The ecology and behaviour of pumas (Puma concolor) in northern California, U.S.A.

Abstract

Large carnivores are important components of many ecosystems and play an integral role in determining the composition and structure of ecological communities. The influences of pumas (Puma concolor) on other species, including prey and competitors, vary across their range and among individuals. I used novel methodologies, including intensive real-time GPS investigations of potential kill sites using ARGOS satellite collars, and motion-triggered video cameras to study the intra- and inter-specific interactions of pumas and understand their influences on ecological communities. Results from my dissertation support previous findings that pumas play an integral role in shaping their respective ecosystem, but that pumas are also influenced substantially by their local environment. Overall, my dissertation highlights the importance of understanding intra- and inter-specific interactions of large carnivores when attempting to understand their influences on ecological communities. I tested whether pumas exhibited sexual variation in their use of communication behaviours at community scrape areas, and what factors influenced their mating strategies. I found that males more frequently exhibited and spent longer durations on ‘producing’ behaviours (scraping and body rubbing), while females more frequently exhibited and spent longer durations on ‘consuming’ behaviours (olfactory investigation and flehmen response behaviours). This suggests that male reproductive strategy is based on advertisement for possible mates, while female reproductive strategy is based on assessment of potential mates. Pumas also exhibited sexual variation in their patterns of visitation. Males were regular visitors, while females were irregular visitors whose visitation cycles were apparently correlated with oestrus. Mate selection by females was complex and based on multiple cues, the two most important of which were the visitation rate and mass of males. The frequency of male visits and the display of some behaviours were influenced most by visits from female pumas, but were also influenced by visits from competing males. I used real-time and fine-scale GPS location data to find prey killed by individual pumas, and analysed seasonal patterns to understand local influences on puma behaviour and feeding ecology. I found that black-tailed deer (Odocoileus hemionus columbianus) were the main prey of pumas, constituting 98.6% of their diet by mass, and that the elevations at which pumas killed black-tailed deer correlated significantly with seasonal elevations used by black-tailed deer. I found pumas had relatively high ungulate kill rates ( ̅ = 1.07 ungulates/week, and ̅ = 5.78 kg/day), and that kill rates in ungulates/week varied among seasons and were highest in summer and autumn. Importantly, the handling times of black-tailed deer >1 year old showed an inverse seasonal relationship with kill rates in ungulates/week, and the lower handling times may have been due to black bear kleptoparasitism. These findings suggest that puma feeding ecology can be strongly influenced by seasonal behaviour of their prey and dominant scavengers. Given the potential for large carnivores to influence scavengers, I studied the influences of both pumas and black bears on the scavenger community. I found that pumas and black bears were a source of limitation for scavengers, both on the species richness and sum feeding times of the scavenger community, as well as the occurrence, total feeding times, and mean feeding bout durations of scavenger species. However, pumas had some positive influences, for example they facilitated the acquisition of carrion by scavengers, and they apparently initiated a cascading pattern that led to an increase in the acquisition of carrion by small carnivores. In contrast, black bears, as dominant scavengers, monopolized carrion resources and substantially limited the acquisition of carrion by other scavengers, and in fact they had larger limitations for scavengers than pumas as top-level predators. The influences on carrion acquisition suggest that large carnivores have important influences on the scavenger community, and their influences could be a mechanism for the effects large carnivores have on community composition.