Sex differences in incubation behaviour but not mortality risk in a threatened shorebird

Abstract

Sex-related variation in survival is common in birds and, as it influences effective population size and population growth, is important for conservation and species management. Here we assessed incubation behaviour and sex-related survival in a threatened sexually monomorphic shorebird, the St Helena Plover Charadrius sanctaehelenae. Males incubated at night, the period of highest activity of cats, which are likely to be predators of breeding birds. In spite of behavioural differences between the sexes, adult survival was not significantly different between males and females, suggesting that sex-biased behaviour need not lead to sex-related survival, and thus behavioural differences may not impact upon the adult sex ratio.

The bright incubate at night: sexual dichromatism and adaptive incubation division in an open-nesting shorebird

“…predators can detect incubators before incubators can detect predators, either because of structural complexity of habitats or because of the relative visual abilities of incubators and predators). We argue that high depredation risk by visual predators may answer the question of why in many other Charadrius species the bright males are more likely to incubate at night [31][32][33]. Such an adaptation requires clear day/night differences, which are available in lower latitudes during the breeding season but not at high arctic latitudes with permanent daylight during the breeding season [50][51][52].…”

“…Shorebirds (plovers and sandpipers) are ground-nesting birds in which often both sexes attend the nest [29,30]. Generally, at lower latitudes with a clear night/day rhythm, males contribute more to nocturnal incubation duties, whereas females predominantly perform diurnal incubation [31][32] (but see [33]). It has been hypothesized that the brighter coloration of males leads to the predominance of nocturnal incubation by this sex.…”

No evidence that cameras affect shorebird nest survival on the coastal plain of Arctic National Wildlife Refuge, AK

“…Cameras are increasingly being used as a method to monitor nests (Cutler & Swann 1999, Bolton et al 2007 to determine nest fate, identify predators (Pietz & Granfors 2000, Bolton et al 2007, Liebezeit & Zack 2008, Ball & Bayne 2012, Demers & Robinson-Nilsen, 2012, Bentzen et al 2017, Brown 2019, evaluate behaviour of the attending adults (Smith et al 2012, Burns et al 2013, Meixell & Flint 2017 and estimate daily nest survival. However, placing a novel object near the nest may impact the parameters the device is ultimately being used to determine.…”

“…2012, Burns et al . 2013, Meixell & Flint 2017) and estimate daily nest survival. However, placing a novel object near the nest may impact the parameters the device is ultimately being used to determine.…”

Using remote cameras to validate estimates of nest fate in shorebirds

“…, Burns et al . ) and identify nest predators (Bolton et al . , Liebezeit & Zack , Demers & Robinson‐Nilsen ).…”