| Density estimation... | Density estimation... | Article | Abundance
Density
Demographic closure
Sampling |
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Type:Article Subject:Abundance
Density
Demographic closure
Sampling |
Description:Abundance is commonly sought after as a state variable for the study of populations. However, density (number of animals per unit area) can be a more meaningful metric because it casts the state of a population into a common currency. For example, using closed capture models from Chapter 14, we estimate 500 animals at site A and 200 animals at site B. Thus one conclusion we may reach is that habitat management at site A has positively impacted the population there compared to site B. However, if we know site A is 250 hectares and B is 100 hectares, then we realize that each has 2.0 animals/hectare. That is, on a relative scale, the different management scheme at A had no effect compared to site B. Conversely, we may estimate abundance at 2 sites to be similar and conclude management actions, or habitat types, or harvest regulations, etc. are having a similar impact, but if the sites are different sizes, then the impacts are actually quite different on a relative scale and our conclusion is erroneous. Thus, while abundance can be a useful metric, estimating density can be helpful as well. [show more]
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| Habitat and herbivore density: response of mule deer to habitat management | Habitat and herbivore density: response of mule deer to habitat management | Article | Abundance
Colorado
Environmental change
Habitat management
Mark–resight
Mule deer
<em>Odocoileus hemionus</em>
Resighting probabilities |
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Type:Article Subject:Abundance
Colorado
Environmental change
Habitat management
Mark–resight
Mule deer
<em>Odocoileus hemionus</em>
Resighting probabilities |
Description:The suite of demands competing for wildlife management funds necessitates direct assessment of management decisions, especially when these decisions have direct costs, as well as tangible opportunity costs. We conducted a mark–resight study that estimated mule deer (Odocoileus hemionus) density across multiple study units in southwest Colorado that had been exposed to different intensities of habitat treatments. Our treatments were comprised of common habitat management techniques including hydro-axe and roller-chopper disturbances as well chemical control of weeds and reseeding with desirable mule deer browse species. Reference study units received no habitat management treatments. Total deer densities varied between 20–84 deer/km2 in southern study units and 4–12 deer/km2 in northern study units. We did not observe a consistent pattern of higher deer density on advanced treatment study units despite it being the primary hypothesis of the study. We observed a wide range of variation in deer density among years. Resighting probabilities (range 0.070–0.567) were best modeled as an interactive function of study unit and year, although sampling method was also influential. We recommend that if population density is to be used as a population response variable, it be used in tandem with other, possibly more sensitive parameters such as overwinter survival or late winter body condition. [show more]
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| Less invasive monitoring of cougars in Colorado's Front Range | Less invasive monitoring of cougars in Colorado's Front Range | Article | Abundance
Auditory
Cougar
Mark–resight
Noninvasive
Predator calls
<em>Puma concolor</em> |
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Type:Article Subject:Abundance
Auditory
Cougar
Mark–resight
Noninvasive
Predator calls
<em>Puma concolor</em> |
Description:From 2014 to 2016, in the Front Range of Colorado, USA, we assessed noninvasive approaches to sampling cougar (Puma concolor) populations in an attempt to provide a new method that would be less field intensive, less expensive, and could be applied over large spatial extents compared with current methods. We assessed the use of predator calls to lure cougars to a site with remote camera traps for detection and also evaluated hair snags at sites to noninvasively identify individual animals. Predator calls effectively attracted cougars to specific sites with an average of 82 unique photographic detections of cougars per survey year (0.03 detections/trap-night). However, obtaining hair samples from these animals was less effective because animals did not always pass through hair snags and ability to uniquely identify individuals by genotype was poor. We evaluated different approaches to estimating cougar density and found mark–resight to be a viable option in our study system. Mark–resight density estimate after correcting for partial use of the sampling area by cougars was 4.1 cougars/100 km2 (95% CI = 2.4, 5.8). Our results indicate that combining methods of noninvasive genetic sampling and auditory calls to monitor cougar populations can provide reliable density estimates over large geographic areas and areas with significant amounts of inaccessible private lands. [show more]
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| Landscape and anthropogenic features influence the use of auditory vigilance by mule deer | Landscape and anthropogenic features influence the use of auditory vigilance by mule deer | Article | Acoustic ecology
