Prefledging Growth and Recruitment of Female Lesser Scaup

Abstract

Annual variation in juvenile recruitment is an important component of duck population dynamics, yet little is known about the factors affecting the probability of surviving and breeding in the first year of life. Two hypothesized mechanisms to explain annual variability are indirect carry-over effects (COEs) from conditions experienced during the prefledging period and direct effects from climatic conditions during the postfledging period. We used Cormack-Jolly-Seber models to estimate apparent survival and detection rates of 643 juvenile female lesser scaup (Aythya affinis) marked just prior to fledging at Red Rock Lakes National Wildlife Refuge in southwestern Montana, USA, 2010-2018. We evaluated COEs from hatch date, a hatch date × spring phenology interaction, and conspecific duckling density in addition to a direct climatic effect of winter conditions (indexed by the El Niño Southern Oscillation [ENSO]) and spring habitat conditions on the study area. We used growth data from a subset (n = 190) of known-aged ducklings to estimate the influence of hatch date and conspecific density on prefledging growth to help identify mechanisms underlying COEs. Prefledging growth and juvenile apparent survival were negatively related to measures of conspecific duckling density. We found evidence that detection probability varied annually for juvenile (but not adult) scaup, possibly representing decisions to delay breeding and not return to or remain at the study site in their first year of life. Like with apparent survival, there was suggestive evidence that detection probability decreased with increasing duckling density in the previous year. Hatching date was weakly negatively related to detection probability, but unrelated to apparent survival, whereas neither vital rate was related to winter ENSO index. Our results are consistent with a process where density-dependent growth rates in the prefledging period carry over to influence fitness in subsequent life-cycle stages. If this pattern generalizes to other systems, this density COE may have important implications for our understanding of duck population dynamics and reaffirms the importance of maintaining abundant brood-rearing habitats in conservation and management of ducks.

Using learner‐generated poetry to help students understand technical scientific literature

“…During the last 2 weeks of the semester, we compared students’ perceived understanding of peer‐reviewed scientific literature by using a pre‐ and post‐survey design. We created pool of recently published articles (2016–2021) in Journal of Wildlife Management that broadly covered topics relevant to the course, including wetlands and waterfowl management (Anderson et al., 2018; B. M. Ballard et al., 2021, D. C. Ballard, 2021; Croston et al., 2018; Dyson et al., 2018; Finger et al., 2016; Fino et al., 2017; Fowler et al., 2020; Kemink et al., 2019; Livolsi et al., 2021; Marty et al., 2020; Meehan et al., 2021; Messmer et al., 2021; Triezenberg & Knuth, 2018; Williams et al., 2021). Much of the science covered in these papers was already broadly addressed in lectures and laboratory exercises during the semester.…”

Long‐term increase in female body condition and its effect on reproduction in two European red‐listed species, Common Pochard (Aythya ferina) and Tufted Duck (Aythya fuligula)

“…Furthermore, studies focusing on survival in earlier life stages among Aythya species, i.e. offspring survival to fledging (Dawson & Clark 1996, Blums et al 2002, Broyer 2019) and post-fledging survival to recruitment to the breeding population (Messmer et al 2021), are lacking in the literature. Both of these demographic variables alongside a lower proportion of females breeding could cause a population decline and are important issues for future studies on population dynamics of these species.…”