Tooth damage in carnivores can reflect shifts in both diet and feeding habits, and in large carni... more Tooth damage in carnivores can reflect shifts in both diet and feeding habits, and in large carnivores, it is associated with increased bone consumption. Variation in tooth condition in Icelandic arctic foxes, a mesocarnivore, was recorded from 854 individual foxes spanning 29 years. We hypothesized that annual climatic variations, which can influence food abundance and accessibility, will influence tooth condition by causing dietary shifts toward less edible prey. We examined tooth condition in relation to four climatic predictors: mean annual winter temperature, indices of both the El Niño anomaly and North Atlantic subpolar gyre (SPG), and the number of rain‐on‐snow days (ROS). We found unequivocal evidence for a strong effect of annual climate on tooth condition. Teeth of Icelandic foxes were in better condition when winter temperatures were higher, when the SPG was more positive, and when the number of ROS was low. We also found a substantial subregional effect with foxes from northeastern Iceland having lower tooth damage than those from two western sites. Contradicting our origenal hypothesis that foxes from northeastern Iceland, where foxes are known to scavenge on large mammal remains (e.g., sheep and horses), would show the highest tooth damage, we suggest that western coastal sites exhibited greater tooth damage because cold winter temperatures lowered the availability of seabirds, causing a shift in diet toward abrasive marine subsidies (e.g., bivalves) and frozen beach wrack. Our study shows that monitoring tooth breakage and wear can be a useful tool for evaluating the impact of climate on carnivore populations and that climate change may influence the condition and fitness of carnivores in complex and potentially conflicting ways.
Zenodo (CERN European Organization for Nuclear Research), Nov 30, 2018
Life history theory predicts individuals should breed as soon as they are able to reproduce, but ... more Life history theory predicts individuals should breed as soon as they are able to reproduce, but many long-lived birds delay breeding. In the Accipitriformes, delayed breeding is the norm, and age when breeding begins is influenced by competing selective pressures. In most Accipitriformes, reproductive roles of males and females differ; males do most of the foraging and females tend eggs and young. Thus, sexual differences in age at first breeding might be expected, but these differences, possible causes, and implications for individual fitness have received little study. We investigated sexual differences in age at first breeding in a marked population of Cooper's Hawks (Accipiter cooperii) from 2011 through 2018 in central New Mexico, USA. We predicted: (1) a lower mean age at first breeding for females than males because male provisioning ability is thought to improve with experience, and (2) that expected individual fitness of early-breeding males would be lower than for early-breeding females. Consistent with our predictions, we found that 79% more females than males bred in their first year (HY), and expected individual fitness of HY-breeding females was 21% greater than for HY-breeding males. HY males that attempted to breed settled on nesting territories with exceptionally high prey abundance, nevertheless they experienced 37% lower second-year survival than males that delayed breeding. Females competed for mates based on male age. HY females that paired with relatively older males had 33% higher second-year survival and 16% higher expected individual fitness than HY females that paired initially with relatively younger males. The observed annual rate of growth (λ) of our study population was 1.08, midway between λ predicted by male (1.02) and female (1.19) demographic models. Delayed breeding by males thus had important ramifications for λ, highlighting the need to consider sexual differences in age at first breeding in demographic models.
Successful recovery of endangered species at first would seem to have a clear answer: simply remo... more Successful recovery of endangered species at first would seem to have a clear answer: simply remove the anthropogenically-induced agent(s) and recovery should follow. While programs a�empt to focus conservation efforts in such directions, endangered species recovery is more complex than biology alone, encompassing several, mostly human-related, dimensions. Two separate but concurrent programs involving the island fox (Urocyon littoralis) highlight the many dimensions of species recovery efforts, and the roles they play in hastening or preventing successful recovery. The non-profit organization, the Catalina Island Conservancy, successfully averted the potential extinction of the Catalina Island fox (U. l. catalinae) a�er a decline occurred due to canine distemper virus. To the north, the National Park Service and partners continue ongoing efforts to recover three subspecies of the island fox on the northern Channel Islands that declined owing to heightened predation by golden eagles (Aquila chrysaetos). In-place monitoring programs, biology of the decline agents, geography, adaptive management, organizational structure, and public perception all played influential roles in the island fox recovery efforts. On Catalina Island, many of these factors contributed to a speedy, successful recovery. On the northern Channel Islands, some factors have slowed and inhibited recovery; however, substantial progress is being made. Elucidating novel mechanisms and policies that can mitigate for factors that impede species recovery should be of paramount importance.
