I always wondered if ALL female hummingbirds that migrate to SE Michigan in the spring lay eggs? Seems like I see females that are kind of chubby and some that are thin at this time of year.---thanks---ED
No, not all female hummingbirds that migrate will lay eggs. Although they typically reach sexual maturity in their 1st year, sometimes they don't. For one reason or another, even some adult females will not be in good enough condition to lay eggs. First year females may not have quite reached sexual maturity yet in their first year if they've had a really hard winter.