Lack of spatial and behavioral responses to immunocontraception application in African elephants (Loxodonta africana).

Opinions are divided as to whether human intervention to control elephant (Loxodonta africana) population growth is desirable, partly because of elephant welfare concerns. Female contraception through immunization with porcine zona pellucida (PZP) proteins is viable. The effects of sustained use and application of the PZP vaccine on elephant behavioral and spatial responses were examined by evaluating herd ranging, fission-fusion dynamics, association patterns, and reproductive and sexual behaviors. Minimal change was anticipated as a result of long calf dependence on and association with cows, a reduced but not indefinite 0% growth rate and the known mechanism of action of PZP vaccines, and minimal expected change in resource requirements necessitating behavioral or spatial use adaptations. Although behavioral effects identified in previous hormonal contraceptive trials were evident, it was demonstrated that immunocontraception caused no prolonged behavioral, social, or spatial changes over the 11-yr study period. Individually identified elephants were monitored from 1999 to 2011. Minimal, short-term social disruption, with temporary changes to the herds' core ranges, was observed during the annual treatment events, particularly in the first three treatment years, when vaccinations were conducted exclusively from the ground. Thereafter, when vaccinations were conducted aerially, minor disruptions were confined to the morning of administration only. Despite sustained treatments resulting in demographic changes of fewer calves being born, treatments did not alter spatial range use, and no adverse interherd-intraherd relations were observed. Similarly, resource requirements did not change as calving still occurred, although in fewer numbers. It was concluded that PZP immunocontraception has no detectable behavioral or social consequences in elephants over the course of 11 yr, providing a convincing argument for the use of sustained immunocontraception in the medium to long term as an important tool for elephant management. Behavioral consequences of alternative management approaches should all receive similar scrutiny to enable managers to make informed decisions when weighing management interventions.

Implementing immunocontraception in free-ranging African elephants at Makalali conservancy.

The goal of programmes to provide contraception for elephants should be to formulate an approach that does not require the relocation or immobilisation of the same individual year after year, which would be long-lasting and cause minimal disruption to social and reproductive behaviour. The programmes should be simple to administer, safe and cost-effective, and must meet the objectives defined by managers in the field. An immunocontraceptive programme was initiated in a small free-roaming population of elephants at the Greater Makalali Private Game Reserve in Limpopo Province in 2000 to determine whether the porcine zona pellucida (pZP) vaccine can successfully control population sizes. Further objectives were to determine implementation costs and efficiency through a multi-faceted approach. We have demonstrated that immunocontraception meets the objectives set by managers in the field. Minimal social disruption was observed over the course of treatment, with the mode of delivery (ground or aerial vaccinations) determining the degree of stress within herds and speed of resumption of normal movement patterns. Aerial vaccinations resulted in the least disturbance, with target herds being approachable within a day. In 2005, implementation costs were R880-R1000/elephant/year, inclusive of darts, vaccine, helicopter and veterinary assistance. Irrespective of the source or method of vaccine delivery, a non-pregnant elephant is rendered infertile from 1st vaccine administration. The sooner immunocontraception is implemented, the sooner population growth rates can be controlled. pZP contraception is a realistic alternative management tool, particularly if used as part of a long-term management strategy. Mass-darting from the air eliminates the need for detailed individual histories of each elephant or for employing a person to monitor elephants. Thus, implementation of immunocontraception in larger populations is feasible and practical.

Field applications of immunocontraception in African elephants (Loxodonta africana).

The primary aim of the Makalali elephant immunocontraception programme is to test the efficacy of porcine zona pellucida (PZP) vaccine for practical population control of elephants in small, enclosed reserves, with the goal of stabilizing the current growth rate and reducing it to the 5-10% per annum displayed currently in the Kruger National Park. A secondary aim is to test the hypothesis that PZP treatment does not affect patterns of elephant social behaviour. Eighteen sexually mature cows (age > 12 years) were vaccinated in May 2000 using remote darts. Behavioural observations before, during and after vaccination included noting the activity of individual animals every minute for 15 min. No changes in general behaviour patterns have been noted to date although the animals' spatial use of the reserve was erratic during the period of vaccination, indicating irregular or disturbed patterns associated with vaccination. Normality was resumed on completion of the vaccinations. No aggressive or indifferent behaviour related to nursing, calf proximity or bull-cow interactions have been noted. Ten of the females were in various stages of pregnancy when treated. Subsequently, seven of them gave birth to healthy calves and the other three females are expected to calve shortly. It is too early in the study to draw conclusions about stabilization of growth rates.