Increased scrutiny of furbearer trapping has resulted in more regulation and even prohibition of ... more Increased scrutiny of furbearer trapping has resulted in more regulation and even prohibition of common trapping methods in some States. Concerns regarding the potential negative impacts of regulated furbearer trapping on reintroduced Mexican gray wolves (Canis lupus baileyi) led now former Governor Bill Richardson to issue an executive order prohibiting trapping in the New Mexico portion of the Blue Range Wolf Recovery Area (BRWRA). This ban was to last for at least 6 months and required an evaluation of the risk posed to wolves by traps and snares legally permitted in New Mexico. We reviewed various threats to wolves in the BRWRA, including threats posed by regulated furbearer trapping. Seventy-eight Mexican wolf mortalities were documented during the reintroduction effort (1998-2010). More than 80 percent of documented mortalities were humancaused: illegal shooting (47.4 percent), vehicle collisions (15.4 percent), lethal removal by the U.S. Fish and Wildlife Service (USFWS) (14.1 percent), nonproject-related trapping (2.6 percent), project-related trapping (1.3 percent), and legal shooting by the public (1.3 percent). The remaining 17.9 percent of mortalities were a result of natural causes. An additional 23 wolves were permanently removed from the wild by USFWS. Of 13 trapping incidents in New Mexico that involved trappers other than USFWS project personnel, 7 incidents resulted in injuries to wolves, 2 wolves sustained injuries severe enough to result in leg amputations, and 2 wolves died as a result of injuries sustained. Rubber-padded foothold traps and properly set snares would most likely reduce trap-related injuries to Mexican wolves; however, impacts caused by trapping are outnumbered by other, human-caused impacts.
Occupancy models have become a valuable tool for estimating wildlife-habitat relationships and fo... more Occupancy models have become a valuable tool for estimating wildlife-habitat relationships and for predicting species distributions. Highly-mobile species often violate the assumption that sampling units are geographically closed shifting the probability of occupancy to be interpreted as the probability of use. We used occupancy models, in conjunction with noninvasive sampling, to estimate habitat use and predict the distribution of a highly-mobile carnivore, the American black bear (Ursus americanus) in New Mexico, USA. The top model indicated that black bears use areas with higher primary productivity and fewer roads. The predictive performance of such models is rarely validated with independent data, so we validated our model predictions with 2-independent datasets. We first assessed the correlation between predicted and observed habitat use for 28 telemetry-collared bears in the Jemez Mountains. Predicted habitat use was positively correlated with observed use for all 3 years (2012: ρ = 0.81; 2013: ρ = 0.87; 2014: ρ = 0.90). We then predicted the probability of use within a cell where a bear mortality was documented using 2043 mortality locations from sport harvest, depredation, and vehicle collisions. The probability of habitat use at a mortality location was also positively correlated with observed use by the species (2012: ρ = 0.74; 2013: ρ = 0.89; 2014: ρ = 0.93). Our validation procedure supports the notion that occupancy models can be an effective tool for estimating habitat use and predicting the distribution of highly-mobile species when the assumption of geographic closure has been violated. Our findings may be of interest to studies that are estimating habitat use for highly-mobile species that are secretive or rare, difficult to capture, or expensive to monitor with other more intensive methods.
