Experts tackle readers’ garden questions.
Q: On a recent cold morning, I saw something hanging from my hummingbird feeder. It was a little hummingbird, hanging from its feet upside down but not moving. I took down the feeder and held the bird in my hands. It was still warm and wasn’t dead. I took it to the Wildlife Care Association. They told me it was in torpor. I had never heard of such a thing. What happened?
Barbara Wilson, Sacramento
Bee garden writer Debbie Arrington: As you discovered, torpor (pronounced TOR-purr) is like really deep sleep and is used by birds (as well as some small mammals such as bats) to withstand cold winter weather. It’s similar to hibernation, but generally lasts only a few hours or overnight.
Hummingbirds that do not migrate, such as the Anna’s hummingbird you found, commonly use torpor to cope with extreme cold. Their metabolism slows down to just a tiny fraction of normal and their body temperature drops. This way, the bird can conserve energy and survive.
Before drifting into torpor, hummingbirds usually find a favorite perch where they feel safe and near a ready food source, such as your bird feeder. According to bird experts, it’s important for a hummingbird to eat right after coming out of torpor.
There have been many reports of hummingbirds hanging upside down while in torpor. As you saw, they may look dead or frozen and don’t respond to touch. It takes 20 minutes or more for a bird to come out of torpor, so they are slow to react.
The best thing to do when observing what looks like a deep sleeping hummingbird (especially upside down) is to leave it alone. As the weather warms, the bird will awaken – and look for breakfast. At first, the bird may seem to be shivering, but it’s just warming up.
The Audubon Society also suggests keeping hummingbird feeders filled during winter – and to prevent feeders from freezing – so resident Anna’s hummingbirds have enough food to get them through these cold months when fewer flowers are available.
While in torpor, hummingbirds are very vulnerable to predators because they can’t react to potential threats. So, if you see “sleeping” hummers, keep cats indoors.
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