Alligators page 4 Feeding

ALLIGATOR BEHAVIOR page 4: FEEDING
This page was born 12/27/2003. Rickubis designed it. (such as it is.) Last update: 10/18/2011
Images and contents on this page copyright © 2001-2011 Richard M. Dashnau

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 2c SOCIAL SIGNALS 3                       Spiders at Brazos Bend State Park Page 2
Alligators page 3 CONFLICT AND CANNIBALISM

Alligators page 4b FEEDING 2
Alligators page 4c FEEDING 3
Alligators page 4d FEEDING 4
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

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)

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--------------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" (wmv 29mb).

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 lunge 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.
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--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!
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RAT-BREAKFAST OF REPTILES

June 15, 2003 David 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.

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SOME MOUTHFUL! GOT MILK? 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.
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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, 2003 I 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.
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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.
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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.
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16                                       17                      THAT'S NOT CUTE!