Contraception use in captive animal management: understanding long-term health, behavioural and reproductive impacts

Zoological collections worldwide fulfil multiple functions: as visitor attractions, holders of conservation’s ambassador species, for public engagement about conservation and biodiversity, and for ex situ population management and breeding. Moreover, zoological collections generate a non-trivial revenue stream for conservation activities. These collections face an ongoing challenge of how to effectively managing their populations while retaining naturalistic behaviours. Reversible chemical contraception offers a solution for population management but they also are often administered for their putative psychological effects, including management of aggression, rather than for contraception. The EAZA Group on Zoo Animal Contraception group has compiled an unprecedented resource of contraception use across more than 400 species.

The project will have and interdisiplinary team of supervisors, with expertise in endocrinology, behaviour , psychology and development. The project is split into three main parts.

Part 1: Understanding contraceptive efficacy.

The EGZAC wildlife contraception database contains bout records for contraceptive treatments [progestins, GnRH agonists and vaccines, immunocontraceptives] with individual ID, sex, age, weight, medical and reproductive history, and social environment. Measures of effectiveness include: reproductive outcomes, reversal status, psychological (descriptive changes in aggression, rank, and oestrus behaviours), and physiological (endocrine) changes. However, the completeness of information varies between records. The first part of the project will concentrate on gathering missing data from focal taxa (Old World primates, carnivores, artiodactyls), especially for recent EU cases. Milestones: identification of missing data; finalisation of database for analyses.

The student will then evaluate species and individual traits associated with the efficacy of different contraception treatments. There is reported variation in the efficacy of contraception; for example, Deslorelin appears to be highly effective in some species yet ineffective others (Herbert et al 2004). Moreover, age and reproductive history impact on individual responses. For each target order, the student will use a phylogenetic mixed modelling approach to identify which species (i.e. reproductive physiology, seasonality, mating system, phylogenetic position) and individual (sex, age, reproductive history, housing/social environment) characteristics are associated with effectiveness measures for each treatment.

Part 2. Understand welfare and population management impacts of GnRH targeted contraception

 The second part of the study will establish endocrinological evidence for the reversibility of ‘temporary’ contraception. There is extensive evidence for the effectiveness of GnRH agonists (i.e. Deslorelin) for down-regulating reproductive systems, however, there is comparatively little information on reversibility (Trigg et al 2001; Munson 2001; Junaidi 2009; Kaffold et al 2010; Bertschinger et al 2001). In many cases, the individuals had not returned to reproductive cycling by the end of the study. In the EGZAC database reversibility is available for 3% of cases. The student will target ‘expired’ cases with no reversal information in UK Old World primates. Where reproductive state is unknown, they will regularly collect faeces over a minimum of two reproductive cycles (females) or against matched non-treated controls (males) and use enzyme immunoassays for reproductive hormone analysis.

Part 3. Behavioural impacts of GnRH contraception

Finally, to complement the physiology data, the student would conduct a meta-analysis and targeted comprehensive survey study of the behavioural impacts of down-regulating reproductive hormones with GnRH agonists. Down regulating reproductive hormones is thought to reduce aggressiveness and dominance behaviours. The student will develop a questionnaire for keepers and where feasible target cases to establish monitoring protocols before, during and administration of the drug to quantify changes in aggression, social network position and dominance and differences between GnRH versus progestin type contraceptive products in relation to welfare and population management.




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