Saturday, 12 July 2008

The Good Old Food Web In Action

Fruits of the Kuranda Satinash, Syzygium kuranda.

These hard, golf ball-sized fruits of the Kuranda Satinash or Cherry Satinash (Syzygium kuranda) have been dropping from a height of some 40 ft on to our corrugated iron roof at night. Sounds like gunshots and it’s very hard to get used to. The reasons are Spectacled Flying-fox (Pteropus conspiculatus) (See April blog “Mammals”) chomping on the fruits and then dropping them and moving to another.

The ground is littered with these balls and has been for the past 6 weeks or so. Our sleep patterns have been disrupted. Fortunately this does not happen every year, in our experience, only every three years.

But there is a reason for all this. The bats drop the fruits and a host of other animals feed on them. Rats carry them away, Musky Rat Kangaroos gnaw on them scraping at bit off and Cassowaries eat them and thereby move the seeds, and the plant species to different sites. We observed the female eat 19 in a row. Sulphur-crested Cockatoos feed on the fruits and sometimes fly off with one. They don’t seem interested in the seed itself, only the external coating. They eventually drop the seed some distance away from the parent plant, thereby spreading the species.

Fruit of the Kuranda Satinash after feeding by the Spectacled Flying-fox bat—and dropped from about 40 ft on to our roof!

Food seems scarce for ground dwellers during the dry season. There is not much around. We see seeds of the Lawyer Palms (Calamus spp.) But the hard fruits of the Kuranda Satinash are consumed by our largest visitor, the Cassowary. Only the adult Cassowary seems to eat these fruits. The juveniles pick them up but drop them. Perhaps, their digestive system is such that either the fruit its too large or too hard for it to be digested. I noticed that the Cassowary was very choosey. It dropped fruits that had been gnawed by the bats and only ate ones that were mainly intact.

Mr Cassowary feeding on Kuranda Satinash fruit.

Kuranda Satinash fruits in Cassowary dung. They are probably ready for germination.

Time for a lie-down. Must not be getting enough sleep. It’s probably the noise!

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