Adaptive Significance of Egg Size in the European Starling: Experimental Tests

Abstract

Reproductive success in relation to egg size was studied in European Starlings (Sturnus vulgaris) by swapping whole clutches between nests at the stare of the incubation period. Egg size did not reflect parental quality as no measure of reproductive success was correlated with the foster mothers' mean egg size. There was a significant positive relationship between the mean size of the cross—fostered egg and the subsequent mean size of hatchlings. The mean size of cross—fostered eggs did not affect hatching success or nestling growth rates, and initial nestling size differences between broods with large and small eggs persisted for <1 wk. No effect of mean egg size on mean nestling survival could be detected. Furthermore, a partial cross—fostering experiment, where nestlings were swapped between nests the day after hatching, failed to demonstrate any lasting effect of egg size on nestling size. It is suggested that mean egg size may only influence reproductive success during particularly inferior environmental conditions.

The Effect of Egg Size on Growth and Survival of the Tree SparrowPasser montanusNestlings

“…But we did not find correlation between egg size and nestling survival, like many other authors (e.g. Jarvinen & Ylimaunu 1984, Magrath 1992, Smith et al 1995and Styrsky et al 1999. Schifferli (1973) found such a correlation only for the second brood, Ojanen (1983) only in some years, and Smith & Bruun (1998) in a poorer habitat.…”

“…Magrath 1992, Nilsson & Svensson 1993, Smith et al 1995, Smith & Bruun 1998. Only Ricklefs (1984) did not find any relationship between egg size and nestling growth.…”

“…After the review by Williams (1994), several papers were published on the relation of egg size to growth and survival of passerine nestlings (e.g. Smith et al 1995, Smith & Bruun 1998, Reed 1999, Styrsky et al 1999. Styrsky et al (1999) found that the mass of nestling House Wren Troglodytes aedon was related to the mean egg mass in the clutch by day 6 in the first brood, and by day 10 in the second brood.…”

Variation in egg and clutch size of the Black Redstart (Phoenicurus ochruros) at the northeastern edge of the Qinghai-Tibetan Plateau

“…Therefore, he suggested that the most important effect of variation in egg size might be in determining the probability of offspring survival in the first few days after hatching (Williams 1994). Large eggs appear to have an advantage in harsh environments (Smith et al 1995;Fox and Czesak 2000). On the Tibetan Plateau, elevation affects the breeding ecology of birds (Lu et al 2007(Lu et al , 2008(Lu et al , 2010Du et al 2012Du et al , 2014 through the strong effects of temperature and rainfall, which also affect plant distribution and food availability.…”

“…The disadvantages of low temperature and less precipitation would adversely affect the survival of the nestlings. The Black Redstarts adopted the strategy of laying larger eggs, which would improve the fitness of the nestlings under the harsh environment to recover the costs conferred by the environment (Smith et al 1995;Fox and Czesak 2000). Therefore, because large eggs are produced in response to the harsher environment, a reduction in clutch size becomes a more favorable strategy, which can increase the input of each egg, whereas reducing the number of offspring can ensure that the offspring have a higher survival rate for future generations.…”