Banner image: A ring-tailed lemur in a tamarind tree in a reserve in Madagascar. (Credit: by Frank Vassen via )
In 2003, a team of primatologists led by 兔子先生传媒文化作品 trapped, tagged and released a male ring-tailed lemur in the Bez脿 Mahafaly Special Reserve in Madagascar. The researchers captured him one more time in 2004, but after that, the lemur disappeared, never to be seen again.
That is, until 2008 when his internally placed electronic tag, similar to a dog鈥檚 microchip, showed up in a pile of scat from a forest cat. This predator is related to domestic cats and was likely introduced to the island off the coast of Africa hundreds of years ago.
Now, that case of cat predation is part of a new study exploring how such attacks could endanger the conservation of lemurs. Over the course of 14 months, researchers from the United States and Madagascar became lemur crime scene investigators. They gathered a wide range of data, including camera trap photos, scat samples and eye-witness reports to unravel the mystery of who is eating these primates at Bez脿 Mahafaly.听
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Camera trap photos from the听Bez脿 Mahafaly Special Reserve showing, from top to bottom, a troop of ring-tailed lemurs, two听Verreaux鈥檚 sifakas, a forest cat and a听dog. (Credit: Michelle Sauther/Frank Cuozzo)
Their findings suggest that predators not native to Madagascar, such as forest cats and dogs, may kill more lemurs than scientists once believed. Lemurs live only in Madagascar, and several species are already in danger of going extinct.听
鈥淚t鈥檚 not that people didn鈥檛 know that predation was happening,鈥� said Michelle Sauther, lead author of the new study and a professor of anthropology at 兔子先生传媒文化作品. 鈥淏ut they鈥檝e mostly been looking at other conservation priorities like the effects of deforestation.鈥�
She and her colleagues in the journal Folia Primatologica.
The study focused on Bez脿 Mahafaly, a roughly 242-acre protected area at the southwestern tip of Madagascar. Here, tamarind trees grow along river drainages, turning a lush green during the rainy season from October to March. The reserve is home to four species of lemurs: the ring-railed lemur () and Verreaux鈥檚 sifaka (), which are out during the day; the white-footed sportive lemur () and the grey-brown mouse lemur () are awake at night. Of those, all but the mouse lemur are considered endangered or critically endangered.听
Sauther, who has been studying lemurs in Bez脿 Mahafaly since the late 1980s, sees the research as an example of what scientists can discover when they really get to know a natural area.
鈥淲hen you鈥檙e doing a long-term study and you come back year after year, you find out things are not always the way you think they are,鈥� she said.
Scat detectives
Lemurs have several natural predators. They include the fosa (), a strange mammal that is related to the mongoose but is much bigger and looks a bit like a puma. Before this study, researchers thought that the fosa had been extirpated from the area.听
In 2008, Sauther and her colleagues noticed that something seemed to be amiss in the reserve. One day, they heard a troop of ring-tailed lemurs screaming and found a recently killed lemur on the forest floor.
鈥淭hat year, we were walking through the forest looking for lemurs, and we kept finding dead guys,鈥� she said. 鈥淲e thought: 鈥楽omething鈥檚 going on.鈥欌��
Her team, including Frank Cuozzo, who earned his doctorate in biological anthropology from 兔子先生传媒文化作品 in 2000, decided to investigate. The study was a massive operation: From June 2008 to July 2009, the group set up cameras at nine locations throughout the reserve. Researchers walked for miles along trails every week to search for scat and lemur predation. They then sifted through those droppings to look for bones or other evidence of predation.
In all, the team collected 13 examples of predator attacks on lemurs, including the case of the ring-tailed lemur whose electronic tag showed up in cat scat. At least six of those primates were probably killed by dogs or cats. Another five may have been the victims of either cats or fosa, which leave behind similar tooth marks. The team concluded that a combination of fosa, forest cat and dog predation can lead to potentially dangerous spikes in lemur deaths.
鈥淭hat鈥檚 when we really started thinking: 鈥榃ow, there's a lot of predation here from endemic animals like the fosa, but also the introduced animals like dogs and forest cats,鈥� said Cuozzo, now affiliated with the Lajuma Research Centre and the Mammal Research Institute at the University of Pretoria in South Africa.听
Predator spectrum
Sauther noted that cats and dogs may be so effective at preying on lemurs because the primates haven鈥檛 had much time to evolve defenses against these new arrivals. In a previous study, she and her colleagues used DNA evidence to show that Madagascar鈥檚 forest cats are descended from domestic cats from the Arabian Sea region鈥攁nd likely came to the island aboard merchant ships.
She and Cuozzo can鈥檛 be sure how much of a dent these predators are making in lemur numbers. But they suspect that it鈥檚 more than scientists have previously accounted for. Across Madagascar, populations of most lemur species are continuing to decline today. 听
The researchers urge scientific funding groups to support more long-term research projects that can unravel the full spectrum of threats facing endangered species.听
鈥淧redation is a dynamic process,鈥� Sauther said. 鈥淵ou can鈥檛 just say: 鈥楥ats are doing this, and dogs are doing that.鈥� You really have to look at what the whole predator group is doing.鈥�
