Extraction of stepping-stone corridors for birds in urban areas using remote sensing and GIS

Hiroshi HASHIMOTO, Jianjun DONG, Junichi IMANISHI and Yukihiro MORIMOTO

Abstract: Some residential birds widen their habitat ranges in the non-breeding season. Their wintering habitats may be determined not only by the quality of the habitat but also by the connectivity from source habitats. In this study, we extracted some possible stepping-stone corridors, and evaluated which corridors explain the presence/absence of four residential birds: Bush Warbler, Long-tailed Tit, Varied Tit, Masked Grosbeak, in possible wintering habitats in Kyoto City. A bird survey was conducted in 18 woods (>0.6 ha), almost all the possible breeding areas for these four species in the urban area of Kyoto. We assumed that patches in which each bird species was recorded during the breeding season and mountain forests around the city were their source habitats, and we analyzed whether their source and the possible wintering habitats are connected by corridors. About a 15 m by 15 m resolution of vegetation-cover ratio (VCR) map was derived from Terra/ASTER and Quick Bird images. We assumed a minimum VCR in a 15 m by 15 m grid for stepping-stones as 0.25 (15 m - 0.25 stepping-stones) or 0.50 (15 m - 0.50), or 0.50 in a 30 m by 30 m grid (30 m - 0.50), and created buffer zones from each stepping-stone at seven distances: 50 m, 75 m, 100 m 125 m, 150 m, 200 m and 250 m, and 21 types of corridors were extracted from continued buffer zones. Note that the maximum interval between stepping-stones is twice the distance of the created buffer. We used over 80% sensitivity and Cohen's kappa to evaluate the maximum tolerable intervals. As a result, the maximum tolerable intervals in stepping-stone corridors for each species are 200 m (15 m - 0.25) or 250 m (30 m - 0.50) for the Bush Warbler, 300 m (15 m - 0.50 or 30 m - 0.50) for the Long-tailed Tit and 100 m (15 m - 0.25) for the Varied Tit. The interval for the Masked Grosbeak is difficult to judge from this result, and a 250-300 m interval between stepping-stones may be a tolerable distance.


H. Hashimoto, J. Dong, J. Imanishi and Y. Morimoto (2004) Extraction of stepping-stone corridors for birds in urban areas using remote sensing and GIS. Proceedings of IUFRO International Workshop on Landscape Ecology 2004 : Conservation and Management of Fragmented Forest Landscape (Tsukuba, Ibaraki, Japan): 68-71.