Mapping trees can aid with counting endangered lemurs

Counting how many endangered lemurs are left in the wild isn't easy, but researchers say that the plants they rely on for food might help. | Credit: David Haring, Duke Lemur Center

A majority of lemur species are near to extinction, warn scientists. But this might not bring bad news for every lemur species- there actually might be as many as 1.3 million white-fronted brown lemurs still living in the wild, for example, and the number of mouse lemurs may number more than 2 million, reports a study led by Duke University.

“For some lemurs, there may be healthy populations remaining and our conservation efforts are preserving them,” said James Herrera from the Duke University, who is also the lead author of the study.

In a study published recently in the Journal of Biogeography, researchers report that lemurs are less abundant in areas that do not have certain tree species — even when the environmental conditions such as temperature, precipitation and elevation are perfectly suitable.

Using this association, the team came up with the first estimates of the total population size for some lesser-known species, like Crossley’s dwarf lemur. These estimates can be vital for providing the baseline data for managing the lemurs that are left.

Nearly 95 percent of all lemurs fear extinction because of deforestation, hunting and other factors. Since the 1950s, more than 40 percent of their habitat has been destroyed. Forests are logged and cleared each year to make way for farms and pastures. Sometimes even burned and harvested as charcoal.

But obtaining reliable and accurate population numbers for these elusive animals that live in the wild is extremely difficult. Counting every lemur is nearly impossible. But there is one alternative route that scientists can take, which is based on statistical modeling, it uses the correlation between species densities at a subset of sites and environmental conditions at those locations to get data on how many individuals are present over larger areas.

Between 2011 and 2016, many teams of researchers strolled through the Ranomafana National Park, Makira Natural Park and Masoala National Park in Madagascar- looking for lemurs.

“We would wake up at 4:30 or 5:00 in the morning, hike for six to eight hours to look for lemurs, and then go back out at night with our headlamps on to search,” added Herrera, a postdoctoral associate in Duke professor Charlie Nunn’s lab.

“A lot of these species are small nocturnal animals that are only active at night,” so researchers rarely see them, Herrera said. “You can walk for hours and not see a single lemur.”

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