Abstract: Information on the bird’s diet composition is essential to understand how wetland reclamation affects diversity of passerine birds. Samples of feathers of Reed Parrotbill (Paradoxornis heudei) and Oriental Reed Warbler (Acrocephalus orientalis) and samples of potential dietary insects were collected in the southern Hangzhou Bay (Shangyu, Shaoxing City), during the breeding season from July to August in 2017. Food sources were analyzed by measuring δ¹³C and δ¹⁵N values in bird feathers and insect samples. The results showed that the contribution of various diet composition of Reed Parrotbill ranked as: Noctuidae pupa > Lepidoptera > Arachnida > Hymenoptera > Homoptera. The contribution of various diet composition of Oriental Reed Warbler ranked as: Hymenoptera > Arachnida > Odonata > Lepidoptera > Coleoptera > Homoptera. The value of feeding niche breadths of Reed Parrotbill and Oriental Reed Warbler was 5.21 and 5.95, respectively. There was no significant difference in the δ^13C values between the two species, indicating an overlap between their feeding niches (P>0.05). However, there was a significant difference in the value of δ¹⁵N, with feeding niche overlap being 6.25, suggesting some differences of nutritional levels (P<0.01). Lepidoptera, Arachnida, Hymenoptera, and Homoptera were overlapping foodsource insects for the two passerine species. The narrower niche breadth of Reed Parrotbill was inferior, and the loss of reed habitat had greater impacts on Reed Parrotbill. Our results provide information for habitat establishment, conservation and management of passerine birds in the coastal reclamation area.

Key words: cadmium, znic, bioavailability, pig manure, chicken manure, rice straw.