Eagles are jerks!

Earlier in the week, I took a quick trip out to Lake Mattamuskeet on the coast of NC.  At some level, it’s a weird thing to call “quick”.  From Charlotte, it’s about a 6 hour drive to get there so there’s some investment in heading out there.  I did, however, just go, bird and turn around to come home the next day.  I just needed a quick hit of some coastal swamp birding.  Even though I was too late for most of the migrants, I still got quite a show.

One of the nicest parts of the show was that I got to view lots of raptors.  Kestrels, Merlins, Red-taileds, Harriers, Eagles- they were all over the place.  The Bald Eagles, in particular, were putting themselves on display very nicely for me.  One juvenile sat very calmly in the breeze so that I could circle the tree it was in and take pictures.  Unfortunately, it was less generosity on the part of the eagle than a bit of self-confidence.  Eagles can be jerks.  I’ll fill in the details on this point in just a minute…

One of the areas where I spent a few hours birding was a swampy area full of reeds and tall grasses.  Dozens of Eastern Meadowlarks were singing and foraging throughout this area.  They quieted down anytime I got close to them or anytime a Northern Harrier flew over.  I ended up watching the Harrier patrol this area for quite awhile, teetering back and forth low over the grass in slow flight.  They’re actually fantastic birds to watch because their flight seems almost impossible- like a drunk person walking up a hill.  Anyway, I watched this Harrier flying back and forth for a little while when suddenly it shot down to the ground and grabbed something.  It was too far away for me to see what it had- a rodent or maybe one of those Meadowlarks.  Within 10 seconds of the Harrier’s catch, that young Bald Eagle flew down on top of it.  I saw the Eagle go into the grass and a second later, the Harrier shot out with empty talons. The Eagle stayed there in the grass for a bit, so I’m assuming that whatever the Harrier caught now belonged to the Eagle.  That’s why Eagles are jerks.  Let someone else do the work and then just steal it from them!

In truth, this particular thieving behavior is something people have recognized in many species of raptors.  In the behavior literature, we call it kleptoparasitism.   Eagles are particularly well-studied examples of kleptoparasites.

Jorde, D.G. and G.R. Lingle.  1988.  Kleptoparasitism by Bald Eagles wintering in south-central Nebraska.  J. Field Ornithology  59:  183-188.

So while they do look really impressive and majestic, those Eagles are really just big bullies!


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.
This entry was posted in birds, ecology, foraging, predation, raptors. Bookmark the permalink.

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