Search of the Week: “can hummingbirds drink water heated by the sun”

Rufous/Allen's hummingbird at feeder

A young Rufous/Allen’s hummingbird drinking on a hot summer afternoon.

Of course they can, as long as it’s not straight out of a solar water heater.

But don’t take my word for it when you can easily prove it to yourself. Leave your hummingbird feeder in full sun for a few hours on a hot summer day, then check the temperature of the sugar water.

Unless you’ve hung your feeder near a highly reflective surface and/or inside an enclosed greenhouse-like space, the liquid won’t be much warmer than the surrounding air. This is because a relatively small small volume of liquid in an uninsulated container loses heat to the surrounding air about as fast as it gains it.

Hummingbirds are not delicate, fragile creatures. If the feeder solution isn’t hot enough to damage human skin, it’s not going to burn their tongues.

Addendum, June 23, 2014: A complete answer to this question involves numbers, and I finally got around to getting some on a hot afternoon here in the high desert of southern Arizona:

  • Air temperature in full sun: 95° F. (35° C.)*
  • Feeder solution temperature in full sun: 105° F. (40.6° C.)*

For comparison:

  • Hummingbird body temperature: ~104° F. (~40° C.)
  • Highest air temperature ever recorded in the U.S.: 134° F (56.7° C).
  • Optimum hot beverage temperature: 136° F (57.8° C).
  • Water hot enough to cause third-degree burns to human skin in 5 seconds: 140° F. (60° C.)
  • McDonald’s coffee, pre-lawsuit: 180–190° F. (82–88° C.)

* Air and sugar water temperature measured with a cooking thermometer in my yard at around 2 p.m.; the feeder is a fancy HummZinger with a translucent top, which probably adds a little greenhouse effect to the direct solar heating.

References:

LiveScience: What’s the highest temperature ever recorded in the U.S.?

Brown F., and K.R. Diller. 2008. Calculating the optimum temperature for serving hot beverages. Burns Aug;34(5):648-54. Link (PubMed)

Wikipedia: Liebeck v. McDonald’s Restaurants

The Burn Foundation: Safety Facts on Scald Burns

Search of the Week: “can hummingbirds survive 100 degree heat?”

Costa's Hummingbird

Costa’s Hummingbirds are true desert dwellers, but all North American hummingbirds can tolerate summer heat if they have plenty of water.

Yes. They’ve been doing it for millions of years. As long as they’ve got shelter from the sun and plenty of water for evaporative cooling, they should be fine.

Hummingbirds will drink plain water when conditions are particularly hot and dry and/or nectar is hard to come by, but the usual sources of water pose risks of disease transmission from other birds, poisoning from rain or irrigation runoff contaminated with pesticides, weed killers, oil, antifreeze, etc. It’s safer to put out a separate feeder filled with plain water or change the sugar-to-water ratio of your feeder solution.

When the daytime highs start creeping into the 90s F., I reduce the concentration of my solution to 1 part sugar to 4 parts water. When temperatures rise to over 100° F. (which they don’t very often here in the high desert), I back off to 1:5. In parts of the Southwest where temperatures are topping 110° F., a 1:6 ratio would be advisable. Weaker solutions tend to spoil faster, but on the plus side they also tend to be less attractive to bees.

Providing water for the outside of the bird is another way to help beat the heat. I added a mister to our drip irrigation system that runs for a few minutes a day, spraying into the foliage over my hummingbird garden. It’s used year round but is especially appreciated in summer, helping to keep the birds cool and their insulating plumage in top condition.

I hate to end on a down note, but the hard fact is that every organism on Earth is going to have to adapt to rising average temperatures and greater extremes, and those that aren’t well suited to withstand “the new normal” just won’t survive.

Reference:

Hiebert, S.M. and W.A. Calder III. 1986. The osmoregulatory consequences of nectarivory and frugivory in hummingbirds and other species. Proc. XIX Internat. Ornith. Cong ., Ottawa, Canada.

Related post:

Feeder Solution Evolution Part I: The basics