Madagascar – Nocturnal Lemurs, What big eyes you have

Written by Ute Radespiel, TiHo Hannover
Photos Courtesy of Ben Evans

Nocturnal lemurs account for more than two thirds of all known lemur species but we know much less about many of them than about their diurnal cousins. Like all lemur species, they are endemic to Madagascar, meaning that they cannot be found anywhere outside Madagascar. We are surveying the Mariarano forest for these elusive creatures as part of the Operation Wallacea activities and my research program at the Institute of Zoology in Hanover, Germany. We study the behavior and ecology of these elusive creatures of the dark, since we ultimately aim to understand their evolution and their chances of survival in the remaining forest fragments in Madagascar. How do we study them? The first way is that we conduct nocturnal surveys (performing distance sampling) along forest paths at the beginning of the night. Surveys are conducted at a very slow pace so that we don’t overlook the lemurs. How do you detect them? You have your headlamp on and if you’re lucky, you’ll see two little orange eyes glowing up next to the trail that you are walking on. If the eyes are tiny, they belong to a mouse lemur, the smallest primates living on earth (30-70g). If the eyes are larger, you’re probably meeting a cat-sized sportive lemur or a woolly lemur (ca. 1kg). Sometimes, you only hear their voices which are very prominent and characteristic in the case of sportive lemurs. Mouse lemurs, on the other hand, can more easily be seen than heard, since their vocal communication is mostly in the ultrasonic range, i.e., high above our own hearing range. Once we spot a lemur we note down the species name, the number of individuals, the perpendicular distance from the observer and the GPS coordinates of where we are. This data is then recorded in our database back at camp and used to monitor patterns and trends in the abundance and distribution of mouse lemurs in the Mariarano forest. As well as walking sample routes to collect data on their distribution within the forest we are also trapping  them to  collect morphological data to study their population ecology and we determine characteristics such as their weight, sex, and body condition. When we catch them we are also able to mark them permanently with unique microchips and provide them with small radiocollars that enable us to locate them and perform direct observations of individually known animals at nighttime to collect data on their behavioral ecology (e.g. feeding behavior and location of sleeping sites). At the end of each trapping day we release the mouse lemurs back into the forest. There are still so many open questions that we will not run out of interesting student projects for the next years to come.

Golden-Brown Mouse Lemur, Microcebus ravelobensis

An Account from our Students

“In almost 2 weeks time we have gone from being confused and meeting our supervisors to confidently doing our observations on our nocturnal lemur routes. Every night we go out to a route and keep our eyes peeled for eye shine and vocalizations. There was one night that a sportive lemur called right next to our trail and scared us silly. Even though we are focused on looking for woolly, sportive, and mouse lemurs at night we get to see all kinds of creatures during the day and night. We’ve seen tons of chameleons, geckos and snakes. Along with working on our project we lend a hand with other dissertation projects as well, identifying birds, frogs, reptiles, invertebrates, and of course mammals; getting hands on experience on a daily basis. Free time is also a blast since the people are amazing. At camp we pass the time by joking around, playing games, impersonating each other’s accents and watching movies. All of us are animal obsessed which is great because it is impossible to go a day without seeing animals that you literally cannot see anywhere else. This is truly a trip of a lifetime and we cannot wait to see what tomorrow has in store for us.”

Milne-Edwards’ Sportive Lemur, Lepilemur edwardsi