Temperature during egg formation and the effect of climate warming on egg size in a small songbird

Abstract

Keywords:Breeding phenology revealed that despite females consistently laying larger eggs when they experienced warmer temperatures during the prelaying and laying periods, there was an overall negative response -i.e. decreasing egg volume and breadth with increasing spring (May) average temperatures -across individuals. This trend is hypothesised to be caused by the mismatched breeding phenology, in relation to climate warming, of this population. Except in the unlikely cases of populations capable of perfectly synchronising their phenology to changes in their environment, maladjustments are likely for traits such as egg size, which depend strongly on female condition. Slight changes or absence thereof in breeding dates may be followed by mismatched dates, in terms of food abundance, for optimal egg formation, which would be reflected in smaller average egg size, contrary to early predictions on the effects of climate warming on bird egg size..

Advanced breeding dates in relation to recent climate warming in a Mediterranean montane population of Blue Tits Cyanistes caeruleus

“…4). Contrary to what occurs in Pied Flycatchers in the same study area (Sanz et al 2003;Potti 2008), average laying dates of Blue Tits are unrelated to mean temperatures in May (Table 1).…”

Heritability and genetic correlation between the sexes in a songbird sexual ornament

“…We studied a population of pied flycatchers breeding in nest boxes in La Hiruela, about 100 km northeast of Madrid, central Spain, in the breeding seasons from 1987 to 2009 (for example, Potti, 2008). Breeding adults were captured, measured for tarsus length ('size', hereafter; with callipers, to the nearest 0.01 mm), weighed (precision 0.1 g), marked for individual identification with numbered and colour rings and released.…”

A long-term study of egg dimensions in the Tree Sparrow Passer montanus in relation to climate change

“…So far, relatively few studies have examined the impact of climate change on egg dimensions, and the results appear to be variable. According to Potti (2008), in Pied Flycatcher Ficedula hypoleuca, population analyses demonstrate that egg breadth, yet not egg length, has decreased significantly along the 16-year period, leading to marginally nonsignificant decreases in egg volume. Tryjanowski et al (2004) found a decrease of mean egg size with warmer temperatures in Polish populations of Red-backed Shrike (Lanius collurio), while Järvinen (1994) found exactly the opposite trend in a Pied Flycatcher (Ficedula hypoleuca) population in Finland.…”