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The red fox ( Vulpes vulpes ) is one of the most common generalist mesopredators. Its legal status is often at the centre of controversy between those who wish to protect it and those who wish to control its numbers. In France, foxes are legally hunted and can also be classified as a \"species likely to cause damage\" (ESOD), the latter status allowing them to be shot and trapped throughout the year. There are a number of legal reasons for this, including damage to poultry. Here, we report the results of a 3.8-year experiment comparing two areas where the fox is protected with areas where it is classified as ESOD. Fox populations were monitored for 4 years before and during the experiment and 231 henhouses were surveyed. 1105 birds were predated in 109 of the 231 henhouses, with an average permanent poultry population of 10,883. 48.3% of damage could be attributed to the category ‘fox’ or ‘likely fox’. Our results show that ESOD status, in the local context, did not lead to a significant reduction in fox numbers or differences in damage rates between areas. However, top and bottom fence protection of outdoor runs significantly reduced fox predation. Better protection for poultry should come from increased security of sheds and outdoor runs, rather than from management of the fox population. The role of dedicated multi-stakeholder working groups for such an evidence-based management at local level is also discussed.

Knowledge gaps regarding the potential role of pesticides in the loss of agricultural biodiversity worldwide and mixture-related issues hamper proper risk assessment of unintentional impacts of pesticides, rendering essential the monitoring of wildlife exposure to these compounds. Free-ranging mammal exposure to legacy (Banned and Restricted: BRPs) and currently used (CUPs) pesticides was investigated, testing the hypotheses of: (1) a background bioaccumulation for BRPs whereas a \"hot-spot\" pattern for CUPs, (2) different contamination profiles between carnivores and granivores/ omnivores, and (3) the role of non-treated areas as refuges towards exposure to CUPs. Apodemus mice (omnivore) and Crocidura shrews (insectivore) were sampled over two French agricultural landscapes (n = 93). The concentrations of 140 parent chemicals and metabolites were screened in hair samples. A total of 112 compounds were detected, showing small mammal exposure to fungicides, herbicides and insecticides with 32 to 65 residues detected per individual (13-26 BRPs and 18-41 CUPs). Detection frequencies exceeded 75% of individuals for 13 BRPs and 25 CUPs. Concentrations above 10 ng/g were quantified for 7 BRPs and 29 CUPs (in 46% and 72% of individuals, respectively), and above 100 ng/g for 10 CUPs (in 22% of individuals). Contamination (number of compounds or concentrations) was overall higher in shrews than rodents and higher in animals captured in hedgerows and cereal crops than in grasslands, but did not differ significantly between conventional and organic farming. A general, ubiquitous contamination by legacy and current pesticides was shown, raising issues about exposure pathways and impacts on ecosystems. We propose a concept referred to as \"biowidening\", depicting an increase of compound diversity at higher trophic levels. This work suggests that wildlife exposure to pesticide mixtures is a rule rather than an exception, highlighting the need for consideration of the exposome concept and questioning appropriateness of current risk assessment and mitigation processes.

The relationship between intake rate and food density can provide the foundation for models that predict the spatiotemporal distribution of organisms across a range of resource densities. The functional response, describing the relationship between resource density and intake rate is often interpreted mechanistically as the relationships between times spend searching and handling. While several functional response models incorporate anti-predator vigilance (defined here as an interruption of feeding or some other activity to visually scan the environment, directed mainly towards detecting potential predators), the impacts of environmental factors influencing directly anti-predator vigilance remains unclear. We examined the combined effects of different scenarios of predation risk and food density on time allocation between foraging and anti-predator vigilance in a granivorous species. We experimentally exposed Skylarks to various cover heights and seed densities, and measured individual time budget and pecking and intake rates. Our results indicated that time devoted to different activities varied as a function of both seed density and cover height. Foraging time increased with seed density for all cover heights. Conversely, an increased cover height resulted in a decreased foraging time. Contrary to males, the decreased proportion of time spent foraging did not translate into a foraging disadvantage for females. When vegetation height was higher, females maintained similar pecking and intake rates compared to intermediate levels, while males consistently decreased their energy gain. This difference in anti-predator responses suggests a sexually mediated strategy in the food-safety trade-off: when resource density is high a females would adopt a camouflage strategy while an escape strategy would be adopted by males. In other words, males would leave risky-areas, whereas females would stay when resource density is high. Our results suggest that increased predation risk might generate sexually mediated behavioural responses that functional response models should perhaps better consider in the future.

