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.