The effects of fertility control for wild animals is tightly linked to population ecology. Mortality, fertility and migration will change as a result of using fertility control, and these changes in turn most likely impact the welfare of the individuals in the treated population, in one way or another. Efforts to understand the welfare impact of wildlife fertility control have so far focused predominantly on negative side-effects. However, there are theoretical reasons to expect positive welfare effects of fertility control used on wild animals in certain contexts, but these theoretical arguments have received little attention so far.
Results/Conclusions
There are three theoretical reasons to expect welfare benefits to treated wild animals in many circumstances: reduced sibling competition, the potential for increased somatic maintenance in parents when fewer resources are invested into reproduction, and lower intra-specific competition for resources in populations of reduced size. In short, having fewer siblings or conspecifics to compete with might improve health and wellbeing, while a lowered reproductive rate would allow reallocation of resources to the health and wellbeing of the would-be parents. The potential welfare benefits of fertility control are affected by the method, species, and population in question. In particular, resource constrained populations are expected to more frequently experience positive welfare effects from the use of fertility control. These theoretical reasons to expect welfare benefits are seemingly supported by some empirical data, which suggests positive effects on survival and body condition in certain contexts. These theoretical considerations will be presented and evaluated against available empirical evidence of potential positive welfare effects, and the value of research in population ecology and related fields to test these predictions will be discussed.
