The African spurred tortoise, Geochelone sulcata, is the largest tortoise native to Africa. It inhabits the southern fringe of the Sahara Desert. These tortoises excavate large burrows where they retreat to protect themselves from Africa’s extreme heat. They are vegetarians feeding ongrass and other plant material.

Possibly the largest spurred tortoise on record was a male kept at the Giza Zoological Gardens, Cairo, Egypt, in the early 1900’s. It weighed 105.5Kgand measured 83cm straight line and 104 cm over the shell (Flower, 1925). Most specimens will never approach that size but they can get big just the same. Females typically grow from 52 to 62 cm and weight 23 to 40 kg. Males get larger and will grow from 62 to 72 cm and weigh 40 to 64 kg. They are sexually mature at 38 to 46 cm.

The African spurred tortoise has proven to be one of the most successful tortoise species in captivity. Unfortunately wild populations have continued to fall. Some published statistics state that there may be as few as 18,000 left in the wild. The total wild population has declined from an estimated100,000 tortoises in 1950 to just 18,000-20,000 currently (CFR, March 8, 2000). Captive breeding has resulted in a completely different picture outside of Africa. Not only is the African spurred tortoise thriving in captivity, but also a new ivory coloured albino African spurred tortoise has just been introduced into the pet trade. It has been dubbed the "Ivory Tortoise".

The African spurred tortoise was almost unheard of in captive collections a mere 15 years ago but now the African spurred tortoise is common place in captivity. In 1979, a census found only 13 Geochelone sulcata in zoos and private collections in the Western Hemisphere (Sterns, 1986). In 1981 there were only 12 tortoises represented in two US zoos (Slavens, 1981), several specimens in European Zoos, and a handful in private collections.

In 1986 exporters began to ship the "giant" spurred tortoise from Africa. At first astronomical prices were paid for large adult specimens. As more were imported the price began to fall. In 1986 there were 5,097 tortoises exported from Africa (World Conservation Monitoring Centre). Today exports have been halted but there are estimates that as many as 10,000 hatching tortoises may be produced in captivity each year at tortoise farms in the United States.

I own and operate one such farm. The African spurred tortoise is only one of several species that I am working with. I have a small herd of African spurred tortoises, which includes first and second generation animals.

My farm is located several thousand feet above the desert floor in extreme southeastern Arizona. The habitat is high desert grassland and is situated at the foot of the Huachuca Mountains. The Huachuca Mountains rise nearly another mile into the sky and are often refereed to as the sky islands. These mountains were once the home of thick-billed parrots and jaguars. Now several hundred species of birds, rare reptiles and amphibians, bears, mountain lions, coati-mundis, and other animals still find refuge here.

My property overlooks the San Pedro valley whose river flows north as water seeps from underground aquifers to the surface creating an oasis and flowing stream. Across the valley two dozen miles away sits the historic town of Tombstone. The OK corral still stands where the gunfight involving, Wyatt Earp, Doc Holliday, the Clanton brothers and others is regularly reenacted.

Over a century ago my great-great grandfather hauled timber from his lumber mill in the Chiricahua Mountains to the silver mines in Tombstone. The Spanish explorer Coronado, the great Indian chief Cochise, and the renegade Apache Geronimo probably past by my property in their day. Buzzards sit on the dead branches of an ancient oak tree struck by lightning in a storm.

Gold dust has been panned from the intermittent stream on my farm.

My herd of spurred tortoises thrives here. They graze on the grass watered by the cooling summer rains. They spend their nights and cold winter days housed in a 2,700 square foot greenhouse that is heated by a 145,000 BTU furnace. Due to the intensity of the sun at this latitude and elevation the greenhouse is quickly heated as the sun rises in the morning and even with snow on the ground my cooling system may turn on.

In the winter, if the day is sunny I open the doors of the greenhouse and the tortoises go out and bask in the sun. Outside air temperatures may be as low as 10 C but the sun will quickly warm the tortoises’ shell. The heat will penetrate deep into their bodies and they become active.

My tortoises lay their eggs during the winter. Nesting begins in late morning as soon as the tortoises have been sufficiently warmed by the sun. Females begin by digging a shallow burrow with their front legs. When the burrow is deep enough to hide the tortoise the female will turn around, back into the hole, and begin digging with her hind legs. She meticulously shapes the nest cavity with her long toenails. As the eggs are being laid I collect them and set them up in an incubator where the temperature has been adjusted to control the sex of the hatchlings.

It is an exciting day when the eggs begin to hatch, but not as exciting as one special summer morning. African spurred tortoises had been hatching every day for the past several weeks. As was my routine, I checked the incubator first to see how the newly hatched tortoises were doing. This particular morning I opened a plastic shoebox that contained African spurred tortoise eggs that were due to hatch. To my surprise a little ivory head was poking out from a chalky-white eggshell.

