Photos of the Northern Giant Mouse Lemur

Scientists have discovered a pipsqueak lemur sports some giant testes, breaking the world record for the biggest testis relative to body size of any primate. The little furball, which was only named in 2005, lives in the forests of Madagascar. (Images are courtesy of Eva Johanna Rode-Margono.) [Read the full story on the lemur's giant testes

Ready to procreate

The northern giant mouse lemur, Mirza zaza, has the largest testis per body size as any primate. If the lemur were human-sized, its testicles would be the size of grapefruits. The large testicles indicate that this lemur mates with many females, who in turn mate with multiple males. Greater testicle volume means more sperm to compete with rival males. 


The northern giant mouse lemur was first described by scientists in 2005. It lives in northwestern Madagascar, rarely coming down from the treetops, said Christoph Schwitzer, the director of conservation at the Bristol Zoological Society in the U.K. Adults weigh only about 11 ounces (300 grams) and the lemur's large eyes reflect its nocturnal habits. 

A young'un

A juvenile northern giant mouse lemur walks along a branch in Madagascar's Sahamalaza National Park. Deforestation is threatening the habitat of these newly discovered lemurs. They are listed as endangered by the International Union for Conservation of Nature. Efforts are underway to reforest parts of Madagascar to join scattered habitats, Schwitzer told Live Science. But it will be a long time before those new forests can shelter these and other lemurs. 

Tracking our friends

A northern giant mouse lemur wearing a radio collar so researchers can track its movements in the wild. Eva Johanna Rode-Margono of Oxford Brookes University and the Bristol Zoological Society caught 12 of these lemurs in live traps and fitted them with temporary collars. She found that they nest in groups of 8 or so. Unusually, these groups often include multiple unrelated males, a rare arrangement for primates. 

Tasty snacks

A radio-collared northern giant mouse lemur descends a tree in northwestern Madagascar. Rode-Margono observed three mating events during her fieldwork. Though the animals were largely obscured by vegetation, she could see the pairs sniffing and following one another, and could hear "hn" vocalizations, she reported in the American Journal of Physical Anthropology.

Whatcha lookin' at?

The northern giant mouse lemur is unusual among lemurs in that it seems to mate year-round. Only the aye-aye and the red-bellied lemur show this kind of "relaxed" mating pattern, Schwitzer said. Other lemurs have specific breeding and birthing seasons. 

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Stephanie Pappas
Live Science Contributor

Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.