Viewpoint: Measuring the effects of wildlife contraception: the argument for comparing apples with oranges

Abstract

There are few wildlife populations existing today that can be supported without some form of management. Wildlife fertility control, as one option, has moved from the research stage to actual application with a number of species, including wild horses, urban deer, captive exotic species and even African elephants, but this approach remains controversial in many quarters. Strident debate has arisen over the possible effects of contraception on behaviour, genetics, stress and even management economics, among other parameters. Part of the debate arises from the fact that critics often fail to recognise that some form of alternative management will be applied, and a second problem arises when critics fail to identify and demand the same concern for the consequences of the alternative management approaches. Thus, any rational debate on the merits or possible effects of contraceptive management of wildlife must also recognise all alternative management approaches and apply the same concern and questions to these alternative approaches--including 'no management'--as are currently being applied to fertility control. Only then will the stewards of wildlife be in a position to make wise and informed decisions about management options.

Fertility control to mitigate human–wildlife conflicts: a review

“…Conversely, many hunting groups, particularly in North America, oppose the use of fertility control because of concerns that this method will replace sport hunting (Kirkpatrick 2007;Curtis et al 2008;Fagerstone et al 2010). These polarised views suggest that at the planning stage, comprehensive stakeholder consultation and engagement is crucial to agree on common goals as well as methods to achieve these goals to manage wildlife.…”

All Your Eggs in One Basket: Mechanisms of Xenobiotic Induced Female Reproductive Senescence

“…Although effective immediately, these methods are seen as inhuman, unsustainable, and ineffective over the long term. Manipulating the reproductive rate, particularly in females, instead of increasing the mortality rate is potentially more humane, species specific, and effective at curtailing populations (Kirkpatrick, 2007). The use of ovotoxic xenobiotics as agents of contraception/sterilisation represents a novel approach to fertility control.…”

Multi-year fertility reduction in free-roaming feral horses with single-injection immunocontraceptive formulations

“…However, mortality manipulation can cause increased population growth due to compensatory growth (Garrott and Taylor 1990;Kirkpatrick and Turner 1991), changes to animal movements (Henderson et al 2000) and public objections (Stout et al 1997;Lauber et al 2007). Consequently, non-lethal methods of control, usually involving fertility manipulations, are becoming increasingly advocated when traditional culling methods are impractical or undesirable (Kirkpatrick 2007).…”

“…Contraception has become a relatively widely used non-lethal technique to manage overabundant wildlife populations and is usually considered a more humane and politically acceptable long-term approach to population control because animals remain in the wild and most treatments are reversible (Oogjes 1997;Kirkpatrick 2007). In particular, immunocontraception, which uses an animal's own immune system to inhibit fertility, has been tested extensively in many wildlife species to prevent pregnancy, particularly formulations that block oestrous cycling or fertilisation through GnRH immunisation (Miller et al 2000a;Baker et al 2002;Killian et al 2006;Conner et al 2007) or treatment with porcine zona pellucida (PZP) (Kirkpatrick et al 1992;Turner et al 1996;Fayrer-Hosken et al 2000;Miller et al 2000b;Turner et al 2001;Delsink et al 2002;Naugle et al 2002;Walter et al 2002;Rutberg et al 2004;Lane et al 2007;Turner et al 2007).…”

“…Despite this trend, lethal control is largely unacceptable to the public. Past management techniques have focused on the 'round-up and adopt-out' method, but there have been concerns about the efficacy of these programs and their impact on animal welfare (Kirkpatrick 2007). Contraceptive formulations have been extensively researched in feral horses (PZP; Kirkpatrick et al 1990;Kirkpatrick et al 1996;Turner et al 1997; and show promise for population control that may be more cost effective than removals over the long term (Bartholow 2007).…”