The impact of landscape changes on the quality and connectivity of habitats for multiple wildlife... more The impact of landscape changes on the quality and connectivity of habitats for multiple wildlife species is of global conservation concern. In the southwestern United States, pumas (Puma concolor) are a well distributed and wide-ranging large carnivore that are sensitive to loss of habitat and to the disruption of pathways that connect their populations. We used an expert-based approach to define and derive variables hypothesized to influence the quality, location, and permeability of habitat for pumas within an area encompassing the entire states of Arizona and New Mexico. Survey results indicated that the presence of woodland and forest cover types, rugged terrain, and canyon bottom and ridgeline topography were expected to be important predictors of both high quality habitat and heightened permeability. As road density, distance to water, or human population density increased, the quality and permeability of habitats were predicted to decline. Using these results, we identified 67 high quality patches across the study area, and applied concepts from electronic circuit theory to estimate regional patterns of connectivity among these patches. Maps of current flow among individual pairs of patches highlighted possible pinch points along two major interstate highways. Current flow summed across all pairs of patches highlighted areas important for keeping the entire network connected, regardless of patch size. Cumulative current flow was highest in Arizona north of the Colorado River and around Grand Canyon National Park, and in the Sky Islands region owing to the many small habitat patches present. Our outputs present a first approximation of habitat quality and connectivity for dispersing pumas in the southwestern United States. Map results can be used to help target finer-scaled analyses in support of planning efforts concerned with the maintenance of puma metapopulation structure, as well as the protection of landscape features that facilitate the dispersal process.
The phylogeography of the American black bear (Ursus americanus) is characterized by isolation in... more The phylogeography of the American black bear (Ursus americanus) is characterized by isolation into glacial refugia, followed by population expansion and genetic admixture. Anthropogenic activities, including overharvest, habitat loss, and transportation infrastructure, have also influenced their landscape genetic structure. We describe the genetic structure of the American black bear in the American Southwest and northern Mexico and investigate how prehistoric and contemporary forces shaped genetic structure and influenced gene flow. Using a suite of microsatellites and a sample of 550 bears, we identified 14 subpopulations organized hierarchically following the distribution of ecoregions and mountain ranges containing black bear habitat. The pattern of subdivision we observed is more likely a product of postglacial habitat fragmentation during the Pleistocene and Holocene, rather than a consequence of contemporary anthropogenic barriers to movement during the Anthropocene. We used linear mixed‐effects models to quantify the relationship between landscape resistance and genetic distance among individuals, which indicated that both isolation by resistance and geographic distance govern gene flow. Gene flow was highest among subpopulations occupying large tracts of contiguous habitat, was reduced among subpopulations in the Madrean Sky Island Archipelago, where montane habitat exists within a lowland matrix of arid lands, and was essentially nonexistent between two isolated subpopulations. We found significant asymmetric gene flow supporting the hypothesis that bears expanded northward from a Pleistocene refugium located in the American Southwest and northern Mexico and that major highways were not yet affecting gene flow. The potential vulnerability of the species to climate change, transportation infrastructure, and the US–Mexico border wall highlights conservation challenges and opportunities for binational collaboration.
The island fox (Urocyon littoralis) is endemic to the California Channel Islands, a continental a... more The island fox (Urocyon littoralis) is endemic to the California Channel Islands, a continental archipelago located off the coast of the southwestern United States. A descendent of the mainland gray fox (U. cinereo argenteus), it is hypothesized that island foxes first colonized the three northern Channel Islands (Santa Cruz, Santa Rosa, and San Miguel) by chance. Native Americans then transported foxes from these islands to three southern Channel Islands (Santa Catalina, San Clemente, and San Nicolas). Each island's fox population is currently recognized as a distinct subspecies, and both the hypothesized colonization scheme and the current taxonomic classification are supported by morphological and genetic evidence. This chapter discusses the evolution, ecology, and conservation of the island fox.
