Rickubis Bird Page #7: Vultures!
This page was born 04/16/2015.  Rickubis designed it.  (such as it is.) Last update: 
Images and contents on this page copyright 2002-2015 Richard M. Dashnau

Here are my other Brazos Bend and/or critter pages:
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Alligators at Brazos Bend State Park Introduction             Critters at Brazos Bend State Park Page 1
Snakes-nonvenomous 1------------------------------------------- Critters at Brazos Bend State Park Page 3
Snakes-nonvenomous 2-------------------------------------------------Insects, non-toxic
Snakes-nonvenomous 3------------------------------------------------Spiders
Snakes-venomous------------------------------------------------------Mammals
Birds-Waders Hawks & Eagles-Anhingas & Comorants - -------Lizards!--Turtles!
 Grebes -Herons  Bitterns  Pelicans
Misc. Birds    Owls & Falcons

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Welcome to Brazos Bend State Park. That's me on the trail. One of the most popular reasons for people to visit BBSP is to see the birds. Although *I* started going to the park mainly for the alligators, one cannot be there for long without learning to enjoy the birds. Over the years, I've captured a few pictures and video clips of them, and here they are. I've collected all my shots of raptors onto this page.

February 19, 2012-- Consider a character that eats dead and rotting flesh. Imagine also that it never brushes its teeth.  

It doesn't take much to imagine that that character wouldn't be very popular. So, our character eats rotten flesh, and it can't brush its teeth. Why not? Well...first, it doesn't have any teeth. Second, it doesn't have any hands. So, its breath is probably not too pleasant.

Since it has no hands; when it eats, it has to poke its head into the nasty flesh. And if it has anything rough on its head-the nasty stuff would be caught in that fluffiness and also be rather unpleasent. So... it has a naked head to minimize the amount of moist gunk that sticks there. Still...some material must still be left there.  Bad (well, putrid) breath and stinking rotten gunk on its head could make our character rather unpopular. But that's not all.

When it's hot, our character doesn't really sweat very well, so to help cool itself it lets liquid excrement run down its legs. The evaporation of the liquid part causes cooling of the legs (which are covered with bare skin). This acts like a heat exchanger--like the radiator on your car--and circulation brings cooled blood into the body and hot blood out to cool. NOW it's easy to imagine our character is pretty nasty...and no fun to be around.

The character is a Black Vulture. They eat carrion--dead and rotten carcasses. Their heads are bare of feathers because they like to eat into carcasses where the soft parts are. They cool themselves with a process called "urohidrosis", which is defecating on their legs and allowing it to evaporate.  I'd never considered that with these habits, vultures must be pretty unpleasant characters to be around. But, they don't seem to smell like rotted flesh. Why not?

I found out at least one reason today...

I was leading the Creekfield hike, and when I got to the long pier, there was a huge group of Black Vultures--the collective noun is a "Wake of Vultures", at the end of the pier. The Vultures allowed us to get very close before they flew off. They didn't want to leave. 


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Some flew off to the Vulture-filled tree across the lake. But some just landed on the nearby island; which, I noticed, was covered with Vultures. Many of them had their wings open and their backs facing towards the sun. What the heck were they doing? 

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There were also two HUGE alligators on the same island, but the Vultures crowded on their portion and left the alligators to theirs.

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As the park visitors and I watched the Vultures, and the Alligators many folks asked what was going on. I noticed that Vultures landing on the island were wet...very wet. So, they were drying themselves.   But how were they getting wet?
I finally found the answer through my binoculars. There were many Vultures in a large tree directly across the lake from the end of the long pier. But under the tree, protected by distance and the heavy brush, the Vultures were washing themselves! With all the Vultures I've seen at the park and elsewhere, I'd never seen them washing themselves. This was done very much like other, smaller birds do in birdbaths and puddles everywhere.

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As I watched through binoculars, I saw them wash their heads, dunk their beaks, lie in the water, and "scoop" water across their backs with their wings.  After a few minutes of this, they'd fly back to our side of the lake and dry out. There they were, feathers clear, heads clean, and legs poop-free. And I'd got to see another part of life as a vulture. Maybe now they'd be ready for some social activity.  Along with the photos posted here, I was able to capture some video clips  (a few of the images here are frame grabs from the video). I've edited some them together into this video clip (wmv 28mb).

