ИСТИНА

South-East Asian forest birds ecology is studied insufficiently, only a few works related to hole-nesting passerines which are very uncommon here in lowland monsoon forests. In 2008–2013 we studied the biology of white-rumped shama (Copsychus malabaricus) nesting in nestboxes (105–209 per breeding season) and in natural nest cavities in Cat Tien National Park, southern Vietnam. This species is mostly common in forest and forest edges of Cat Tien and the only one which used nestboxes. During 6 breeding seasons between 56,5 and 11,5% nestboxes were occupied, totally 331 active nests were under our control, 744 birds were marked with color and metal rings. Habitats, population density, territorial behavior, annual cycle and breeding biology were described. The high level of nest predation was shown in study area for several species of passerines birds, as well as a strong competition for nest cavities with more then 45 species of other animals. In these circumstances white-rumped shama successfully uses the niche of small cavity-nester in lower storey of vegetation. Nesting failure was 17,8% (n=59) for couples breeding in nestboxes and 62,9% (n=17) for natural cavities. Our observation data and special experiments with nestboxes demonstrate that a male strongly prefers to choose nest cavities not used by it previously (these are unknown to predators and not containing parasites), it also prefers recently formed cavities. Shama is a sedentary bird with very small home range (about 0,3 ha), therefore it can find fresh cavities easily. Additionally this species is characterized with high level of plasticity when choosing a place for nest building. Thus, we suppose that such strategy of choice of nest localities helps to white-rumped shama to be a high density representative of a guild of very uncommon hole-nesting passerines in rich tropical lowland forests of South-East Asia.