Nest site selection and nesting biology of Rock Ptarmigan Lagopus muta japonicus in Japan

Capsule The population of Rock Ptarmigan in Japan have the southernmost distribution of Rock Ptarmigan in the world; they nest in moderately open sites which facilitate the detection of predators. Aims To assess nest site selection of this population of Rock Ptarmigan and to compare the data with those for other populations of this species. Methods Nest site characteristics were recorded and compared with random sites. Nest success, clutch size, and hatching rate were determined. Results All nests (n = 24) were found in Pinus pumila shrubs. Vegetation height at nests was significantly lower than at random sites. While the nests were well concealed, one direction of lateral cover was moderately open and its cover was significantly less than at random sites. Such nest placements may provide a good view from the nests, facilitating the detection of predators. Nesting success was 75.3% in 2006 and 61.1% in 2007, which is higher than reported in other populations of this species. Conclusion Rock Ptarmigan selected P. pumila shrubs with moderately open sites for their nests. We propose that these nest characteristics are related to nesting predation. Selection of nesting sites may depend on several factors. We suggest how this information can be used to guide conservation measures for this and perhaps other populations of Rock Ptarmigan. The population in Japan are at risk of extinction due to global warming and/or habitat loss.