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Olives spreading. (Journal extracts).

LIKE THE people of the Mediterranean, many birds and small mammals are fond of olives. In Australia, this fondness can be indulged on a grand scale, as olive groves for commercial or hobby purposes have been planted in almost every state. But the olive oil industry these groves were originally destined to supply did not succeed, and so today, many groves stand neglected, visited only by their furred and feathered friends.

As feral olives are considered noxious weeds in some states -- they form dense crowns that prevent native trees regenerating -- the foraging activities of birds and small mammals is a problem.

In a recent review of birds that consume olives, Dirk Spennemann and Richard Allen, from Charles Sturt University at Albury, showed that a number of native Australian birds contribute to the spread of olive trees.

They found that the pied currawong, emu, Australian magpie, satin bowerbird and black-faced cuckoo-shrike, were all tong distance seed dispersal agents. The regurgitated pellets of pied currawongs for example, have been found to contain up to 23 olive seeds. Exotic birds, such as blackbirds and common startings, are also guilty of seed dispersal.

But some Australian birds enjoy olives without contributing to their dispersal. These include the galah, sulphur-crested cockatoo and crimson rosella, which feed on fallen olives or remove droops from the tree and drop the pits beneath.

Although birds are the principal seed dispersal agents, rabbits, sheep, goats, foxes and mice also play a role. Spennemann and Allen warn that the variety of dispersal agents will increase as the size of olive droops decreases -- a consequence of naturalisation and neglect -- which may accelerate the dispersal of olives as weeds.

Spennemann DHR and Allen LR (2000) The avian dispersal of olives Olea europaea: implications for Australia. Emu, 100: 264-273.
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Title Annotation:certain animals and birds contributing to spread of feral olives
Author:Pyper, Wendy
Article Type:Brief Article
Geographic Code:8AUST
Date:Jan 1, 2001
Previous Article:Lone box warning. (Journal extracts).
Next Article:Modelling the forces of nature.

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