Habitat loss and fragmentation seriously threaten global species diversity. Understanding the impact on species and communities is a core issue for ecology and conservation biology. A guild acts as a functional unit within a community. Bird guild research can help to analyze relationships among different species and evaluate their responses to habitat fragmentation. Much research has focused on bird guilds in terrestrial fragments, while other fragmented systems, such as land-bridge islands, draw relatively less attention. Because different systems tend to display different geological and ecological patterns, we needed to verify whether terrestrial fragments and land-bridge islands share common patterns of response to habitat fragmentation. The land-bridge islands in the Thousand Island Lake, which were created by dam construction, are an ideal platform for the study of habitat fragmentation. To test bird sensitivity to habitat fragmentation across seasons, we conducted bird guild studies on 41 land-bridge islands in the Thousand Island Lake during the breeding season (April-June) and winter season (November-January) of each year between April 2009, and January 2012. We classified birds into guilds according to dietary type, foraging strata, and migratory status. We used an equation with logarithmic transformation from island biogeography, S=CA^z, to clarify the relationship between bird guild species richness and island fragment area. In this equation, S represents species richness of each bird guild, A represents island area, C is a constant, and z is the slope of the species-area curve. This variable can be considered a measurement of sensitivity to habitat fragmentation. The bigger the value of z, the greater the sensitivity of the bird guild. We extracted and compared the slope of each species-area relationship curve (z value) to determine whether there exists significant variation in sensitivity to habitat fragmentation among the different bird guilds. Our research indicated that omnivorous birds were more sensitive to habitat fragmentation than insectivores during the winter season, while no significant difference was found for the breeding season. Understory birds were more sensitive to habitat fragmentation than canopy birds, both in breeding and winter seasons. Resident birds were more sensitive than migrants in winter, while no significant difference between them were observed in the breeding season. Both omnivorous and resident birds showed seasonal changes in their sensitivity to fragmentation. Other guilds, including insectivorous birds, canopy birds, understory birds, and migratory birds, showed no significant seasonal changes. Previous studies conducted in terrestrial fragments support our findings that responses of bird guilds to habitat fragmentation differ and that seasonal changes in the responses to habitat fragmentation do exist. These results may aid in the effective management of bird habitats and in the design of nature reserves. Future studies may focus on other bird guild types and determine if differences in responses to habitat fragmentation occur at a larger temporal scale.