Here comes the rain again

Oh Annie Lennox, how true your words.  It’s been a rainy couple of days here and the mornings have been chilly again.  It’s kept me inside (not a fan of running in cold rain), but it hasn’t stopped the birds.  One, in particular, has been pretty busy this morning.  An American Robin has been singing outside mostly non-stop since about 5am.  Sure, he was joined at times by a Northern Cardinal and by Carolina Chickadees, but that one robin is really a trooper.

Singing this loud (and this constant) can make for a weird morning.  My alarm doesn’t go off at 5.  It waits ’til closer to 6am, so hearing the robin that early can make for a strange morning.  He was loud enough that I became aware of him and woke up.  He was also constant enough to make it into those early morning-half-asleep-dreams that occur when you drift off, again.  For instance, like the kind of dream where the police car in the dream has a flashing light and a ‘cheerily cheer up, cheerily’ song to it.

Anyway, that robin has been singing pretty constantly, but why?  This question actually makes me think about work, again, too.  Some days I wish I had more than one of me, so that I could be doing two things at once.  Well, birds have that same limitation.  At any given point in the day, there may be more than one thing that a bird would (or should) be doing:  getting a mate, feeding, defending a territory.  The problem is that it can be hard to do more than one thing at the same time.  This presents a bird with an opportunity cost- the cost of choosing to do one behavior is the missed opportunity to do something else.  Non-stop singing seems means that little guy is not also out chasing down food or nest building or watching Good Morning, America.  Whatever happened to Joan Lunden, anyway?  But what are his other options?  Here’s where we get to see some interesting things about American Robins.

Rain, especially cold rain, was enough to convince me not to run this morning, but a robin’s feathers are actually pretty good insulation against most rains.  They wouldn’t protect against a downpour, but they’re more than enough to keep a bird dry in a light rain.  The problem with rain, though, is that heavy rains tend to decrease the activity of the things that the robin would be eating.  People have looked at this interaction in a number of ways (to see the rain’s effects on the number of offspring, for instance).

Foster, M.S.  1974.  Rain, feeding behavior, and clutch size in tropical birds. Auk 91:  722-726

From the robin’s perspective, what does all this stuff mean?  Well, primarily, it’s the removal of that opportunity cost!  “Hmm…what should I do now, sing or forage?  Ah, if I can’t forage, then I don’t have to worry about my choices!  I’m not losing out on anything by devoting my energy to this particular behavior at this time.”  A simple understanding of how the cost-benefit analysis can change for a bird is a handy tool for thinking about behavior.  There is, of course, another benefit for the robin.  His extra effort in singing did catch my subconscious attention and as a result, he gets a post.  I’m not entirely sure where internet fame sits on the ‘benefits’ scale for a robin, but I wouldn’t rule it out just yet.


About thomasbiology

I'm an Associate Professor of Biology at Queens University of Charlotte with a background in animal behavior with an emphasis in bird song. I've got two secret goals with this blog (well, since I'm sharing them, they're not so secret): 1. To encourage people to look at the natural world around them- not just as a hiking destination, but to notice all the little things moving around them all the time; and 2. To show some of the science that relates to these little things moving around. There's some really fascinating research out there that so few people get to see.
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