Nature Notebook – Infertile Eggs in the Wild

As the spring nesting season approaches, we wondered: do wild birds lay infertile eggs as domestic chickens do?

Malnourishment or poor health cause egg problems. It takes a lot of energy to produce the next generation. Birds of larger species also take a bit longer to mature into successful egg laying. Immatures will occasionally lay eggs; these will almost certainly be infertile.

However, unlike domestic chickens, wild birds do not constantly lay eggs (fertile or infertile). Their ovaries shrink after the breeding season ends, probably to reduce the weight they must carry in flight.

Other egg-laying animals also produce infertile eggs. For some species it is a survival tactic.

The strawberry poison dart frog lays an unfertilized egg in the water of her tadpole’s bromeliad nursery each time she visits. This food helps the young survive to metamorphosis.

It has been found that some sharks also produce infertile eggs that become the sustenance for the pups hatched out of the fertile eggs.