Space use by giant anteaters in a protected area within human‐modified landscape

Blog written by Alessandra Bertassoni. Read the full article here.

Shaggy, toothless, great snout and slow… These are common adjectives applied to the Giant Anteater – the largest anteater species in the Neotropic. This is a species that attracts curiosity, as well as having gaps in our knowledge of its ecology. Despite its large distribution (from Honduras to southern South America), it can be locally rare or very threatened in some areas (e.g. Central America and at the south of its distribution).

Numerous risks threaten the persistence of populations, such as wildfires, poaching, conflicts with dogs, road-kills, fragmentation, and habitat loss – these last two are the major threat to populations. To try to preserve natural habitats, countries have adopted the creation and maintenance of protected areas. On one hand, this is a good conservation strategy in times of huge changes to global systems – mostly driven by intensive human activities. On the other hand, some protected areas and their communities are immersed and isolated in human-modified landscapes. Large mammals require extended space, and the borders of the protected area are often bypassed.

This is the background of our study – “Space use by giant anteaters (Myrmecophaga tridactyla) in a protected area within the human‐modified landscape”. Our work took place in the Santa Bárbara Ecological Station (SBES), a protected Cerrado biome remnant (27 km²) surrounded by human-modified landscape in the State of São Paulo, Southeastern Brazil (Figure 1).

Figure 1: Santa Barbara Ecological Station (SBES, black polygon) and its surroundings in Southeastern Brazil. The green polygon is a Pinus sp. Plantation, the red traces are roads and Aguas de Santa Barbara municipality is represented as a light orange diamond.

This area is considered to have high biological importance due to its typical Cerrado vegetation. However, it is surrounded by pasture, sugarcane, exotic timber plantations (green dash line, Figure 1), and urban zones. It is also divided by a road network (red dash line, Figure 1). There is a resident population of giant anteaters within the SBES. We hypothesized that they would be highly dependent on the natural features of the protected Cerrado remnant because of their extreme specializations and habitat requirements. We also predicted that their home ranges will be primarily located within the SBES and the resources inside will be more used than the surroundings. Finally, we predicted that home ranges will overlap by more than 50% due to the small size of the protected area. This was a pioneer study of giant anteaters in a highly human-modified area.

To pursue these ideas it was necessary to track giant anteaters in the SBES and surrounding area. This species needs to be captured actively, as methods such as cage traps or baits are ineffective. Therefore, the team has to be in the field to search, find and catch giant anteaters.

In 2015, we spent three months in the SBES and its surrounding area. We covered approx. 12,000 km (three field campaigns) and we succeeded in capturing eight giant anteaters; four females (F) and four males (M). We fitted them with GPS-harnesses (see Figure 2).

Figure 2. A tracked giant anteater with GPS harness in the Santa Barbara Ecological Station, Southeastern Brazil.

For a few months (10 – 147 days, 91 on average), we were able to record 13,170 locations of the tracked individuals (Figure 3). This enabled us to record a great deal of interesting ecological data. Five giant anteaters (2 F and 3 M) remained almost exclusively inside the SBES and the other three (F1, M2, and M4) had more than 20% of their locations recorded outside of it. This gives us some indication that the SBES area and its requirements are not enough alone to accommodate this population. Residing outside of the protected area could be the best choice for individuals that require more space or are searching for specific resources which are too many exploited or limited within the SBES.

Another clue was the increasing trend in the home-range area of the two males (M2 and M4) to leave the SBES. From a conservation genetic perspective, individuals that leave a population to reach another can be considered propagules that contribute to the genetic pool. But, in a human-modified landscape, leaving protected areas is too risky, especially in a place that has more than one road.

In the two years that we spent in the study area, we found giant anteaters, deer and other animals killed by collisions with traffic. We predicted a great deal of overlap between individuals due to the SBES size, and we reported that dyads of opposite sex presented larger area-overlap than same-sex dyads, using two space-sharing indexes. However, this is not breaking news. Much more elucidative data came from the analysis of combined trajectories. This revealed proximity events in five dyads of opposite sexes and a male-dyad.

Figure 3. Giant anteaters locations inside the SBES and surroundings, Southeastern Brazil. M = male and F = female.

.What does this mean? Proximity events could indicate higher levels of coexistence than previously reported for this species, or that the study site is too small, meaning the anteaters interact more often. In addition, proximity analysis highlights that low home-range overlap cannot be strongly interpreted as a lack of individual interaction. Proximity events could indicate reproductive behaviour.

