Whether born of a desire to breed tortoises for profit or out of simple curiosity, many tortoise enthusiasts wonder how many eggs tortoises can produce. It’s actually a very important subject, as tortoise clutch sizes influence things ranging from the sale prices of hatchlings to the preparations breeders need to make to the prospects of a species’ survival in the wild.
In actuality, tortoise clutches vary in size pretty significantly, based on a variety of factors. Read on to understand precisely how many eggs most tortoises lay, as well as learning about some of the factors that influence the final egg count.
Common Species Clutch Sizes
Different tortoise species exhibit a number of important behavioral, biological, and ecological differences.
They live in different regions and prefer different habitats. They consume different plant species and exhibit different mating behaviors. They even cope with different environmental challenges and face different predators.
So, it should come as no surprise that these individual species have evolved traits that are best suited for the specific environment that they find themselves in. And this includes their reproductive effort, especially as it relates to clutch size.
Generally speaking, tortoises produce clutches ranging from only a single egg to well over 20. And though many factors will influence the size of any individual clutch, a tortoise’s species plays a significant role in this number.
Some of the average egg clutch sizes for different tortoise species are provided below:
- Sulcata (Centrochelys sulcata): 15 to 30
- Red-footed tortoise (Chelonoidis carbonaria): 5 to 15
- Yellow-footed tortoise (Chelonoidis denticulata): 4 to 8
- Russian tortoise (Testudo horsfieldii): 2 to 6
- Hermann’s tortoise (Testudo hermanni): 5 to 8
- Greek tortoise (Testudo graeca): 5 to 10
- Desert tortoise (Gopherus agassizii): 4 to 7
- Leopard tortoise (Stigmochelys pardalis): 6 to 10
- Pancake tortoise (Malacochersus tornieri): 1 to 2
- Burmese star tortoise (Geochelone platynota): 1 to 10
- Spider tortoise (Pyxis arachnoides): 1
- Egyptian tortoise (Testudo kleinmanni): 1 to 4
- Aldabra tortoise (Geochelone gigantea): 9 to 25
- Galapagos tortoise (Chelonoidis spp.): 2 to 25 (depending on the species)
Number of Egg Clutches
One of the important things to consider when thinking about the number of eggs a tortoise produces is the frequency with which the species produces egg clutches. Unlike many mammals, who only produce young once per year, many tortoises produce several clutches each year.
This means that even those species who do not produce very large clutches can deposit quite a few eggs over the course of a year – and those who produce large clutches can produce an incredible number of offspring.
But as with clutch size, the number of clutches a tortoise produces varies with the species (as well as some other factors, such as food availability and the size of the mother). Some species, such as desert tortoises tend to produce only one or two clutches per year. By contrast, sulcatas and leopard tortoises may produce as many as five to seven clutches per year.
Factors That Influence Tortoise Clutch Size
As you can probably tell by now, there aren’t many hard-and-fast rules about the number of eggs (or even clutches) a given tortoise will produce in a year. Aside from the tortoise’s species, a variety of factors play into a mother’s overall reproductive effort, including the following things:
- Size of the Mother: Generally speaking, larger mothers tend to produce larger egg clutches. They’re also more likely to produce more clutches than smaller members of their species.
- Health of the Mother: As with most other reptiles, tortoises tend to produce larger clutches (in terms of egg number) than those who’re suffering from poor health. In fact, female tortoises who’re not healthy may not produce eggs at all in a given year.
- Food Availability: Typically, years in which food is more abundant yield larger tortoise clutches.
- Social Factors: In some tortoise species, including most notably, Aldabra tortoises, clutch sizes can vary based on population density. In such cases, clutch size tends to decrease as population density increases.
- Individual Variation: Because each individual tortoise is unique, different individual tortoises will tend to produce clutches of different sizes.
- Environmental Factors: Years that experience poor weather may cause the tortoises in a given area to suffer from reduced clutch sizes.
Largest Recorded Tortoise Clutch
Scientists occasionally stumble upon egg clutches deposited by wild tortoises, but it doesn’t happen very often. Some species have been tracked for several years at a time, which allows scientists to study their clutch sizes, but this has typically occurred with species who don’t produce large numbers of eggs.
Instead, most of what we know about tortoise egg clutch size comes from the observations of zookeepers, breeders, and pet owners. Unfortunately, there’s not a common repository in which this kind of data is curated. This means that reports of large egg clutches are scattered.
Nevertheless, the largest clutch we can find a reliable account of involves a Burmese black mountain tortoise (Manouria emys phayrei) who produced a clutch of 68 eggs. This was obviously an outlier, as most clutches produced by these tortoises are much smaller. However, at least one other clutch produced by this species contained 62 eggs.
How Many Tortoise Eggs Hatch from a Clutch?
One-hundred percent hatch rates are rare in captivity and they’re likely even less common for eggs deposited in the wild, where fluctuating temperatures, imperfect soil conditions, and predators are common. So, it is important to understand that even if your tortoise lays 10 eggs, you probably won’t end up with 10 hatchlings.
Hatch ratios tend to vary based on a variety of factors, including the health and age of the mother, the quality of the incubator used, the water-to-incubation-media ratio, and the breeder’s skill level. However, hatch rates in the 80% to 90% range are usually considered normal.
It is worth noting that in the wild, many hatchling tortoises will die at the hands of predators before reaching maturity. For some species, this results in an overall survival-to-maturity rate of only 2% to 5%. By contrast, the vast majority – likely upwards of 90% — of captive-bred hatchlings will survive to maturity.
How Do Clutch Sizes Affect Pet Tortoise Prices?
Basic market forces mean that clutch size has a very significant effect on the sale price of hatchlings. Tortoises who produce large clutches are more readily available, which helps to keep their price low. By contrast, species who only produce a relative handful of eggs remain somewhat rare and therefore command higher prices.
However, there are a few other factors that also play into the prices associated with hatchling tortoises. For example, some species are simply more desirable than others, which obviously influences their price. Additionally, some species are simply harder to maintain or breed.
If you’ve enjoyed this article, here’s a link to Is a Box Turtle a Tortoise? that you may also enjoy.
Citations
- Animals — Monitoring of Unhatched Eggs in Hermann’s Tortoise (Testudo hermanni) after Artificial Incubation and Possible Improvements in Hatching
- Journal of Herpetology — