Study of Nest Trees and Nest Sites of the Taiwan Barbet{Psilopogon rtuchalis) in an Urban Habitat

摘要

Taiwan Barbet Psilopogon nuchalis is a primary cavity nester, and it creates niches for a variety of cavity-nesting and cavity-roosting organisms. However, information on barbet nesting innatural cavities is lacking. We present the results of a 5-yr study on natural nest-sites of the TaiwanBarbet in an urban area. The data, including descriptions of nest cavity trees and locations, werecollected during the breeding seasons ot!2008~2012 in Taipei Botanical Garden and its surrounding sidewalks. A variety of tree species and wide ranges of tree heights and tree diameters wereselected by the barbets as nest trees. In nest trees, numbers of limbs of the first order had largeranges, as did those of the second order. Nest heights and tree (branch) diameters at nests also considerably varied. Large-diameter camphor trees Cirmamomum camphora were the major nest treesused by the Taiwan Barbet, for which the possible reasons might be camphor tree's dominance andits moderate oven-dry specific gravity (i.e., 0.4 g cm '). Live trees with dead limbs were excavatedby the birds 4 times as often as dead trees. One possible reason is that the number of dead trees inthis urban area was limited, because some dead trees had been removed to prevent damage to people and their property. Although the Taiwan Barbet mostly used live trees as nest trees in this urbanarea, we found most of the cavities on decaying trunks or limbs of live nest trees. This fact indicated that the decayed part might facilitate cavity excavation by the birds. About half of nest sites hadtree or branch diameters of 14-19 cm, which indicated that a barbet usually selected a mediumsized trunk or branch to make its nest cavity. When managing urban forests, it is recommended thatmedium-sized dead trees and medium-sized dead limbs on live trees be retained to meet the cavityneeds of the barbet's urban populations. Furthermore, the cavity resources will also benefit cavityusing communities in urban areas.