This research intends to evaluate trophic interactions mediating the relationships of one of South America’s most outstanding native communities, including Andean condors (Vultur gryphus), pumas (Puma concolor), foxes (Lycalopex griseus and Lycalopex culpaeus), vicuñas (Vicugna vicugna) and guanacos (Lama guanicoe). Particularly, we are looking at the main components of condor, puma, and fox diets across southern Argentina to better understand how diet is mediated by pumas and humans. We are also investigating how resource availability and seasonality influences guanaco movements and habitat use.
Condor Foraging Ecology
One of the components of this research focuses on understanding the dynamics of diet in condor populations, who – as obligate scavengers – depend on the interaction of carnivores and their prey. We used a multifaceted analysis, based on pellet content, bulk stable isotope of molted feathers, and compound-specific stable isotopes analysis of amino acids to determine the proportion of different items in condor’s diet as well as the trophic positions of the community. We are comparing condor diet in geographical sites under different management scenarios in central Argentina to evaluate the importance of native wild camelids as food sources to condors. We also are disentangling the heterogeneity of the consumed carcasses by incorporating plants (from the gut), the carrion, and the embedded microbes into the condor diet. We expect to find sex-based differences in their dietary habits, given the hierarchical behavior due to their sexual dimorphism. Furthermore, we are GPS tracking Andean condors simultaneously with pumas and vicuñas to investigate how the abundance and distribution of predators and prey influence condor space use and behavior. We will also genotype molted feathers collected in these areas to look into condor dispersal movements and gain a further understanding of their space use in the region.
Carnivore Community Interactions
Another component of this research focuses on the community interactions within the carnivore guild across a human-use gradient. Large, terrestrial carnivores can create niche space for subordinate guild members by decreasing the abundance of competitively dominant species, supplying carrion, and via non-consumptive (fear) effects. Specifically, we aim to evaluate divergent space use, habitat selection and foraging between members of the carnivores guild. We will use camera trap surveys to assess habitat preferences and diel overlap by the two fox species and pumas. By using occupancy models, we will test how pumas affect each species’ occupancy and detection probability, and consequently determine the capacity of these carnivore species to coexist. However, the effects that humans can have in mediating these interactions are often overlooked. Thus, it is crucial to understand the mechanisms by which apex carnivores shape carnivore communities across human gradients and, conversely, how human presence can mediate the coexistence of carnivores. Additionally, we want to evaluate the response and plasticity of puma’s dietary niche to human disruption by examining the diet niche width, the proportion of small/large and native/introduced prey, and the trophic position of pumas in different sites of Argentina.
Guanaco Migration
Finally, we are also focusing on the ecology and seasonal habitat use of puma’s main prey item in southern Patagonia, the guanaco. Migration is a widespread strategy among ungulates to avoid the resource constraints and energetic deficits of winter, and guanacos are the only current southamerican species that is believed to have remaining migratory populations. The aim of this study is to describe guanacos migratory habits and patterns, as well as the drivers dictating these seasonal movements, with special focus on the seasonality and phenology of the study area. We predict guanacos will migrate along an altitudinal gradient, with summer ranges located at higher altitudes than winter ones. To look into this will use GPS data from collars we deployed on 21 individuals to track their movements. We will then use remote sensed data to look into vegetation green-up as well as snow cover progression along the landscape to determine whether guanaco migrations are being driven by a need to track resources, to avoid snow, or to a combination of both.
Project Members: Mauriel Rodriguez Curras, Gonzalo Barcelo
This work is funded by AZA, CREOI, Hawk Mountain, The National Birds of Prey Trust, and Rewildlind Argentina.