While perusing this AFP piece about a poaching bust in the Central African Republic, we stopped and mumbled “hmmmmm” upon reading this hard-to-swallow stat:
Experts say some 38,000 African elephants are killed each year for their tusks.
Really? That seems like such a ridiculously high figure; at that clip, wouldn’t the species (or, to be precise, the genus) be entirely extinct before the next Summer Olympics, if not sooner?
As it turns out, African elephants are seemingly much more plentiful than their Asian brethren. But we must take the estimate of 600,000 survivors with a grain of salt, because counting pachyderms is a tricky, tricky business. The animals not only hide from aerial surveyors but, as we’ve noted previously, may conceal the corpses of their deceased relatives. So what’s the solution? Using sound:
Geophones were used to record the footfalls of elephants and other large mammal species at a water hole in Etosha National Park, Namibia. We were able to discriminate between species using the spectral content of their footfalls with an 85% accuracy rate while only using a single geophone. This was done using correlation coefficients comparing the shape of the spectra for various species. An ANOVA found significant differences between these correlation coefficients (F4,1785 = 147.78, P = 0.000). An estimate of the energy created by passing elephants (the area under the amplitude envelope) can be used to estimate the number of elephants passing the geophone.
We do wonder, however, if such a method is able to account for the footfalls of babies—or, for that matter, how it differentiates between the sounds made by elephants, hippos, and rhinos in areas where the giant mammals co-exist.
(Image via Sideshow World)