In having a few encounters with this species, I wondered why they were of concern and considered a "reportable" bird. In all my years of birding, I have only seen them a few times myself. My yard is pretty attractive for a wide variety of wildlife having woods of mature trees and a swampy pond area behind the property. Yet, only a few times in my life have I had the pleasure of saying my yard hosted a Rusty Blackbird. My first observation was in the winter of 2007, again in 2008, and finally just this weekend - all single individuals and at times when the weather was really crummy or it was snowing out. Only one other time did I see a few in one place at a fellow birder's house during an annual Christmas Bird Count.
This was once a common bird, and according to the Connecticut Audubon Society and Cornell websites, this species has declined so significantly and reasons are yet to be determined. So, it is a big deal to see them and report them in. A group in New Hampshire has banded several birds and ask that people report them in to Carol Foss at firstname.lastname@example.org. Below is a link to the page on the CT Audubon site with further information about the bands and how to report the birds.
The bird itself is not much larger than a Red-winged Blackbird and during the winter months when my area would be more apt to see them, both males and females sport a rusty red coloration over their heads and backs and pale yellow/white eyes. In breeding season, the males are black with rusty colored feather edges and the pale colored eyes while females have an overall greyish brown coloration and the pale eyes and the rusty color over the top of the head down the back.
The irony here with a species that has declined so significantly - 85-90% overall during the last fifty years according to the sites mentioned above - is that it is not listed on the Connecticut list or national list for threatened and endangered species. This is rather puzzling to me. Below are some links to further information about the Rusty Blackbird and what you can do to help them out. The one common suggestion - report them in no matter how brief your encounter is!
Connecticut Audubon Society State of the Birds