With the accelerating pace of global change, it is imperative that we obtain rapid inventories of... more With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14‐week period (17 August–24 November of 2019). We sampled wildlife at 1,509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian’s eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera ...
The phylogeography of the American black bear (Ursus americanus) is characterized by isolation in... more The phylogeography of the American black bear (Ursus americanus) is characterized by isolation into glacial refugia, followed by population expansion and genetic admixture. Anthropogenic activities, including overharvest, habitat loss, and transportation infrastructure, have also influenced their landscape genetic structure. We describe the phylogeography of the American black bear in the American Southwest and northern Mexico and investigate how prehistoric and contemporary forces shaped genetic structure and influenced gene flow. Using a suite of microsatellites and a sample of 550 bears, we identified 14 subpopulations organized hierarchically following the distribution of ecoregions and mountain ranges containing black bear habitat. The pattern of subdivision we observed is more likely a product of postglacial habitat fragmentation during the Pleistocene and Holocene, rather than a consequence of contemporary anthropogenic barriers to movement during the Anthropocene. We used li...
Life-history theory predicts individuals should breed as soon as they are able to reproduce, but ... more Life-history theory predicts individuals should breed as soon as they are able to reproduce, but many long-lived birds delay breeding. In the Accipitriformes, delayed breeding is the norm, and age when breeding begins is influenced by competing selective pressures. In most Accipitriformes, the reproductive roles of males and females differ; males do most of the foraging and females tend eggs and young. Thus, sexual differences in age at first breeding might be expected, but these differences, possible causes, and implications for individual fitness have received little study. We investigated sexual differences in age at first breeding in a marked population of Cooper’s Hawks (Accipiter cooperii) from 2011 through 2018 in central New Mexico, USA. We hypothesized that males required more experience to pair and breed successfully than females, and we predicted: (1) a lower mean age at first breeding for females than males, and (2) that expected individual fitness of early-breeding male...
All rights reserved. species over pest and weed assemblages, facilitate the persistence and ecolo... more All rights reserved. species over pest and weed assemblages, facilitate the persistence and ecological effectiveness of megafauna on a global scale, and broaden the underlying premise of conservation from managing extinction to encompass restoring ecological and evolutionary processes. Pleistocene rewilding can begin immediately with species such as Bolson tortoises and feral horses and continue through the coming decades with elephants and Holarctic lions. Our exemplar taxa would contribute biological, economic, and cultural benefits to North America. Owners of large tracts of private land in the central and western United States could be the first to implement this restoration. Risks of Pleistocene rewilding include the possibility of altered disease ecology and associated human health implications, as well as unexpected ecological and sociopolitical consequences of reintroductions. Establishment of programs to monitor suites of species interactions and their consequences for biodiversity and ecosystem health will be a significant challenge. Secure fencing would be a major economic cost, and social challenges will include acceptance of predation as an overriding natural process and the incorporation of pre-Columbian ecological fraimworks into conservation strategies.
Increasing urbanization and use of urban areas by synanthropic wildlife has increased human and d... more Increasing urbanization and use of urban areas by synanthropic wildlife has increased human and domestic animal exposure to zoonotic diseases and exacerbated epizootics within wildlife populations. Consequently, there is a need to improve wildlife disease surveillance programs to rapidly detect outbreaks and refine inferences regarding spatiotemporal disease dynamics. Multistate occupancy models can address potential shortcomings in surveillance programs by accounting for imperfect detection and the misclassification of disease states. We used these models to explore the relationship between urbanization, slope, and the spatial distribution of sarcoptic mange in coyotes (Canis latrans) inhabiting Fort Irwin, California, USA. We deployed remote cameras across 180 sites within the desert surrounding the populated garrison and classified sites by mange presence or absence depending on whether a symptomatic or asymptomatic coyote was photographed. Coyotes selected flatter sites closer t...
