Most
people have seen programs on television showing crocodiles attacking
large
animals like deer and cattle. While this is amazing, and sometimes
horrifying,
those creatures
are not alligators. The function of
a crocodile's
dentition is somewhat different than an alligator's. Alligators favor
prey
items that will fit inside their head. That is, if they can
swallow it
whole, then they will normally attack it. While I've heard witnesses
tell
of alligators taking deer in the park, the prey was very small fawns.
Alligators
have also been seen
with large nutria. But, most of the time, they will
eat things like small fish, frogs, and crayfish. Snakes and turtles are
also pursued, with alligators seeming to be especially
well-adapted for
eating turtles. A recent study done in Texas examined the stomach
contents
of about 50 alligators (which were unharmed). Research showed that only
one of
these alligators had eaten a bird (which couldn't be identified,
it might have already been carrion when taken), and the rest had
stomach
full of small fish and shellfish. I've seen
11-foot
alligators going
after prey that was no larger than their largest teeth (very small
frogs
and fish).
May
05,
2002
After this, I moved back towards 40-Acre lake, where I'd left my car.
At
the Observation Tower, there were two alligators (about 5 to 6 feet
long)
that were feeding in the shallow pool
at the head of Pilant Slough.
This
was quite interesting, since most of us don't often see alligators
feeding.
These two moved all around the pool, and sometimes foraged directly
under
where we
were standing--on the concrete wall where the floodgate was. (CHOMP!,
below)
---------------
----------
----CHOMP!--
-----COME
HERE, I WON'T HURT YOU.
While
they were foraging, I observed some very odd behavior. Well, it looked
odd, although it seemed to be functional. The alligator would move near
the shore, and suddenly begin fanning
one of
its forelegs (wmv 2.2mb
or flv video
538kb) and the image COME HERE,above.
in a
sort of "come-here" motion. Then, it would turn its head sideways,
towards
the moving foot, and grab something.
They did this often.
Here are
two more short clips showing this behavior. Alligator
Fishing one (wmv 2.0mb
or flv video
533kb ) Alligator
Fishing two (wmv 757kb
or flv video
288kb). Sometimes,
the alligator would be completely submerged, and then I could see just
the foreleg coming out of the water, and moving around.
I guessed
that the alligators might have been harvesting crawfish, or possibly
tadpoles,
but in any case something slow enough for them to grab this way. David
Heinicke, one of the park naturalists,
thought this might be the prey
as
well. Looking closely at the video, I can see lots of small fish
jumping
away from the alligator. Perhaps the alligators were
harvesting mouthfuls
of minnows. In one
other behavior we saw, the
alligator moved
backwards a few steps, slowly swishing its tail, and then moving
sideways
towards the shore. It then would hook its tail towards the shore, and
do
the "foreleg
scoop", and snatch some food.
I had
some errands to attend to, so I had to leave the park earlier than
usual
today. However, I certainly saw a lot!
UPDATE 10/18/2011-- In
the 9 years since I wrote the entry for May 05 above, I've seen
alligators do this kind of thing many times. They ARE trapping food. I
call this behavior "SEINING
".
I don't know
if anyone else has named this alligator hunting
technique, but this is what I named it. They
occasionally do a few additional movements that make this hunting
technique even more productive. Sometimes
they will move into the
deeper water (submerging if possible), and agitate the water to flush
prey. Then it picks a bank, and works towards it. Sometimes alligators
will use their tail to cause the water to
flow, and then hunt the
current. Besides converting the original uploaded clips to
wmv
format, I've tried to produce another one with a larger frame size.
So, here is the newly-edited video, from footage
shot in
2002:
Demonstration
of an Alligator "Seining" (mp4).
May
25,
2002 I
saw a little social interaction
between some alligators this morning. Before, during, and sometime
after
this little event, at least one--and sometimes more--
alligators
would be hanging
around the pier, acting like delinquents, and
generally
being a nuisance. At various points along the Elm Lake trail, they also
started bothering fishermen. The pictures below show one of these
alligators.
Note the jaws slightly agape (I'M JUST FLOATING)
in the
first image. I've noticed this in alligators who are hunting. This
position
could also make more sense when one thinks about function of the DPRs
(noted
below). If the mouth is already open, then the grab for food
could
take a bit less time. On the other hand, depending on the
size of
the prey. if the jaws were closed at the start of a quick sideways
l
unge
for food, then opened suddenly during the lunge, a slight pressure
difference
could form which might serve to draw prey into the mouth.
This alligator
seemed to be the one who preferred this area. The
others would come by,
and then leave. Look closely at WHEN HE GETS A FISH, and you will be
able
to see the fishing line going into the water. We do NOT feed
the alligators
at Brazos Bend Park. Visitors
who are fishing, and attract
alligators,
are advised to move to another pier, or otherwise leave the immediate
area.
