A bit of death in the morning makes for a good meal

Over the holidays, I was visiting Virginia and while out running with my sister, came upon a lovely smell.  Well, actually, before we smelled anything, we saw the vultures.  Right on the side of the road was a group of them- 4 Black Vultures and a Turkey Vulture off to the side.  Up in one of the nearby trees was another Turkey Vulture just keeping an eye on things.   As we moved in closer to get a better view of things, the Black Vultures lifted up their heads and turned their bodies away from us, but didn’t fly off, they just sort of got prepared.  Now, why anyone would bum rush a vulture, I don’t know, but they were ready for us, anyway.

It was, at about 30 feet, that we could smell the carcass.  Half-buried under the leaves was part of a deer.   I couldn’t see what the damage was, but I’m guessing it was car-related.  The actual death, however, is beside the point.  The cool part was the vultures.  As we initially approached, the 4 Black Vultures were the ones that were clearly on the carcass.  The Turkey Vulture that was on the ground was at least 10 ft away from where the body lay.  These are the dynamics that I find the most interesting.

Turkey Vultures are probably known best for their sense of smell.  Unlike most birds, Turkey Vultures have a good one, though it probably works best relatively close to the ground.  In conjunction with that sense of smell, they have a comparatively light body to allow for slower (and lower) flight than other vultures which could explain why Turkey Vultures are usually the first birds to arrive at a carcass.

Wallace, M.P. and Temple, S.A.  1987.  Competitive interactions within and between species in a guild of avian scavengers.  Auk 104:  290-295.

Another interesting point that comes out of this article is that in one-on-one interactions, Turkey Vultures will usually successfully drive away individual Black Vultures from carcasses.  The unfortunate part of that statement is that it is restricted to one-on-one interactions.  Black Vultures, unlike Turkey Vultures, rarely seem to forage alone.  They do rely on foraging groups.

Rabenold, P.P.  1987.  Recruitment to food in black vultures:  evidence for following from communal roosts.  Animal Behaviour 35:  1775-1785.

This group foraging behavior can give them better abilities to find food and also increase their competitive advantage at a carcass.  Turkey Vultures who find small carcasses can access food quickly, before Black Vultures arrive.  Once Black Vultures do find a large carcass, they will commandeer it and drive off the Turkey Vultures.  Black Vultures are more likely to return to carcasses several days in a row, while Turkey Vultures tend not to return.

Buckley, N.J.  1996.  Food finding and the influence of information, local enhancement, and communal roosting on foraging success of North American Vultures.  Auk 113:  473-478.  

So what we saw that day, was (probably) a recently killed deer that had been spotted by the Turkey Vulture and taken over by the Black Vultures.  Sadly, in the few minutes that we watched the birds, the Black Vultures seemed to have no interest in sharing with the Turkey Vulture.  The holiday spirit, apparently, doesn’t extend to dead deer.

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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, communication, ecology, foraging, raptors, vultures. Bookmark the permalink.

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