What type of bird is this?

These birds have come to our feeder in London Ontario.... similar size to Sparrows.... but can't seem to find any pics that look similar to this bird....

I think you might have a Slate Junco there, they are common at this time of year, they stay throughout the winter, and then they are gone again.

We get them here in St Thomas too, they seem to travel in flocks and when they fly, you can see a flash of black and white as they fly away.

If any of our readers know for sure what this bird is, please let us know!