Original post The Star Newspaper
Secondary Source africanhuntinginfo.com
By Rudi van Aarde
The effort involved in stabilising a large elephant population through birth control is labour intensive, costly and unrealistic.
Take, for example, the average age at which cows have their first calves (a crucial determinant of growth rates). This will increase only if 50 percent of cows under 15 years old are on birth control.
In the case of the Kruger, a zero growth rate can be achieved only if nearly 75 percent of adult cows are treated continuously for a minimum of 11 years and indefinitely after that.
This equates to administering the vaccine to at least 4 000 cows, then finding those same cows on an ongoing basis to deliver the boosters.
African countries and conservation agencies have neither the finances nor the infrastructures to sustain such intensive operations. Contraception is suitable only for small, confined populations and then it will only reduce growth rates - not impact.
Contraception can reduce the growth rate of populations.
The pZP vaccine seems safe to use, even during pregnancy. In elephants it has no side effects other than occasional lumps at the site of vaccination and increased incidences of sexual heat.
pZP is administered remotely by darting and immobilisation is not required.
Contraception does not reduce elephant numbers, it reduces birth rates and relies on natural mortality to decrease the population.
It raises ethical questions, as it excludes cows from the gene pool.
Despite some optimism, steroid-based contraceptives may have side-effects on the health and behaviour of cows. Reducing reproductive rates will destabilise the age structures of breeding herds, which in turn could affect social behaviour.
It can be expensive - cows need to be darted repeatedly, which means paying for helicopter flying time, the services of a vet and the darts and vaccines.
An endless succession of sterile oestrous cycles in elephants is not good.
As far as males are concerned, all must be treated for contraception to be effective.