Considering the entire life history of a species is fundamental to developing effective conservation strategies. Decreasing populations of five-needle white pines may be leading to the decline of Clark's nutcrackers (Nucifraga columbiana). These birds are important seed dispersers for at least ten conifer species in the western U.S., including whitebark pine (Pinus albicaulis), an obligate mutualist of Clark's nutcrackers. For effective conservation of both Clark's nutcrackers and whitebark pine, it is essential to ensure stability of Clark's nutcracker populations. My objectives were to examine Clark's nutcracker breeding season home range size, territoriality, habitat selection, and foraging behavior in the southern Greater Yellowstone Ecosystem, a region where whitebark pine is declining. I radio-tracked Clark's nutcrackers in 2011, a population-wide nonbreeding year following a low whitebark pine cone crop, and 2012, a breeding year following a high cone crop. Results suggest Douglas-fir (Pseudotsuga menziesii) communities are important habitat for Clark's nutcrackers because they selected it for home ranges. In contrast, they did not select whitebark pine habitat. However, Clark's nutcrackers did adjust their use of whitebark pine habitat between years, suggesting that, in some springs, whitebark pine habitat may be used more than previously expected. Newly extracted Douglas-fir seeds were an important food source both years. On the other hand, cached seeds made up a relatively lower proportion of the diet in 2011, suggesting cached seeds are not a reliable spring food source. Land managers focus on restoring whitebark pine habitat with the assumption that Clark's nutcrackers will be available to continue seed dispersal. In the Greater Yellowstone Ecosystem, Clark's nutcracker populations may be more likely to be retained year-round when whitebark pine restoration efforts are located adjacent to Douglas-fir habitat. By extrapolation, whitebark pine restoration efforts in other regions may consider prioritizing restoration of whitebark pine stands near alternative seed sources.

In the face of widespread environmental change, understanding and promoting resilience and stability of plant-animal seed disperser mutualisms is key to effective conservation strategies. My two primary objectives were to (1) investigate the response of the keystone mutualism between whitebark pine (Pinus albicaulis) and Clark's nutcrackers (Nucifraga columbiana) to declining habitat in the Greater Yellowstone Ecosystem, and (2) suggest management strategies to help ensure persistence of Clark's nutcrackers, and their important seed dispersal function. Between 2009 and 2016, I studied Clark's nutcracker demography and behavioral plasticity by evaluating breeding ecology, space use, seasonal habitat selection and use, foraging ecology, and emigration, as a function of habitat quality and abundance. I carried out occupancy surveys, tracked individuals via radio and satellite, conducted behavioral observations, and monitored nests. Clark's nutcracker demography and behavior was intimately associated with whitebark pine habitat. Population-wide failure to breed followed low whitebark pine cone crops, and in breeding years, fledging success increased with whitebark pine abundance, but decreased in higher mortality stands. Clark's nutcracker occurrence was associated with both presence of cone-bearing whitebark pines, and landscape-scale abundance of the pines, suggesting conservation strategies should focus efforts at the landscape scale. The birds selected disproportionately high amounts of Douglas-fir (Pseudotsuga menziesii) habitat for their home range, and foraged heavily on Douglas-fir cones, suggesting that whitebark pine should be managed within a habitat mosaic with Douglas-fir. The Clark's nutcracker-whitebark pine mutualism appears functional in the region because birds were available to disperse seeds. However, it is unclear whether the mutualism is stable. Clark's nutcrackers are highly mobile facultative migrants, and the majority of radio- and satellite-tagged birds disappeared during both the 2012 high and 2015 moderate whitebark pine cone crops. Managing Clark's nutcrackers presents a complex conservation challenge, but I suggest promoting stability of Clark's nutcracker populations, and focusing on the metapopulation in particular, is necessary for effective whitebark pine conservation. In this dissertation, I conclude by outlining recommended management strategies and key research questions that still need to be answered, finishing with important considerations that should be taken into account when designing a conservation plan for plant-animal seed disperser mutualisms.

