Monitoring wildlife responses is essential to assess restoration projects. Birds are widely used as bioindicators of ecosystem restoration, but most studies use only taxonomic descriptors to compare ...categories of reference and restoring sites. Here, we used forest structure as a continuous predictor variable to evaluate avifaunal taxonomic and functional indicators in riparian forest reference and restoration sites on southeastern Brazil. Reference sites were riparian forest remnants, and restoration sites were pasture before seedling reintroduction. Forest structure variables (mean tree height, canopy depth, mean diameter at breast height, basal area, tree layering, tree density, and grass cover) were reduced into two axes using a Principal Component Analysis (PCA), Forest Axis 1 (tree biomass vs. grass cover) and Forest Axis 2 (canopy depth vs. tree density). Bird species were classified in relation to five functional categories (i.e., diet, foraging stratum, nest height, cavity dependence for nesting, and forest dependence). Forest Axis 1 influenced the functional diversity of bird assemblages and the relative abundance within levels of each functional category (except for nest height). The relative abundance of all functional categories combined was also affected by Forest Axis 2. Therefore, forest structure affected the predominant functional traits of bird species in riparian sites under restoration. Sites with higher tree biomass were the richest, with canopy birds that were insectivores and frugivores of high forest dependence, whereas more open sites were associated with birds of low forest dependence and ground-foraging insectivores. Forest structures of similar-aged sites were strongly variable, due to natural and anthropic disturbances, so restoration age was a poor indicator of forest development. These unpredictable disturbances can change the development of sites under restoration, so that forest structure can be a better descriptor of the trajectory of these ecosystems.
Incubation is an energetically costly parental task of breeding birds. Incubating parents respond to environmental variation and nest‐site features to adjust the balance between the time spent ...incubating (i.e. nest attentiveness) and foraging to supply their own needs. Non‐natural nesting substrates such as human buildings impose new environmental contexts that may affect time allocation of incubating birds but this topic remains little studied. Here, we tested whether nesting substrate type (buildings vs. trees) affects the temperature inside the incubation chamber (hereafter ‘nest temperature’) in the Pale‐breasted Thrush Turdus leucomelas, either during ‘day’ (with incubation recesses) or ‘night’ periods (representing uninterrupted female presence at the nest). We also tested whether nesting substrate type affects the incubation time budget using air temperature and the day of the incubation cycle as covariates. Nest temperature, when controlled for microhabitat temperature, was higher at night and in nests in buildings but did not differ between daytime and night for nests in buildings, indicating that buildings partially compensate for incubation recesses by females with regard to nest temperature stability. Females from nests placed in buildings exhibited lower nest attentiveness (the overall percentage of time spent incubating) and had longer bouts off the nest. Higher air temperatures were significantly correlated with shorter bouts on the nest and longer bouts off the nest, but without affecting nest attentiveness. We suggest that the longer bouts off the nest taken by females of nests in buildings is a consequence of higher nest temperatures promoted by man‐made structures around these nests. Use of buildings as nesting substrate may therefore increase parental fitness due to a relaxed incubation budget, and potentially drive the evolution of incubation behaviour in certain urban bird populations.
Studies of parental care in tropical birds are still relatively scarce in comparison with northern temperate species, especially regarding to the division of parental tasks, leading to a biased and ...incomplete knowledge of avian reproductive strategies. Herein, we studied the sexual division of parental care in a sexually monomorphic Neotropical passerine, the Pale-breasted Thrush (
Turdus leucomelas
). We recorded food provisioning and food quantity rates (e.g. feeding trips/h and food items/h, respectively), nest sanitation rate (e.g. events of faecal sacs removal/h), and the time devoted to nest attendance and brooding behaviours by each parent. Throughout the 2015–2017 breeding seasons, we video-recorded 153.5 h of parental care in 33 nesting attempts by 26 breeding pairs in a suburban area of south-eastern Brazil. We found that males had higher food provisioning rates and delivered more food items to larger broods, while female did not respond to brood size. As expected, brood age positively affected food provisioning and food quantity rates of both sexes. Faecal sacs were removed predominantly by ingestion throughout the nesting stage, and males had higher nest sanitation rates. Nest attendance reached 34 ± 27% of the time and decreased with nestling age following a decrease in brooding behaviour, a female-only task, while males stayed in the nest for only 4 ± 4% of observation time. Although most of the parental activities are performed by both sexes, males and females differed in which tasks they invested the most, with brood size and brood age being important modulating factors.
Neophobia (i.e. the degree of avoidance to novel situations) is a personality trait that may predict the ability to exploit new resources, which potentially affects the success of settlement of urban ...animal populations. Despite the increasing amount of information on birds using artificial structures as nesting supports, the hypothesis that the propensity to nest on buildings is related to parental personality has never been tested. In a field experiment, we addressed the relationship between female neophobia and the use of buildings as nesting sites in an urban population of the pale-breasted thrush, Turdus leucomelas, in southeast Brazil. We placed novel objects near active nests placed on buildings (N=16) and trees (N=12) and measured the latency of incubating females to resume incubation. Using linear mixed-effects models, we estimated the individual repeatability of this behavioural response and tested whether latency times differed between neophobia and control tests within nesting substrate types. We found significant repeatability for the latency to resume incubation during neophobia tests (r=0.353), indicating that this behaviour was consistent at the individual level as expected for personality-mediated responses. Latency was higher in neophobia than in control tests, but only among females that nested on trees. Previous studies suggest that less neophobic individuals tend to express more exploratory and innovative behaviours, which may have enhanced the use of buildings as nesting sites by fearless females. We conclude that less neophobic females are more prone to nest on buildings in the pale-breasted thrush. Our study is the first to link bird neophobia and the use of buildings as nesting substrates, evidencing that the exploitation of artificial resources may be associated with the predominance of certain animal personalities in anthropic environments.
•We examined how personality affects nest site choice in T. leucomelas.•We compared neophobia of incubating females that nested on trees and on buildings.•We placed objects near nests and measured female latency to resume parental tasks.•Females that nested in trees showed higher neophobia.•Anthropogenic resources may favour dominance of certain personalities in cities.
ABSTRACT Parental division of offspring care in the post-fledging stage of passerines is scarcely studied, especially for neotropical species. We describe the division of parental care in the ...post-fledging stage of the pale-breasted thrush, Turdus leucomelas Vieillot, 1818, focusing on the food provisioning rate, its effects on fledgling vocalization and foraging, as well as the way parents divide their brood for care. We made direct observations on 13 fledglings from eight families (mean ± standard deviation: 1.88 ± 0.83 fledglings per family) for 70.2 hours. We found no differences in food provisioning rate between adult males and females, nor was it affected by brood age or size. Food provisioning rate was not associated with the frequency of foraging and vocalization by fledglings; foraging was the only behavior that varied with brood age, increasing in frequency. Although there was no difference between parents in food provisioning, pale-breasted thrushes presented four different arrangements of fledgling care: male-only care (while females incubated a new clutch), brood division between the two parents, female-only care (in the absence of a new nesting attempt), and biparental care (both adults take care of the same fledgling). The mode of parental care (uniparental or biparental) did not affect the rate of food provisioning to fledglings. The diversity in modes of brood division between parents was greater than expected, which calls for further studies to uncover the underlying reasons for such variation.
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