Incubation And Hatching Of Alligator Eggs

The method and timing of egg collection is very important. Alligator embryos are very sensitive to handling (mechanical injury) from 7 to 28 days after they are laid. Many embryos will die if handled during this period.

Current recommendations are either to collect eggs within the first week or wait until the fourth week of natural incubation.

Collecting eggs within the first 24 hours after being laid has several advantages:

Eggs are not easily damaged because the embryo is not yet attached to the shell. Egg collection allows the farmer to separate good eggs from infertile or dead eggs.

Eggs that were laid upright can be repositioned. It eliminates losses caused by predation and/or bad weather. It eliminates losses in breeding pens when more than one female tries to lay eggs  in the same nest.

After 4 weeks of incubation the embryo has developed enough to resist most damage from handling. Most alligator eggs cannot be turned or repositioned when taken from the nest (unlike bird  eggs).

Eggs should be marked with an “X” across the top before removing them from the nest so that they can be maintained during transport and incubation in the same position as they were laid.

Eggs that are laid upright in the nest (long axis perpendicular to the ground) will die unless repositioned correctly (long axis parallel or laying on its side and not on end) before artificial  incubation.

This repositioning can only take place in the first few hours after nesting. Some captive alligators will aggressively guard their nests. Use caution collecting eggs. It is a good idea to work with  another person  while collecting eggs. If the female is not aggressive then do not antagonize her.

Many times an aggressive animal can be chased away or kept at bay using a long sturdy pole. During collection place 8 to 12 inches of nesting material or grass hay (moisten several days in advance) in the bottom of the collection container to support the eggs.

Place the marked eggs in a single layer in the container and in the same position that they were in the nest. Cover the eggs with 2 to 3 inches of nesting material. Transport very gently! Age of the eggs and developmental progress can be observed by changes in the opaque banding that occurs during incubation. Figure 1 shows the sequence of banding associated with proper egg development.

Incubation and hatching:

Artificial incubation, compared to wild nesting, improves hatching rates because of elimination of predation and weather-related mortality. The best hatching rates for eggs left in the wild is less than 70 percent. Hatching rates for eggs taken from the wild and incubated  artificially average 90 percent or higher.

Eggs should be transferred into incubation baskets and placed in an incubator (environmental chamber) within 3 or 4 hours after collection. Air circulation around the eggs during  incubation is critical. Egg baskets or trays are best made from PVC coated 1 x 1/2 inch steel wire mesh or 1/2 inch heavy duty plastic mesh.

Top, bottom and sides of the baskets should be made from the mesh material to enhance air circulation. Dimensions for egg baskets can vary (1 foot x 2 feet, 2 feet x 2 feet and 2 feet x 3 feet are common) but should be 6 inches in depth to accommodate eggs and nesting material.

Eggs must be completely surrounded by nesting material.  The decomposition of the nesting material aides in the breakdown of the egg shell. Without this natural decomposition, hatching alligators will have a difficult time breaking out of the shell and some may die.

Fresh, natural nesting material composed mostly of grasses is best. If natural nest material is not available, use grasses which have  been soaked for about a week. Sphagnum moss can also be used as incubation material.

Producers with captive breeders dip the eggs and incubation substrate in an antifungal agent like chlorhexadine diacetate before incubation to reduce potential disease problems. Wild eggs are seldom treated before incubation.

Hatching baskets are set on shelves or brackets about 3 inches above the water in an incubator. The temperature, humidity and water level are controlled in the incubator. Figure 2 is a construction diagram of a small environmental chamber developed at the Rockefeller Wildlife Refuge at Grand Chenier, LA. The cost to build this environmental chamber was approximately $5,000.

Other producers use separate buildings with temperature and humidity control or small tanks housed inside a temperature- controlled grow-out building. Relative humidity should be kept above 90 percent within the chamber, and incubation media should be moistened with warm water as necessary to maintain dampness.

Incubation temperature is critical to survival and proper development. It also determines the sex of the hatchlings. Temperatures of 86°F and below produce all females while temperatures of 91°F and above produce all males.

Temperatures much above 91° or below 86°F, however, cause abnormal development usually resulting in high mortality. Both sexes are produced at temperatures between 86°F and 91°F. The critical temperature period for sex determination is around 20 to 35 days after the eggs are laid. Most producers now incubate eggs at 88° to 90°F.

This produces a mixed sex population with good survival and growth. Hatchling alligators make peeping or chirping sounds after hatching. When 10 to 15 percent of the clutch has hatched many producers carefully open unhatched eggs.

Eggs are cracked and opened at one end to free the baby alligator, but care must be taken not to detach or damage the umbilical cord. If the umbilical cord is broken the hatchling is likely to bleed to death or develop an infection.

Hatchlings are retained in their hatching baskets for 24 hours to allow the shell and umbilical cord to separate naturally. After 24 hours the hatchlings are removed from the egg baskets,  sorted into uniform size groups, and moved into environmentally controlled grow-out facilities.

Closely sizing the alligators is very important. Smaller, weaker individuals will not be able to compete with their larger siblings. Hatchlings can be moved into small tanks , 2 feet * 2 feet and larger in size, that are heated to 86 to 89dec F.

Maintaining hatchlings at 89 degF for the first week helps increase yolk absorption. Usually hatchlings will start to feed within three days at this temperature. Some producers do not offer feed until day three or after, while others offer feed immediately.

Young that do not start  feeding on their own  can be  force fed using a large syringe. Hatchling tanks need to be cleaned daily to prevent possible disease outbreaks.  A few producers specialize in producing hatchlings for resale to other farms.

Most hatchlings are not sold until they are actively feeding. Once they are actively feeding they are ready to be moved to grow-out facilities.

 

Author:

Michael P. Masser