Pointy eggs more likely to stay put in birds' cliffside nests, study finds

Date: August 22, 2018

Source: University of Illinois at Urbana-Champaign

Natural selection -- that merciless weeder-outer of biological designs that are out of step with the times -- also is a wily shaper of traits. Exhibit A is the pointy murre egg, according to new research published in the Journal of Experimental Biology.

Common murres and thick-billed murres tend to nest in tightly packed colonies on craggy seaside cliffs. The ledges on which they lay their eggs can be quite narrow, sometimes "as shallow as the egg is long," the authors of the new study wrote.

"Very little is known about how the murre egg shape affects its stability and viability in this setting," said University of Illinois animal biology professor Mark Hauber, who conducted the study with former Hunter College graduate student Ian Hays. Many have theorized that the shape makes the eggs less likely to roll off of cliff ledges, he said. "But earlier studies failed to isolate specific features of the eggs -- such as elongation, asymmetry and conicality -- to robustly test this hypothesis."

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