Intraguild competition among mesopredators

Garvey, P. M., Glen, A. S., & Pech, R. P. (2014). Foraging Ermine Avoid Risk: behavioural responses of a mesopredator to its interspecific competitors in a mammalian guild. Biological Invasions, 1-13.
Interference competition between predators strongly influences the structure and composition of ecological communities. These interactions are usually asymmetrical as larger predators dominate in aggressive encounters. Smaller predators are forced to balance the conflicting demands of obtaining food while reducing the risk of a confrontation. We tested the behavioural responses of 16 wild captured stoats (Mustela erminea) to the presence of a feral cat (Felis catus) and a ferret (Mustela furo), which we refer to as “larger predators” due to their superior body size. Stoats were released individually into an outdoor arena and nocturnal activities were recorded on infra-red video cameras. On treatment nights, one of the larger predators was placed inside a segregated holding cage on one side of the arena, while an empty cage was placed on the opposite side as a control. A stoat’s daily food allocation was divided into two equal portions, one placed in front of each holding cage to form a food “patch”. Stoats’ perception of risk was assessed by comparing behaviour in the risky patch (close to the caged predator) versus the safe patch (close to the empty cage). Stoats harvested less food at the risky patch. They avoided the area containing the larger predator, both spatially and temporally, and increased vigilance at the risky patch. The results show that stoats alter their foraging behaviour due to perceived interference competition when they encounter larger predators. Understanding trophic interactions between invasive species will help to inform conservation decisions and maximise the effectiveness of management intervention.

Bottom-up and top-down processes interact to modify intraguild interactions in resource-pulse environments

Greenville, A. C., Wardle, G. M., Tamayo, B., & Dickman, C. R. (2014). Bottom-up and top-down processes interact to modify intraguild interactions in resource-pulse environments. Oecologia, 1-10.

Top predators are declining globally, in turn allowing populations of smaller predators, or mesopredators, to increase and potentially have negative effects on biodiversity. However, detection of interactions among sympatric predators can be complicated by fluctuations in the background availability of resources in the environment, which may modify both the numbers of predators and the strengths of their interactions. Here, we first present a conceptual framework that predicts how top-down and bottom-up interactions may regulate sympatric predator populations in environments that experience resource pulses. We then test it using 2 years of remote-camera trapping data to uncover spatial and temporal interactions between a top predator, the dingo Canis dingo, and the mesopredatory European red fox Vulpes vulpes and feral cat Felis catus, during population booms, declines and busts in numbers of their prey in a model desert system. We found that dingoes predictably suppress abundances of the mesopredators and that the effects are strongest during declines and busts in prey numbers. Given that resource pulses are usually driven by large yet infrequent rains, we conclude that top predators like the dingo provide net benefits to prey populations by suppressing mesopredators during prolonged bust periods when prey populations are low and potentially vulnerable.

Space use and intraguild interactions among three opportunistic predators

Krauze-Gryz, D., Gryz, J. B., Goszczyński, J., Chylarecki, P., & Zmihorski, M. (2012). The good, the bad, and the ugly: space use and intraguild interactions among three opportunistic predators—cat (Felis catus), dog (Canis lupus familiaris), and red fox (Vulpes vulpes)—under human pressure. Canadian Journal of Zoology, 90(12), 1402-1413.

Examples of interspecific interactions have been described for mammalian predators, but less is known regarding disturbances of native predator guilds by domestic predators. We investigated intraguild interactions among three opportunistic predators (dog (Canis lupus familiaris L., 1758), cat (Felis catus L., 1758), and red fox (Vulpes vulpes (L., 1758)) co-occurring in the extensive farmlands of central Poland. Their space use was monitored using tracking stations distributed in field and forest plots along a distance gradient from buildings and analyzed using the occupancy-modeling framework. For all three species occupancy decreased with increased distance from buildings, although for the fox the pattern was relatively weak. The occurrence of cats at the stations was higher in the forest than in the field; for fox and dog, there was a strong variation between study plots. For all three predators, the probability of detection was higher during the night than during the day and varied between the seasons; however, the exact patterns were species-specific. The presence of one predator was also linked to the presence of the other two species—generally, a given species was detected more frequently in the absence of the other two species. We recorded spatiotemporal niche segregation among the three species. We conclude that interspecific antagonistic interactions and differences in foraging ecology are the main drivers shaping co-occurrence of the three species in the agriculture landscape.