The Rose-Breasted Grosbeak, or Pheucticus ludovicianus has a beautiful rose colored chest, black head and black wings. The female is brown with white stripes and almost looks like a large sparrow.
Male grosbeak
The birds stay in pairs, keeping a close eye on each other. I have never seen a "group" of grosbeaks - it's always two of them that settle down in the back yard to raise one or two young.
Grosbeaks are very shy and will hang out in trees near the feeder for a long while, watching the situation. While they can eventually be lured to a seed feeder, they are extremely cautious birds. Also, being fairly large birds (around robin sized) they need a feeder that they can fit on!
Baby female grosbeak on the right
Male rose-breasted grosbeak photos
Female rose-breasted grosbeak photos
Baby rose-breasted grosbeak photos
Birding Encyclopedia