Leaves turn colors in the fall in response to the dwindling amount of daylight. I just learned that Ruby-throated Hummingbirds use the same cue to migrate. I thought all the hummers were gone for the season, but I just spotted one (feeding on the salvia ‘Sea Breeze’) in my backyard, and I wanted to find out more about how they know when it’s time to leave.
Ruby-throated hummingbirds spend their winters in Mexico and Central America. While many birds migrate at night, hummingbirds migrate during the day. The exception is when they are crossing the Gulf of Mexico. Since they can’t stop in the ocean to rest (unless they come upon a ship), they have to fly up to 20 hours straight. Not all hummers have the stamina to cross the Gulf. Some fly along the Texas coast into Mexico instead.
Before they are ready to leave on their migration they fatten up, sometimes doubling their body weight. Because they are so tiny and vulnerable to cold temperatures, they can’t migrate at high altitudes like songbirds. Instead they fly just above the tree tops.
Hummers migrate alone and some follow the same path every year. So if you’ve had them in your backyard before and you continue to grow the same plants (and/or put out hummingbird feeders), there’s a good chance you’ll see the birds again next year.
I wish this one luck on her long journey!