Learn to Get to Grips with the Avian Food Chain ; Here's What I Think ... About the Decline of Small Birds

Summary

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P HEMMINGS' letter "Birds in Decline" in these pages on Wednesday, June 9, asks for readers' opinions on the decline of small birds.

I can offer the following. The sparrowhawk is a top level predator and can only survive if sufficient food is available for it to take. In any food chain, the top level predator is the first to decline in the event of a shortage of food, followed by each level in the chain all the way down to the plant at the foot of the chain. A simple example, using simple numbers for ease of understanding, would be a single oak tree whose 1,000,000 leaves support 10,000 caterpillars.

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Learn to Get to Grips with the Avian Food Chain ; Here's What I Think ... About the Decline of Small Birds

Those caterpillars are taken as food by a single blue tit that lives in the tree. However, the single oak tree cannot support a top predator and it would take 10...

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