I was told recently that it was due to the number of hours of daylight. Males leave first, then females, then immature birds.

Journey North is probably the best website for tracking migration, and answering such questions as why they migrate, etc. I've attached a link for you so you can check it out!

Susan

Here is a link that might be useful: Journey North - Hummingbirds

Thanks, the length of day seems to be the moving factor. At least this year the countryside here will be green soon, helping them north. Thanks for the link Susan.

Let us know when you see your first hummers, Rob, if you would be so kind. I can't wait for the Monarchs either. This has seemed like the longest winter with the worst weather that I recall in Oklahoma City, and I know most everyone in the US has had a much more severe winter than in the past.

Susan

I don't know why they migrate, but I do remember being told that their northern migration coincides with the blooming of the red buckeye tree. Supposedly, it has the first red, tubular blooms in the spring, and an early, natural source of food for them. This winter has been harder than the last few and I'm curious to see when they arrive !!
~ Judy

Susan, I will post when I get the first hummers here, hopefully with some photographs. Last year they were here in March. Males first,then females. With sparse blooming vegetation here in March, they home in on available feeders. (smile!) My feeders go out March 1.

Thanks Gymnmore. It has been a cold winter here as well. And Tuesday the low is to be back in the thirties once again. My poor Salvias are struggling, but occasionally blooming. I hope I can get something to bloom for them in March.

rob

I too have been puzzeled by the whys when and hows of migration. Most every artcle is the same they go north to breed and south because the days get shorter. But that was not enough for me so I kept searching and I wasnt believing that because the days got shorter they headed south, so the hummers have watches. Till I found this certain site which is loaded with info and is divided into like chapters. To make a long story short to migrate north first there are hormonal urges that hit and since its so crowded they need to go north for more open space for breeding purposes. To migrate south they still say its shorter days and other factors and Im guessing maybe its also cooler air drifting very slowly out of canada along their instinctive kick that its time to go. Maybe this site will help clear things in your mind.

Here is a link that might be useful: migration north and south