Latest Issue of Science News


News

Risk of egg diseases may rush incubation

Bird eggs can catch infections through their shells, and new tests in the wild suggest that this risk may be one of the pressures driving avian parents to start incubating eggs with a timing that puzzles biologists.

Birds lay an egg a day at most. Many bird species let early eggs in a brood sit unincubated for several days but begin incubation before the last eggs are laid. Since the eggs need the same number of incubation days, the eggs end up hatching at different times. This leads to siblings of different sizes, the bigger of which sometimes kill the smaller ones.

The debate over possible benefits for this staggered hatching has overlooked the risk of egg diseases, according to Mark I. Cook of the University of California, Berkeley. Studies of farm fowl have shown that a warm parent on top of an egg keeps moisture away and discourages microbial growth. So the longer a parent waits to start incubating, the greater may be the chance of eggs becoming infected.

Note: To comment, Science News subscribing members must now establish a separate login relationship with Disqus. Click the Disqus icon below, enter your e-mail and click “forgot password” to reset your password. You may also log into Disqus using Facebook, Twitter or Google.

X
This article is available only to subscribing members. Join SSP today or Log in.