Ross, HA & Ian A McLaren. 1981. Lack of differential survival among young Ipswich Sparrows. The Auk, 98: 495-502.

Summary (AGH): To understand how well animals can reproduce, we need to not only understand how many young they produce, but also how well their young survive to eventually breed on their own. This is hard to know for most animal populations, because the young could end up anywhere. However, since Ipswich Sparrows breed only on Sable Island, any young that are raised there must come back to breed there. To see how well young Ipswich Sparrows survive to adulthood, and to determine which ones do survive, from 1976 to 1979, over 1000 Ipswich Sparrow nestlings were banded and recaptured as adults. Survival rates were very low (2-4 % of hatched young), perhaps because of harsh winters in those years. Young that survived might have been slightly bigger than those that didn’t, but otherwise, in this study, survival was unrelated to several measures of how a nestling was raised or how well it grew, maybe because intense winters are hard on all youngsters.