‘Tis the season for year-end “Best of” lists, so I thought I’d do something of the sort for my 2017 banding station birds. Except it turns out that we had too many cool birds this year to fit in one blog post, so I’ll be doing a series of banding station highlights posts. First up: the small and fuzzy.
In the field, I become especially attentive to temperature. Is it too cold to catch birds? Are my hands warm enough to not chill a bird when I hold it? Recently, a friend very kindly let me take his FLIR ONE to the field: this is a device that fits over your phone and lets you take photos of heat. (Normal photos are of visible light.) Warmer objects show up as yellows and whites; colder objects are blue and black. The photos it takes aren’t of absolute temperature—that is, 40 degrees F isn’t always the exact same color—but rather of relative temperature: within the same photo, you can use the colors to compare temperatures, but you can’t compare across photos.
This was a lot of fun to use in the field, especially since the weather so generously gave us lots of temperatures to observe by snowing on us. Did you know that snow is cold, and humans are warmer than snow?
It’s the time of year for hot chocolate and blankets and pictures of soft, fuzzy, round animals.
A reader question today! Dolores asks: Would the body heat of a modest mixed gathering of water birds (gulls, ducks etc) melt ice at the edges of a pond?
The answer to this depends on context. We can start by establishing some extreme end-points: one duck at the edge of a huge lake in way-below-freezing weather would not be able to melt any ice.
Twenty ducks splashing around spiritedly in a kiddie pool with the barest skin of ice in weather just at the freezing point would probably, if you waited long enough, cause the ice to melt.
Between our two endpoints are more “normal” circumstances: a group of waterbirds hanging out at a pond. Could they melt any ice?
Happy New Year! In honor of brand-shiny-new 2013, I have… a continuation of the last post. I left a few things out of that post, since it was starting to get quite long; and then in the course of researching to answer some comments, I found some more things; so here are a few more ways that birds keep warm.
I’m currently visiting Chicago, relishing the finger-stiffening, face-numbing cold and wind that make up a proper midwest winter. Whenever I look out from the warmth of my big puffy coat and see a bird, I feel a little bad for enjoying the weather so much. I can go home and make myself hot tea; they can’t.
Like mammals, birds are endothermic (“warm-blooded”), meaning that they maintain their body temperature independent of the outside environment. This almost always means keeping themselves warmer than the outside air. Birds have quite high natural body temperatures, even higher than ours, so any given outside temperature seems even colder to them than it does to us.
Birds are also smaller than we are (well, omitting the ostrich), which means that they have a higher surface-area-to-volume ratio than we do. This is a problem because the volume (inside) of an animal is where heat is produced and stored, while the surface (skin) of the animal is where heat is lost to the environment. Imagine holding your hand in a bitter wind: how would you keep it warm? By making a fist. Making a fist reduces the surface-area-to-volume ratio of your hand, and lets it keep warm longer. In contrast, if you hold your hand out flat with all the fingers spread, your surface-area-to-volume ratio is larger, and your hand will get cold very quickly. Because birds have higher surface-area-to-volume ratios than we do, keeping warm is harder for them. How do they do it?