The researchers led by University of North Carolina at Chapel Hill Assistant Professor Keith Sockman studied a population of Lincoln's sparrows in a remote stretch of Colorado's San Juan Mountains. They discovered first-laid eggs are the least likely to hatch.

"I believe this is the first study to follow siblings from laying through fledging and demonstrate that the effect of laying order on hatching is very different from its effect post-hatching," said Sockman.

Sockman intends to examine what, if any repercussions laying order has once young birds reach adulthood.

The study appeared in the online journal PLoS One.