 |
How many animals
have to be treated?
This is an often-asked question,
but usually it is asked without
much understanding. The number of animals or percent of an
animal population that needs to be treated is dependent upon
many factors and there is no simple answer. For example, what
is the goal? Is it the absence of all animals (impossible
with contraception), or a 20% reduction or a 50% slowing of
the growth rate or zero population growth? Even after the
goal has been identified, data required to answer this question
include at very least the reproductive rate, mortality rate,
and immigration and emigration rate of the population. Equally
important, these data on reproduction and mortality must be
site-specific to the particular herd in question and not generalized
data or data derived from other locations and populations.
One of the most serious deficiencies noted at discussions
of new projects is the lack of sound biological data and vague
or no goals.
Another consideration is the length of time necessary to achieve
population goals. Contraception is not a good way to reduce
population numbers rapidly. It takes time for animals to die
off and, as seen earlier, one of the results of wildlife contraception
may be increased longevity among treated animals (see Turner
and Kirkpartrick 2002). Wildlife contraception must be viewed
as a long-term commitment. Also, humans should consider that
most wildlife overpopulation problems were created over many
years and that quick solutions are not the result of rational
thought or fair to the wildlife.
|
|