In the face of widespread environmental change, understanding and promoting resilience and stability of plant-animal seed disperser mutualisms is key to effective conservation strategies. My two primary objectives were to (1) investigate the response of the keystone mutualism between whitebark pine (Pinus albicaulis) and Clark's nutcrackers (Nucifraga columbiana) to declining habitat in the Greater Yellowstone Ecosystem, and (2) suggest management strategies to help ensure persistence of Clark?s nutcrackers, and their important seed dispersal function. Between 2009 and 2016, I studied Clark?s nutcracker demography and behavioral plasticity by evaluating breeding ecology, space use, seasonal habitat selection and use, foraging ecology, and emigration, as a function of habitat quality and abundance. I carried out occupancy surveys, tracked individuals via radio and satellite, conducted behavioral observations, and monitored nests. Clark?s nutcracker demography and behavior was intimately associated with whitebark pine habitat. Population-wide failure to breed followed low whitebark pine cone crops, and in breeding years, fledging success increased with whitebark pine abundance, but decreased in higher mortality stands. Clark?s nutcracker occurrence was associated with both presence of cone-bearing whitebark pines, and landscape-scale abundance of the pines, suggesting conservation strategies should focus efforts at the landscape scale. The birds selected disproportionately high amounts of Douglas-fir (Pseudotsuga menziesii) habitat for their home range, and foraged heavily on Douglas-fir cones, suggesting that whitebark pine should be managed within a habitat mosaic with Douglas-fir. The Clark?s nutcracker-whitebark pine mutualism appears functional in the region because birds were available to disperse seeds. However, it is unclear whether the mutualism is stable. Clark?s nutcrackers are highly mobile facultative migrants, and the majority of radio- and satellite-tagged birds disappeared during both the 2012 high and 2015 moderate whitebark pine cone crops. Managing Clark?s nutcrackers presents a complex conservation challenge, but I suggest promoting stability of Clark?s nutcracker populations, and focusing on the metapopulation in particular, is necessary for effective whitebark pine conservation. In this dissertation, I conclude by outlining recommended management strategies and key research questions that still need to be answered, finishing with important considerations that should be taken into account when designing a conservation plan for plant-animal seed disperser mutualisms.

In highly variable environments, conditions can be so stressful in some years that entire populations forgo reproduction in favor of higher likelihood of surviving to breed in future years. In two out of five years, Clark's nutcrackers (Nucifraga Columbiana) in the Greater Yellowstone Ecosystem exhibited population-wide failure to breed. Clark's nutcrackers at the study site experienced substantial interannual differences in food availability and weather conditions, and the two nonbreeding years corresponded with low whitebark pine (Pinus albicaulis) cone crops the previous autumn ([less than or equal to] an average of 8 ± 2 cones per tree versus [greater than or equal to] an average of 20 ± 2 cones per tree during breeding years) and high snowpack in early spring ([greater than or equal to] 61.2 ± 5.5 cm versus [less than or equal to] 51.9 ± 4.4 cm during breeding years). The average adult body condition index during the breeding season was significantly lower in 2011 (-1.5 ± 1.1), a nonbreeding year, as compared to 2012 (6.2 ± 2.0), a breeding year. The environmental cues available to the birds prior to breeding, specifically availability of cached whitebark pine seeds, may have allowed them to predict that breeding conditions would be poor, leading to the decision to skip breeding. Alternatively, the Clark's nutcrackers may have had such low body energy stores that they chose not to or were unable to breed. Breeding plasticity would allow Clark's nutcrackers to exploit an unpredictable environment. However, if large-scale mortality of whitebark pines is leading to an increase in the number of nonbreeding years, there could be serious population-level and ecosystem-wide consequences.

A beautifully illustrated survey of Yellowstone’s breathtaking birdlife, written by a team of renowned ornithologists and wildlife biologists Established in 1872, Yellowstone National Park is the oldest and arguably the most famous national park in North America, attracting millions of visitors each year. While many come to the park for its recreational activities, the wildlife of Yellowstone is just as alluring. This book brings together more than 30 leading experts to provide the first comprehensive survey of the natural history, science, and conservation of birds in Yellowstone. Covering most bird species breeding within the great park as well as the many migrants that pass through, Yellowstone’s Birds is a scientific tour de force and an essential resource for visitors to Yellowstone and bird lovers everywhere. Tallies more than 200 species, including migrants Describes the natural history, status, and latest science on the birds of Yellowstone Features fact-filled, easy-to-read chapters, informative sidebar essays, maps, infographics, and photos that present current science in an easily understood way Accompanied by videos by award-winning cinematographer Bob Landis Draws on a wealth of data on Yellowstone’s birds collected over many decades With contributions by many of today’s leading bird experts, this is a long-overdue survey of Yellowstone’s breathtaking avian fauna