The influence of habitat fragmentation on Marbled Murrelet (Brachyramphus marmoratus) habitat quality in southwestern British Columbia

I investigated the effects of habitat fragmentation on habitat quality on the marbled murrelet (Brachyramphus marmoratus), a threatened seabird that nests on mossy side branches in old-growth forests. I compared relative predation risk and nest-site availability between forest interior sites and three edge types: "hard" (recent clearcuts), "soft" (regenerating forest), and natural (i.e. riparian areas). Higher artificial nest disturbance from avian predators at edges relative to interiors occurred at hard, but not soft edges, suggesting that predation risk initially increases, but then decreases with time. Differences in moss abundance at anthropogenic edges relative to natural-edged patches provided evidence that fragmentation will reduce the availability of marbled murrelet nest-sites. Landscape-scale surveys of murrelet nest predators suggested that populations of common ravens and Steller's jays will increase with habitat fragmentation. To mitigate impacts on murrelet breeding success, I recommend that harvesting patterns minimize the ratio of hard edge to interior old-growth habitat.