Singing (or sitting) in the rain

I get asked a lot “what do birds do when it rains?”.

My standard answer is that they go inside and watch their stories on the moving picture box.  After a quizzical eye roll (or sometimes a blank stare), I’ll sometimes try to clarify things.  But in doing so, we’ve got a couple things to address:

  1. Birds don’t live in nests.  Nests are for reproduction.  Outside of the breeding season, most birds just find a place to roost (perched on a branch somewhere).
  2. Birds, like mammals, are endotherms.  They make their own body heat, which allows them to remain active when the environment is a lot colder than their body temperature.
  3. Feathers are great insulators.  They trap warm air close to the body and so keep birds really well-protected.  I wrote about this fact in another blog post somewhere awhile ago.
  4. Feathers are also good at repelling water, which is really important to their ability to be good insulators.  But, feathers only work this way when they’re well-taken-care-of, which is why you often see birds preening.  Now, in ducks and a lot of water birds, there is a gland (the uropygial gland).  The secretions from this gland give the feathers of these birds an extra degree of protection from water.

But what about the cardinals and finches in my yard?  And here’s what people are normally getting at.  What happens to songbirds when it rains.  Last week in Charlotte was a good time to see the various strategies that birds use.  The rains went on for a long time, but the intensity changed dramatically.  At times, they were strong and intense.  Other times it was a light drizzle.  And the birds?  Well, they responded to these differences.

During the lighter rains, the cardinals, finches, wrens, towhees, and thrashers in my yard kept doing their things.  Flying around, vocalizing, talking smack.  Songbirds can do this without worry not because of the oils from the uropygial gland, but because of the physical structure of a feather.  Feathers are very cool (and complicated) structures at the microscopic level.  It’s not a solid thing, but a lot of very small barbs and hooks with tiny air holes between them.  This structure actually helps make water bounce right off.

Bormashenko, E., Y. Bormashenko, T. Stein, G. Whyman, and E. Bormashenko.  2007.  Why do pigeon feathers repel water?  Hydrophobicity of penne, Cassie-Baxter wetting hypothesis and Cassie-Wenzel capillarity-induced wetting transition.  Journal of Colloid and Interface Science.  311:  212-216,

Now, if you don’t want to dig into that article, don’t worry.  It’s not really for bird people. It is however, for product designers.  And that’s a separate little thought-let in my head.  Birds do some pretty amazing things.  We’re still figuring out how they solve problems like staying dry and we’re using that knowledge to change how we build our own new materials and structures.  Cool, eh?

During the heavy rains, though, this mechanism doesn’t work as well.  If their feathers get saturated or water gets under them to their skin, they can get too cold.  So what’s a bird to do.  Well, if you had been looking out my windows during the last storm (which would have been odd, since I don’t know you), you would have seen about 5 House Finches and a Northern Cardinal perched under the eaves of my neighbor’s house.  I had a House Finch sitting on my drain pipe, right under one of the eaves, and a Carolina Wren perched on my front porch.  Birds find places to shelter themselves from the heaviest rains to keep their feathers dry.  Even leaf-less bushes and trees offer a lot of protection in a bad storm like that.

So next time it rains, check your drainpipes and eaves for birds.  Or better yet, go set up a nice, big umbrella near your feeder and watch them kick back and wait for the storm to end.

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Herd of deer?

Yeah, I’ve heard of deer.  Lately, I’ve been seeing them a lot, too.  I live right in the middle of Charlotte (within spitting distance of Independence Blvd) and I’ve had groups of deer around my yard (and eating my plants) a lot.  In fact, the other day, there were 6 deer slowly meandering their way across the street as a friend and I pulled up to my driveway.

The first question that came up was, “what’s a group of deer called?”  As a biologist, this one comes up a lot with all sorts of different animals.  Last year, someone in my family asked what a group of groundhogs was called.  For the groundhog answer, I took the magic of the interwebs. ” Why,” asked my family, “don’t you know the names of these animal groups?”

“‘cuz we never use them,” was my unsatisfactory answer.  And then, on a reddit line about the “official” names for a group of groundhogs, I found this quote:

Yep.  That definitely sounds like my people.  When biologists talk about sets of animals, it’s usually with respect to what they’re doing or how they’re arranged, which brings me back to my deer.  The group  of deer that has been hanging around my neighborhood has gotten larger and more casual in their responses over the last couple years.  I think that people have realized deer have moved in all over Charlotte- a result of the rapid growth of the city into previously undeveloped wooded areas and farms.  The deer that have really moved into the city may, in fact, now be surviving better than the deer that live along the margins of the city (though certainly not as well as those living in undisturbed habitats).  This urbanization effect has been studied in the Florida Key Deer (a relative of the White-tailed Deer we get up here.

