Could invasive lagomorphs increase the predation risk for guanaco (Lama guanicoe) by puma (Puma concolor) in the Chilean Central Andes?

Abstract

Invasive species can have complex direct and indirect impacts on ecosystems. The impacts of invasive prey species on native prey can be difficult to observe if the latter migrate seasonally, and when the interaction is indirect. We hypothesize that invasive lagomorphs and snow dynamics indirectly drive predation risk for guanaco by puma. We employed camera-trapping data collected over multiple years and seasons in an altitudinal gradient in the Andes of Central Chile. We predicted a high spatial and temporal association between puma and lagomorph detections, given these prey species comprise most of puma diet in the area. We also expected a higher spatiotemporal association between guanaco and puma detections towards higher snow cover in the study area, because of downward altitudinal migration of the ungulate. We obtained 4863 mammalian detections. Our data shows that the detection of puma was positively associated with hare capture rate year-round. In addition, puma detection was positively associated with the interaction of snow cover and guanaco capture rate. Puma temporal activity strongly overlapped with hare, whereas puma apparently increased diurnal activity with an increase in guanaco capture rate. Predation risk for guanaco increased when snow cover was higher and decreased when guanaco migrated to higher altitudes during dryer months. We conclude it is of conservation concern that lagomorphs may be subsidizing pumas and modifying patterns of consumptive and non-consumptive effects of the predator on native prey populations.