Saving large mammals such as elephants and rhino from extinction could
be made more effective by focusing efforts on individual species as
well as their habitats.
Scientists at the Zoological Society of
London’s Institute of Zoology (IoZ) and Imperial College London have
identified fundamental new approaches to improve the success of large
mammal conservation. Published today in the journal Science, the
largest study of its kind analyses key factors linked to the extinction
large bodied mammals are at greater risk of extinction," comments
Professor Georgina Mace of the IoZ, "Now we understand the mechanisms,
we are able to tailor conservation programmes dependant on size, to
ensure they’re more effective."
The study showed that extinction
risk in smaller mammals, below approximately 3kg (about the weight of a
small domestic cat), is determined primarily by the size and locations
of their distributions, and the human impact to which they are exposed.
Larger mammals have the additional pressure of biological disadvantages
such as long gestation period and late weaning age to contend with,
significantly increasing their susceptibility to extinction.
a world dominated by people, being big is substantially more of a
disadvantage than we realised, which implies that the conservation of
large mammals should assume a particular urgency," said Dr Marcel
Cardillo of Imperial College London.
"From a conservation policy
angle, the message would be: small may be conservable but it is a
little trickier for the larger mammals," commented Dr Andy Purvis of
Imperial College London.
The research findings suggest smaller
species, of around less than 3kg, would benefit from conservation of
their habitat area, whereas, larger bodied animals require a different
approach, focusing upon the specific species, their biology and their
"This understanding enables us to predict what species
are most at risk in the future," said Dr Purvis. "That provides a way
for conservationists to go on the front foot rather than wait for
accidents to happen. We can try to work out which species are the ones
we can do something for, and do some pre-emptive conservation planning.
Of course, prevention is always cheaper than cure."
means large bodied mammals such as ungulates (which include rhino and
zebra) and many primates are more likely to be predisposed to decline
Biological traits such as low population
density, slow life history, late weaning age and extended gestation in
mammals above a certain size means they are evolutionarily
disadvantaged in the face of human impact, compared to species of
smaller size. Large mammals may therefore need a more complex
conservation strategy, which takes into account their biology in
combination with the external threats they face.
Imperial College London. July 2005.