PREDATION ON ARTIFICIAL NESTS IN FORESTED RIPARIAN BUFFER STRIPS

We used artificial nests to examine predation in riparian buffer strip s created by commercial clear-cutting and in unharvested control areas on industrial forestlands in eastern Maine. Nests in riparian buffer strips were depredated more often than those in intact riparian forest s. This pattern was similar for both ground and shrub nests and for bo th trials. Predation rate for nests in control stands was 15%, compare d to 31% in 20-40m wide buffer strips along tributary streams (P = 0.0 16) and 23% in 60-80m wide buffer strips along mainstem streams (P = 0 .045). Predation rates were similar (P = 0.41) in mainstem and tributa ry buffer strips. Greater predation rates documented for nests in ripa rian buffer strips likely resulted from an elevated number and diversi ty of predators associated with the narrow, linear forest stands. Remo tely-triggered cameras placed on a subset of nests revealed 6 species of nest predators. Predators identified at nests were mostly forest sp ecies and not species directly associated with riparian habitats. Red squirrels (Tamiasciurus hudsonicus) and blue jays (Cyanocitta cristata ) were responsible for >50% of the identified depredations, Black bear s (Ursus americanus) were photographed only in tributary buffer strips and may have been using them to travel between larger forested stands . increased predation of eggs and young probably reduces the nesting s uccess of birds in riparian buffer strips. Managers should leave wide (greater than or equal to 150-m) buffer strips along riparian zones to reduce edge-related nest predation, especially in landscapes where bu ffer strips are an important component of the existing mature forest.