There has been a pair of crows visiting the back yard for a couple of months, where they compete with the squirrels for the old bread we put out. We assume they are a male and a female, as one is notably larger than the other.
Today only the larger one is coming round. I’m guessing that the assumed female has laid some eggs and is staying with them. The larger, presumably male, crow picked up as much bread as it could and flew away, then came back and ate some on the spot. Probably playing the breadwinner and taking food home to the little missus?
As it is March, and overnight temperatures are no longer freezing here in the coastal Northwest, is this about the time the crows would be laying eggs?
According to one source on the Internet (take with a grain of salt)… “It depends on where you are, but in the Northern United States and Canada they start nesting at the end of March, fledging young in late May or June”
I think in general many animals tend to have babies born in the spring. That gives the offspring as much time as possible to mature before cold weather returns.
Male and female crows are the same size. There are, however, different kinds of crows: American crow, fish crow, and Northwestern crow. From my Sibley book, it appears that the Pacific Northwest has possibly all three. The American crow is 17.5", the Northwestern crow is 16", and the fish crow is 15". Further, there are variations in sizes in all 3 kinds. The only way to determine which kind it is is by its call. Hence, you cannot assume that they are male and female, but more likely just two different crows - possibly even different kinds.
For many birds, such as eagles and other predators, that’s true, but I don’t know if “most” is correct. I would say, and a glance through Sibley corroborates, that in most birds there is no difference in size. The difference in the sexes is mainly color, if there is a difference. In most cases, the male has the more beautiful color (to attract a mate) while the female is drab (to be inconspicuous), but there are exceptions.
