Rufous hummingbirds didn't freeze
Tough bird, looking to refuel at feeder, kept its cool when sugar water froze overFebruary 2, 2018
A rufous hummingbird showed up at our hummingbird feeders despite temperatures in the low teens and a snow-covered backyard under dense cloud cover.
The plump male bird, with a deep-red throat and rusty-orange hues on the crown, sides and tail, had migrated to our yard in October from breeding grounds in the Pacific Northwest up to southern Alaska at 61-dgrees north latitude, which is farther north than any other hummingbird ventures to breed.
Cold weather was nothing new to this bird. But it did need energy from sugar water in the feeders to power its daily activities.
Unfortunately, the sugar water in the feeders was frozen and a cake of ice covered the feeding portals.
9 Rufous hummingbirds are annual winter residents in Houston neighborhoods.
9 They prefer wooded neighborhoods with nectar-producing plants and hummingbird feeders.
9 Females differ from males by green crown and back with ruddy sides.
9 Both males and females are fiercely aggressive at hummingbird feeders, even chasing off songbirds.
9 Additional western hummingbirds occasionally spending winters in Houston include broad-tailed, Calliope and Allen's, which are virtually identical to rufous.
So we mixed up fresh sugar water, filled up spare hummingbird feeders and replaced the frozen ones. It didn't take long though for ice to again cover the feeding portals.
I splashed hot water over the feeders to melt the ice. I must have had a brain freeze about chemistry and physics - hot water freezes faster than cold water. Duh!
I scraped the ice off the portals. The sugar water wouldn't freeze for at least several hours because, as my unfrozen brain remembered, icy molecules cannot move quickly through sugar water.
Whew. The hummingbird got fresh sugar water. Good thing, too, because our nectar-producing shrimp plants along with similar plants were drooping ghosts in the hard freeze.
The rufous hummingbird did fine during the day, feeding on sugar water and tree sap for energy. The bird got its required protein from eating insects that, though dormant during the freeze, were still retrievable from tree bark, beneath leaves and even from traps in tree sap.
Protein metabolizes slowly and sustains the rufous through freezing nights. The hummingbird also survives nights by going into a state of torpor, when the metabolic rate slows down, body temperature lowers by 50 percent and heart and breathing rates slow down.
At daybreak, a bird awaking out of torpor needs food fast, in the form of nectar or sugar water, to revitalize itself.
We should have known nighttime temperatures hitting the low teens would freeze sugar water in the feeders, and we should have brought the feeders inside and put them back out at dawn. Not a mistake we'd make again.
Still, our rufous hummingbird did fine on that first icy day. Must have had enough tree sap to tide him over until we got our act together.
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