After yelling at the top of my lungs, and doing the dance of joy I pinched myself to be sure I was awake. I ran into the house and dragged my wife into the reptile building so she could verify what I had just seen. Unable to stand the anticipation of what might emerge from that egg I ever so carefully removed a few small pieces of shell and exposed the carapace of an "ivory tortoise".

The clutch numbered 13 very small eggs. I knew the mother had to be one of four young captive-hatched female tortoises that had produced similar clutches of small eggs. They were in separate pens with males that were their sibling. Which pair of these were the parents of this little ivory tortoise? I checked the record card attached to the plastic shoebox that contained the eggs. I had only written the number "3," on the card. Who was number three? I went out to the tortoise yards and began to look for a number three written on the back of a tortoise. All the pencilled numbers had worn off the shells of the tortoises.

I examined all the shoeboxes containing eggs that remained in the incubator hoping I would find a clue. There was a box of small eggs laid one month later than the eggs in question. The clutch size was the same. Fortunately, instead of just a number on the card, I had actually described the female. Evidently the number had worn off the tortoise by the time this next clutch of eggs had been laid, so I described in detail the tortoise instead of just writing down a number. This was the only clutch of eggs laid that had a description and not a number.

If an albino hatched from this clutch I would know who the mother was. I had at least a month to wait! After what seemed more like an eternity than a month the eggs started to hatch. The first little tortoise poked its head out. It was normal. Eleven more babies hatched and they were all normal. No albino tortoise had hatched so far and only one egg left!

I was working with the other tortoises in the greenhouse. I heard screaming and yelling from my wife. I immediately knew that the last egg had hatched and that it was an albino tortoise. Now I knew for certain who the parents were.

What are the odds of an albino just showing up in a clutch of eggs? How did it happen? Unknown to me one of the grandparents of these ivory tortoises possessed a recessive gene for albinism (lacking melanin). The term for having one recessive gene and one dominant gene is called heterozygous. The other grandparent had two dominant genes for dark pigment or melanin. The

term for having two identical genes (two dominant or two recessive genes) is homozygous.

There is a 50% chance that a heterozygous parent could pass a recessive gene for albinism to its offspring and the homozygous parent would pass a dominant gene for melanin. The resulting offspring would be heterozygous. Both parents of the ivory coloured offspring carried a recessive gene for albinism but looked normal because they also had a dominant gene for melanin. I had no way of knowing their genetics until I produced offspring by breeding this brother and sister together.

By using the "Punnet Square" statistically the offspring of heterozygous parents should be 25% albino (homozygous for albinism), 50% heterozygous (dominant and recessive genes), and 25% normal (homozygous for melanin). When I breed two albino tortoises together 100% of their offspring will be albino. Are these really albino tortoises? Several terms are beginning to be common place among reptile enthusiasts. They are albino, amelanistic, leucistic, and hypomelanistic. All of these terms actually refer to albinistic animals and are all, forms of albinism.

The term albino most often refers to the type of albinism called amelanistic (lacking melanin) or tyrosinase-negative albinism. This means the animal is lacking the tyrosinase enzyme that is involved with the production of melanin. The tortoise will have little or no pigment in the eyes, skin and shell. The shell and skin colour is yellow or white and the tortoise has pink eyes. Leucistic refers to the type of albinism in which the skin and shell are pure white (not yellow or pink), and the iris is blue. Leucistic means white, colourless, or weakly coloured.

Hypomelanistic refers to the type of albinism that is Tyrosinase-positive. The tyrosinase enzyme is present but not functioning properly. The skin and shell are yellow not white (distinguishing it from a leucistic animal) and the iris is blue, gray, yellow, or brown. Hypomelanistic means less than normal melanin or dark pigment.

It is quite hard to actually determine the colour of the iris in my hatchling tortoises. The iris is not pink but appear to be blue or blue/gray. The pupil is black. The shell and skin colour is yellow or ivory. The term hypomelanistic would most accurately describe this tortoise. The blue or blue/gray iris is actually a blessing to this desert species. Exposure of pink eyes to the bright sun would certainly be damaging.

I expect egg production to increase next year and I should see more albinos. The eggs were incubated to produce females this year. Next year some will be incubated for males. African spurred tortoises can become sexually mature within five to seven years. At that time the availability of the "ivory" tortoises will be in reach of the serious hobbyist. Until then a very few tortoises will be available each year to the very serious collectors and breeders.

I expect these little "Ivory Tortoises" to be spectacular as adults. They have so far proven to be every bit as hardy as the normal coloured African spurred tortoises. The African spurred tortoise has a good future outside of Africa. especially here in the United States. I predict the ivory tortoises will also.