However, we still do not know if there is reproductive seasonality for the species, and this needs further study to advance our knowledge of this species’ natural history. Despite giant anteaters being most well-studied anteater species, we still lack the basic knowledge to to ask the right questions. We need to apply much more effort to studies on human-modified areas, to reach the minimal information needed to understand population trends and to move conservation forward.

Denning in brown bears

Blog written by Enrique González-Bernardo. Read the full article here.

Hibernation represents an adaptation for coping with unfavorable environmental conditions. For brown bears (Ursus arctos), hibernation coincides with winter in seasonal environments generally associated with low temperatures and low food abundance during which pronounced temporal reductions in several physiological functions occur. It is a critical period because at that time: (a) pregnant females give birth and undergo lactation while in dens; (b) energy savings during hibernation can be substantial; and (c) premature exit can negatively affect energy conservation and cub survival.

Brown bears are widely distributed around the northern hemisphere, with populations of different characteristics inhabiting very diverse habitats. Thus, the management and conservation of this species requires detailed knowledge about denning ecology of different populations, identifying patterns or gradients of denning behavior throughout the distribution range of the species and highlighting possible differences between populations. It is reasonable to expect that: (1) den chronology may vary by sex and bear reproductive status; (2) the duration of hibernation also depends on environmental factors, i.e. snow, temperature and food availability; (3) a relationship may exist between denning period and latitude, longitude and altitude; and (4) although the choice of a den and den surroundings may be variable, some differences may still exist by class, age and sex.

There are differences between sexes and ages in relation to denning chronology, with pregnant females enter the den earlier and exit later than other bear classes to take care of new-born and males and subadults generally having shorter denning periods. Hibernation in brown bears is mostly governed by a trade-off between environmental conditions metabolic dietary-related and energy conservation needs, with the exception of pregnant females which ultimate reasons are reproductive needs. As a general rule, the duration of hibernation in different brown bear populations seems to be conditioned by both snowfall/snow depth and snowmelt in spring. Snowfall can act as a major impetus to begin hibernation, as well as the ambient temperature. Warmer winters seems to be associated with a decrease in the length of the hibernation period and the postponement of den entry, while low autumn temperatures may cause early den entry. Den emergence seems to be regulated in some way with an increase in temperature, but not depending on the exact ambient temperature on the day of emergence (probably because den emergence is a longer process), but by the temperature the previous weeks. However, the hibernation period is primarily affected by a decrease in food availability due to the snow cover, which guides den entry and exit. Continuous availability of food and mild climates may prompt individuals to spend the winter outside dens, with bears in more northern areas spending more time hibernating than bears in the southernmost latitudes. There is an evident gradient between den chronology and latitude, but it seems to affect primarily to adult bears. Similarly, altitude has been described as influencing denning dates, with bears denning at lower altitudes emerging earlier than those hibernating at higher altitudes. Den abandonment occurs naturally, but human activities, such as industrial and forestry activity, hunting, transit of people or even research activity have been reported as the main cause. It may have negative consequences for populations, such as increases in cub mortality. In some populations where there are natural food sources during the winter, part of the population may not hibernate. This phenomenon is especially intense where supplementary food is provided during winter, which may alter the chronology of hibernation or winter.

The choice of a den and its surroundings may affect individual fitness, for example, loss of offspring and excessive energy consumption. Den selection is the result of broad- and fine-scale habitat selection, mainly linked to den insulation, remoteness, and availability of food in the surroundings of the den location. The most common den types are those excavated in the ground or located inside natural caves, but other types of dens such as depressions under rock shelters, nest dens and tree cavities have been reported. The typical conformation of a den consists of an entrance, a tunnel and the chamber where the bear builds the nest. Brown bears select sunny slopes and sites with deeper snowpack, which have insulating properties that help maintain a constant temperature protection. Other selected features are the slope of the hillside (simpler digging, stability, solar radiation and protection) and the distance and altitude (more permanent snow cover and further from human disturbances). Differences have been described in terms of sex, with pregnant females hibernating higher because they have a longer hibernation and need more isolation, while adult males hibernate in lower areas, which would provide them with greater food availability at den emergence, rapidly increase body mass and thus improve breeding success.

