UC Santa Cruz

Members of the family Canidae (e.g. foxes, coyotes, wolves, dogs) are among nature’s most elite endurance athletes. To support their cursorial lifestyles, large canids achieve aerobic metabolic rates nearly three times those of similarly sized mammals and can play crucial roles in the structure and function of ecosystems. Fortunately, the field of animal energetics unites physiology and ecology by providing a common currency that links the performance of individuals to their interactions with the surrounding environment. Yet quantifying animal activity patterns and energy demand in the wild has been historically challenging, particularly for wide-ranging large canids. As a result, we are often left with in an incomplete understanding of the interplay between physiological and environmental factors driving movement, foraging, and ultimately population persistence in these species. In this dissertation, I present a laboratory-to-field approach for integrating behavioral and physiological data to forecast the resource demands required for survival by these highly mobile predators. In my first data chapter (Chapter 2), I utilize biomechanics, kinematics, and energetics to quantify the effects of domestication and selective breeding on locomotor gait and economy in canids, using several dog breeds as a model. I find that in addition to their close genetic and morphological ties to gray wolves, northern breed dogs have retained highly cursorial kinematic and physiological traits that promote economical movement across the landscape. Taking these lab-derived parameters into the field, in Chapter 3 I investigate the impact of maximal performance parameters (e.g., speed, acceleration, maneuverability) on real-time chase outcomes of large canids and felids. Using hounds (as a proxy for wolves) to recapture pumas, I reconstruct pursuit and evasion tactics by each species to identify both physiological constraints and adaptive strategies that ultimately facilitate the coexistence of these species in the wild. Finally, in Chapter 4 I measure free-ranging travel patterns and their costs in Alaskan wolves over 8 months after calibrating accelerometer- and GPS (Global Positioning System)-equipped collars on captive conspecifics. I demonstrate that activity and energy expenditure in wolves is highly varied across the Denali National Park & Preserve, reflecting regional habitat and prey heterogeneity. Ultimately, these chapters provide novel insight into how the elevated energetic demands of canids influence their ability to structure the ecological communities they inhabit. Although the drivers of activity and predation by canids are complex, the results of this work demonstrate the capability of animal-born technology to identify instantaneous to seasonal-scale patterns in energy expenditure and its role in shaping moving ecology and species interactions.