Spring weather conditions influence breeding phenology and reproductive success in sympatric bat populations.

1. Climate is known to influence breeding phenology and reproductive success in temperate zone bats, but long-term population level studies and interspecific comparisons are rare.
2. Investigating the extent to which intrinsic (i.e. age), and extrinsic (i.e. spring weather conditions), factors influence such key demographic parameters as the proportion of females becoming pregnant, or completing lactation, each breeding season, is vital to understanding of bat population ecology and life-history traits.
3. Using data from twelve breeding seasons (2006 - 2017), encompassing the reproductive histories of 623 Myotis daubentonii and 436 M. nattereri adult females, we compare rates of recruitment to the breeding population, and show that these species differ in their relative sensitivity to environmental conditions and climatic variation, affecting annual reproductive success at the population level.
4. We demonstrate that i) Spring weather conditions influence breeding phenology, with wa...