Fewer Tusks: Elephant Surveys After the Poaching Years

Counting Tusks from the Air

1The wildlife club at Dunmore Middle School meets once a month by video with Dr. Thandi Mokoena, an ecologist at a large wildlife reserve in southern Africa. This month eighth grader Alejandro Brennan-Moyo asked her about a photo of an adult female elephant with no tusks at all.

2Dr. Mokoena explained that tusks are long teeth. Elephants use them to dig for water and salt, strip bark from trees and push things aside. Being born without tusks is an inherited trait, and almost all tuskless elephants in the reserve are female. A tuskless female can still eat, raise calves and live a long life. Female elephants usually have their first calf at about 12 years old and only one calf every four or five years.

3Ivory comes from tusks, and for 15 years the reserve suffered heavy poaching, meaning illegal hunting, for ivory. Poachers mostly shot elephants with tusks. Just before those years, rangers flew over the reserve in a small plane and photographed every adult female they could find. They identified each one by the notches and tears in her ears and recorded whether she had tusks. This was Survey A. Each survey took about three weeks of flying, and the same two rangers checked every photo. When guards finally stopped the poaching, the rangers flew again and checked which of those same females were still alive. This was Survey B. None of the females from Survey A had changed from tusked to tuskless.

4Twelve years after the poaching ended, the rangers ran Survey C. This time they counted young females born after the poaching, aged 3 to 11, old enough for any tusks to show. They also used the ear records to find each young female's mother. Half of the mothers they found were tuskless, and half had tusks.

5Alejandro noticed that Survey C had fewer tuskless young females than he expected. Dr. Mokoena said that a tuskless mother passes the trait to many of her daughters, but not to all of them. She added that scientists have seen the same kind of change in other parks where elephants were hunted heavily for their ivory.