<em>Odocoileus hemionus</em>
Vigilance
Mule deer |
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Type:Article Subject:Acoustic ecology
<em>Odocoileus hemionus</em>
Vigilance
Mule deer |
Description:While visual forms of vigilance behavior and their relationship with predation risk have been broadly examined, animals also employ other vigilance modalities such as auditory vigilance by listening for the acoustic cues of predators. Similar to the tradeoffs associated with visual vigilance, auditory behavior potentially structures the energy budgets and behavior of animals. The cryptic nature of auditory vigilance makes it difficult to study, but on-animal acoustical monitoring has rapidly advanced our ability to investigate behaviors and conditions related to sound. We utilized this technique to investigate the ways external stimuli in an active natural gas development field affect periodic pausing by mule deer (Odocoileus hemionus) within bouts of rumination-based mastication. To better understand the ecological properties that structure this behavior, we investigate spatial and temporal factors related to these pauses to determine if results are consistent with our hypothesis that pausing is used for auditory vigilance. We found that deer paused more when in forested cover and at night, where visual vigilance was likely to be less effective. Additionally, deer paused more in areas of moderate background sound levels, though responses to anthropogenic features were less clear. Our results suggest that pauses during rumination represent a form of auditory vigilance that is responsive to landscape variables. Further exploration of this behavior can facilitate a more holistic understanding of risk perception and the costs associated with vigilance behavior. [show more]
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| On-animal acoustic monitoring provides insight to ungulate foraging behavior | On-animal acoustic monitoring provides insight to ungulate foraging behavior | Article
| Acoustic monitoring
Bayesian hierarchical model
Colorado
Foraging behavior
Herbivore foraging
Mule deer
<em>Odocoileus hemionus</em>
Spatial ecology |
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Type:Article
Subject:Acoustic monitoring
Bayesian hierarchical model
Colorado
Foraging behavior
Herbivore foraging
Mule deer
<em>Odocoileus hemionus</em>
Spatial ecology |
Description:Foraging behavior underpins many ecological processes; however, robust assessments of this behavior for free-ranging animals are rare due to limitations to direct observations. We leveraged acoustic monitoring and GPS tracking to assess the factors influencing foraging behavior of mule deer (Odocoileus hemionus). We deployed custom-built acoustic collars with GPS radiocollars on mule deer to measure location-specific foraging. We quantified individual bites and steps taken by deer, and quantified two metrics of foraging behavior: the number of bites taken per step and the number of bites taken per unit time, which relate to foraging intensity and efficiency. We fit statistical models to these metrics to examine the individual, environmental, and anthropogenic factors influencing foraging. Deer in poorer body condition took more bites per step and per minute and foraged for longer irrespective of landscape properties. Other patterns varied seasonally with major changes in deer condition. In December, when deer were in better condition, they took fewer bites per step and more bites per minute. Deer also foraged more intensely and efficiently in areas of greater forage availability and greater movement costs. During March, when deer were in poorer condition, foraging was not influenced by landscape features. Anthropogenic factors weakly structured foraging behavior in December with no relationship in March. Most research on animal foraging is interpreted under the framework of optimal foraging theory. Departures from predictions developed under this framework provide insight to unrecognized factors influencing the evolution of foraging. Our results only conformed to our predictions when deer were in better condition and ecological conditions were declining, suggesting foraging strategies were state-dependent. These results advance our understanding of foraging patterns in wild animals and hig [show more]
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| Local climate determines vulnerability to camouflage mismatch in snowshoe hares | Local climate determines vulnerability to camouflage mismatch in snowshoe hares | Article | Adaptation
Camouflage mismatch
Climate change
Latitudinal gradient
Phenological mismatch
Phenotypic plasticity
Range edge
Snow
Snowshoe hares |
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Type:Article Subject:Adaptation
Camouflage mismatch
Climate change
Latitudinal gradient
Phenological mismatch
Phenotypic plasticity
Range edge
Snow
Snowshoe hares |
Description: Aim Phenological mismatches, when life-events become mistimed with optimal environmental conditions, have become increasingly common under climate change. Population-level susceptibility to mismatches depends on how phenology and phenotypic plasticity vary across a species’ distributional range. Here, we quantify the environmental drivers of colour moult phenology, phenotypic plasticity, and the extent of phenological mismatch in seasonal camouflage to assess vulnerability to mismatch in a common North American mammal.
