Mastromonaco, Gabriela

Globally, fledglings of more than 50 seabird species are vulnerable to stranding in human settlements near their colonies as they leave their nests for the first time. This phenomenon has been attributed to attraction toward and disorientation by artificial light at night (ALAN). Grassroots rescue programs find more birds in illuminated locations than in dark ones, but it is unclear to what extent this pattern is driven by seabird versus rescuer behaviour. I studied behavioural responses to ALAN in stranding-prone Atlantic puffin (Fratercula arctica) and Leach's storm-petrel (Hydrobates leucorhous) fledglings and investigated detection probabilities of 3D-printed puffin fledgling decoys by rescuers. I hypothesized that seabird strandings are due to attraction toward ALAN; that post-stranding behaviour varies with taxon and lighting conditions; and that post-stranding behaviour (e.g., concealment) and lighting conditions drive variance in detection probability of stranded seabirds by rescuers. To address my first hypothesis, I alternately illuminated two beaches near a Newfoundland puffin colony and found significantly more puffin fledglings stranded when the beaches were illuminated than when they were dark, supporting the light attraction hypothesis. Stranded puffins similarly moved toward light over darkness in a Y-maze choice experiment and were less active under LED light than in darkness or under high-pressure sodium light, demonstrating a preference toward certain light conditions post-stranding. In contrast, storm-petrels predominantly avoided lit conditions in a Y-maze and were less active in darkness than under light. Further, when provided with a place to hide, more than half of storm-petrels concealed themselves when in light conditions versus none in darkness. To test my third hypothesis, I deployed puffin decoys and found that rescuers detected them more easily in higher light levels, in less concealed locations, and with increased search effort. My results support historical deductions that seabird fledgling strandings are caused by attraction toward artificial light but demonstrate that post-stranding behavioural responses to ALAN depend on species and light type, which may in turn affect detection probability by rescuers.

Author Keywords: artificial light, atlantic puffin, charadriiform, Leach's storm-petrel, light attraction, procellariiform

The influence of stress exposure on the body temperature of vertebrates has been known for nearly two-thousand years. While the proximate mechanisms supporting this phenomenon are well described, the ultimate mechanisms remain enigmatic. In this thesis, I propose a novel hypothesis which states that changes in body surface temperature (henceforth "surface temperature") following stress exposure occur to reduce energetic expenditure toward thermoregulation, thus freeing energy for use in the stress response (hereafter, the "Thermoprotective Hypothesis"). Using a paired experimental design, I first show that black-capped chickadees (Poecile atricapillus, Linnaeus, 1766) exposed to repeated stressors decrease their surface temperatures at low ambient temperatures, and increase their surface temperatures at high ambient temperatures relative to unstressed controls. These changes in surface temperature contribute to a relative reduction in heat loss in the cold, and a relative increase in heat dissipation in the warmth among stress-exposed individuals, thus reducing their energetic demands toward more costly thermoregulatory strategies. Next, I show that stress-induced changes in surface temperature are most pronounced in chickadees that experience naturally-occurring resource-restrictions, suggesting that this response occurs to balance allocation of energy among the stress response and thermoregulation (i.e. a true energetic trade-off ). Third, I show that the magnitudes of chronic, stress-induced changes in surface temperature are highly variable among, and highly consistent within, chickadees, therefore suggesting that this response could hold adaptive significance if such variation among individuals is heritable. Finally, using domestic pigeons (Columba livia domestica, Gmelin, 1789) as a model species, I show that stress-induced changes in surface temperature are highly pronounced at bare tissues with a critical role in thermoregulation for some avian species (the bill), when compared with responses at surrounding bare tissues (the eye region). Together, these findings strongly support the Thermoprotective Hypothesis and suggest that endotherms may trade energetic investment toward thermoregulation with that toward the stress response in resource-limiting environments.

Author Keywords: heat transfer, infrared thermography, stress physiology, surface temperature, thermoregulation, trade-off

Many facilities attempt to alleviate the risk of chronic stress in captivity by providing environmental enrichment shown to minimize behavioural disorders and stress in several species. One potential form of enrichment used in zoos is training animals to perform rides for guests, however, the effect of this activity on the welfare of individual animals has never been examined. I validated the use of saliva for assessing stress in dromedary camels (Camelus dromedarius) an animal commonly used for rides. I then measured variation in salivary cortisol in four male camels during animal rides for guests at the Toronto Zoo. The camels were sampled during the ride season (from June to August) using four treatments: 1) in their pasture, 2) at the ride area not performing rides, 3) performing a low number of rides (n=50/day) and 4) performing a high number of rides (n=150/day). Furthermore, samples were taken before and after the ride season for comparison. There was a significant difference between the post-ride season treatment and the three treatments involving guest presence during the ride season (ride area, low rides, high rides. This indicates that performing rides is not a stressful experience based on the stress metrics I used, and suggests that rides may be a form of enrichment for dromedary camels.

Author Keywords: ACTH challenge, animal welfare, camels, environmental enrichment, salivary cortisol, stress