Harveson, P.M, R.R. Lopez, B.A. Collier, and N.J. Silvy.  2007.  Impacts of urbanization on Florida Key deer behavior and population dynamics.  Biological Conservation 134: 321-331

Related to that information (and supported by what I usually see in my yard) is that there is a lot of intersexual difference in behavior in these deer.  Most of the groups in my neighborhood are entirely female (or females with yearling fawns).  Lately, I’ve only seen males by themselves, including one irritating male who stood at my bird feeder lapping up seed.  When I opened the backdoor, he just stared at me.  It wasn’t until I started walking towards him that he sauntered away to the back of the yard.  I don’t always like the anthropomorphize these animals, but it was most definitely a snotty saunter.

Anyway, other people have reported that urban populations of deer are general sex-specific, except in the mating season when mixed groups became more common (though always with more females than males in them).

Richardson, K.E. and F.W. Weckerly. 2007.  Intersexual social behavior of urban white-tailed deer and its evolutionary implications.  Canadian Journal of Zoology 85:  759-766

Clearly, these deer do get together in the mating season because there were at least two new ones running around the neighborhood in the summer.  Well, running around the neighborhood and my yard (and eating my plants!).  Now, as I said earlier, I don’t like to anthropomorphize and I don’t tend to use cute names for groups of animals, but after covering and recovering and finding bits of plants torn to shreds, I think that one of the other names for a group of deer might be apt:  a mob of deer.  My young fig tree was apparently a protection fee that I paid to this mob of deer.  I’m going to see about some other form of payment next year.

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Will the real blue bird of happiness please stand up?

Please stand up

Please stand up.

What does it mean when the bluebird of happiness isn’t actually a bluebird.  Well, what if it’s a blue bird, but not a bluebird?  To make things even more complicated, what if the bird isn’t even always all that happy?

Yeah, I know.  It’s a confusing situation!  For me, the moment arrived just the other day at about 6:30am.  There was enough light to see things outside, but it wasn’t yet bright enough to make out lots of colors.  I was getting coffee and getting ready for work and looked out into the backyard where there was a strange little bird sitting on the edge of my azalea bush, which was full of white flowers.  Against the white, the bird looked blue, but I figured that was the morning light and sleepiness tricking me.  So I went to the window and made that morning squinty face to see if I could see it better.  And that’s when I got happy!  It was a blue bird, but it wasn’t an Eastern Bluebird.  It was, in fact, an Indigo Bunting.  Now I’ve seen them before, but not really in my yard.  And here was one just sitting in my bushes.  Crazy.  By the time I could get back with my camera, though, the bird was gone.  It was a couple days later that I saw it, again, outside of my kitchen window and from there you get this picture.

For me, this was my bluebird of happiness.  I was thrilled because they’re such pretty things.  But, as with everything, happiness is a matter of perception.  As a human, I’m pretty happy seeing these birds, but I do wonder if they’re always happy to see each other.  Buntings haven’t been researched to the same extent that sparrows and other birds have.  But there are a few ways that they do pop up in the literature and one of them is that they’re not so loyal to each other.

Apparently, Indigo Buntings can go into the “frisky” category of birds, with as many as 35% of offspring in an area being fathered by someone other than the male at the nest.

Westneat, D.F. 1990.  Genetic parenting in the indigo bunting: a study using DNA fingerprinting.  Behavioral Ecology and Sociobiology 27:  67-76

And while Buntings don’t hold the record on amount of extra-pair copulations, they’re up there.  Males at their own nest apparently recognize when they’ve been cuckolded, too, and reduce the amount of parental care they provide.

Westneat, D.F.  Male parental care and extra pair copulations in the indigo bunting.  Auk 105:  149-160.  

So when Indigo Buntings see each other, do you think they get that suspicious side-eye.  ‘Hey!  Have you been in my nest?’  Maybe they’re not such happy birds, after all.

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Parental fatigue

When is it time for kids to go off on their own?  Certainly, what’s in the kid’s interest is not always the same as what’s in the parent’s interest.  In animal behavior, we call that “parent-offspring conflict”.  Everybody else just talks about it in the context of kids living in the basement.

This came up today because a colleague came in to my office to say, “there’s a hawk on the ground making a lot of noise!”.  In fact, that hawk (a juvenile Red-tailed Hawk) had been making a lot of noise all day.  Every time I walked outside today, I could hear it calling.  After my colleague mentioned it, though, I went out check out the bird.  This juvenile clearly didn’t relish being expected to fend for itself.

Now, after a hawk fledges, they remain with their parents for a period of time.  During this time, the bird is learning to forage on its own, but is still the recipient of food brought to it.  These hunger calls have been seen in birds from when they leave the nest until the point where they are completely independent, which may be 100 or so days.

Fitch, H.S., F. Swenson, and D.F. Tillotson.  1946.  Behavior and food habits of the Red-tailed Hawk.  Condor 48:  205-237.