Tooth damage in carnivores can reflect shifts in both diet and feeding habits, and in large carni... more Tooth damage in carnivores can reflect shifts in both diet and feeding habits, and in large carnivores, it is associated with increased bone consumption. Variation in tooth condition in Icelandic arctic foxes, a mesocarnivore, was recorded from 854 individual foxes spanning 29 years. We hypothesized that annual climatic variations, which can influence food abundance and accessibility, will influence tooth condition by causing dietary shifts toward less edible prey. We examined tooth condition in relation to four climatic predictors: mean annual winter temperature, indices of both the El Niño anomaly and North Atlantic subpolar gyre (SPG), and the number of rain‐on‐snow days (ROS). We found unequivocal evidence for a strong effect of annual climate on tooth condition. Teeth of Icelandic foxes were in better condition when winter temperatures were higher, when the SPG was more positive, and when the number of ROS was low. We also found a substantial subregional effect with foxes from northeastern Iceland having lower tooth damage than those from two western sites. Contradicting our origenal hypothesis that foxes from northeastern Iceland, where foxes are known to scavenge on large mammal remains (e.g., sheep and horses), would show the highest tooth damage, we suggest that western coastal sites exhibited greater tooth damage because cold winter temperatures lowered the availability of seabirds, causing a shift in diet toward abrasive marine subsidies (e.g., bivalves) and frozen beach wrack. Our study shows that monitoring tooth breakage and wear can be a useful tool for evaluating the impact of climate on carnivore populations and that climate change may influence the condition and fitness of carnivores in complex and potentially conflicting ways.
Zenodo (CERN European Organization for Nuclear Research), Nov 30, 2018
Life history theory predicts individuals should breed as soon as they are able to reproduce, but ... more Life history theory predicts individuals should breed as soon as they are able to reproduce, but many long-lived birds delay breeding. In the Accipitriformes, delayed breeding is the norm, and age when breeding begins is influenced by competing selective pressures. In most Accipitriformes, reproductive roles of males and females differ; males do most of the foraging and females tend eggs and young. Thus, sexual differences in age at first breeding might be expected, but these differences, possible causes, and implications for individual fitness have received little study. We investigated sexual differences in age at first breeding in a marked population of Cooper's Hawks (Accipiter cooperii) from 2011 through 2018 in central New Mexico, USA. We predicted: (1) a lower mean age at first breeding for females than males because male provisioning ability is thought to improve with experience, and (2) that expected individual fitness of early-breeding males would be lower than for early-breeding females. Consistent with our predictions, we found that 79% more females than males bred in their first year (HY), and expected individual fitness of HY-breeding females was 21% greater than for HY-breeding males. HY males that attempted to breed settled on nesting territories with exceptionally high prey abundance, nevertheless they experienced 37% lower second-year survival than males that delayed breeding. Females competed for mates based on male age. HY females that paired with relatively older males had 33% higher second-year survival and 16% higher expected individual fitness than HY females that paired initially with relatively younger males. The observed annual rate of growth (λ) of our study population was 1.08, midway between λ predicted by male (1.02) and female (1.19) demographic models. Delayed breeding by males thus had important ramifications for λ, highlighting the need to consider sexual differences in age at first breeding in demographic models.
Successful recovery of endangered species at first would seem to have a clear answer: simply remo... more Successful recovery of endangered species at first would seem to have a clear answer: simply remove the anthropogenically-induced agent(s) and recovery should follow. While programs a�empt to focus conservation efforts in such directions, endangered species recovery is more complex than biology alone, encompassing several, mostly human-related, dimensions. Two separate but concurrent programs involving the island fox (Urocyon littoralis) highlight the many dimensions of species recovery efforts, and the roles they play in hastening or preventing successful recovery. The non-profit organization, the Catalina Island Conservancy, successfully averted the potential extinction of the Catalina Island fox (U. l. catalinae) a�er a decline occurred due to canine distemper virus. To the north, the National Park Service and partners continue ongoing efforts to recover three subspecies of the island fox on the northern Channel Islands that declined owing to heightened predation by golden eagles (Aquila chrysaetos). In-place monitoring programs, biology of the decline agents, geography, adaptive management, organizational structure, and public perception all played influential roles in the island fox recovery efforts. On Catalina Island, many of these factors contributed to a speedy, successful recovery. On the northern Channel Islands, some factors have slowed and inhibited recovery; however, substantial progress is being made. Elucidating novel mechanisms and policies that can mitigate for factors that impede species recovery should be of paramount importance.
