After decades of conservation efforts, the common hippopotamus population has finally recovered after years of poaching. The good news was announced in a newsletter published by the International Union for Conservation of Nature's Pigs, Peccaries, and Hippos Specialist Group.

"The hippo is one of Africa's iconic species, one that is becoming increasingly threatened by hunting and other factors," said Deo Kujirakwinja, Wildlife Conservation Society Scientist and the author of the report. "Our findings that hippos are on the increase is encouraging and evidence that efforts to protect hippos and other species are working. "

The increase in the number of hippopotamus is likely the result of improved enforcement in Virunga National Park's portion of Lake Edward and nearby river systems. Local fishermen and park authorities in both the Democratic Republic of Congo and Uganda also collaborated to support conservation efforts.

In the past, scientists had relied partly on aerial surveys. In recent years, more ground surveys were done since plane-based counts had to be avoided in many areas due to the presence of militias. Kujirakwinja and his team estimated that the current population of hippos in the park represents only 11 percent of the original population and only 8.2 percent of the peak population estimate of about 30,000 individuals made in the 1970s.

Virunga National Park used to contain Africa's largest known hippo population in the 1970s, with especially large groups found in both the Rwindi and Rutshuru rivers. Later surveys showed a dramatic decrease in the hippo population as a result of hunting, human development and agriculture. "This recent surveys have shown that the Ishasha River on the border with Uganda is now very important for their conservation and shows that transboundary conservation efforts are succeeding there," stated Andrew Plumptre, Wildlife Conservation Society senior scientist and co-author of the report.

The common hippo is known to be one of the largest mammals in Africa, reaching up to 13 feet in length and weighing up to 4,400 pounds. With a herbivorous diet and nocturnal feeding patterns, the hippopotamus would often be spotted at pools, rivers, and lakes where they can stay submerged for up to six minutes. The common hippo is listed as "Vulnerable" on the International Union for Conservation of Nature's Red List.