Brown bears hibernate for several months during which they do not eat, drink, defecate or urinate. This huge metabolic challenge has demanded a series of physiological adaptations in tissues and organs, many of them unique, enabling bears to survive under nutritional deprivation and to overcome anuria, hyperlipidaemia and immobilization, preserve muscles and bones avoiding osteoporosis or sarcopenia and prevent diseases such as metabolic syndrome, diabetes and cardiovascular pathologies. During hyperphagia, brown bears becoming temporary insensible to leptin which allows a constant appetite. Bears exhibit an increase in body mass of around 40% during the pre-hibernation hyperphagia, mainly fat. During hibernation, the mass loss could reach 4 kg per day. The metabolic rate drops to a quarter of the active state level and the temperature drop is about 3-5 °C, starting days before the den entrance. As a result, heart rate begins to decrease up to 80%. During hibernation, brown bears exhibit blood parameters that would be indicators of pathology in humans and as a consequence of fat-based metabolism, maintaining concentrations of phospholipids, cholesterol and free fatty acids much higher than healthy human values. However, atherosclerosis, fatty streaks, foam cell infiltration and inflammation have not been reported in hibernating bears. The bladder becomes permeable and both water and nitrogenous substances re-enter the blood. This and other adaptation, such as a reduction of urea synthesis and reincorporating urea into skeletal muscle and other proteins, allow recycling of nitrogenous substances and prevent renal complications or azotemia. Organs involved in digestive, metabolic and excretion processes, such as the liver and kidneys, have their activity decreased compared to the active period decrease in function. Brown bears do not appear to suffer from skeletal muscle and bone dysfunction or bone loss during hibernation, despite immobilization and lack of food. Brown bears are able to maintain both muscle and bone mass and function by reducing catabolic processes and maintaining a certain level of mechanical activity, such as shivering. Brown bears give birth during hibernation, around January-February, when there is no intake of food and water. Pregnant females appear to have delayed implantation of the embryo. In older females, as well as in females with high body fat content, den entry dates and birth dates tend to be earlier and the lactation period may be longer than in other females. In addition, in females with a higher percentage of fat and lean mass, implant embryos and cub birth occur earlier and the mortality of their cubs during the first summer is lower than in other females.

Concerning the hibernation of brown bears it is important to correctly distinguish between actual drivers of hibernation (temperature, snow, food availability) and their correlates (physiological changes). We suspect that the correlates of proximate factors might fluctuate according to current environmental variations. Predicted variations in air temperatures generally point towards an increase in temperature and precipitation variability has already affected biological systems by altering the phenology. Inter-annual fluctuations in hibernation chronology are expected to occur due to inter-annual variations in climate, extreme climatic events and temperature anomalies resulting from climate change. These fluctuations are probably unpredictable for many organisms, including bears. It has been reported how brown bears advance the den exit by increasing spring temperature, and how the total duration of hibernation is reduced. Brown bears have been reported showing a noticeable plasticity when hibernating, adapting their denning behavior to environmental factors, availability of food during hyperphagia or changing snow conditions during the winter. Despite this, energy demands of hibernating mammals would increase with higher winter temperature, and mismatches could be expected between the den exit dates and food resources, in addition to a reduction in their abundance or availability. Altering hibernation conditions could have a negative effect on reproductive success and cub survival. Such increased mismatches might also increase the likelihood of bear-human conflicts if bears emerge earlier. It is important to highlight here the potential effect of anthropogenic food, and especially supplementary feeding (provided with hunting, eco-tourism and the mitigation of human-bear conflicts purposes), on the chronology of hibernation, being able to halve the denning period or increase den abandonments. For all this, future research is important to know how changes in climatic factors might affect the ability of bears to face global climate change and the human-mediated changes in food availability. In addition to this, a better understanding of how hyperphagia, predenning and denning periods, including for those populations in which bears do not hibernate every year, and how to approach the study of bear denning merging insights from different perspectives, that is, physiology, ecology, and behavior.

Red listing isn’t all black and white: embracing the grey areas of a penguin conservation assessment

Blog written by Christina Hagen and Andrew de Blocq. Read the full paper here.

The International Union for the Conservation of Nature’s (IUCN) Red List of Threatened Species is a useful conservation tool for prioritising conservation and tracking the status of species. During a Red List assessment, a species’ extinction risk is given as one of nine categories ranging from Extinct to Least Concern. There are five criteria used to classify extinction risk which look at changes in population size or geographic range, quantitative analysis showing probability of extinction and the special cases of small populations. By far the mostly commonly used criterion examines the rate of decrease in the population over 10 years or three generations (whichever is longer).