LocationNorth America.
Time period2010–2017.
Major taxa studiedSnowshoe hare (Lepus americanus).
MethodsWe used > 5,500 by-catch photographs of snowshoe hares from 448 remote camera trap sites at three independent study areas. To quantify moult phenology and phenotypic plasticity, we used multinomial logistic regression models that incorporated geospatial and high-resolution climate data. We estimated occurrence of camouflage mismatch between hares’ coat colour and the presence and absence of snow over 7 years of monitoring.
ResultsSpatial and temporal variation in moult phenology depended on local climate conditions more so than on latitude. First, hares in colder, snowier areas moulted earlier in the fall and later in the spring. Next, hares exhibited phenotypic plasticity in moult phenology in response to annual variation in temperature and snow duration, especially in the spring. Finally, the occurrence of camouflage mismatch varied in space and time; white hares on dark, snowless background occurred primarily during low-snow years in regions characterized by shallow, short-lasting snowpack.
Main conclusionsLong-term climate and annual variation in snow and temperature determine coat colour moult phenology in snowshoe hares. In most areas, climate change leads to shorter snow seasons, but the occurrence of camouflage mismatch varies across the species’ range. Our results underscore the population-specific susceptibility to climate change-induced stressors and the necessity to understand this variation to prioritize the populations most vulnerable under global environmental change. [show more]
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| The cascading effects of human food on hibernation and cellular aging in free-ranging black bears | The cascading effects of human food on hibernation and cellular aging in free-ranging black bears | Article | Adaptations
Senescence
Demography
Hibernation
Aging
Bears
Food |
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Type:Article Subject:Adaptations
Senescence
Demography
Hibernation
Aging
Bears
Food |
Description:Human foods have become a pervasive subsidy in many landscapes, and can dramatically alter wildlife behavior, physiology, and demography. While such subsidies can enhance wildlife condition, they can also result in unintended negative consequences on individuals and populations. Seasonal hibernators possess a remarkable suite of adaptations that increase survival and longevity in the face of resource and energetic limitations. Recent work has suggested hibernation may also slow the process of senescence, or cellular aging. We investigated how use of human foods influences hibernation, and subsequently cellular aging, in a large-bodied hibernator, black bears (Ursus americanus). We quantified relative telomere length, a molecular marker for cellular age, and compared lengths in adult female bears longitudinally sampled over multiple seasons. We found that bears that foraged more on human foods hibernated for shorter periods of time. Furthermore, bears that hibernated for shorter periods of time experienced accelerated telomere attrition. Together these results suggest that although hibernation may ameliorate cellular aging, foraging on human food subsidies could counteract this process by shortening hibernation. Our findings highlight how human food subsidies can indirectly influence changes in aging at the molecular level. [show more]
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| A call to action: standardizing white-tailed deer harvest data in the Midwestern United States and implications for quantitative analysis and disease management | A call to action: standardizing white-tailed deer harvest data in the Midwestern United States and implications for quantitative analysis and disease management | Article | Adaptive management
Chronic wasting disease (CWD)
Conservation
Hunting |
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Type:Article Subject:Adaptive management
Chronic wasting disease (CWD)
Conservation
Hunting |
Description:Recreational hunting has been the dominant game management and conservation mechanism in the United States for the past century. However, there are numerous modern-day issues that reduce the viability and efficacy of hunting-based management, such as fewer hunters, overabundant wildlife populations, limited access, and emerging infectious diseases in wildlife. Quantifying the drivers of recreational harvest by hunters could inform potential management actions to address these issues, but this is seldom comprehensively accomplished because data collection practices limit some analytical applications (e.g., differing spatial scales of harvest regulations and harvest data). Additionally, managing large-scale issues, such as infectious diseases, requires collaborations across management agencies, which is challenging or impossible if data are not standardized. Here we discuss modern issues with the prevailing wildlife management framework in the United States from an analytical point of view with a case study of white-tailed deer (Odocoileus virginianus) in the Midwest. We have four aims: (1) describe the interrelated processes that comprise hunting and suggest improvements