Increasing rates of habitat
destruction and exhaustive exploitation of natural resources have necessitated
the rapid collection of accurate data on the existing state of global
biodiversity. The 1992 U.N.
Conference on Environment and Development (known as the Rio Earth
Summit) produced eight internationally endorsed documents (including the
Convention on Biological Diversity)
that stress the importance of developing programs for the proper measurement
of recent changes in species diversity.
Extinctions are irreversible
changes in global biodiversity - therefore, we are very concerned about
measuring them accurately. Surveys describing the numbers and patterns
of recent extinctions help scientists better understand the processes
that cause these events. These surveys are also used by conservation
biologists and policy makers to provide measurements of negative impacts
The problem is that it is difficult
to know when the continued absence of a species means that it is extinct.
The problem may seem uncomplicated: a species is either still
around, or it is not -- what is there to disagree about? Unfortunately,
it is not so simple. A species that has not been collected or seen for
a long time may be extinct, or it may simply have escaped detection.
It is difficult, if not impossible, to prove that the absence of a species
(in recent times) is equivalent to its extinction. The best approach
is to compile all available evidence that a species is absent, and then
decide when the weight of that evidence is sufficient to assume that
extinction has occurred.
CREO has developed a research
program to determine what sort of evidence should be collected,
and how should that evidence be analyzed in order to determine when
and why a species went extinct. Data collected through this program
has a number of conservation applications
that can help us better understand the impact of extinctions on global