COS 64-8 - Despite lower levels of neophobia, black-billed magpies (Pica hudsonia) lose resources to kleptoparasitism by nearby American crows (Corvus brachyrhynchos)

Thursday, August 11, 2016: 10:30 AM
305, Ft Lauderdale Convention Center
Rhea M. M. Esposito and Daniel J. Povinelli, Biology, University of Louisiana at Lafayette, Lafayette, LA

Behavioral characteristics of species are often important in shaping the dynamics in nesting communities. For example, one species may exploit the behavioral characteristics of another to gain foraging opportunities when they are associated. In Jackson Hole, Wyoming, smaller black-billed magpies (Pica hudsonia) show a gradient of association with larger American crows (Corvus brachyrhynchos). We studied whether these species differed in their neophobic responses to novel foraging opportunities. Specifically, we examined if one species was exploiting the characteristics of the other in order to access more resources. To do so, we analyzed latencies and habituation patterns associated with a novel set of resource extraction problems that were presented at individual nests of both species. We also provided an additional set of tests termed resource discovery tests, wherein we placed food resources at locations equidistant from crow and magpie nests and observed which species was first to discover the resource. During both testing regimes, we measured a) the latency to land and consume the resource, b) whether the resource was kleptoparasitized by a hetero- or conspecific, and c) how vigilant individuals were while at the resource.


Species differed in the levels of neophobia exhibited in response to resource extraction problems presented at nests, with crows being more neophobic than magpies. Crows had a longer latency to approach novel food and solve the problem after landing, and had a greater change in latency across solutions of the first resource extraction problem, indicating slower habituation. However, there was no difference in latency between species or in first species to land during the first resource discovery test, indicating that magpies were not capitalizing on the comparatively higher neophobia of nearby crows to access shared resources. Further, as discovery testing continued, crows were able to dominate the resource and exclude magpies. Magpies were also kleptoparasitized by crows more than the reverse during both testing regimes, and crows showed less vigilance when kleptoparasitizing. Thus, despite differences in neophobic behaviors that could favor the bolder magpies, magpies lost food resources to crows near their nests through increased kleptoparasitism.