Abstract
Animals can respond to dynamic environments through phenological plasticity of life history events; however, changes in one part of the annual cycle can diminish the success of subsequent life history events. Our aims were to determine the associations between reproduction and moult phenology across years and to quantify phenological plasticity across varying environmental conditions. We conducted demographic surveys of 4,252 flipper-tagged Weddell seals (Leptonychotes weddellii) in the Ross Sea, Antarctica during four austral summers. At each sighting, seals were assigned a moult code based on the visible presence of new fur and the start date of each animal’s moult was back-calculated. Reproductive success and parturition dates were obtained for the breeding season prior to and following the moult. We found that successful reproduction delayed moult by 16 days relative to non-parturient females. Phenology of the intervening moult was indicative of previous reproductive dynamics but not predictive of subsequent reproductive outcomes. Across years, moult phenology varied by about two weeks and covaried strongly with sea ice break-out timing for all reproductive categories. Our findings suggest these polar mammals have some flexibility within the annual cycle that allows adjustment of moult phenology to fluctuating environmental conditions without compromising future reproductive success.
Highlights
Animals can respond to dynamic environments through phenological plasticity of life history events[1,2]
We found that post-parturient females and males moulted later than non-parturient females
We found that later birth was associated with later moult
Summary
Animals can respond to dynamic environments through phenological plasticity of life history events[1,2]. Changes in one part of the annual cycle can impact subsequent processes (i.e. carry-over effects3,4;) and these shifts can in turn diminish future success in foraging, breeding, or survival[5,6,7] Among most vertebrates, it is uncommon for moult and reproduction to overlap due to the high energetic costs of both[8,9,10]. The role of the moult as an intermediate life history event between two breeding seasons has been studied almost exclusively in birds[15,23] In these studies, reproductive success has been found to delay moult relative to sexually mature but non-parturient conspecifics[13,14,24,25,26,27]. The ages and reproductive histories of most individuals are known due to a 45-year demographic study[38,39]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
