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A toehold on swimming

Gteborg, Sweden - Ian Thorpe, the teenage Australian with size-seventeen feet, collected two world records and two gold medals on the Olympics opening day. Large feet are all very well, but asymmetric toes are the real aids to underwater swimming, at least in one unusual bird.

In this week's Nature magazine, Ulla Lindhe Norberg and L. Christoffer Johansson of Gteborg University, Sweden, report on the lopsided feet of the great crested grebe (podiceps cristatus) - a member of an ancient bird group with no close living relatives.

The skin flaps on grebe toes are thinner on the lateral side of the toe. This helps to keep the toes steady as the feet generate the hydrofoil-like lift that powers the birds through the water - similar to the action of feathers during flight.

Butterflies - the new canary in the coalmine

CLEAR CREEK CANYON, COLO. - Butterflies fill the sky over Clear Creek Canyon like a ticker-tape parade. Aphrodites, lupine blues, coral hairstreaks, and a western tiger swallowtail large enough to cast a shadow over wild carrot and dill plants, all flutter within 50 yards of a bustling mountain road.

Since 1976, amateur lepidopterists, have flocked to this gorge west of Denver for the annual butterfly census. The event is repeated nationwide by 4,000 volunteers at 450 locations.

The butterfly count is not an act of frivolity. Butterfly populations indicate an ecosystem's vitality. They are acutely sensitive to environmental change, pesticides, and pollution. The 2000 results were good and bad with 102 species documented, 11 shy of the record. It is a remarkable sum considering the very dry weather in the West. The bad news: Many species are represented by only one or two insects.

(c) Copyright 2000. The Christian Science Publishing Society

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