| Summary: | 碩士 === 國立屏東科技大學 === 野生動物保育研究所 === 97 === Loss of habitat and fragmentation of environment due to urbanization has been identified as negative effects to raptors, but a few species can successfully nest and use food resources in some urbanized areas. The crested goshawk (Accipiter trivirgatus formosae) is an urban raptors poorly studied in Taiwan. The purposes of this study were to : 1) investigate the distribution and use of nest habitat by crested goshawks in an urban environment in southern Taiwan; 2) use multi-scale analyses to understand nest-site selection by goshawks in urban areas; and 3) explain the effects of urbanization on crested goshawk nest-site selection and the food. Results are important for the conservation of this species in urban environments.
Results showed that, in urban areas in southern Taiwan in 2008, crested goshawk used introduced tree species as nest trees more often than native species (n=36). Height, dbh, and canopy cover of urban nest trees were greater than random samples. Micro-habitats (0.04 ha centered around nest tree) were characterized by average height, density, basal area and numbers of trees >5 cm dbh as compared to random sites. There were no significant differences between nest and random trees in the nearest distance to paths (P>0.05), roads (P>0.05), and buildings (P>0.05).Distance to water was significiant (P<0.05). Area, amount, percentage and median shape of forest patches were significantly greater in 7 ha centered around nest sites than at random sites (P<0.05), indicating that forest patches were important for nesting crested goshawks. Logistic regression model demonstrated that tree height and forest patch area were the two most important factors for crested goshawk nest-site selection. Analysis of diet indicated the primary prey species in percentage and biomass of crested goshawks were birds (69%), mainly red turtle doves (Streptopelia tranquebarica) and rock doves (Columba livia ). These prey species were common residents in urban environments.
Urbanization of crested goshawks in southern Taiwan is probably associated with greater trees, forest patche size, water, and prey abundance in the city. Increasing the availability of nest-site habitats for crested goshawks in urban environment will require maintaining and increasing tracts of large trees and appropriate planting of exotic trees.
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