FSD 2010 - Lemurs

5th International Symposium-Workshop on Frugivores and Seed Dispersal (1985-2010)

Lemurs

Mongabay.com News, August 20, 2009: "New pictures released by Conservation International depict a troubling development in Madagascar: the emergence of a commercial bushmeat market for lemurs."

Lemurs are primates endemic to the island of Madagascar and smaller surrounding islands, such as the Comoros. Lemurs usually have a vegetarian diet, consisting of leaves and fruit, although they will occassionally eat insects or smaller animals. Among them, the small cheirogaleoids are generally omnivores, eating a variety of fruits, flowers and leaves (and sometimes nectar) as well as insects, spiders and small vertebrates. The remainder of the lemurs - the lemuroids - are primarily herbivores, although some species supplement their diet with insects. Other such as all indriids are vegetarians, eating leaves, buds, fruit, bark, and flowers. They occupy a plant-eating primate niche that is occupied by howler monkeys in the neotropics and and leaf-eating monkeys in Africa and Asia.

Lemurs are Seed Dispersers

Herebelow, we reproduce most parts of an article of John Roach for National Geographic News because it is very interesting and fits with the scope of FSD2010.

"On the African island nation of Madagascar, only primates called lemurs are big enough to move the seeds of many trees around and thus improve the chances of the trees' survival.

"Lemurs are very important seed dispersers in Malagasy rainforests," said Chris Birkinshaw, a biologist with the Missouri Botanical Garden in St. Louis who is an expert on lemur seed dispersal. Birkinshaw recently conducted a study in the Lokobe reserve in the northern part of the country. He found that 54 percent of the tree species and 67 percent of individual trees there had grown from seeds dispersed only by the black lemur, a medium-size primate. Lemurs spread the seeds by eating the trees' fruits and expelling the seeds as they defecate. Lemur populations are dwindling on the 225,000-square-mile (580,000-square-kilometer) island. Conservationists fear that the trees that rely on lemurs will disappear along with the primates

"[The trees' fruits] are some big foods, and there's nobody around anymore except lemurs and maybe, possibly, [introduced] pigs who can eat these foods and disperse the seeds," said Joerg Ganzhorn, a primatologist at the University of Hamburg in Germany.

The clearing of forests to make way for seasonal crops and provide grazing for cattle are the major threats to Madagascar's forests. But areas that look healthy but contain small lemur populations presumably contain trees without adequate seed dispersal, Birkinshaw said.

"In such forests, wind-dispersed trees or trees dispersed by small birds would have a competitive advantage over lemur-dispersed species, leading perhaps to changes in their relative abundances," he said. "Reintroduction of seed-dispersing lemurs should be considered in such circumstances." The lemurs swallow seeds of such size because they are covered in a fleshy reward that the primates are unable to separate from the seed. To get it, they have to swallow. "The seeds are normally shaped so that they are easy to swallow—similar to the shape of capsules or tablets given by the doctor—and are also slippery, so that once they are taken into the mouth, they are swallowed almost without noticing," Birkinshaw said. As the lemurs digest the fleshy fruit, the seed is passed through their system, normally away from the parent tree. Once on the ground, the seeds take root.

Special Adaptations?

According to Birkinshaw, some fruits in Madagascar are especially adapted to lemurs. For example, he said their fruits tend to be dull in color, owing to lemurs' poor color vision, but have a smell the primates find attractive.

Birkinshaw said that while he is unable to distinguish the smell of the fruits, lemurs have a much greater sense of smell and "clearly can" smell a particularly desirable fruit from a great distance. (Birkinshaw 2001)

"Sometimes groups move a long way, say 300 meters [1,000 feet] out of their normal territory to exploit a particularly desirable fruit source that they had not previously been near," he said. "I can only think that they knew it was fruiting because of the scent of the ripe fruits."

The other alternative, he said, is that

the lemurs are able to predict when particular fruit sources are available in different parts of the forest based on previous experience. "[That] would be even more remarkable," he said. Ganzhorn, the German primatologist, said he has a difficult time finding convincing evidence that fruits are adapted to lemurs, which he says will eat anything that is ripe.

"There are definitely fruits that are only eaten by lemurs and that situation is in all forests of Madagascar," he said. "But except for size, there is no convincing correlation between characteristics." Nevertheless, lemurs are the only animals left on the island nation large enough to disperse many of these seeds. And they have become a long-term conservation priority, Ganzhorn said. "If these animals are gone, then the forest has a harder time regenerating. For long-term conservation, it is important [to have lemurs]," he said. "The problem is that in the short interval and time scale, these forests will be gone, because people simply cut them."

References

Birkinshaw, C. 2001. Fruit characteristics of species dispersed by the black lemur (Eulemur macaco) in the Lokobe Forest, Madagascar. Biotropica 33:478-486. Abstract

Bollen, A., L. Van Elsacker, and J. U. Ganzhorn. 2004. Tree dispersal strategies in the littoral forest of Sainte Luce (SE-Madagascar). Oecologia 139:604-616. Abstract

Bollen, A., Donati, G., Fietz, J. Schwab, D., Ramanamanjato, J-.B., Randrihasipara L., van Elsacker, L. and Ganzhorn, J. 2005. An Intersite Comparison of Fruit Characteristics in Madagascar: Evidence for Selection Pressure Through Abiotic Constraints Rather Than Through Co-Evolution. pp. 93-119. In Dew, J. L. and Boubli, J. P. (Eds), Tropical Fruits and Frugivores, Springer Netherlands. Abstract.

Dausmann, K. H., J. Glos, K. E. Linsenmair, and J. U. Ganzhorn. 2008. Improved recruitment of a lemur-dispersed tree in Malagasy dry forests after the demise of vertebrates in forest fragments. Oecologia 157:307-316. Abstract

Ganzhorn, J. U., J. Fietz, E. Rakotovao, D. Schwab, and D. Zinner. 1999. Lemurs and the regeneration of dry deciduous forest in Madagascar. Conservation Biology 13:794-804. Abstract

Irwin, M. T., K. E. Samonds, J. L. Raharison, and P. C. Wright. 2004. Lemur latrines: Observations of latrine behavior in wild primates and possible ecological significance. Journal of Mammalogy 85:420-427. Abstract

Lahann, P. 2007. Feeding ecology and seed dispersal of sympatric cheirogaleid lemurs (Microcebus murinus, Cheirogaleus medius, Cheirogaleus major) in the littoral rainforest of south-east Madagascar. Journal of Zoology 271:88-98. Abstract

Lehman, S. M. 2007. Spatial variations in Eulemur fulvus rufus and Lepilemur mustelinus densities in Madagascar. Folia Primatologica 78:46-55. Abtsract (not operational)

Wright, P. C., V. R. Razafindratsita, S. T. Pochron, and J. Jernvall. 2002. The key to Madagascar frugivores. Pages 121-138 in Symposium on Tropical Fruits and Frugivores - The Search for Strong Interactors, Panama City, PANAMA. Abtsract

Web

Mongabay - Photos of lemurs are courtasy wildmadagascar.org - More photos - News about Madagascar

Chris Birkinshaw at MOB

Lemurs News IUCN group

Conservation International Madagascar

WWF Madagascar

Wildlife Conservation Society Madagascar

Interview of Patricia Wright by Mongabay - Patrica Wright