NATURAL HISTORY NOTES
The following questions were answered by Noel Kinler, alligator specialist for the Louisiana Department of Wildlife and Fisheries.
What is the average number of eggs per nest?
The average clutch size is reported in the literature as 40. This number is probably good for brackish marshes. Overall in Louisiana, I would say that the average is probably around 30 to 35 and the range would be 25 to 45 with only a few occurrence outside of these figures.
What is the average time the young spend with the mother after hatching?
The female will open the nest to allow the hatchlings to escape from the egg cavity. The hatchlings will generally stay in the vicinity of the nest if there is an adjacent water source (marsh pond). Often the female will remain in that vicinity as well. It is not unusual to see multiple year classes of young alligators in the same pond. There seems to be little actual maternal care on the part of the adult female, even though they may spend a fair amount of time in the same area.
During winter, do our gators simply rest on the bottom, or do they burrow into the bottom (or use holes that actually enter an underground "cavern")?
Alligators frequently utilize dens that are burrowed into the sides of ponds, lakes or bayous. The entrance holes are usually at or below the normal water level so they are not usually visible. During periods of drought they are readily visible. I believe that the alligators use these dens in both the winter and summer time. In deep water areas I think the alligators also spend a fair degree of time resting on the bottom.
Can you give me the average number of nests in Louisiana per year?
Nest production has fluctuated a substantial amount over the last 5 years. Drought conditions in 1996, 1998, and 2000 resulted in low nest production while 1997 and 1999 had the highest production on record since 1970. The five year average was 34,000 nests for the coastal marshes. This does not include any nest production in the cypress-tupelo swamps or inland lakes
The overall social interactions may be broken down into three elements:
Visual: includes head and tail elevation, head slaps, jaw claps, and other postures.
Auditory (sound): Males bellow for a variety of reasons, but mostly for defining territory and attracting a mate. It may be done anytime, but is most usual from April to June, and done early in the morning. The males often emit musk from their musk glands on their lower jaws. Females create a bellow/growl (much quieter) that excites the males to growl. Males also use subaudible sound (see below).
Olfaction (smell): Alligators have two sets of oily musk glands. One set is at the rear of the lower jaws (used when bellowing), and the other is in the cloaca (used when head slapping). It appears that musk is used mostly on the surface of the water, and less so in the air. The following eight elements of communication bellowing and/or head slapping) are quite variable, but predictable. Their function may be the following:
- attract others to the courtship grounds
- aggressive signal to all others of the same sex
- give information on size, sex, and dominance of the bellower
- synchronize group activities
- define territories early in the season (there is evidence of fighting among males at this
- Elevated posture. The body is straight, and most of the length is above water.
- Head oblique (at an angle), tail arched (HOTA). The body is straight, the head is held at an angle above water, the back is below the water, and the tail is arched out of the water. This is the same posture used when bellowing.
- Water dance (subaudible vibrations [SAV], infrasound). In the HOTA position, the sides are vibrated to produce sounds that humans cannot hear (too low in frequency) which produce ripples and water jumping from the surface. This is done only by males and is done immediately before or during head slapping.
- Jaw clap. Snapping of the jaws.
- Head slap. From the tilted position, the head is slapped down to the water surface to make a noise. Done mostly by males. It is contagious - when done, others immediately begin doing it, too. Head slapping is often done in a secluded place. Oily musk may float to the surface from the cloacal glands. Establishes and/or maintains dominance or hierarchical position in the group.
- Growl. Usually by males. Often done before, during, or after head slaps or jaw claps.
- Inflated position. Typically follows head slaps or jaw claps. The legs are fully extended, back is arched, tail at or above the water surface, head above or below surface, jaws closed or open.
- Tail wag. Generally done during the inflated position. During intense displays,commences before head slap and intensifies afterward.
Louisiana Alligator Harvest Story
SUMMARY: In the 1960s, alligators were headed toward being placed on the endangered species list. Since beginning its alligator harvest program, Louisiana has seen a huge increase in the number of alligators. This is mainly because, since the alligators have value to landowners, they are fiercely protected and managed. The alligator harvest has resulted in more alligators than ever before!
