Ecological significance of tool-use in the woodpecker finch Cactospiza pallida

The Woodpecker finch, one of 14 Darwin's finches of the Galapagos Islands, uses twigs or cactus spines to pry insects and spiders out of tree-holes. The advantage of using tools may seem evident, but empirical evidence is scarce.

In a paper soon to appear in Ecology Letters, Tebbich and colleagues present the first study on the ecological relevance of tool-use by a bird species.

Woodpecker finches hardly use tools in humid areas where food is abundant and easily accessible. In contrast, in arid coastal areas where food is scarce, Woodpecker finches rely almost exclusively on the extraction of food from bark and tree-holes and use tools frequently. They acquire a greater proportion of food with this technique than any other animal hitherto studied.

In the dry areas tool use is even more profitable than using conventional foraging techniques. Although it takes more time, prey obtained with the help of tools is larger and contains more energy.

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