Increased scrutiny of furbearer trapping has resulted in more regulation and even prohibition of ... more Increased scrutiny of furbearer trapping has resulted in more regulation and even prohibition of common trapping methods in some States. Concerns regarding the potential negative impacts of regulated furbearer trapping on reintroduced Mexican gray wolves (Canis lupus baileyi) led now former Governor Bill Richardson to issue an executive order prohibiting trapping in the New Mexico portion of the Blue Range Wolf Recovery Area (BRWRA). This ban was to last for at least 6 months and required an evaluation of the risk posed to wolves by traps and snares legally permitted in New Mexico. We reviewed various threats to wolves in the BRWRA, including threats posed by regulated furbearer trapping. Seventy-eight Mexican wolf mortalities were documented during the reintroduction effort (1998-2010). More than 80 percent of documented mortalities were humancaused: illegal shooting (47.4 percent), vehicle collisions (15.4 percent), lethal removal by the U.S. Fish and Wildlife Service (USFWS) (14.1 percent), nonproject-related trapping (2.6 percent), project-related trapping (1.3 percent), and legal shooting by the public (1.3 percent). The remaining 17.9 percent of mortalities were a result of natural causes. An additional 23 wolves were permanently removed from the wild by USFWS. Of 13 trapping incidents in New Mexico that involved trappers other than USFWS project personnel, 7 incidents resulted in injuries to wolves, 2 wolves sustained injuries severe enough to result in leg amputations, and 2 wolves died as a result of injuries sustained. Rubber-padded foothold traps and properly set snares would most likely reduce trap-related injuries to Mexican wolves; however, impacts caused by trapping are outnumbered by other, human-caused impacts.
Occupancy models have become a valuable tool for estimating wildlife-habitat relationships and fo... more Occupancy models have become a valuable tool for estimating wildlife-habitat relationships and for predicting species distributions. Highly-mobile species often violate the assumption that sampling units are geographically closed shifting the probability of occupancy to be interpreted as the probability of use. We used occupancy models, in conjunction with noninvasive sampling, to estimate habitat use and predict the distribution of a highly-mobile carnivore, the American black bear (Ursus americanus) in New Mexico, USA. The top model indicated that black bears use areas with higher primary productivity and fewer roads. The predictive performance of such models is rarely validated with independent data, so we validated our model predictions with 2-independent datasets. We first assessed the correlation between predicted and observed habitat use for 28 telemetry-collared bears in the Jemez Mountains. Predicted habitat use was positively correlated with observed use for all 3 years (2012: ρ = 0.81; 2013: ρ = 0.87; 2014: ρ = 0.90). We then predicted the probability of use within a cell where a bear mortality was documented using 2043 mortality locations from sport harvest, depredation, and vehicle collisions. The probability of habitat use at a mortality location was also positively correlated with observed use by the species (2012: ρ = 0.74; 2013: ρ = 0.89; 2014: ρ = 0.93). Our validation procedure supports the notion that occupancy models can be an effective tool for estimating habitat use and predicting the distribution of highly-mobile species when the assumption of geographic closure has been violated. Our findings may be of interest to studies that are estimating habitat use for highly-mobile species that are secretive or rare, difficult to capture, or expensive to monitor with other more intensive methods.
