Sublethal effects of pesticide residues differ between strains of captive Grey partridge: consequences in terms of rearing conditions.

International audienceOver the last 50 years, farmland bird populations have declined steeply in Europe and North America. Reintroductionor reinforcement for populations unable to self-maintain are popular management tools to overcomeextinction risk through captive rearing and release. However, released birds tend to have lower survival ratesthan their wild conspecifics. Here, we aimed to mimic the diet shift that Grey partridge (Perdix perdix) encountersonce released (poultry food to natural grain) and compared (i) differences in responses to this transitiondepending on strain (wild or farm) and (ii) the consequences of ingesting organic or conventional grains onindividual body mass, haematocrit and behavioural traits (anti-predator responses, activity, exploration) that arelikely critical for post-release survival. Our experimental procedure involved 40 farm-strain and 40 wild-strainpartridges fed with commercial poultry food during early life then with wheat and corn for 3 months, fromeither organic or conventional (clopyralid residues) agriculture. The results suggest that the haematocrit andbody mass index of farm-strain partridges were lower at the end of the experiment, probably due to diet shift.Birds fed conventional grains (with clopyralid residues) exhibited lower flight duration and flight initiationdistance, and were more likely to translocate by running rather than flying. The findings suggest that, whenrearing partridges of farm-strain origin, birds fed organic grains experience better post-release survival than birdsfed conventional grains containing pesticide residues