Abstract:

The efficacy of nest-site choice ultimately determines the breeding success of birds. Comparisons of the reproductive strategies of various bird species which inhabit the same habitat may provide insights on the evolution of the diverse life-history strategies in birds. In this study, nest-site choice and breeding success of four species of passerine birds that rely on reeds for reproduction were investigated in a wetland in Hebei, China. The four species were the Oriental reed warbler (Acrocephalus orientalis) (ORW), the blunt-winged warbler (Acrocephalus concinens) (BW), the reed parrotbill (Paradoxornis heudei) (RP), and the vinous-throated parrotbill (Sinosuthora webbiana) (VP). Our results showed that breeding nests of the four species were distributed in a mosaic pattern within the same habitat, with similar nest shapes/structures and nest-sites in the reeds. The only characteristics which differed significantly among the species were nest height above the water surface, height of reeds where nests were placed, and density of reeds around the nest site. In addition, the starting time of reproduction clearly differed for the four species. The breeding success rates of the four species were 34.5% (86/249) for ORW, 35.3% (6/17) for BW, 38.5% (15/39) for RP, and 40.9% (9/22) for VP in the two study years. The main factors affecting the breeding success were nest predation and poor weather conditions, like heavy rainstorms and wind, while nest parasitism by the common cuckoo (Cuculus canorus) represented an important factor for breeding failure only in the Oriental reed warbler. Our study demonstrated that these four sympatric species of passerine birds inhabiting the same wetland exhibit differences in terms of nest-site choice and breeding phenology.

Key words: nest-site choice, breeding success, sympatric species, nest predation, niche differentiation