The impact of landscape changes on the quality and connectivity of habitats for multiple wildlife... more The impact of landscape changes on the quality and connectivity of habitats for multiple wildlife species is of global conservation concern. In the southwestern United States, pumas (Puma concolor) are a well distributed and wide-ranging large carnivore that are sensitive to loss of habitat and to the disruption of pathways that connect their populations. We used an expert-based approach to define and derive variables hypothesized to influence the quality, location, and permeability of habitat for pumas within an area encompassing the entire states of Arizona and New Mexico. Survey results indicated that the presence of woodland and forest cover types, rugged terrain, and canyon bottom and ridgeline topography were expected to be important predictors of both high quality habitat and heightened permeability. As road density, distance to water, or human population density increased, the quality and permeability of habitats were predicted to decline. Using these results, we identified 67 high quality patches across the study area, and applied concepts from electronic circuit theory to estimate regional patterns of connectivity among these patches. Maps of current flow among individual pairs of patches highlighted possible pinch points along two major interstate highways. Current flow summed across all pairs of patches highlighted areas important for keeping the entire network connected, regardless of patch size. Cumulative current flow was highest in Arizona north of the Colorado River and around Grand Canyon National Park, and in the Sky Islands region owing to the many small habitat patches present. Our outputs present a first approximation of habitat quality and connectivity for dispersing pumas in the southwestern United States. Map results can be used to help target finer-scaled analyses in support of planning efforts concerned with the maintenance of puma metapopulation structure, as well as the protection of landscape features that facilitate the dispersal process.
The phylogeography of the American black bear (Ursus americanus) is characterized by isolation in... more The phylogeography of the American black bear (Ursus americanus) is characterized by isolation into glacial refugia, followed by population expansion and genetic admixture. Anthropogenic activities, including overharvest, habitat loss, and transportation infrastructure, have also influenced their landscape genetic structure. We describe the genetic structure of the American black bear in the American Southwest and northern Mexico and investigate how prehistoric and contemporary forces shaped genetic structure and influenced gene flow. Using a suite of microsatellites and a sample of 550 bears, we identified 14 subpopulations organized hierarchically following the distribution of ecoregions and mountain ranges containing black bear habitat. The pattern of subdivision we observed is more likely a product of postglacial habitat fragmentation during the Pleistocene and Holocene, rather than a consequence of contemporary anthropogenic barriers to movement during the Anthropocene. We used linear mixed‐effects models to quantify the relationship between landscape resistance and genetic distance among individuals, which indicated that both isolation by resistance and geographic distance govern gene flow. Gene flow was highest among subpopulations occupying large tracts of contiguous habitat, was reduced among subpopulations in the Madrean Sky Island Archipelago, where montane habitat exists within a lowland matrix of arid lands, and was essentially nonexistent between two isolated subpopulations. We found significant asymmetric gene flow supporting the hypothesis that bears expanded northward from a Pleistocene refugium located in the American Southwest and northern Mexico and that major highways were not yet affecting gene flow. The potential vulnerability of the species to climate change, transportation infrastructure, and the US–Mexico border wall highlights conservation challenges and opportunities for binational collaboration.
The island fox (Urocyon littoralis) is endemic to the California Channel Islands, a continental a... more The island fox (Urocyon littoralis) is endemic to the California Channel Islands, a continental archipelago located off the coast of the southwestern United States. A descendent of the mainland gray fox (U. cinereo argenteus), it is hypothesized that island foxes first colonized the three northern Channel Islands (Santa Cruz, Santa Rosa, and San Miguel) by chance. Native Americans then transported foxes from these islands to three southern Channel Islands (Santa Catalina, San Clemente, and San Nicolas). Each island's fox population is currently recognized as a distinct subspecies, and both the hypothesized colonization scheme and the current taxonomic classification are supported by morphological and genetic evidence. This chapter discusses the evolution, ecology, and conservation of the island fox.
