Three true blackbirds can be found here

There are a lot of black birds but not all of them are Blackbirds.
We have quite a few birds in the same family, including orioles, meadowlarks, and the bobolink. But we also have three black birds which are true Blackbirds, and can be quite confusing to the amateur birder.
•Brewer’s Blackbird (Euphagus cyarocephalus)
The male of this bird is black, of course, with quite a high gloss of purple and green. The female is duller, with more brown or greyish, especially on the underparts.
The male bird has a yellow eye, the female a brown one. Watch those eyes–they have some importance! Both become much less coloured in the fall.
In the summer, they generally hang around in fairly small groups in fields, pastures, and on lawns.
Brewer’s has a terrible voice–a sort of harsh, grating squawk. It is a western bird but rapidly spreading into the eastern provinces.
•The Rusty Blackbird (Euphagus carolinus)
This is quite hard to differentiate from the first one. This time, both male and female have yellow eyes. Once again, the male is black with an iridescence of faint purple or green. The female is similar but duller.
But here’s where the name comes from. In the fall and winter, the female becomes decidedly rusty looking, mottled with various browns.
This bird is most often found near water–marshes, pond shores, river banks, and so on. It nests in small groups. And once again, its voice is terrible, usually described as being like a rusty hinge.
Rusties breed right across Canada from coast to coast. To tell the males of the two species apart is quite a feat.
•Common Grackle (Quiscalus quiscula)
This one is much larger than the other two. It also has a big, wedge-shaped tail, and the iridescence is very prominent–purple on the head part and bronze on the back.
A while ago, they were thought to be two separate species, Bronze and Purple, but now we know that they are just variations of the same one.
This bird is found from Alberta east to the Atlantic. Its song is a short squeak but it goes around saying “chack” a lot. It is quite easy to recognize.
In the fall, blackbirds of all kinds tend to flock together. In Canada, a flock of several thousand can do a lot of damage to a farmer’s corn in the early part of autumn.
But how about flocks of four or five million? That’s the kind they get in Kentucky and Tennessee. These flocks can do terrible damage to agriculture, are always a danger to aircraft, and may present a problem in human health.
Lots of people want to eliminate several million of these birds while they are available in such large concentrations. But examination of their food indicates they consume immerse quantities of weed seeds and harmful insects, as well as some grain.
A lot more study will have to be done to find out how to control these birds, or if we really do want to control them. Questions in nature never seem to have a black-and-white answer.

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