Biology subjects

Bechet, A.

Publications and source records attributed to Bechet, A..

4 recordsLinked to original sources

bioRxiv2025

Gradual ontogenetic shifts in the mobility and space use of long-lived migratory greater flamingos

O_LIHow early-life exploration shapes the adult annual cycle routines of migratory animals remains challenging to study, especially in long-lived species. Delayed recruitment often observed in long-lived migratory birds suggests that the first breeding attempt may be constrained by a protracted learning process in which individuals develop their annual itinerary, which may involve extensive exploration of the winter and breeding sites, potentially causing inexperienced young to wander beyond traditional population areas. C_LIO_LIUsing greater flamingo Phoenicopterus roseus GPS tracking data from 83 individuals tagged as nestlings in the Mediterranean, we analyzed ontogenetic changes in mobility and space use for up to 8 years of age. We segmented autumn-winter and spring-summer tracks (n = 223 device-bird-year combinations) into staging events (n = 1914). We then computed seasonal staging metrics and analysed how they changed with age. We map the traditional congregation sites of flamingos to investigate age-related changes in space use between males and females. C_LIO_LIFlamingos were more exploratory during their early years, gradually transitioning to a more sedentary lifestyle as they grew older. With each additional year of age, the number of staging events decreased by 16%, while the average duration of staging events increased by 8 days. C_LIO_LIBirds remained faithful to the non-breeding staging sites where they spent most of their time during the first year of life. Over time, they returned progressively closer to their natal sites, even after years of exploration at non-traditional locations. Breeding was rare (8%) and occurred at a relatively late age ([≥]5 years), highlighting an extended exploratory phase, a pattern observed in other long-lived species. C_LIO_LIOlder birds were more likely to use traditional sites and spent more time at these sites, particularly after age 5. Our study reveals the individual exploration process underlying natal and non-breeding dispersal patterns previously laid bare by ring-resighting studies and shows that flamingos retain long-term memory of sites learned in early life. C_LI

ecology↗

bioRxiv2024

Lead in the head: persistent lead poisoning of waterfowl in the Camargue (southern France) ten years after the ban on the use of lead shot in wetlands

Lead pollution remains a worldwide environmental and health issue with persistent detrimental effects on human and wildlife. Despite having been identified as an issue for wildlife a long time ago, the use of lead shot for hunting in wetlands was banned only in 2006 in France. Here, we took advantage of a long-term monitoring of waterfowl lead shot contamination in the Camargue (southern France) to (1) assess the local effectiveness of the French regulation in reducing waterfowl contamination and to (2) assess local compliance regarding the use of nontoxic shots in wetlands from 2007 onwards. We collected waterfowl gizzard from 38 hunters in the Camargue during 20 hunting seasons (1998 to 2017) for a total of 2306 gizzards from 28 different species. From 2008 to 2019, we also systematically collected the cartridge casings at three sites of communal wetland hunting. Ratio of lead vs nontoxic cartridges found in the field allowed monitoring hunter compliance with the new regulation. Despite a ten-year long ban on lead shot our results do not show any significant reduction in waterfowl exposure to lead through shot ingestion in the Camargue over the 20-year monitoring period. Indeed, gizzards of harvested waterfowl were as likely to contain at least one lead shot before the ban as after with a mean prevalence of 12% over the 13 species considered across the study period. Cartridge casings showed the persistence of use of lead shots by hunters in the Camargue wetlands despite a slow increase in the use of nontoxic cartridges. This unequivocally indicates that the law is far from being strictly applied, pointing to an insufficient policy enforcement. Our results support the need for a complete ban of lead ammunition for both wetland and terrestrial wildfowl which will facilitate policy enforcement and compliance.

ecology↗

bioRxiv2022

Field margins as substitute habitat for the conservation of birds in agricultural wetlands

Breeding birds in agricultural landscapes have declined considerably since the 1950s and the beginning of agricultural intensification in Europe. Given the increasing pressure on agricultural land, it is necessary to identify conservation measures that consume little productive land. We tested the compensation hypothesis which states that field margins may represent substitute habitats for bird species in agricultural wetlands. We monitored bird species in 86 crop fields in rice paddy landscapes of Camargue (southern France), a wetland of international importance for birds. We investigated whether the area of three types of field margins (reed strips, grass strips and hedgerows) within a 500 meter buffer around the centroid of each crop fields had an effect on the abundance of bird species from three groups defined based on their primary habitat (reedbeds, grasslands, and forest edge species). We controlled for the area of each type of semi-natural habitat (wetlands, grasslands, and woodlands), crop diversity (rice, wheat, alfalfa, rape, and market gardening) and mean crop field size. Results show partial support of the compensation hypothesis with species-dependent responses to primary and substitute habitat area. Some species within the reedbed and grassland bird guilds are favored by the area of their primary habitat as well as by the area of field margins, in line with the compensation hypothesis. Eurasian reed warbler is favored by the area of both wetlands and reed strips. Corn bunting is favored by grassland and grass strip areas. We could not confirm the compensation hypothesis for other species. However, this may be due to the fact that most of these species did not respond to their primary habitat. These results therefore suggest that field margins may represent substitute habitats for some species but further studies, in contexts where species are strongly associated with their primary habitat, would be needed to confirm the generality of this hypothesis. Our results also suggest that species response to increasing the area of a field margin type may vary among guilds and even within guilds. Therefore, it may be difficult to favor all species within a given landscape and management actions may need to be tailored to whichever species are locally associated with the highest conservation priority. To tackle this challenge, it may be necessary to design landscape management actions at different spatial scales.

ecology↗

bioRxiv2018

Dispersal-dependent juvenile survival in a sexually dimorphic long-lived bird, the Greater Flamingo Phoenicopterus roseus

The viability and dynamics of spatially structured populations depend critically upon dispersal behaviour. Yet, in long lived species with delayed maturity, the fitness consequences of post-fledging dispersal, dispersal from the birthplace after independence and before first breeding attempt, are poorly understood although it is a critical determinant of natal dispersal.\n\nWe aimed at estimating sex-specific variations of juvenile survival in a long-lived bird species with sexual size dimorphism, the greater flamingo, as a function of post fledging dispersal destination. Using capture-recapture models, we estimated the survivorship of flamingos ringed in the Camargue (south of France) and wintering in the Mediterranean.\n\nDispersal probability from France was > 0.66 with important annual variations in preferred dispersal destinations. First-year survival increased along the winter temperature gradient with estimates below 0.50 {+/-} 0.07 in France and above 0.60 {+/-} 0.07 in African wetlands. The survival of flamingos wintering in France dropped by 30-50 % depending on sex between fall and spring of their first year.\n\nIn African sites and in Italy, there was no detectable difference of survival between sexes suggesting favorable wintering conditions. Body condition at fledging did not explain variations in first-fall survival within genders. Males wintering in France had a better survival than females.\n\nThese results show that sex and post-fledging dispersal destination affect juvenile survival, support the energetic hypothesis predicting an advantage of large body size to cope with cold temperatures and the competition hypothesis, and suggest the existence of sex-specific post fledging dispersal tactics.

ecology↗