Habitat specificity of butterflies along urban environmental gradients in T ama C ity, T okyo

Abstract Butterfly assemblages were monitored by transect counts in a riverine area along T amagawa River ( RIV ), a residential area on the plain ( RES 1), a residential area on the hill ( RES 2), the core area of the city ( COR ), the T ama E xperimental S tation of F orestry and F orest P roducts R esearch I nstitute ( TES ) and T okyo M etropolitan S akuragaoka P ark ( MSP ) in T ama City, T okyo, in 2005. The butterfly assemblages in forest‐dominated TES and MSP were more species‐rich than those in the other areas. The assemblage in the grassland‐dominated RIV was characterized by the highest abundance of individuals. Species richness and abundance were lowest in COR . Ordination of the areas by detrended correspondence analysis placed RIV , MSP and TES in increasing order of scores along axis 1, and RES 1, RES 2 and COR had higher scores along axis 2 than RIV , TES and MSP . In axis 1, grassland species had low scores and forest species high scores; the two groups were generally separated, coinciding with T anaka's classification. However, the scores for two “forest species”, P apilio xuthus and Y pthima argus , were low and those for two “grassland species”, P otanthus flavus and A nthocharis scolymus , were high, challenging the validity of the classification. Most species recorded in this study were “seminatural type”, with relatively few “natural type” species, according to Sunose's classification. Most “urban type” species occurred in several different habitats and were not specific to highly human‐dominated RES 1, RES 2 and COR .