Climate warming induced a stretch of the breeding season and an increase of second clutches in a passerine breeding at its altitudinal limits

Abstract

The increase in the average air temperature due to global warming has produced an early onset of the reproduction in many migratory birds of the Paleartic region. According to the ‘mismatch hypothesis’ this response can lead to a decrease in the breeding output when the conditions that trigger the departure from the wintering areas do not match the availability of food resources in the breeding ground. We used 653 brooding events registered during the period 1991-2013 to investigate the link between climatic variables and individual breeding performance of a partially migratory passerine, the Rock Sparrow Petronia petronia, breeding at the altitude limit of its distribution. The laying date of the earliest first clutch was associated with local spring (minimum) temperatures but did not show a significant trend during the period considered. The laying date of the latest first clutch had a positive and statistically significant trend, unrelated to local covariates and resulting in a longer breeding season (∼1.5 day per year). A longer breeding season allowed birds to produce more second clutches, which proportion increased from 0.14 to 0.25. The average breeding success was also positively correlated with the average temperature in July and with the duration of the breeding season. Contrary to expectations, the most important climate-dependent effect was a stretch of the breeding season due to a significant increase of the laying date of the latest first-clutches rather than an earlier breeding onset. We show how climate changes act on bird populations through multiple paths and stress the need to assess the link between climatic variables and several aspects of the breeding cycle.

High nest failure but better nestling quality for early breeders in an alpine population of Northern Wheatear (Oenanthe oenanthe)

“…2022) and longer seasons (alpine population of the Rock Sparrow Petronia petronia ; Mingozzi et al . 2021), whereas others show lower fledging success in years with an early onset of breeding (Snow Bunting Plectrophenax nivalis ; Fossøy et al . 2015), or the fitness advantage of early breeding has been reduced over time (Wheatear; Arlt & Pärt 2017).…”

Early Breeding Conditions Followed by Reduced Breeding Success Despite Timely Arrival in an Alpine Migratory Songbird

“…Clutches experiencing a rainy season or severe weather events, such as snow storms, have a prolonged incubation period, exposing the nest to predators for a longer period at the same time, and generally higher failure rates (due to abandonment, hatch failure and predation) than clutches in a dry season (Rauter et al, 2002;Kluen et al, 2011;Higgot et al, 2020;Marcelino et al, 2020). Further explanations for variations in breeding success in alpine birds include annual variations in temperature, where success is lower in years with lower mean temperatures (Mingozzi et al, 2021), but also variations in weather-dependent resources (Barras et al, 2021) and local predation risk (Rauter et al, 2002).…”

Heterozygosity, genetic similarity and extra‐pair paternity variation in two populations of rock sparrow Petronia petronia: a within and between populations comparison

“…1, population A), is characterized by a level of EPP (around 50% of the broods contain extra-pair offspring; Pilastro et al 2002, Nemeth et al 2012, which is among the highest reported for passerines (Brouwer and Griffith 2019). The location of this population in the range limit of the species distribution (Mingozzi et al 2021) may support the hypothesis that the high level of EPP may occur to compensate reductions in the population's genetic diversity expected in marginal populations (Eckert et al 2008). To answer this question, we estimated the rate of EPP in a rock sparrow population located in the core of its distribution range (central Spain, Fig.…”