Alligators have long been important to Louisianans due to the value of their skins (belts, shoes, boots, luggage, the small chin scales for watch bands, etc.) and meat (sauce piquante, gumbo, sausage, etc.). They have played a major role in the development of our culture
Back in the 1960s and before, alligator populations were declining everywhere. Much of the loss was due to habitat loss, but most was due to poaching and other forms of unmanaged slaughter. In the mid-1960s, alligator hunting was outlawed, but the slaughter continued.
Typically, the folks who owned and managed marsh where alligators lived considered alligators the enemy. Most of these folks made their living trapping and fishing and they viewed the alligator as competition for these resources. If they did not kill alligators themselves, they certainly did not attempt to prevent poachers from doing so. Why would they? The poachers were doing them a favor!
With protection, poaching did not totally disappear, but it decreased markedly. Alligator populations began to enlarge, especially in prime habitat. Studies by the Louisiana Department of Wildlife and Fisheries (LDWF), led by Ted Joanen and Larry McNease at Rockefeller Wildlife Refuge in Cameron Parish, indicated that the alligator could be a managed natural resource. Louisiana petitioned the U.S. government to allow an alligator harvest season in areas of high population. Louisiana had its first legal alligator season in September, 1972, much to the consternation of many animal and environmental groups. LDWF maintained that, if managed properly, alligators could contribute to the economy while their populations remain strong.
What does “managed properly” mean? LDWF set forth a management plan that was based on scientific knowledge of the species’ natural history. The following steps were mandated:
1. The season would be in September each year. This assures that nesting females are confined to marsh areas.
2. Alligators can only be caught on hook and line. This prevents “hunters” (we’ll call them harvesters since they are really simply running trot lines) from selecting the alligators they take. The catch is random. “Poling,” the practice of using a long pole with a hook on the end, was outlawed since it is not random and gives the hunter the advantage.
3. Bait can legally be set anywhere, but by far the easiest location for the harvester is in canals and channels. During September, most female alligators are out in the marsh and most alligators in canals and channels are male. If most harvesting is in canals, most alligators taken will be male. Since one male can service many females, this insures that the egg producers are protected and it is thought that enough males would be left to take care of the ladies.
4. Hunters are advised to hang their bait high enough over the water so that only larger alligators can reach it. There is no fast rule of thumb, but some of my colleagues hang their hooks at 8" above the water and they have never caught an alligator of less than 6 ft long. When they hang at 18", they get gators about 10 ft and up. The level above the water becomes critical when harvesting is done in tidal zones where the tide may come in and submerge the bait (a good way to catch small gators and catfish!).
5. Harvesters must either own or lease the property where they set their lines. This controls who is where.
6. Each year, LDWF censuses alligators parish-by-parish. Their estimates are in alligators-per-acre-of-swamp/marsh and they annually determine how many alligators can be taken in each parish depending on how many acres each harvester controls. If population estimates are low, they set the harvest low; if high, they set it high. They can, of course, close the season, overall or locally, if their data suggest they should.
7. On the basis of “6”, each licensed harvester is issued a certain number of tags. Each of these tags represents one alligator that they can harvest. If they lose a tag, that is one less alligator that can be harvested.
All of this adds up to a plan based on the knowledge of science of the species, annual population estimates, and controlling who harvests where. This should work well, but does it? I have been on several trips to harvest alligators. On these trips, I have witnessed the following:
1. LDWF personnel have met us and indicated, before they could even see us, that they knew who should be in the boat and how many alligators we had on lines.
2. All that we harvested (some 30 or so) have been males.
3. Their sizes have ranged from 4-13 feet.
4. In one instance, an alligator that had a tag affixed thrashed about in the boat and lost its tag. LDWF personnel required us to place a new tag on the skin, thus reducing our harvest by one.
5. The next spring, I saw plenty of alligators in the harvest area.
In addition to the annual harvest, there are two other sources of alligator skins and meat.
a. Farming: Adult alligators are maintained in captivity; mated; their eggs incubated, hatched, and raised; the young are harvested.
b. Ranching: Alligator eggs are harvested from wild nests and removed to alligator farms. The eggs are hatched and the young raised. When the young reach 4' in length, 17% are required to be returned to the site of collection. This works well for alligator populations because 1) normally only 17% reach this size in the wild and 2) at this length, there are few predators (most predation takes place on the younger individuals). [Recently, there has been controversy. Dr. Robert Chabreck, L.S.U., has published that most of the released alligators are immediately eaten by adults. There is strong disagreement from Ted Joanen, our state’s recognized expert on alligators.]