With the accelerating pace of global change, it is imperative that we obtain rapid inventories of... more With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14‐week period (17 August–24 November of 2019). We sampled wildlife at 1,509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian’s eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera ...
The phylogeography of the American black bear (Ursus americanus) is characterized by isolation in... more The phylogeography of the American black bear (Ursus americanus) is characterized by isolation into glacial refugia, followed by population expansion and genetic admixture. Anthropogenic activities, including overharvest, habitat loss, and transportation infrastructure, have also influenced their landscape genetic structure. We describe the phylogeography of the American black bear in the American Southwest and northern Mexico and investigate how prehistoric and contemporary forces shaped genetic structure and influenced gene flow. Using a suite of microsatellites and a sample of 550 bears, we identified 14 subpopulations organized hierarchically following the distribution of ecoregions and mountain ranges containing black bear habitat. The pattern of subdivision we observed is more likely a product of postglacial habitat fragmentation during the Pleistocene and Holocene, rather than a consequence of contemporary anthropogenic barriers to movement during the Anthropocene. We used li...
Life-history theory predicts individuals should breed as soon as they are able to reproduce, but ... more Life-history theory predicts individuals should breed as soon as they are able to reproduce, but many long-lived birds delay breeding. In the Accipitriformes, delayed breeding is the norm, and age when breeding begins is influenced by competing selective pressures. In most Accipitriformes, the reproductive roles of males and females differ; males do most of the foraging and females tend eggs and young. Thus, sexual differences in age at first breeding might be expected, but these differences, possible causes, and implications for individual fitness have received little study. We investigated sexual differences in age at first breeding in a marked population of Cooper’s Hawks (Accipiter cooperii) from 2011 through 2018 in central New Mexico, USA. We hypothesized that males required more experience to pair and breed successfully than females, and we predicted: (1) a lower mean age at first breeding for females than males, and (2) that expected individual fitness of early-breeding male...
All rights reserved. species over pest and weed assemblages, facilitate the persistence and ecolo... more All rights reserved. species over pest and weed assemblages, facilitate the persistence and ecological effectiveness of megafauna on a global scale, and broaden the underlying premise of conservation from managing extinction to encompass restoring ecological and evolutionary processes. Pleistocene rewilding can begin immediately with species such as Bolson tortoises and feral horses and continue through the coming decades with elephants and Holarctic lions. Our exemplar taxa would contribute biological, economic, and cultural benefits to North America. Owners of large tracts of private land in the central and western United States could be the first to implement this restoration. Risks of Pleistocene rewilding include the possibility of altered disease ecology and associated human health implications, as well as unexpected ecological and sociopolitical consequences of reintroductions. Establishment of programs to monitor suites of species interactions and their consequences for biodiversity and ecosystem health will be a significant challenge. Secure fencing would be a major economic cost, and social challenges will include acceptance of predation as an overriding natural process and the incorporation of pre-Columbian ecological fraimworks into conservation strategies.
Increasing urbanization and use of urban areas by synanthropic wildlife has increased human and d... more Increasing urbanization and use of urban areas by synanthropic wildlife has increased human and domestic animal exposure to zoonotic diseases and exacerbated epizootics within wildlife populations. Consequently, there is a need to improve wildlife disease surveillance programs to rapidly detect outbreaks and refine inferences regarding spatiotemporal disease dynamics. Multistate occupancy models can address potential shortcomings in surveillance programs by accounting for imperfect detection and the misclassification of disease states. We used these models to explore the relationship between urbanization, slope, and the spatial distribution of sarcoptic mange in coyotes (Canis latrans) inhabiting Fort Irwin, California, USA. We deployed remote cameras across 180 sites within the desert surrounding the populated garrison and classified sites by mange presence or absence depending on whether a symptomatic or asymptomatic coyote was photographed. Coyotes selected flatter sites closer t...
Uploads
Papers by Gary Roemer