January 22, 2012-- While walking past the water station at Elm Lake, I noticed a large group of vultures on the ground between the trail and the lake. I thought this was strange, so I moved slowly towards them and observed what they were doing. As I got closer, I noticed that 3 or 4 alligators were watching the vultures, or whatever had caught the vultures' attention. The vultures nearest the water were watching the alligators. The alligators seemed to be paying attention to the vultures. Then, some of the vultures near the alligator started pulling at the grass and poking the ground with their beaks. Occasionally they seemed to be tossing grass or dirt towards the alligators. This "standoff" continued for some time, but was finally broken off when a park visitor rode a bicycle past the flock of vultures. The vultures flew off, but just to the nearest island on Elm Lake. When I examined the ground where the Vultures had been gathered, I couldn't see or smell anything dead. The images below are photos and frames from video clips that I shot of the events I describe. I've edited two video clips from this. The pictures show below, and the video clips are here (43.2 mb wmv) and here (49 mb wmv).

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A few hours later, I found out that an alligator or alligators had been chewing on the carcass of a feral hog for at least a few days. The alligators in the area of Elm Lake between pier 6 and pier 5 were moving around a lot--swimming back and forth between the islands and the banks near the trail. While looking down the line of islands, I noticed a large alligator standing on one of them, chewing on something large. I'd found the alligator with the carcass!
I hurried over in time to see the alligator on one of the islands, alone, tossing the carcass, and then crushing it--as alligators do with large prey that has bones. A vulture landed on the island, near the alligator. Then another vulture. And another...and more until a group of vultures surrounded the alligator. The vultures slowly moved closer to to the alligator...starting to crowd around it.
The alligator stood up with the carcass (actually just the head of the hog), and high-walked into the water.
As the alligator swam away, the vultures began picking at the dirt and grass where the alligator had been holding and shaking the hog carcass.
It seemed that fragments or even just droplets from the carcass caused the area to smell like dead hog--and the vultures (and alligators) were attracted to this.
Meanwhile, the other alligators tried to take the hog's head from the alligator that had it.

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However, that alligator was able to submerge and confuse the carcass thieves. It climbed up onto another island to try again to swallow the hog's head. Again, it chomped on the hog. And then the vultures landed on the island, and gathered around the alligator. One by one the vultures sidled closer to the alligator. While the alligator was resting after a bit of chewing, some of the vultures moved in and grabbed at the hog's head while it was still in the alligator's mouth! They actually pulled a piece off the head before the alligator moved into the water again; where it was chased by the other alligators. Finally, the alligator moved around the end of one of the islands, and was able to almost close its jaws entirely around the remainder of the hog. The vultures stopped harrassing it, and the other alligators couldn't see it.
The Black Vulture (Coragyps atratus) is called "New World" vultures, along with the Turkey Vulture (Cathartis aura).  Recent studies have genetically and morphologically linked these vultures to the Storks. One study can be found here: http://www.pnas.org/content/91/11/5173.full.pdf  That is, Black Vultures are related to Storks, such as the Wood Stork. Besides certain physiological similarities, the two types share some behaviors--such as "urohidrosis (or urohydrosis). This is the act of wetting the bare surfaces of the legs with liquid waste in order to allow the evaporation of the waste to cause cooling through the skin.
Addition 2/25/2012
After further thought, I  realized that Black Vultures might also be called kleptoparasites. (I mention kleptoparasitism in relation to spiders on this page). A "kleptoparasite" is an animal that will supplement its diet by stealing food procured by other animals. According to The Sibley Guide to Bird Life and Behavior, Black Vultures can "dominate Turkey Vultures at carcasses" (page 185), driving them off of kills that the Turkey Vultures find with their greater sense of smell and more efficient soaring abilities ("light wing-loading" (page 185)).  As shown here, the Black Vultures are stealing food from the alligator as well.

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If you'd like to know more about the park follow these links:

Brazos Bend State Park   The main page.

Brazos Bend State Park Volunteer's Page  The volunteer's main page.
 

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