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Here
are my other alligator
pages:
OR, FOR OTHER ANIMALS:
Alligators
page 2a SOCIAL SIGNALS 1
Critters at Brazos
Bend State Park Page 1
Alligators
page 2b SOCIAL SIGNALS 2
Spiders
at Brazos Bend State Park Page 1
Alligators
page 2b SOCIAL SIGNALS 3
Spiders
at Brazos Bend State Park Page 2
Alligators
page 2b SOCIAL SIGNALS 4
Alligators
page 2b SOCIAL SIGNALS 5
Alligators
page 3 CONFLICT AND CANNIBALISM
Alligators
page 4 FEEDING
Alligators
page 5a BABY ALLIGATORS 1
Alligators
page 5b BABY ALLIGATORS 2
Alligators
page 5c BABY ALLIGATORS 3
Alligators
page 6a ON LAND 1
Alligators
page 6b ON LAND 2
Alligators
page 7 GIANT FOSSIL CROCS
Alligators, although they are ectothermic and also equipped with a small brain, exhibit a surprising diversity in their responses to their environment and to each other. They are for more complex than mere animated logs or 12-foot-long eating machines. This group of pages show some of what I've been able to see in just two years (starting September of 2001) at Brazos Bend State Park.
05/17/2009--
Alligators seem to have been less active at the park during mating season
this year. In other parts of Texas, alligator populations were reduced
by the effects of Hurricane Ike and the resultant salt water intrusion.
Brazos Bend State Park didn't suffer such intrusion. However, I was finally
able to sit in on a chorus of bellows, and I was able to record some bellows
with some high-framerate video.
In "Social Signals of Adult
American Alligators", by Leslie Garrick, Jeffrey Lang, and Harold
Herzog (Bulletin of the American Museum of Natural History NY, 1978; click this link to go to the digital AMNH library and see the pdf.) they
break down an alligator's bellow into 4 parts.
While reviewing this footage,
I've expanded this into six parts, since many different things
are happening during the original
4 parts. This is usually repeated in a cycle of 4 or 5 bellows in a
single bout. Sometimes, there
is a single bout; but if other alligators answer, then there are often
repeated
bouts. Here are the 6 parts
as I divided them:
1) REST
2) INHALATION--the head and the body rises, air is taken in, and the head begins to tilt up, the gular pouch extends
3) INFLATION--the head continues to tilt up; air is gulped in and throat valve closes; the body begins to sink.
4) PRE-EXHALATION--the head tilts down and the body sinks.
5) EXHALATION--the head raises, tail arches, exhalation starts
6A) VOCALIZATION A--the gular pouch inflates, back vibrates and bellow begins
6B) VOCALIZATIONb--the body sinks as the bellow fades
Return to rest position (step 1)
I cannot capture sound while recording the slow-motion video. Without audio one can't pick the various sounds during the bellow. (the gulping sound can be pretty distinct) that might help identify what is going on internally. The appearance of the bellows is still fascinating. The images below are screen grabs from the video.
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INHALATION/INFLATION--
INFLATION
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VOCALIZAION A----
-- VOCALIZATION
B
VOCALIZATION B.
I've
edited the clips together into a single video clip. It can be seen here
(wmv, 47mb). It's worth watching, to see how the bellow's energy travels
through the water.
4/13/2008--It's
been a while since I've seen a lot of alligator behavior in one day.
Well, today was one of those days. First thing, I encountered the female
alligator and her babies. This female has been in the same area since last
August, and seems to have most of her babies. It's the same female that
I saw on February 10th, but she's moved across the trail into 40-acre lake.
So, at about 9:00 a.m., I saw her with her babies. The image below shows
them together.
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Map 1
I made
my way to Elm Lake. The image above (Map 1) is a satellite view of the
end of the Spillway Trail (from Google Maps). The colored numbers on the
image refer to the alligators I'm going to talk about. Pilant lake
is left, Elm Lake is right.
When
I got to the water station, I saw an alligator down at the corner in Pilant
Lake (1) and another swimming in Elm Lake (4). When I moved to the left
(Rick A) I saw one alligator on the trail (5) and later found there was
another right next to it (6). I got off my bicycle. I was talking
to a park visitor when I moved past a tree, and suddenly saw another alligator
in the water with head and tail raised (2). This alligator did a head slap.
See map 2 below. Alligator 4 (yellow) just kept swimming north.
Alligator 5 (light blue) raised its head. Alligator 1 (green) moved
towards alligator 2 (red) and did some "snout bumping", which probably
indicated that (green) alligator was a female. (green)Alligator
then passed by (red) alligator and moved north.
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MAP 2
MAP 3
In map
3 above: (green) alligator moved north. (yellow) alligator moved out of
sight. (Red) turned and crossed the trail without stopping. Sometime in
all this, another alligator 3 (purple) came onto the bank. Below are images
from the alligator crossing the trail. The first two images are from this
video
clip (wmv 6.1mb).
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The
other images are from photos I shot at the same time. That's my bike in
the foreground.
