Differences in mortality rates, dispersal distances and breeding success of commercially reared and wild grey partridges in the Czech agricultural landscape
Abstract
The aim of this study was to evaluate the efficiency of releasing commercially reared individuals of the grey partridge (Perdix perdix) as a method for species recovery. This study compares the mortality risk of grey partridges depending on origin, sex and body condition, controlling for age, infection risk and release method.
In total, 110 locally caught wild individuals and 75 commercially reared game-farm partridges were released and radio tracked within the same study area in the Czech Republic between 2009 and 2011. To exclude a possible effect of age on survival, only individuals in the second calendar year of life were chosen for the analysis.
Commercially reared partridges had significantly higher mortality risk than wild ones. None of the commercially reared birds survived in the wild until the end of the nesting period, and none produced a fledged brood.
Females from game farms showed significantly better survival than males and preferred to mate with wild males, whereas wild females avoided mating with commercially reared males. Predation was the main cause of mortality, and proportion of birds killed by raptors and mammals did not differ between wild and commercially reared birds.
These results highlight the uselessness of releasing adult commercially reared partridges in an effort to establish viable populations of this species in the wild and stress the need for a change from intensive rearing methods aimed predominantly at quantity towards a more conservation breeding-oriented approach aimed at quality.