How Immunocontraception Can Contribute to Elephant Management in Small, Enclosed Reserves: Munyawana Population as a Case Study

Abstract

Immunocontraception has been widely used as a management tool to reduce population growth in captive as well as wild populations of various fauna. We model the use of an individual-based rotational immunocontraception plan on a wild elephant, Loxodonta africana, population and quantify the social and reproductive advantages of this method of implementation using adaptive management. The use of immunocontraception on an individual, rotational basis stretches the inter-calving interval for each individual female elephant to a management-determined interval, preventing exposing females to unlimited long-term immunocontraception use (which may have as yet undocumented negative effects). Such rotational immunocontraception can effectively lower population growth rates, age the population, and alter the age structure. Furthermore, such structured intervention can simulate natural process such as predation or episodic catastrophic events (e.g., drought), which regulates calf recruitment within an abnormally structured population. A rotational immunocontraception plan is a feasible and useful elephant population management tool, especially in a small, enclosed conservation area. Such approaches should be considered for other long-lived, social species in enclosed areas where the long-term consequences of consistent contraception may be unknown.

Fertility control to mitigate human–wildlife conflicts: a review

“…GonaCon administered to 3-4-month-old white-tailed deer fawns did not induce contraception or prevent sexual development (Miller et al 2008b) and, when given to pregnant bison, it did not affect pregnancy . The gradual reversibility of the infertility effect, at least in a proportion of animals treated with ZP-and GnRH-based vaccines, is regarded as desirable in some species (Druce et al 2011;Kirkpatrick et al 2011). Because both vaccines are broken down when ingested, they do not enter the food chain and hence do not pose unacceptable risks to predators or human consumers even if the muscle injected with the immunocontraceptive is ingested.…”

“…Druce et al (2011) introduced the concept of individualbased 'rotational immunocontraception' and showed that using reversible immunocontraceptives on elephants on an individual rotational basis increased inter-calving intervals and lowered population growth to a predetermined rate.…”

“…Beringer et al 2002;Cowan and Quy 2003;Sharp and Saunders 2008;McLeod and Saunders 2014). This growing antipathy toward lethal methods places increasing constraints on wildlife management options, particularly for high-profile, iconic species (Barr et al 2002;Poiani et al 2002;Druce et al 2011). Consequently, there has been growing interest in non-lethal methods such as translocation and fertility control (Duka and Masters 2005;Barfield et al 2006;Fagerstone et al 2010).…”

LACK OF SPATIAL AND BEHAVIORAL RESPONSES TO IMMUNOCONTRACEPTION APPLICATION IN AFRICAN ELEPHANTS (LOXODONTA AFRICANA)

“…This strategy of ''planned'' pregnancies was modeled through to 2012. 21,23,27,28 Furthermore, in June 2005, five cows (of which three cows were treated for 5 yr, one for 4 yr, and one for 3 yr) and then in June 2007 a single cow, (treated for 2 yr) were removed from treatment to test reversibility of the vaccine to expand on the KNP reversibility studies. 10,32 The program was initiated in May 2000.…”

“…94 Similarly, immunocontraception in the Munyawana Conservancy in South Africa's KwaZulu-Natal demonstrated no effects on sexual, social, or ranging behavior of elephants during the 4.5-yr study. 27 However, it is speculated 40,94 that PZP immunocontraception could potentially have short-to medium-term adverse behavioral consequences because females cycle more often, as they are not conceiving, and thus should receive more attention from musth bulls. This predicts that the association of musth bulls with females should increase over time, as the incidence of estrus events increases after contraception.…”