SummarySeabird populations suffer from a variety of natural and human-induced sources of mortality and loss of lifetime reproductive output. On the outer coast of Washington State, Common Murre Uria aalge populations have been in decline for approximately the last decade and are currently reproductively active only at Tatoosh Island. These murres nest in two basic habitat types: crevices (25% of the population) and larger cliff-top subcolonies (75%). Murres in cliff-top subcolonies have suffered dramatic reductions in reproductive success in recent years relative to conspecifics nesting in the crevices, primarily due to egg predation by Glaucous-winged Gulls Larus glaucescens and Northwestern Crows Corvus caurinus, facilitated by the presence of Bald Eagles Haliaeetus leucocephalus. Because predator removal is not feasible and creation of additional crevice habitat is difficult, expensive and potentially ineffective, we have designed a temporary habitat modification (the “silk forest”) which replaces the natural vegetation cover and modifies the interaction between murres and eagles. Within the test subcolony, murres nesting under and immediately adjacent to the silk forest produced nearly twice as many eggs per square metre as their conspecifics nesting in adjacent exposed-ground areas.
Habitat modification by invasive crayfish can facilitate its growth through enhanced food accessibility
