February 28, 2021

I, Science

The science magazine of Imperial College

The female contraceptive pill is often hailed as one of the greatest successes of modern medicine, by both women and men alike. However, contraceptives for conservation is another issue altogether. The vast array of hormonal mechanisms, methods of conceiving and durations of pregnancy that are present within mammals alone is enough to give any reproductive biologist a headache.

The length of time between conception and birth in elephants is the longest known on earth, with the mother carrying its unborn calf for almost 2 years. The mystery behind this long pregnancy has recently been solved with the discovery of a unique hormonal mechanism. This insight may help develop a successful contraception to control the spread of wild elephant populations and may aid conservationists in stabilising endangered populations.

The need to control some populations of elephants may come as a surprise as other populations such as the Asian elephant are endangered due to poaching and reduced habitat size. However, the ban on elephant culling in South Africa in 1995 was so successful that a population boom soon followed, with elephant numbers increasing from 8,000 to 18,000 in just 13 years. The large numbers of elephants were thought to reduce already limited water resources and cause damage to valuable woodland areas through the consumption of vast quantities of vegetation. Therefore, in 1998 the ban on elephant culling was lifted and the use of contraceptives advocated.

Elephants are not the only population to have come into contact with contraceptives. Having only recently returned to the UK, wild boar populations have reached large numbers in areas such as the Forest of Dean. Here, frequent clashes between boar populations and humans meant that in 2008 an experiment commenced using long-lasting contraceptives on the sows, which could produce up to 15 piglets a year. Another example closer to home is the familiar story of the grey squirrel invasion. Immuno-contraceptives were thought to be a potential solution to the over-populating grey squirrel. But difficulties with mass delivery of the contraception has meant that a significant impact on the population has not yet been seen.

Whether to aid conservation or to control a population, the need for effective contraception within wild animals may be necessary, if only to reduce the controversial use of culling. Therefore every tiny insight gained into the complex reproductive systems present within every wild species has huge significance for breeding management programs in the UK and further afield.

Journal: Proceedings of the Royal Society B, published online June 20 2012 [DOI: 10.1098/rspb.2012.1038]

More > Check out Joel Winston’s coverage of the UK government’s handling of BTB in badgers in our Science vs. Politics blog.

Image: via flickr | owlana