Like most begging calls, these hunger calls are irritating (probably to the parents as much as to people) in part because of their desperate sound.   When I went to investigate this bird, it was no longer making calls, but was standing on the ground.  Apparently, this posture was what worried my colleague.  Watching the juvenile in this position was fascinating, though.  It repeatedly jumped onto a pine cone, then tilted sideways, several times tossing the cone into the air.  It would hop and land, talons splayed in the pine needles.  When other people approached the bird, it had no problems getting into the air and would land on branches nearby, then come back to its spot on the ground near the pine needles.  Several times it picked up an object in its beak and would then manipulate it with its talons, too.

These signs weren’t those of an injured bird.  Taken together, these behaviors seemed to beIMG_3464 that of a bird learning how to forage- very rudimentary hunting.  Even after all the high-drama screaming, a little bit of neglect from the parents gave this juvenile enough alone time to begin practicing itself.

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Key ears

It is a pretty iconic (and common) sound around Charlotte.  The keeyeeer of the Red-shouldered Hawk, that is.   There is a pair that has been really active in my neighborhood this year.  Red-shouldered Hawks are one of the birds that has taken really well to suburban habitats like Charlotte.  In one study of reproductive success, suburban birds had the same number of successful fledging events as birds from more rural areas.  It’s a useful thing to know about these birds- especially when paired with the information that nest site selection stays about the same.  Red-shouldered Hawks may nest in a variety of tree species, but on average, they prefer to nest in areas with high canopy cover and old trees (with wide trunks).

Dykstra, C.R. et al.  2000.  Nest site selection and productivity of suburban Red-shouldered Hawks in southern his.  Condor 102:  401-408.

Suburban Charlotte (which really is most of the city) definitely meets these criteria and so provides them with a great array of nesting options.   So keep your eyes and ears out for these gorgeous birds.  DSC_0404

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The prodi-gull son returns

Ok, so this post isn’t about gulls, but it has been a long time since I’ve posted anything.  It’s time to break that streak and report on some new, fun things.  There are a few things that I’ve found, recently, that have really excited me, but the siting that brought me back in is this one:

These birds are new to my yard this year and have been coming back every day, now.  One male and two females.   They’re almost 2 weeks into their visit and all three have been regulars at the feeder.  They’re stocky birds, but a bit flighty.  Cardinals landing on the feeder will usually cause the Grosbeaks to fly back into the trees.

I’m doing everything I can to keep these birds happy and support them this year.  There is at least one report of Rose-breasted Grosbeaks using the same nest in successive years:

Friesen, L.E. et al.  1999.  Nest reuse by Wood Thrushes and Rose-breasted Grosbeaks.  Wilson Bulletin 111:  132-133.  

Now, we are at the southern edge of their breeding range (check out the USGS Breeding Bird Survey data) .   There aren’t so many reports of them breeding down here, but- fingers crossed- they’ll be back again next year.  The ‘Prodigrosbeak Returns’ just doesn’t sound quite as good, though.


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Jail-breaking snakes

photo 1photo 2Well, maybe smart is an overstatement. But not dumb is a good way to think about it. Today on campus, someone found a young Corn Snake in a building. Because…well…snakes are snakes, campus police got called to remove it. They brought the cute little thing over to the science building where it sat in a tank all day (snake prison).

Now this little snake is about as wide as a pencil and maybe twice as long. I went down to check on it (as a parole officer) and found it curled up in the corner of a 15 gallon fish tank. The tank was entirely empty, except for the snake…well, and the mesh cover that had a heavy bucket balanced on top. A bucket? For a snake that probably weighs about as much as a silver dollar (8g)?

Barnard, S.M., T.G. Hollinger, and T.A. Romaine. 1979. Growth and food consumption in the corn snake, Elaphe guttata guttata. Copeia 4: 739-741.

After checking on the snake, I went back to finish some things up in my office. When I returned to it, the little guy was checking out the edges of the mesh covering. It was both an amazing bit of gymnastics and an impressive way to evaluate its environment.

Now the quick version of the story is that I picked up the snake, put it in my lunch container (from which the lunch had been removed) and brought it home to release in my yard (pictures below). It took off quite willingly into the bushes when I set it free. The more fascinating part, though, is related to how that snake evaluated its environment. Lucky for us, people have studied this very thing in Corn Snakes.

Holtman, D.A.; T.W. Harris; G. Aranguren; and E. Bostock. 2008. Spatial learning of an escape task by young corn snakes, Elaphe guttata guttata. Animal Behaviour 57: 51-60.

What they found was that corn snakes are good at learning about their spatial neighborhood. By putting snakes into an enclosed arena with a lot of holes, but only one escape, they were able to see how snakes did at the task of finding the escape over multiple trials. Snakes regularly got faster (over 4 days) at finding the way out of the enclosure. This result means that 1) snakes recognize where they are and have memory and 2) they’re not just dumb reptiles. That little snake in the fish tank was investigating its enclosure and looking for an escape route. Had the bucket not been there (or had I taken too long to get back, it might well have Alcatraz’ed right out of there. Luckily for both the snake and everyone in the science building, the snake is now in my backyard, instead.

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