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Urbanisation constitutes one of the most rapid human-induced environmental changes, developing at the expense of natural and semi-natural habitats. It often implies alterations of many abiotic and biotic factors and contributes to create new environmental conditions, including temperature, food resources, competition and predation. Despite increasing empirical evidence of intra-specific divergence in phenotypic traits (e.g., physiological, behavioural or morphological) between urban and rural individuals, such patterns have often remained disconnected from the underlying mechanisms involved. In the current study, we tested for divergence in functional morphological traits that are related to feeding ecology (i.e., bill morphology, body mass and condition) and/or to the locomotory performance in escaping from predators (i.e., wing, tarsus and tail morphology, body mass and condition) along a chronological gradient of urbanisation (old urban, recent urban and rural areas), using the New Zealand fantail, an endemic insectivorous passerine species. We found divergences in phenotypic traits related to bill morphology along the urban–rural gradient: birds inhabiting the old urban area had stubbier bills (i.e., shorter, deeper and wider bills) than those inhabiting the recent urban and rural areas. We did not detect any difference in locomotion-related morphological traits. Our results suggest the urbanisation-induced alteration in food resources may drive morphological divergence in bird populations. We emphasized the need for mechanistic and experimental studies, with a particular focus on resource-based mechanisms, to identify more precisely the morphological responses of urban populations to changes in food composition, and the resulting implications for communities in urban ecosystems.

13 pages; International audience; Behavioral adjustments are of critical importance for the survival of animals when exposed to risk and resource variations in their environment. Moving to safer habitats allows prey to reduce the risk of mortality triggered by predation. This response has been well studied at the population level to assist in identifying key habitat components for wildlife conservation. However, while individuals may differ in their response to risk and thus in their survival expectancy, the determinants of individual adjustments in space and habitat use are largely unknown in management and conservation studies. Using GPS monitoring, we investigated the relationship between individual traits (morphometry, personality, health status) and adjustments in the use of space relative to risky features (hedgerows, roads/tracks, woodlands, built-up areas) with regard to predation risk. We used the gray partridge (Perdix perdix) as a study model (captive-reared birds released into the farmlands). During the diel cycle, predation risk mainly occurs by carnivores at night, whereas human hunting pressure occurs during the day. We found that personality and health status had an effect on adjustments in the use of space as response to risky features. At night, when carnivore activity is expected to be high, bolder individuals were farther from hedgerows relative to the day. Similarly, individuals in good health were located farther from hedgerows, roads/tracks, and woodland at night relative to the day. We discuss the need for better consideration of individual traits in management and conservation programs, with a particular focus on recovery programs that rely on translocation of captive-reared individuals.

In human-dominated landscapes, human disturbances may contrast (spatially and/or temporally) with risk imposed by non-human predators. However, how prey adjust behaviour to minimize risk from multiple threats remains unclear. In Central-Western France, we investigated patterns of activity, space and habitat use, and causes of variations during the diel cycle of the grey partridge (captive-reared, released), a farmland bird facing multiple risks (nocturnal predation, diurnal hunting pressure). We also investigated influence of individual space use, relative to risk-related features on the fate of birds. Birds adjusted their behaviours in ways consistent with the reduction of risk from nocturnal carnivores at night and hunters during daytime. We recorded bimodal crepuscular activity, likely explained by commuting movements between spatially-separated diurnal and nocturnal sites composed of different habitats: selection of open terrains and avoidance of predator reservoirs at night vs. use of high-vegetation cover during daytime. We observed space use differences between surviving, hunted and predated birds. Predation and hunting activities act as contrasting pressures, selecting birds based on their spatial behaviour, which has likely shaped diel adjustments at the population level. An improved consideration of temporal variation in environmental pressures would help to reliably address factors constraining populations, so increasing wildlife management efficiency.

International audience; Interspecific competition is expected to occur between phylogenetically closely related species when sharing resources. In birds, interspecific competition often occurs by song-mediated interference and frequently implies asymmetrical outcomes between the species pairs involved. Habitat loss resulting from agricultural intensification is expected to have aggregated bird species in the remaining suitable habitats, thus increasing the likelihood of interspecific competition. However, this process has rarely been considered as a potential factor limiting population recovery in farmland birds. We investigated whether interspecific competition occurs between grey, Perdix perdix, and red-legged, Alectoris rufa, partridges, two phylogenetically related species. Originally parapatric, they have suffered an artificial increase in their contact zone due to huge human-mediated gamebird releases. We analysed territorial behaviour through a playback stimuli experiment and investigated shifts in habitat niche in the absence and presence of a hypothetical competitor. Results showed that the grey partridge appeared less territorial when co-occurring with the red-legged partridge and shifted its habitat niche away from the latter, while no such change was detected for the red-legged partridge. These asymmetrical patterns in behaviour and ecology are predicted under an interspecific competition scenario beneficial to the red-legged partridge, and therefore suggest that they are competitively dominant to grey partridges where they co-occur. This result has potentially strong implications for the management of grey partridges as gamebirds, and for their conservation in areas where they are almost extirpated.

In the current context of the anthropocene, the original habitats of many species have been modified or destroyed. Animals may be forced to move from their original habitats, either to refuge habitats that are suboptimal natural habitats, or to substitution habitats that are anthropogenic. The quality of refuge habitats may be lower than that of the original ones, whereas substitution habitats may be of a similar or even better quality. Here, we test this hypothesis empirically, using the example of coastal populations of the bluethroat, Luscinina svecica namnetum. In a radio-tracking survey, we compared the home-range sizes (considered here a proxy of habitat quality) of the breeding males in their original (coastal saltmarshes), refuge (inland reedbeds) and substitution (coastal salinas) habitats. We found that home ranges are up to 15 times larger in the substitution habitat than in the original one, and intermediate in the refuge habitat, suggesting that substitution habitats have the lowest quality and original habitats the highest. To date, most studies and conservation programs related to this species have focused on its substitution habitats. This result challenges the interest of focusing on anthropogenic habitats when studying and conserving such a species, because such habitats may only be low-quality substitutes.