forge ahead with those after posting the final chapter of The Bears of Texas. Either way, thanks for stopping by.

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The complete book, When Worlds Collide: The Troubled History of Bears and People in Texas, is now available as a Kindle download on Amazon. Thanks for reading.