The alligators have the right of way in the park. If one takes your
fish
or your bait, cut the
line and let him have it. Do not feed
caught
fish or leftover bait to the alligators. Alligators will
follow movement
in the water (see the note below) and some have learned to associate a
moving float (or bobber)
with food immediately behind it. It's
generally
asking for trouble to continue fishing near an alligator. One an
alligator
assesses you, and decides you are not a threat, it can become an
implacable
pursuer of
what it wants. It will just "high walk" over to
what it
wants and try to take it. At this point, if a human, or
anything
tries to stop it, it becomes a challange. Here are two short
video
clips of the delinquent at the pier.
Click
on clip
one (flv video 335kb)
or clip
2 (flv video 419kb).
Clip one shows three alligators.
----
--IM
JUST FLOATING---------
---------WHEN HE GETS A
FISH...---
--WHAT'S GOING ON OVER
THERE?
Oh!
One other VERY COOL thing.
Evidently,
the ISOs (Integumentary Sense Organs) that I've mentioned before (see Alligators
at Brazos Bend State Park Page 4 ) have been the subject of
recent
study. I'd mentioned that these ISOs were
probably used for detection
of
movement in water (I read this elsewhere, and my observations also
seemed
to verify it). This recent study evidently has proven that this is the
case. These ISOs (called DPRs,
or "Dome Pressure Receptors" in the
study),
have been found to be very sensitive to pressure changes in water. The
researcher, Daphne Soares, has done some very interesting work. For
more
information,
try these links: NPR
radio , University
of Maryland. I think this is
pretty cool! And, Ms. Soares
has gained my admiration.
July
20, 2002 (Saturday) I
took a small group of
people around the Creekfield Trail, for an informal hike. About 3/4 of
the way through, I noticed a small (about 3 foot) alligator in the
duckweed,
in the shade of a
tree. As I pointed out this one, another alligator
the
same size surfaced, and moved its head, as if it was eating something.
While I moved another step forward, I noticed a dead animal on the
bank,
not far from
the two alligators. These alligators were, by the way,
very
close to us on the trail, although they were in the
water.
When I saw the dead animal--which appeared to be a small (about 4
inches
long) rodent of
some kind--I couldn't really tell what it was, since
all
I could really see was something dead covered in wet, grey fur. I was
about
to mention the alligator behavior of keeping, and sometimes hiding,
larger
prey
items so they can decay enough to tear easily, when the second
alligator
started to move. This little one swam right towards us, walked up on
land,
still facing us, then stopped and rested briefly on the bank. I
thought
then that it was going to sun itself, since its belly was a bit
distended.
However,
it only paused a second or so, then got back up, and walked right over
to the dead whatever-it-was. With a decisive movement of its head, it
grabbed
this carrion, then lifted it; turned, and strutted back
into the water,
where it began chewing on the dead animal. During all this, I was
talking
in my usual dry calm tones, saying "Isn't this GREAT? Look at that!
This
is SO COOL! The alligator might have killed it! Notice
how its head is
above the water. We rarely get to see this!" and other equally inane
observations,
also meanwhile forgetting that I WAS CARRYING A CAMERA. I
grabbed
it out of its case, turned it on, and was
able to snap two pictures
before
the alligator submerged, and swam off to feed in peace. One of these
(see
BREAKFAST OF REPTILES, below) shows the alligator in the duckweed with
the rat (or young nutria,
or whatever) in its mouth. I
usually am
more informative in my lectures than this. But, it was such an uncommon
event!
---------
-------
RAT-BREAKFAST OF REPTILES
June
15, 2003David
Heinicke, Park Naturalist, was out on Elm Lake trail when a
visitor
came running up and told him that an alligator had just seized a
turtle.
He investigated, and put a call out on the radio for
people with
cameras.
I heard this, but could not answer (my radio malfunctioned), so I
missed
this opportunity. Among the people who witnessed this with
David
was John Bradford, who took many pictures, and
even video clips with
his
digital camera. He generously gave me a copy of these, and told me that
I could use his material here. So, here it is.
-----
SOME
MOUTHFUL!
I CAN'T SWALLOW
*THIS*!
NOT MUCH BETTER
THIS
ISN'T
HELPING
The
alligator took about 2 hours (yes, TWO HOURS) to reach the point where
he could swallow the turtle. Almost all of this time was expended by
tossing
the turtle around until it got to a good leverage point within
the
alligator's
jaws. This might be similar to one of us trying to eat a walnut without
using our hands--except that we wouldn't swallow a walnut with shells
and
all. This event seems, to me, to be an excellent illustration
of the
alligator's
feeding strategy, as well as a good example of the competition between
predator and prey. I can't think of any other animal in our
park
that could expend two hours in pursuit of a single meal (a lot
of time
that might be better used finding easier prey), and also could even
breach
the turtle's defense (the shell). The turtle, meanwhile, used its
typical
defense strategy--which is wait for its attacker to give up, and/or
else
scurry away. Only the alligator (as far as I know) had the
attitude
and the power to get into the shell. The alligator was
eventually
successful (see THE END, below), and the turtle fell, to be swallowed
whole.