After
the large (red)alligator (it was about as long as the trail is wide at
that point), it moved towards alligator 3 (purple) on the bank, and stationed
itself about 15 feet out, facing the (purple) alligator. One of the park
Kabodas came by towards the water station and (purple) alligator entered
the water. Not long after, (red) alligator moved towards (purple) alligator
and began bellowing. Meanwhile, I'd moved to "Rick B", and began
filming and taking photos. See map 4 below.
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MAP 4
This
short
video clip (wmv 10.8mb) shows the entire bout of bellowing. While (red)
gator started, (purple) gator joined in. I'm very excited about this, because
you can hear the obvious difference between male and female bellowing.
Some time after this, the female (purple) alligator moved back up on the
bank. Somewhere North, alligators bellowed out of sight. (Red) male turned
towards the sound, and moved quickly off to the North, towards it. I followed
the male and found two alligators half on the bank. The (red) male appeared
and began swimming toward the larger of the two alligators. Suddenly a
female bellowed from behind me in Pilant Lake. (Red) male began trying
to bellow and swimming at the same time ("trying" means that it paused
and raised its head, but sunk and swam forward). It stopped at a branch
and did a single growl. After some time, it moved slowly towards the two
alligators on the bank. It finally got on the other side of the smaller
one (which I assumed was female). (Red) male was half on the bank. Then,
about 5 feet South was the smaller one (about 7 feet long), and about 5
feet further South was the other large one (presumably male). After a bit
more time, the other male (not Red) slid off the bank, and slowly swam
away.
Later,
at about 1:00pm, I was back near the baby alligators. After a few attempts
at counting, the best I could do was count "more than 17". The female stayed
close to the babies, even occasionally sliding up near them, or even through
clumps of them. The last images are of some of the babies on the
mother alligator. Occasionally, one of the babies would seem to tug at
something on the mother alligator--on her skin or something on the skin.
I couldn't see what there was.
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MOM! YOU AWAKE? YEAH,
WHAT
IS IT, KID?
09/30/2007As I was walking downhill towards 40acre lake, I heard alligators bellowing from somewhere in front of me. They sounded like bellows from females. I met another park volunteer, and he told me that he had just seen the mother alligator bellowing. So, that was probably the one I'd heard closest to me.
I examined
the babies and the mother. The babies were scattered in the water and along
the shoreline, in an area about 20 feet long. While I tried to get
some pictures of the babies, a large alligator swam from my left(from the
northwest) midway between the trail I was on and the islands. It stopped
behind the female, but still in the deep water.
After
about 15 minutes, the larger alligator began swimming towards the area
containing the babies, but seemed to be heading towards a point that would
bring it about 8 feet to the side of the female alligator. It swam
a a leisurely pace. Most of its back was showing, as well as the
upper surface of the tail.
It stopped
about 6 feet from the bank.
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The mother
swam out to meet the larger alligator. It moved slowly, but with intent.
As it neared the larger alligator, the larger one lowered its back. This
caused slight elevation of the tip of the nose.
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The female
kept swimming directly towards the side of the big alligator's snout. As
the female got within 12 inches from the male's snout, the large alligator
raised its back again. When the female got to touching distance, the larger
raised its head, and gently rested its chin on the female's snout. Then
it slowly pushed forward--pushing the female's head from the side with
his lower jaw. It moved forward more until the center of its lower jaw
was on the back of the female's skull. The larger began the bobbing motion
characteristic of a bellow. As it did, it moved forward until its chest
was over the female's back (the two bodies were nearly perpendicular to
each other). Then it pushed down--possibly standing on the female with
its forelegs--and began bellowing.
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During
the bellow, all but the tip of the female's snout was left visible at the
surface of the water. She remained motionless. That is, she didn't try
to escape from under the male alligator. The male bellowed 3 more times,
with the bobbing. During all the motion, the female's nose was also briefly
pushed under the water. After the last bellow, the male relaxed, although
his mouth opened in a narrow gape. This is all shown invideo
clip 1 (wmv 16.5 mb).
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As the
bottom of his closed jaws slowly lowered into the water, a brief spurt
of bubbles was expelled from the female's snout. These broke the surface
about 4 inches from the male's head. Her snout broke the surface,
submerged, and then a stream of bubbles broke the surface of the water,
making it appear that she might have been moving her head from side to
side. Slight movements of the male alligator indicated that the female
was probably changing position slightly. 6 Further streams of bubbles appeared,
without the female surfacing in between. There was a pause of 4-10 seconds
between each burst of bubbles. After the last stream, there was a pause
of about 10 seconds and the female's head surfaced as she apparently had
pulled it out from under the male. Her head was covered with mud
and plant matter, so apparently she had been pushed into the lake bottom.
Movement during all of this was very slow.
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The
female shifted forward with the base of her lower jaw pressing against
the nose of the male. She pushed hard enough to shift the male back a couple
inches. Then, she lifted her snout and placed it atop the male's. Then
she pushed his snout under the water. The male did not seem to resist
this. While his back was still high in the water, he moved backwards
about a foot by floating and sliding out from under her snout. The female
submerged. This is all shown invideo
clip 2 (wmv 17.5 mb).
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She resurfaced
near the male's snout again, whereupon she moved towards him and slid her
bottom jaw, staring at the point, up over the front edge of his snout.