to current data collections systems, (2) summarize data collection systems employed by state wildlife management agencies in the Midwestern United States and discuss potential for largescale data standardization, (3) assess how aims 1 and 2 influence managing infectious diseases in hunted wildlife, and (4) suggest actionable steps to help guide data collection standards and management practices. To achieve these goals, Wisconsin Department of Natural Resources disseminated a questionnaire to state wildlife agencies (Illinois, Indiana, Iowa, Kentucky, Frontiers in Ecology and Evolution 01 frontiersin.org Brandell et al. 10.3389/fevo.2022.943411 Michigan, Minnesota, Missouri, Ohio, Wisconsin), and we report and compare their harvest management structures, data collection practices, and responses to chronic wasting disease. We hope our “call to action” encourages reevaluation, coordination, and improvement of harvest and management data collection practices with the goal of improving the analytical potential of these data. A deeper understanding of the strengths and deficiencies of our current management systems in relation to harvest and management data collection methods could benefit the future development of comprehensive and collaborative management and research initiatives (e.g., adaptive management) for wildlife and their diseases. [show more]
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Experimental evaluation of population trend and harvest composition in a Wyoming cougar population
| Experimental evaluation of population trend and harvest composition in a Wyoming cougar population
| Article | Adaptive management
Cougar
Exploitation
Population trend
<em>Puma concolor</em>
Sex–age composition |
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Type:Article Subject:Adaptive management
Cougar
Exploitation
Population trend
<em>Puma concolor</em>
Sex–age composition |
Description:Cougar (Puma concolor) management has been hindered by inability to identify population trends. We documented changes in sex and age of harvested cougars during an experimentally induced reduction in population size and subsequent recovery to better understand the relationship between sex-age composition and population trend in exploited populations. The cougar population in the Snowy Range, southeast Wyoming, was reduced by increased harvest (treatment phase) from 58 independent cougars (>1 year old) (90% C***l = 36–81) in the autumn of 1998 to 20 by the spring of 2000 (mean exploitation rate = 43%) and then increased to 46 by spring 2003 following 3 years of reduced harvests (mean exploitation rate = 18%). Pretreatment harvest composition was 63% subadults (1.0–2.5 years old), 23% adult males, and 14% adult females (2 seasons; n = 22). A reduction in subadult harvest, an initial increase followed by a reduction in adult male harvest, and a steady increase in adult female harvest characterized harvest composition trends during the treatment phase. Harvest composition was similar at high and low densities when harvest was light, but proportion of harvested subadult males increased at low density as they replaced adult males removed during the treatment period (high harvest). While sex ratio of harvested cougars alone appears of limited value in identifying population change, when combined with age class the 2 appear to provide an index to population change. Composition of the harvest can be applied to adaptively manage cougar populations where adequate sex and age data are collected from harvested animals. [show more]
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| Response of waterbirds to experimental disturbances | Response of waterbirds to experimental disturbances | Article | American avocet
American coot
Black-crowned night-heron
Colorado
Disturbance
Gadwall
Mallard
Recreation
Redhead
Ruddy duck
Snowy egret
Waterbirds
White-faced ibis |
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Type:Article Subject:American avocet
American coot
Black-crowned night-heron
Colorado
Disturbance
Gadwall
Mallard
Recreation
Redhead
Ruddy duck
Snowy egret
Waterbirds
White-faced ibis |
Description: Responses of waterbirds to experimental disturbances were studied from April 1984 to August 1985 at Russell Lakes State Wildlife Area in the San Luis Valley, Colorado. Black-crowned night-herons (Nycticorax nycticorax), snowy egrets (Egretta thula) and white-faced ibis (Plegadis chihi) were approached directly by a person on foot or in a motor vehicle. Mean (±SD) flushing distances for these species were 153±66, 93±43, and 95±48 m when approached on foot and 47±26, 57±27, and 54±27 m when approached in a motor vehicle. Reactions of American coots (Fulica americana), redheads (Aythya americana), ruddy ducks (O ura jamaicensis), mallards (Anas platyrhynchos), gadwalls (A. strepera) and American avocets (Recurviroslra americana) to disturbance were also quantified. Intensity of response was independent of agent of disturbances (i.e., person on foot or in vehicle) for all species. Disturbance reduced species diversity and abundance for up to one hour. American coots and avocets were only minimally impacted by the disturbance agents used. [show more]
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