While the criteria are quite clear-cut, the interpretation and analytical methods can differ between assessors and species. Some species are incredibly difficult to count (e.g. if they live in difficult-to-access areas or are cryptic) and this can lead to incomplete, inaccurate, or irregular population estimates. While there are different methods for filling missing data points, most consider the “true” population to follow a deterministic (without randomness) trend which is not realistic in terms of what we know about the real world.

JARA (Just Another Red List Assessment) is a new decision-support tool for assessments using the rate of population change criterion. JARA is notreally just another assessment tool, but rather one that takes uncertainty into account. Essentially, this algorithm considers the uncertainty in population estimates and plots the probability distribution of the population decline against the ICUN Red List categories. This means that a species can be classified as Endangered with 70% confidence, for instance, but with the likelihood that the assessment may have been too harsh (and should be Vulnerable) or too soft (and should be Critically Endangered). If for example, there was a 25% chance that the assessment should have been Critically Endangered, then more urgent action is needed, which may not be recognised without incorporating the uncertainty. Another useful way to use JARA is to plot these trends over time. This shows whether a species’ status is declining steadily or at an accelerating rate, stabilizing, or increasing either slowly or quickly. One can also use the JARA method on different sub-populations to see if the extinction risk differs spatially.

Penguins should normally make burrows in guano, but guano harvesting until the 1960s removed this insulating layer, forcing birds to nest on the surface, putting chicks at risk from predation and the elements. Photo: Andrew de Blocq

In our paper, we use JARA to analyse the decline in African Penguin numbers over the last 40 years. The African Penguin breeds only in South Africa and Namibia, with 32 colonies across the two countries. The colonies are clustered into three regions each separated by about 600 km: Namibia, South Africa’s Western Cape, and the Eastern Cape. Our results support the classification of this species as Endangered, with a high probability (97%). However, using the JARA framework also allowed us to deconstruct the trends over space and time, showing that the African Penguin has not decreased equally across its range nor over time. This is important as understanding the causes of the variation allows conservationists to prioritise different management strategies in each subpopulation.

The Namibian population has declined more slowly than the other regions, enough to allow it to be regionally classified as Vulnerable. However, this masks the fact that the population had decreased by over 70% prior to the start of our dataset in 1986. This is due to the collapse of the Namibian sardine stocks in the 1970s, and the species is at critically low levels compared to when fish stocks were healthy. The Namibian population also experienced an outbreak of avian influenza in 2018 which was much more lethal than a similar outbreak in the Western Cape colonies, so this again shows the importance of considering spatial differences in subpopulations when assessing risk.

The decreases in the South African population have been much more rapid over recent years. The decrease in penguin numbers has coincided with a decrease in sardine and anchovy biomass and the eastward displacement of spawning sardine and anchovy, which when combined with fishing pressure has decreased the availability of prey for penguins to the north of Cape Town. This region is changing the most rapidly, with decreases of 10% per year for the last 20 years. The Eastern Cape population, after decreases in the 2000s and late 2010s, has been relatively stable and now hosts the largest proportion of the global population.

African Penguins at the iconic Boulders Beach colony, a major tourist attraction but historically one of the smaller colonies that has remained relatively stable. Photo: Christina Hagen

The African Penguin is at serious risk as a species. However, it is also clear from our study that these declines are different for the three regional populations and that we cannot implement a one-size-fits-all conservation approach. Ongoing population monitoring is needed in Namibia to keep track of this vulnerable population. The Western Cape was traditionally seen as the stronghold for African Penguins, but with changing environmental conditions and the lack of food, the Eastern Cape has overtaken it as the new population stronghold. This mirrors the southwards and eastward shift shown by other marine species and raises the concern that the bulk of the penguin population is now on the edge of the species’ range. This should influence the priority of conservation action, especially with the colonies in Algoa Bay now facing novel threats from increased ship traffic and marine pollution related to ship-to-ship bunkering and the development of the local harbour.

The IUCN Red List is used extensively to inform scientific and conservation work, policies, and funding resource allocation. This means that assessment methods need to be as robust and transparent as possible, which includes an acknowledgement of the uncertainty that is inherent in each assessment and the breakdown of risk in space and time. The JARA method incorporates observation error (i.e. errors made during data collection or processing) and the variation that is part of any biological process.

Amid the current biodiversity crisis with many competing conservation priorities, we cannot afford for threatened species to be misclassified due to imperfect count data. We also need to make sure that conservation actions are appropriate and will address the correct threats at the correct sites and scales. JARA is a decision-support tool that can be applied to many taxa and can shed light on some of the inevitable uncertainty surrounding population trends.

