I don't know whether they migrate alone, or in groups, but my best guess would be they migrate as individuals, not flocks. That's only a guess.

As for males and females, I understand that within a given breeding area, the adult males depart weeks before the females. Since they play no part in the rearing of the young, there is no reason for them to stay. Females stay to continue caring for the young, and then depart. Young birds hatched that year tend to stay the longest. I don't have personal experience on this, it's simply what I've read, but it seems to make sense.

I have some bird bander friends who work at a bird banding station. I could ask them if what I've read is really true.

I would also imagine that there is a good bit of mixing of males and females, with birds throughout their large range leaving at different times, depending on local climate and food supply.

Maybe someone else knows more about whether they migrate in flocks. I wonder if their territoriality around flowers translates into their behavior during migration. That would tend to suggest they are solitary.

Me again. Here's a link to a website that you may find interesting. The forum would not let me post a second followup. It told me I had to change the subject line. I hope you find this.

Here is a link that might be useful: http://www.hummingbirds.net/migration.html

that is an incredible site. thanks Kristin for posting it.
Be sure to look at the galleries .

Yes, we still have to change the heading to post more than once right away. I usually add a ? or a !

Come to think of it, I've never seen a flock of hummingbirds. It would be my guess that migration is undertaken by individuals.

Thanks Kristin! That answeres everybodys question "when to take down the feeders" Mine will be up untill they start to freeze! :D

Wow, Minnie! I hadn't noticed the galleries. It's late and I'm getting tired, so couldn't do much more than peek at a few photos. It looks like there's enough there to click on for hours, or even days. Thanks for pointing that out.