She pushed, but slid off, moving forward past the tip of his nose. She
stopped with the back of her head just past the front of his nose. There
was a pause. She submerged again. the male's body shifted as she contacted
it under water. She surfaced again at the tip of his snout, with
her face pointing the other way. She'd turned around. There was another
pause.
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The
male turned his head slightly, and when he did, the female turned her head
and placed the side of her upper jaw against the tip of his nose and pressed
briefly. Then, after another press, she submerged. Her head resurfaced
near the male's right leg, then she submerged again, blowing bubbles.
This is all shown in video
clip 3 (wmv 16 mb).
She streamed
more bubbles, then just the tip of her nose resurfaced, pointing away from
the male. The snout moved towards the male, and she pressed against the
male with the side of her snout twice more. Her head surfaced, pointing
away from the male. She turned towards the male, and pushed him again,
this time using the front of her body, as her head went over his submerged
back. After this, she submerged once more, and reappeared close
to the bank again. This is all shown invideo
clip 4 (wmv 14 mb).
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The
male remained where he was. He stayed in the vicinity, without moving far,
for about 30 minutes more. Then he moved off.
The
entire exchange took about 11 minutes. Although this took relatively little
time, many signals were broadcast and recieved by both alligators. I thought
the way the female approached the male was also significant. In my experience,
female alligators will often approach a percieved threat to her offspring
with caution and/or stealth. I feel that she is evaluating the location
and size of the threat. If she can, she will first get between the threat
and the babies. Then, as in this example, she will attempt to threaten
or push the interloper away. This is far from most peoples' perception
of the fierce female alligator protecting her young. Rather than wasting
energy and exposing herself to possible harm by rushing noisily at an intruder
(which at first may seem to be the obvious plan), she saves her energy
and prevents possible injury by advancing slowly. In this particular case,
advancing quickly towards what might be a dominant, larger male might have
cause her severe injury or death.
As soon
as she advanced, the male pushed her snout under water and bellowed. Both
of these are ways to assert dominance. The female submitted to this.
However,
after the submission, she stayed near the male and--by performing movements
associated with mating behavior--began to assert her needs upon
the male. She pushed on the male, but from a submissive position. By using
her snout against the male's snout, and then later against his body, she
eventually succeeded in pushing the male away from the shore.
I have
been able to read some studies of alligator social signals, particularly:
Courtship
Behavior of American Alligators, by Kent A. Vliet, Ph. D.--in pages
383-408 of Crocodilian Biology and Evolution edited by Gordon C.
Grigg, Frank Seebacher, and Craig E. Franklin; Pub. Feb 2001. ; Social
Displays of the American Alligator by Kent A. Vliet in Amer. Zool.,
29:1019-1031 (1989); Social Signals of Adult American Alligators
by Garrick, Lang, and Herzog in the Bulletin of the American Museum of
Natural History Vol. 160:Article 3 1978. Reading these works has
allowed me cross reference some of these behaviors. Sometimes there is
mention of "blowing bubbles" in a social context, but without any clear
suggestion as to any meaning. Considering that alligators can sense pressure
waves via the sensory dots on their snouts, then the "burbling" of the
water caused by a stream of bubbles would probably be sensed by the alligator.
In this instance, the female may have been indicating her position or acknowledging
the male's position (directly over her) by blowing the streams of bubbles.
The
head of the alligator--particularly the edges of the jaws--are used for
gentle physical contact during mating, with the edges of the jaws of one
alligator used to touch various parts of the head and neck of the other
alligator. Sometimes these touches can escalate into "pressing" movements
which can be a demonstration or test of strength. During mating, these
behaviors can lead to the reproductive act. Here, though, the mating season
was long over.
It seems
to me that either the female was using mating behavior to allow her to
approach the male; or that the observed actions are part of a broader scheme
of communication and that some of the signals also happen to be used during
courtship.
Alligators,
although they may seem to move slowly most of the time, can show a wide
range of communication if one has the patience to view their world in "alligator
time".
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.
Here are a few links to more information on alligators. There's a LOT of it out there.
Fish and Wildlife Endangered Species
Here
are my other alligator
pages:
OR, FOR OTHER ANIMALS:
Alligators
page 2a SOCIAL SIGNALS 1
Critters at Brazos
Bend State Park Page 1
Alligators
page 2b SOCIAL SIGNALS 2
Spiders
at Brazos Bend State Park Page 1
Alligators
page 2b SOCIAL SIGNALS 3
Spiders
at Brazos Bend State Park Page 2
Alligators
page 2b SOCIAL SIGNALS 4
Alligators
page 2b SOCIAL SIGNALS 5
Alligators
page 3 CONFLICT AND CANNIBALISM
Alligators
page 4 FEEDING
Alligators
page 5a BABY ALLIGATORS 1
Alligators
page 5b BABY ALLIGATORS 2
Alligators
page 5c BABY ALLIGATORS 3
Alligators
page 6a ON LAND 1
Alligators
page 6b ON LAND 2
Alligators
page 7 GIANT FOSSIL CROCS
Go back to my home page, Welcome
to rickubis.com
Go
back to the See the World
page.
