Compared to how humans prepare for a trip to the topics, hummingbirds are a strange bunch. They are attempting to gain weight and lots of it. Obviously, they aren’t worried about how the bathing suit fits. My cousin said she saw one that was so fat it looked pregnant. Their bodies are normally so sleek they aren’t much wider than their tiny head but not at this time of the year.
These little birds have to have lots of food right now so don’t take your feeders down thinking that will make them go south. One thing that causes them to migrate is cooler temperatures but there’s more. They operate on what’s called a circannual rhythm (sort of like our circadian rhythm only this is a yearly one) that tells them when to leave and it has nothing to do with the availability of food. It is governed by shorter days which cause a hormonal change that increases their appetites. They will molt so their feathers will be fresh and in good shape. And the hormones also cause them to build up some flight muscles. From the looks of their fat little bodies, they will need the muscles to stay in the air. Have you seen how slowly they are flying these days? Another thing you will notice is fewer males. The fellas go south ahead of the females and the youngsters.
When humans prepare to head for sunny climates it’s diet time. When hummingbirds head south they need the calories, so keep feeding and enjoy watching the changes they are going through. I keep waiting for one to waddle in mid-air.