Dr. Caren Cooper is collecting data on variation in House Sparrow (Passer domesticus) eggs.
Because House Sparrows are a nonnative species, they are undesirable inhabitants of nest boxes in North America, but they are an easily accessible study species that can be used to address ecological questions without disturbing native birds.
Researchers at the Cornell Lab of Ornithology are studying this species to help better understand the enormous variation in eggshell patterns and color. House Sparrow eggs exhibit an extraordinary amount of variation. Eggshell coloration and pattern may vary with available calcium, sunlight patterns, or habitat quality, and are expected to differ seasonally and geographically as well.
NestWatch participants are encouraged to submit digital photographs of eggs to Dr. Cooper, together with sufficient information to make scientific comparisons. Follow the link for more details.