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

We studied the relationship between temperature and the coexistence of great titParus majorand blue titCyanistes 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.Peer reviewe

Variation in clutch size in relation to nest size in birds

Peer reviewe

Adaptation for breeding in passerines Case studies using observation, experimental and comparative approaches.

Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Data from: Evolution of parental activity at the nest is shaped by the risk of nest predation and ambient temperature across bird species

Incubation is an important component of parental care in birds and species differ widely in their incubation rhythm. In this comparative study we focused on factors responsible for those differences. As hypothesized by A. Skutch, increased parental activity at the nest increases the probability of nest depredation. High risk of nest predation should therefore lead to the evolution of lower frequency of parental activity at the nest. We thus expected to find a negative relationship between frequency of nest visits and the risk of nest depredation. Using a large dataset of 256 species of passerines breeding worldwide we found that the frequency of nest visits decreased as the risk of nest depredation increased and that this effect was strongest in tropical species. Further, foraging bouts were longer in species experiencing warmer ambient temperatures during incubation and those with domed nests. Incubation bouts were longer and frequency of nest visits lower in species with higher body mass. Our results support the view that natural selection favors lower frequency of nests visits in species under higher risk of nest predation and demonstrate the importance of other factors (temperature, geographic space, nest type, and body mass) in shaping the evolution of incubation rhythm

Full dataset on incubation behavior of passerines

Data on incubation behavior of songbirds (Passeriformes) and other related traits, collected from published literature. Created in MS Excel. First sheet contains population-level data, while the second sheet contains legend to data columns

Broad-scale variation in sexual dichromatism in songbirds is not explained by sex differences in exposure to predators during incubation

The evolution of sexual dichromatism provoked one of the greatest disagreements between Charles Darwin and Alfred Russel Wallace. According to Darwin the main driving force is sexual selection, whereby choosy females prefer showy males, leading to the evolution of conspicuous male plumage. On the other hand, Wallace suggested that dichromatism may arise because nest predation favors more cryptic females. To test the role of natural selection in the evolution of dichromatism we combined quantitative data on differences in parental share in nest attentiveness (representing the strength of natural selection on males vs females) with spectrophotometric measurements of dichromatism in 412 species of songbirds from 69 families. We expected to find stronger dichromatism in open‐nesting species with more divergent parental roles and in body parts exposed during incubation. Dichromatism was not related to the differences in parental share during incubation, but it was most pronounced in lekking species, migrants, and small species. Our results thus suggest that Wallace's hypothesis is not able to explain broad‐scale variation in the dichromatism of songbirds, but point to a role for sexual selection, mutual mate choice, and migration strategy in shaping the extraordinary variation in dichromatism exhibited by songbirds.This study was supported by a Go8 European Fellowship to BM

Data from: Broad-scale variation in sexual dichromatism in songbirds is not explained by sex differences in exposure to predators during incubation

The evolution of sexual dichromatism provoked one of the greatest disagreements between Charles Darwin and Alfred Russel Wallace. According to Darwin the main driving force is sexual selection, whereby choosy females prefer showy males, leading to the evolution of conspicuous male plumage. On the other hand, Wallace suggested that dichromatism may arise because nest predation favors more cryptic females. To test the role of natural selection in the evolution of dichromatism we combined quantitative data on differences in parental share in nest attentiveness (representing the strength of natural selection on males vs. females) with spectrophotometric measurements of dichromatism in 412 species of songbirds from 69 families. We expected to find stronger dichromatism in open-nesting species with more divergent parental roles and in body parts exposed during incubation. Dichromatism was not related to the differences in parental share during incubation, but it was most pronounced in lekking species, migrants, and small species. Our results thus suggest that Wallace's hypothesis is not able to explain broad-scale variation in the dichromatism of songbirds, but point to a role for sexual selection, mutual mate choice, and migration strategy in shaping the extraordinary variation in dichromatism exhibited by songbirds

Long-term and large-scale analyses of nest predation patterns in Australian songbirds and a global comparison of nest predation rates

Juvenile mortality is one of crucial drivers of life-history evolution, and predation is the main cause of nest loss in birds. Thus, understanding how nest predation and failure vary in nature is important for understanding life history evolution and, moreover, for effective conservation. We used published data and unpublished records to study factors influencing nest predation and total failure in 138 populations of 90 species of Australian songbirds. Daily predation (average 2.0% d-1) and failure rates (2.9%) increased from temperate regions to the tropics, over the last four decades, and were lowest in temperate south-western Australia. Predation and failure were higher in smaller species, and failure rates were lower in species with closed nests than in species with open nests. There was no effect of nest height or nest site (ground, shrub, canopy) or social organization on nest predation or failure rates. Nest predation caused on average 72% of total nest failure, similar to other tropical, subtropical, and temperate areas. Our study spanning from the tropics to temperate regions and using >10 000 nests confirmed that tropical birds faced higher nest failure rates. We identified an increase in nest depredation rates in the last four decades in Australia, suggesting that a large-scale ecological phenomenon must be responsible. It may include increases in predator abundances and/or ranges, possibly connected with human-caused habitat change. A global comparison of nest failure rates confirmed that predation is the main source of nest mortality in songbirds worldwide. We discuss implications of our results for the evolution of reproductive strategies and for the conservation of Australian birds

Nest predation in New Zealand songbirds: Exotic predators, introduced prey and long-term changes in predation risk

Predation is a major factor in ecology, evolution and conservation and thus its understanding is essential for insights into ecological processes and management of endangered populations of prey. Here we conducted a spatially (main island through to offshore islets) and temporally (1938-2005) extensive meta-analysis of published nest predation rates in New Zealand songbirds. We obtained information on nest predation rates from 79 populations (. n=. 4838 nests) of 26 species of songbirds belonging to 17 families. Nest predation rates increased from southwest to northeast and also across the last 60. years (by 15-25% points in both cases). We identified a major impact of exotic mammalian predators. Nest predation was lowest in areas where no exotic predators were present (12.8%), higher in areas with ongoing predator control (33.9%), and highest in areas without control that had the full set of exotic and native nest predators (47.5%). Surprisingly, nest predation rates were higher in introduced as compared to native species. Our analyses demonstrated that human-caused factors (introduced predators and prey) overrode factors such as nest type and habitat identified as important in predicting nest predation in North America and Europe previously

Male incubation feeding in songbirds responds differently to nest predation risk across hemispheres

Evolution of parental care behaviour has been of considerable interest to behavioural ecologists for a long time. Incubation feeding, where an individual incubating eggs is provisioned by another individual, is an important component of avian parental care. It may be critical for breeding success by allowing the incubating bird to spend more time on the eggs. However, very little is known about environmental factors shaping incubation feeding, and incubation behaviour in general, of tropical and southern hemisphere birds, and how this differs compared to northern hemisphere species. We collated available data on the rate of incubation feeding in Australian, New Zealand and North American songbirds (78 species from 25 families). There was a strong positive relationship between female incubation attentiveness and incubation feeding by males; however, female attentiveness was higher in North America than in Australia and New Zealand for the same intensity of male incubation feeding. Incubation feeding was not related to species body mass, social organization, geographical latitude or ambient temperature. It differed significantly between families, but overall was not different between regions. Incubation feeding rate was related to nest predation rate, but differently in the two regions. It increased with nest predation rate in Australia and New Zealand, but decreased with nest predation rate in North America. We suggest that this may be caused by different predator-prey interactions in North America versus Australia and New Zealand, which could have shaped the evolution of incubation feeding differently