Meeting Abstract

P1.27  Thursday, Jan. 3  House wrens respond to changes in temperature by adjusting breeding date and clutch size GRINDSTAFF, J.L.*; THOMPSON, C.F.; Oklahoma State University; Illinois State University jen.grindstaff@okstate.edu

The timing of reproduction is a central life history trait that varies with changes in climate and simultaneously has important fitness consequences. House wrens breeding on the Mackinaw study site in central Illinois have been well studied over a period of twenty-seven years. During this time, annual mean temperature has significantly increased and total annual precipitation has significantly decreased near the study area. Here we demonstrate that the breeding phenology of house wrens is strongly influenced by temperatures during the arrival and pre-breeding period such that breeding is initiated earlier in warmer years. Conversely, precipitation does not directly influence the timing of breeding. Furthermore, breeding date strongly positively influences clutch size. Therefore, in warmer years house wrens lay both earlier in the season and produce larger clutches. This demonstrates population-level plasticity in response to climatic cues. Our next step is to determine if individual females differ in their responses to climatic variation. The relative phenotypic plasticity of individuals is a key determinant of the implications of environmental change for population dynamics and evolutionary processes.