European Journal of Wildlife Research

, Volume 58, Issue 1, pp 255–267

Low survival after release into the wild: assessing “the burden of captivity” on Mallard physiology and behaviour

  • Jocelyn Champagnon
  • Matthieu Guillemain
  • Johan Elmberg
  • Grégoire Massez
  • Francois Cavallo
  • Michel Gauthier-Clerc
Original Paper

DOI: 10.1007/s10344-011-0573-3

Cite this article as:
Champagnon, J., Guillemain, M., Elmberg, J. et al. Eur J Wildl Res (2012) 58: 255. doi:10.1007/s10344-011-0573-3

Abstract

Captive-reared animals used in reinforcement programs are generally less likely to survive than wild conspecifics. Digestion efficiency and naive behaviour are two likely reasons for this pattern. The Mallard is a species with high adaptability to its environment and in which massive reinforcement programs are carried out. We studied physiological and behavioural factors potentially affecting body condition and survival of captive-reared Mallards after being released. Digestive system morphology and an index of body condition were compared among three groups: captive-reared birds remaining in a farm (control), captive-reared birds released into the wild as juveniles (released) and wild-born birds (wild). We also compared behaviour and diet of released vs. wild Mallards. Finally, we conducted a 1-year survival analysis of captive-reared birds after release in a hunting-free area. Gizzard weight was lower in control Mallards, but the size of other organs did not differ between controls and wild birds. The difference in gizzard weight between released and wild birds disappeared after some time in the wild. Diet analyses suggest that released Mallards show a greater preference than wild for anthropogenic food (waste grain, bait). Despite similar time-budgets, released Mallards never attained the body condition of wild birds. As a consequence, survival probability in released Mallards was low, especially when food provisioning was stopped and during harsh winter periods. We argue that the low survival of released Mallards likely has a physiological rather than a behavioural (foraging) origin. In any case, extremely few released birds live long enough to potentially enter the breeding population, even without hunting. In the context of massive releases presently carried out for hunting purposes, our study indicates a low likelihood for genetic introgression by captive-reared birds into the wild population.

Keywords

Anas platyrhynchos Digestive system E-SURGE Nasal saddle Scaled mass index Restocking 

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Jocelyn Champagnon
    • 1
    • 2
    • 3
  • Matthieu Guillemain
    • 1
  • Johan Elmberg
    • 4
  • Grégoire Massez
    • 5
  • Francois Cavallo
    • 1
  • Michel Gauthier-Clerc
    • 2
  1. 1.Office National de la Faune SauvageCNERA Avifaune MigratriceArlesFrance
  2. 2.Centre de Recherche de la Tour du ValatArlesFrance
  3. 3.Centre d’Ecologie Fonctionnelle et Evolutive UMR 5175-CNRSMontpellier Cedex 5France
  4. 4.Aquatic Biology and ChemistryKristianstad UniversityKristianstadSweden
  5. 5.Les Marais du VigueiratArlesFrance

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