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Interspecific interactions between the native and introduced White‐eyes in the Bonin Islands
Author(s) -
Kawakami Kazuto,
Higuchi Hiroyoshi
Publication year - 2003
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1046/j.1474-919x.2003.00197.x
Subject(s) - interspecific competition , biology , population , competition (biology) , ecology , population density , zoology , medicine , environmental health
The impact of the introduced White‐eye Zosterops japonicus on the endemic White‐eye Apalopteron familiare was studied on Hahajima and Chichijima of the Bonin Islands. A. familiare preferred primary forests whereas Z. japonicus preferred open habitats, but their distribution greatly overlapped in secondary forests. The population density of A. familiare was stable whereas the Z. japonicus population had increased in number over the last 20 years, probably because of an increase in the area of open habitats. The data suggested that the population density of A. familiare had not been affected by the spreading Z. japonicus . The body weight of fledgling A. familiare was not affected significantly by the presence of Z. japonicus . Food items taken by A. familiare were similar to those of Z. japonicus . Where the species did not coexist, A. familiare foraged at all heights of the forest, but in the area of overlap, this species reduced its use of higher parts of the forest canopy where Z. japonicus foraged frequently. The food selection of A. familiare , however, did not change in the presence of Z. japonicus . This study detected almost no negative ecological relationship between Z. japonicus and A. familiare and suggests that competition is not a significant threat to either species. A. familiare may, if anything, benefit from Z. japonicus by forming a mixed‐species flock in the non‐breeding season.