Nest predation reduces benefits to early clutch initiation in northern cardinals Cardinalis cardinalis

Abstract

Life history theory and empirical studies suggest that early breeding confers higher reproductive success, but the extent to which this advantage can be generalized to human-dominated systems and across species is less well understood. We studied the fitness consequences of clutch initiation for 181 female northern cardinals Cardinalis cardinalis and 1228 nests in forests within urban and rural landscapes of Ohio, USA between 2004Á2007. Cardinals that bred earlier made significantly more nesting attempts, but cumulative number of young fledged was similar to that of later-breeding individuals. The expected number of fledglings produced per successful nest was unrelated to date and remained Â1.8 fledglings across the season, despite the fact that nest survival rates improved dramatically as the season progressed. Because the probability of resighting breeding individuals in subsequent years was unrelated to first clutch initiation date, we have no evidence that clutch initiation affected adult survival. The absence of a clear benefit to early breeding appears to be a consequence of high rates of nest predation early in the breeding season.

Altered breeding biology of the European blackbird under artificial light at night

“…Accordingly, winter broods of urban blackbirds occur (Glutz von Blotzheim and Bauer , Desrochers and Magrath , Moskát et al , Renner , Jamriška et al , Wuczynski ) but are rarely successful (Stephan ) and, therefore, might constitute an ecological trap even though European blackbirds can start several breeding attempts per season (Stephan ). The investment of energy into unsuccessful winter broods is maladaptive as was found for northern cardinals Cardinalis cardinalis , were early breeders start more nesting attempts per season but their cumulative number of fledglings was equal to that of later breeding pairs (Shustack and Rodewald ). However, an unimpaired advance of reproduction into early spring and winter due to high illuminance by LAN is unlikely for the majority of blackbirds because the correlation between lamp density and the advance in egg laying was not linear but highest for changes at low light conditions whereas additional illuminance at bright artificial night light did not further advance the date of clutch initiation.…”

Reproductive Contributions of Cardinals Are Consistent with a Hypothesis of Relaxed Selection in Urban Landscapes

“…Indeed, many birds adjust body condition to balance the risks of food deprivation and depredation (Rogers, 1987) and when trading-off future reproduction or survival to invest in current reproduction (Arcese and Smith, 1988;Tarwater and Arcese, 2017). Whether cardinals engage in such trade-offs remains uncertain, but previous work in our system shows that urban cardinals bred earlier than rural birds, and although individuals that bred early attempted a greater number of nests, there was no measurable increase in numbers of fledglings due to the high rates of predation early in the breeding season (Rodewald et al, 2010;Shustack and Rodewald, 2011). Previous work in our system also provided evidence that cardinals distribute themselves in an ideal-free, or "resource-matching" manner, whereby resourcerich urban sites attain higher densities and support smaller territories, but perform similarly to individuals at lower density site in terms of condition, survival and reproduction (Rodewald and Shustack, 2008).…”

Hatching date influences winter habitat occupancy: Examining seasonal interactions across the full annual cycle in a migratory songbird

“…Distinctive characteristics of our breeding season study site may have decoupled relationships between winter habitat and reproductive success. High nest depredation rates, especially during the beginning of the season when leaf‐out can be delayed in our study system (Akresh, 2012; Akresh et al., 2015), may have caused decoupling among arrival dates, nest initiation dates, hatch dates of successful nests, and seasonal fecundity (Akresh et al., 2019a; Shustack & Rodewald, 2011). Further research is needed on how winter habitat and arrival date may influence extra‐pair paternity in our study population (Reudink et al., 2009).…”