The microclimate of the nests of waterfowl

Abstract

A sophisticated radiotelemetry system was used to monitor continuously the temperature, relative humidity and the incidence of parental movement sufficient to admit light to, or turn the eggs in, the nest cup of (number of days recordings m parenthesis): Black Swan Cygnus atratus (68); Barnacle Goose Hrantal leucopsis (70); Whooper Swan Cygnus cygnus (28) and Greylag Goose Ansev anser (26). The following features were common to all the nests: (1) a slow rise in the temperature of the nest cup with the onset of incuhation; (2) a temperature gradient in the vertical plane of the nest cup throughout incubation; (3) a diurnal rhythm in the temperature and humidity of the nest cup, this being caused by bird behaviour rather than the ambient environment; (4) nesting materials dried out during incubation thereby accentuating the steepness of the diffusion gradient between a real egg and the atmosphere of the nest cup; (5) the eggs, which were turned between 0.594.95 times an hour, were rotated mainly around their long axes.

Egg turning behavior and incubation temperature in Forster’s terns in relation to mercury contamination

“…It is therefore not possible, based on these studies, to unequivocally determine whether egg turning rate changes over the full course of an incubation cycle in seabirds. Although several previous studies on terrestrial birds followed egg turning rate throughout the entire incubation period, the results were equivocal [ 69 , 70 , 71 , 72 , 73 ]. Therefore, more research is needed to fully address whether egg turning rates vary across the incubation period.…”

Vegetation height and egg coloration differentially affect predation rate and overheating risk: an experimental test mimicking a ground-nesting bird

“…There is no consensus on how to conduct this type of experiment. However, as our aim was not to mimic real predation rates but only to detect the influence of nest characteristics (i.e., in absence of parents: Gregoire et al 2003), we chose to use artificial nests and eggs to measure predation rates relative to nest concealment levels regardless of adult behavior (see also Howey et al 1984;Davison and Bollinger 2000;Dion et al 2000).…”

“…Birds therefore have evolved nesting strategies that respond to these selective pressures periods: to protect eggs from predation, they nest in areas which restrain nest accessibility to predators (Martin and Roper 1988;Martin 1995;Dion et al 2000), decrease (Tinbergen et al 1967;Dion et al 2000) or increase (i.e., colonies) conspecific nest densities, reduce nest detection by using cryptic nests (i.e., nest concealment by vegetation structure; Schieck and Hannon 1993;Dion et al2000;Westmoreland and Kiltie 2007), lay mimetic eggs (Solis and de Lope 1995;Avilés et al 2006;Westmoreland 2008), use active nest defense or mobbing (Cresswell 1997;Arroyo et al 2001), reduce clutch size (Perrins 1977;Lundberg 1985;Gregoire et al 2003), or maintain constant presence at nest (Kilner 2006). To avoid extreme temperatures affecting their eggs, birds have also developed various strategies, including selecting nest sites that reduce heat stress (e.g., structural vegetation cover; Colwell 1992;Lusk et al2003;Wells and Fuhlendorf 2005), building nests that reduce temperature variations either through particular shapes (Ar and Sidis 2002;Deeming 2002) or nest materials (e.g., Howey et al 1984;Mayer et al 2009), and keeping permanent presence at nest (Kilner 2006). Additionally, the white ancestral color of eggs (Kilner 2006) could reduce overheating by reflecting solar radiation (Castilla et al 2007).…”

Egg Turning Behavior and Egg Temperature in Relation to Mercury Contamination of Forster's Terns (Sterna forsteri)

“…It is therefore not possible, based on these studies, to unequivocally determine whether egg turning rate changes over the full course of an incubation cycle in seabirds. Although several previous studies on terrestrial birds followed egg turning rate throughout the entire incubation period, the results were equivocal (Weaver and West, 1943;Weller, 1961;Valanne, 1966;Pulliainen, 1978;Howey et al, 1984). Therefore, more research using the latest technology is needed to fully illuminate this question.…”