Interaction of climate change with effects of conspecific and heterospecific density on reproduction

Abstract

We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density‐dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms.

Differential effects of anthropogenic noise and vegetation cover on the breeding phenology and success of two urban passerines

“…The other one did not detect any effect of gas compressor noise on clutch size in tree swallows (MacLeod et al, 2022). It was found for both species that increased spring temperatures advance laying date, while increased winter temperatures reduce clutch size (Møller et al, 2020). Furthermore, in that study, there was an interaction between the density of great tit and winter temperatures on laying date of both species, while the density of blue tit interacted with spring temperature on laying date in great and blue tit.…”

Continent-wide drivers of spatial synchrony in age structure across wild great tit populations

“…Finally, we should expect that fluctuations in age structure are not fully explained by variation in environmental variables because of population-specific density-dependent dynamics. Local density-dependence can affect reproductive responses to environmental stochasticity (Møller et al 2020), and differences in these dynamics between populations reduces spatial synchrony between them (Hugueny 2006; Walter et al 2017). Thus, the spatial scale at which density-dependence remains similar between populations should influence the interaction between age structure and environmental variability, and the resultant spatial synchrony of fluctuations in age structure.…”

Temperature synchronizes temporal variation in laying dates across European hole‐nesting passerines

“…In general, the spatial scale of synchrony in population abundances (Kendall et al, 2000 ; Lande et al, 1999 ) and the spatial covariation in phenotypic selection (Engen & Sæther, 2016 ) decrease with increasing strength of density dependence. Further, population density may also affect the relationship between environmental variables, such as spring temperature, and traits, such as laying date and clutch size (Møller et al, 2020 ).…”

“…These traits also vary substantially across years. Annual variation in timing of breeding, clutch size, and fledgling number has been linked to various environmental variables, including timing and availability of resources (Visser et al 2006), breeding density (Dunn and Winkler 2010), temperature (Sanz et al 2003), precipitation (Öberg et al 2015) and large-scale weather indices like the North Atlantic Oscillation index (NAO, Møller 2002), as well as the interaction between environmental variables (Møller et al 2020).…”

“…These traits also vary substantially across years. Annual variation in the timing of breeding, clutch size, and fledgling number has been linked to various environmental variables, including timing and availability of resources (Visser et al, 2006), breeding density (Dunn & Winkler, 2010), temperature (Sanz et al, 2003), precipitation (Öberg et al, 2015), and large‐scale weather indices like the North Atlantic Oscillation (NAO) index (Møller, 2002), as well as the interaction between environmental variables (Møller et al, 2020). Further, within seasons, clutch size and fledgling number may be affected by the timing of breeding; they generally decrease with later laying (Perrins, 1970), and this seasonal decline is stronger at higher latitudes (Winkler et al, 2014).…”