The alligator can and will digest just about everything, shell
included.
This alligator was at least 11 feet long, and the turtle was quite
large.
This was a good stomachful for the alligator. I warn all
readers
that this is
quite intense imagery, and it is not included here for
sensationalism,
but as an illustration of the quiet power of the alligator's jaws.
-----------
THE END
I
was
also interested, as I usually am, by the leisurely pace of this event.
Not only did the alligator persevere in his quest for his meal, but he
was most languid about it, expending very little effort in movement.
This
speaks again for their efficiency in using available energy
resources.
The four video clips I have linked here illustrate this better than the
photos. These clips have no sound. And, once again, I warn readers
that
some of this footage may be upsetting.l As usual though, we try to let
nature run its course at the park, and sometimes this means witnessing
the death of a favored animal.
Clip1(flv video 515kb) clip3(flv video 513kb) clip3(flv video 514kb) clip4(flv video 540kb)
Thanks again to John Bradford for letting me use this rare footage.
July
13, 2003I
was able to watch some fishing, alligator-style, today. I've
already
shown one style of alligator fishing on alligator
page #6. Today's behavior was a little more
exciting. The alligators
were scattered
around Elm Lake, just floating in the weeds. From time
to
time one would slowly move for a yard or two, and then stop, and lie
still.
Where alligators are concerned, it's sometimes difficult to tell if one
is just resting,
and watching the world; or actually hunting, and
waiting
for prey. In any case, up to 30 minutes or more can
go by with
almost no movement at all.
I've
heard and read it often: "Alligators are opportunistic feeders". From
what
I've observed, this means that they eat whenever an opportunity
presents
itself (like if some food happens to fall into their "lap"...or their
mouth,
and it does, sometimes); rather than actively
hunting prey. If there
are is carrion, they will eat it. If there is small prey (sometimes no
larger than the alligator's teeth!--i.e. minnows and tadpoles) around,
they will
eat it. If something a little larger (perhaps a large
mouthful-sized
animal--i.e. nutria or large turtle) happens to swim or walk in front
of
them while they are hungry, they will attack it. If they are really
hungry, after the
former situations haven't presented themselves (and
in
a healthy habitat like the park, the former situations come up often)
THEN
an alligator may go after larger, vigorous, prey.(i.e. small deer--VERY
rare occurrance)
Cannibalism of 4+ foot alligators does
happen (seealligator
page 3), but this is probably due to territoriality rather
than active
predation.
MOST
HUMANS OLDER THAN 6 YEARS ARE NEITHER THE RIGHT SIZE NOR THE RIGHT
SHAPE
FOR AN ALLIGATOR TO CONSIDER THEM AS FOOD, except perhaps as
carrion--that
is, if the human is already dead.
----
01
03
05
07
So,
these alligators were floating here and there. Suddenly, one
would
rear up out of the water and do a dive (not "sounding" like a whale and
gracefully submerging, more like a twisting belly flop. I've seen this
at other
times.) After this, the alligator would surface,
sometimes
chewing something. The alligators were fishing. I couldn't
see what
they were fishing for, but I also saw large garfish breaking the
surface
as well. The alligators
could have been chasing what the garfish were
chasing,
or pouncing on the garfish. Also, I couldn't see what
triggered the
jump. What decided the alligator to lunge? Was it sight? Is
it something
to do with the ISO/DPRs?
After all, he's lunging at least
half a
body length.
----
09
10
12
14
Frequently,
since alligators spend so much time being almost immobile, it can be
difficult
to catch an alligator in action on film. The immobility lulls
the
observer (or the prey!!) into complacency, and then there is a sudden
movement
(alligators can be very fast!), and something has happened.
Something
that happened too quickly to video tape or
photograph. One
finally has to just pick an alligator, and keep recording it (if using
a video
camera) and hope one gets lucky. I did this, and I got lucky! I
had to keep enough frame around the alligator to catch most of his
leap;
and I had no way of knowing if he'd leap, and in
which direction.
He moved towards the
camera! Today's RICKUBISCAM shows my lucky capture
one of these dives. Above and below, I have a series of
frames from
this clip(remember that clicking each will show a larger image). Notice
how the alligator's
head turns sideways as it comes down. This allows
it
to keep an eye on its prey, and also turns the jaws in the correct
positon
to slice the water and grab whatever it was. Oh, and here is
a link
to the video
clip
(flv video
290kb), and here is a link to the slow
motion video clip (flv video 559kb).
Here's
a question: How does the alligator rear up in the first place? He's
lying
in water! You try to rear up out of the water and
lunge forward
like this when you are in a depth way over your head. In
image number
3 and 5
we may see a hint about this. It looks like there is a sudden
tail
movement just before the lunge.
--
16
17
THAT'S NOT CUTE!
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.
This page shows alligators at the park, on land, near various landmarks at the park.Go back to my main alligator page, Alligators
Go back to my home page, Welcome
to rickubis.com
Go to the main alligator page