Bat CATastrophe: the cause of many wing tears in UK bats

Blog written by Robyn Grant & Kirsty Shaw. Read the full paper here. Featured image of a common pipistrelle bat copyright Hugh Clark (bats.org.uk)

More than a quarter of all mammal species in the United Kingdom (UK) are bats, they also make up around 20% of all mammal species worldwide. Bats play important roles in many ecosystems, being pest controllers, pollinators and seed dispersers. Urbanisation is one of the most dramatic forms of land-use change and many bats, such as the Common pipistrelle (P. pipistrellus), exploit urban environments for roosting, water, and foraging under artificial lights. However, this also exposes them to urban risks, including collisions with man-made structures and predation from species that are concentrated in urban areas, such as cats.

In the UK, thousands of bats are found and rehabilitated by specialist bat carers every year, many of them for wing tear injuries. Indeed, when we surveyed bat carers around the UK, more than 2000 bats with wing tear injuries were reported to be taken to rescue centres annually. This is not a problem that is specific to the UK, wing tears are commonly found in bat populations worldwide. Tears are considered significant and severe injuries. Despite bat wings having resilient fibre structures and a good blood supply to encourage healing, rehabilitation in captivity can take a long time, which can significantly affect a bat’s health and welfare.

The causes of wing tears are not always clear, but may include collisions, fungal infections and predator attacks. We spoke to many bat carers around the UK, and they believed that the main cause of wing tears were cat attacks; however, positively identifying a cat attack can be difficult. In some cases cats can present a bat to their owners, or the tears “appear” to be made by claws. Previous studies have identified that 20-68% of bats admitted to rescue centres may be as a result of cat attacks; however, there is not yet an objective method to corroborate this.

We applied an objective, forensic DNA analysis method to identify the presence of cat DNA on bat wing tears. We asked bat carers to swab bats with wing tears and send us the swabs. We also asked them to take a photograph of the tear, and tell us what they think caused it. Overall, we collected 72 samples from bat carers, including 40 Common pipistrelles, 18 Soprano pipistrelles, 4 Whiskered bats, 4 brown long-eared bats, 2 Natterer’s bats and one Serotine, as well as 3 swabs from unknown species.

Bat wing swab sampling kit provided to bat rehabilitators

Our results showed that 48 out of 72 (67%) samples had cat DNA present. The presence of cat DNA appeared relatively equally across different bat genders, ages, and species, indicating that all bats may be targeted equally. While our method is a very sensitive technique for the detection of cat DNA, this value of two-thirds could still be an underestimation, due to bats not always being brought to carers, low amounts of DNA being transferred from the cat to the bat during the attack and variability in swabbing and storage techniques.

Bat carers tended to receive bats from a small working area within a 20 mile radius. The same bat carers sent us many samples, especially in Kent and East Dorset, so we also looked at using forensic DNA profiling to identify individual cats within these areas. We did not identify any of the same individuals. Other studies have suggested that there are likely to be “super predator cats” that repeatedly target bat roosts, so identifying any individuals that repeatedly predate on bats within a small area will be a useful thing to do in the future.

An example DNA profile which can be matched to an individual cat

Photographs of the tears showed that when cat DNA was present, these tears were often large, running from the internal membrane to the trailing edge, and tended to appear in the more proximal wing sections, close to the body. When bat carers supplied the suspected cause of the tear, they successfully identified a cat attack in all but one sample (in 93% of all cases). This confirms that bat carers are able to make strong, positive identifications of cat attacks.

An example of a bat wing tear close to the body, and an illustration of the most commonly affected areas of the bat wing

Free-roaming domestic cats cause a huge number of bird and mammal fatalities and, with the number of cats increasing annually, the effect of cat predation on wildlife is only likely to rise. Unfortunately, this means that the number of injured bats from cat attacks is also likely to increase in the future. As well as causing wing tears, cat attacks can also lead to bacterial diseases in bats. Cats may even receive a viral infection from the bats, such as Nipah virus and European bat lyssaviruses, which can lead to cat mortality. We would suggest that night-time curfews for cats, as well as anti-predator collars, will have beneficial impacts on the local bats as well as other nearby wildlife.

This is the first time that cat attacks on bats have been objectively identified using forensic DNA analysis techniques. Our results suggest that cat predation on bats, at least in the UK, is likely to be much higher than previously estimated. A better understanding of cat and bat interactions has implications for both cat and bat populations, as well as their health and welfare.

