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The Butaan Project - Foraging behaviour Print E-mail

butaan7.jpgWe use feces to investigate diet and activity areas of butaan. In total we have examined more than 1500 samples, possibly the largest ever collected for a single population of reptiles.  Butaan and their relatives are huge specialised frugivores, much bigger than any other specialised frugivorous animal in  the Philippines. They need a constant supply of fruit but lack the wings that allow other frugivores to forage in different forest fragments. Large and immobile, the butaan depends on a very narrow range of foods.



Butaan on Polillo eat fruit and snails. Sometimes they eat crabs and another animals, but this is rare. Butaan require a mixture of fruit species that are taken either simultaneously or consecutively
The most abundant fruits are only eaten when preferred fruits are not available. Many plant species important in the diet do not show a clear fruiting cycle. Although there are hundreds of fruits in the forest that have the potential to be food, butaan only feed on a very narrow range of mainly large-seeded species. The seeds pass through the lizards without damage and so the lizards act as seed dispersers for the plant. There are few competitors for most of the fruits eaten by butaan. Some of these fruits seem to have evolved to attract large animals, such as elephants, which no longer exist in the Philippines. The butaan has been able to exploit these resources and has evolved a unique ecological niche. At the same time it has provided a very unusual method of seed dispersal for plants that have very limited dispersal strategies, such as Pandanus
700+ species in Africa, Asia and Australasia. 40+ species in Philippines.
Mainly distributed along coasts and waterways.
Exclusive microhabitat of many endemic species of vertebrates, invertebrates, plants and fungi.
Most species are dispersed by water, others by crabs, turtles, rats and by butaan in the Philippines.
We suspect that butaan has a marked effect on the understorey of forest throughout its present range by dispersing Pandanus seeds. This results in high densities and unique distribution patterns of Pandanus on ridges and slopes - clumps of seedlings uphill of any possible parent plant.

This also suggests that areas where the animals were present in the recent past may still show unique patterns of Pandanus distribution.

In recent years we have mapped the distribution of Pandanus and other species in different forest patches and are measuring the seed shadows produced when butaan feed from a tree. The results will shed light on the butaan's role as a seed disperser and how it can alter the dynamics of the forest understorey.





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William Oliver

William Oliver. Champion of biodiversity and its students. So many of us benefited from his advice and expertise. What a character. RIP.


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The Butaan Project
Monitoring Individuals 1

butaan1.jpgButaan are so shy they frequently remain in a tree for more than a week after being frightened. A large male we rescued from a trap hid in a tree for 22 days before coming down!* . Most lizards do not appear traumatised by being caught and released by scientists, and resume normal activity very quickly. But we think that butaan, especially older individuals, may permanently alter their activity areas after such an encounter. Because the animals are so shy, and highly vulnerable to human disturbance, we have had to develop a range of techniques that allow us to learn about them with the absolute minimum of interference.





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