I am always intrigued how the tiny Anna’s Hummingbirds can brave the cold of the winter. Heat loss of small bodies is so much greater due to the body surface ration to body mass. With other words a teaspoon of water freezes much faster than a cup full. Fluffing up alone does not conserve enough body heat, but we know that the hummingbirds can go into a state of torpor.
This is a remarkable adaptation by reducing metabolism by 95%, body temperature by 10 to 30 degrees Celsius to practically putting life-functions on hold. With a metabolic rate of 77 times that of a human starvation happens quickly if no food can be sequestered. Without fuel the body heat cannot be sustained. That is when the hummingbird falls into spontaneous hibernation. It likewise can wake up quickly as the temperature rises to feed again. The trick is to find food (nectar and insects) in the winter.
The Rufous Hummingbirds packs up and travel south but the brave Anna’s Hummingbird stays here all year around on Denman Island. This is only true for about the last decade because winter feeding with sugar water encouraged them to expand their range to the north. But once you start you must continue to do so.
Every day! The hummingbirds need long days of feeding. They show up when you can hardly see in the morning and on until it gets dark outside. I used to take the hummingbird feeder into the house overnight and put them out before the first hummers arrive. That is not always a great joy to do specially before my first cup of coffee. I searched the internet for a heated feeder. Wow $80 to $120 to get it shipped.
Some heat constantly which is not desirable as it overheats the water. So I bought a short plumber’s heat tape for under $30. I either wrapped it around a glass feeder or made a “nest” to sit in it. If you use a plastic flowerpot saucer for the nest do not drill the holes to hold the heat tape with bit of wire, instead use a hot nail and melt the holes that way the plastic will not crack. The heat tape is the ultimate solution. The pilot light shows if it is operating and the thermostat shuts off if it gets warmer than plus 4 to 5 degrees C and conversely turns on below it.
Now I can sleep in the morning and make that cup of coffee while the “hummers” already have a warm breakfast. With the feeder filled up I can even go away for a few of days. It makes life easy for the Anna’s Humming bird and me.
Biological reference: ww.sciencemag.org 2020/09