Blood pathogens may be harmful for birds and thus, represent a potential threat for some populations. To date, only few data are available on the prevalence of hematozoans in the Red Kite, a raptor endemic to the Western Palearctic listed as Near Threatened within its global range. Here, we report the first screening of haemosporidian parasites in Red Kite nestlings from French breeding areas. The blood of 47 nestlings was sampled in three areas in Eastern France and the prevalence of three genera of blood pathogens, Leucocytozoon, Haemoproteus and Plasmodium, was measured based on PCR assays. Thirteen nestlings were positive to Leucocytozoon sp. (n = 13) and Plasmodium relictum (n = 1), which correspond to an overall prevalence of 28%. This prevalence is higher than those previously reported for the Red Kite in other countries. This is the first record of P. relictum, a potential pathogen for birds, in the Red Kite. No relationship was found between the body condition of nestlings and the occurrence of haemosporidians. Our findings suggest that hematozoans could be a limited threat for nestlings but prevalence in adults, a sensitive stage for the population dynamic of Red Kite, remains poorly known and should be further investigated at least in its main breeding areas

Migration is an important event in the life cycle of many organisms, but considerable intraspecific variation may occur in its timing and/or destination, resulting in sexual segregation during wintering periods. In this study, we tested the body size hypothesis, or cold tolerance hypothesis, which predicts that body size dimorphism modulates metabolic costs associated with cold climate. Using the Eurasian skylark, we first investigated whether this species showed sexual differential migration. Then we explored the body size hypothesis by experimentally testing the effect of low ambient temperature (Ta) on both metabolic rate (MR) and body temperature (Tb). We tested for sex-related differences in metabolism and in energy-saving mechanism (hypothermia). We found clear differential migration by sex in skylark wintering populations, with a male-biased sex ratio decreasing toward southern latitudes. Measurements on captive birds at 20°, 6°, and −5°C demonstrated a significant increase in MR when Ta decreased, but there is no difference between sexes. While both males and females reduced their Tb overnight, Tb reduction was more pronounced in females exposed to the coldest temperature treatment. In addition, we found that individuals with the most reduced Tb lost less body weight during the night, suggesting that Tb reduction may help minimize energy expenditure when conditions become constraining. Our study suggests that functional mechanisms may be involved in latitudinal segregation between sexes and supports the hypothesis that sex-specific physiological strategies and thermal tolerance may explain segregation between sexes.

Skylarks (Alauda arvensis) are known to adopt a typical aggregative behaviour during the wintering period. A further benefit is that individuals in larger groups can decrease the amount of time they spent being vigilant, while maintaining a high probability of predator detection. Using wild birds temporarily housed in outdoor aviaries, we investigated the influence of group size (1, 2 and 4 individuals) on individual time budget (vigilance vs. foraging), and the pecking (number of pecks) and intake rates (number of seeds consumed). Results showed that individuals reduced their vigilance and increased their pecking rate when group size increased. However, the intake rate was not maximised in the largest group suggesting that large flocks would negatively affect individual foraging efficiency. A consideration of the whole set of costs and benefits will be necessary before the adaptive value of group living in any species can be fully assessed.

The relationship between intake rate and food density can provide the foundation for models that predict the spatiotemporal distribution of organisms across a range of resource densities. The functional response, describing the relationship between resource density and intake rate is often interpreted mechanistically as the relationships between times spend searching and handling. While several functional response models incorporate anti-predator vigilance (defined here as an interruption of feeding or some other activity to visually scan the environment, directed mainly towards detecting potential predators), the impacts of environmental factors influencing directly anti-predator vigilance remains unclear. We examined the combined effects of different scenarios of predation risk and food density on time allocation between foraging and anti-predator vigilance in a granivorous species. We experimentally exposed Skylarks to various cover heights and seed densities, and measured individual time budget and pecking and intake rates. Our results indicated that time devoted to different activities varied as a function of both seed density and cover height. Foraging time increased with seed density for all cover heights. Conversely, an increased cover height resulted in a decreased foraging time. Contrary to males, the decreased proportion of time spent foraging did not translate into a foraging disadvantage for females. When vegetation height was higher, females maintained similar pecking and intake rates compared to intermediate levels, while males consistently decreased their energy gain. This difference in anti-predator responses suggests a sexually mediated strategy in the food-safety trade-off: when resource density is high a females would adopt a camouflage strategy while an escape strategy would be adopted by males. In other words, males would leave risky-areas, whereas females would stay when resource density is high. Our results suggest that increased predation risk might generate sexually mediated behavioural responses that functional response models should perhaps better consider in the future.