Nest predation, predation rates and predator identity on UMBS property.

Abstract

The predation of ground nesting birds has been extensively studied, and has been researched on UMBS property. Different habitats produce different rates of predation. In our study, simulated ground nests were placed on UMBS property in order to study both predation rates and predator identity. Simulated nests were created, with eggs and fish used as bait. We expected edge sites to have higher degrees of predatio than meadow or forest sites, and racoons to be likely predators. Nest sites were located at Green Star meadow and along a transect at Riggsville Road. A camera system designed to photograph predators with a trip wire trigger was used. The study was conducted from 3 August 1994 to 8 August 1994. Sixteen camers were used. Data was taken on tripped, predated, and tripped/predated cameras. Rates of predation were found to be higher along forest edge, followed by forest and then meadow interior. Predation rates were compared using percentages to compensate for unequal numbers of cameras in each habitat. All of the predators recorded were racoons, except for two opossum visits. Since ground nesting birds have been documented in the area, it is reasonable to asume predation actually occurs. Studies of predation in the Northern Michigan area, specifically Southern (1980) document mammal predation, and predation seems to affect both reproductive success and nestling mortality. Several factors can influence predation prates, including forest density and meadow shrub density (Leingruber, McShea and Rappole 1994, Gregg, Crawford, Drut and Delong 1994). Because predation rates were higher along forest edge and forest, we suspect the predators were more likely to inhabit the forest. Because our main predators were raccoons, we concluded that more human friendly species were likely to predate our nests; predation rates differed for each habitat and this may be correlated with the degree of human disturbance in each area. Weather may have also been a factor concerning nest predation patterns. Because an opposum visited our nests, the first documented on UMBS property, we speculate this may signify invasion of a species due to migration. The study was successful, obtaining informative data, but may have been more conclusive if executed over a longer time period.