The Mystery of the Glacier Bear

Written by Tania Lewis and Neil Barten. Read the full paper here. Featured picture: Glacier Bear in Glacier Bay Alaska, by T. Hausler

There are few animals as elusive and mysterious as the glacier bear in Southeast Alaska and northwestern British Columbia, a region characterized by deep marine fjords left by the Pleistocene ice advances, steep rugged mountains from ongoing tectonism, and large glaciers and ice fields maintained by persistent cold precipitation. Glacier bears, also known as blue bears, are uncommon color variants of black bears (Ursus americanus) whose pelage ranges from white to grey to black with silver tipped guard hairs. The Alaskan Native Tlingit name for these bears was “siknoon” which translates into “a bear that disappears” in reference to their elusiveness and ability to blend in with snowfields (Lewis et al. 2020). These unique creatures are the subject of stories and books, and rare sightings are a once in a lifetime experience for a few lucky people. Glacier bears are also targeted and opportunistically harvested by sport hunters in some areas. Previously there was very little scientific knowledge regarding their range, the frequency, or the genetic basis of their unusual pelage color. This lack of knowledge has made it difficult to manage and predict the future survival of glacier bears.

A black bear mother with two glacier cubs in Glacier Bay, Alaska by C. Edwards

Neil Barten worked as a biologist for Alaska Department of Fish and Game (ADF&G) in Juneau in early 2000s, managing bear-human conflicts during a time when glacier bears were quite common in Alaska’s capital city. Bear problems in Juneau were increasing due to improperly stored trash and other attractants, and a few glacier bears were guilty of perpetuating this problem. Several glacier bears were hit by cars and up to six “nuisance” glacier bears were translocated, including a black mother bear with two glacier cubs and one black cub. Despite their prevalence in the capital city, Neil knew that glacier bears were uncommon in most areas, with only a couple harvested by hunters each year primarily near Yakutat over 100 miles to the northwest. Neil began collecting tissues from glacier bears captured or harvested to take advantage of recently developed genetic methods. As a management biologist, he recognized that genetics may be the key to answering basic questions about this little understood animal.

A glacier bear interacts with a police officer in Juneau, Alaska

Meanwhile Tania Lewis was hired to conduct bear research and management in Glacier Bay National Park and Preserve (GBNP&P), which lies halfway between Juneau and Yakutat. When Tania started digging into park archives to write the park’s first Bear Management Plan, she found a map of glacier bear sightings and harvest locations compiled by Linda Wiggins, wife of Canadian bear safety expert Steve Hererro. Linda had conducted visits to the region to attempt to determine the range of this rare color phase (Lewis et al. 2020). In 2009, at the Third International Human-Bear Conflicts Workshop in Canmore BC, Tania, Neil, Linda and others met for dinner to discuss glacier bears and the need for a collaborative research study to learn more about these mysterious creatures.

Glacier bear hide sealed and sampled by ADF&G

The team began collecting more genetic material of black bears across the range of the glacier bear color morph. GBNP&P and ADF&G staff collected DNA noninvasively from hair as well as tissue samples from harvested bears, noting the color of the pelage. Researchers used the DNA to examine genetic structure between populations of black bears within the geographic extent of glacier bears and explored how this structure related to pelage color and landscape features of a recently glaciated and highly fragmented landscape.

Glacier bear cub in Glacier Bay, Alaska, by E. Weiss

Ten populations of black bears were found in the study area divided largely by geographic features such as glaciers and marine fjords. Glacier bears were assigned to four of the ten populations found on opposite sides of two long fjords (Glacier Bay and Lynn Canal) with a curious absence in the non-glaciated peninsula between. Lack of genetic relatedness and geographic continuity between black bear populations containing glacier bears suggest a possible unsampled population and/or an association between glacier bears and large icefields, which would suggest a selective advantage for glacier bears in glacial environments. Such an association would increase the conservation risk of the color morph as glaciers recede suggesting further investigation is needed to determine the adaptive and evolutionary significance of the glacier bear color morph. Determining the genetic basis of the glacier bear color morph will also be necessary to determine the frequency of the gene(s) across black bear populations containing the rare phenotype. These results shed light on the distribution and population structure of the color morph across the region and may help focus conservation efforts to maximize and preserve genetic diversity of black bears as glaciation of the region decreases with climate change.

Lewis, T. M., Stanek, A. E. & Young, K. B. 2020. Bears in Glacier Bay National Park and Preserve: Sightings, human interactions, and research 2010–2017. Natural Resource Report NPS/GLBA/NRR—2020/2134. National Park Service, Fort Collins, Colorado.

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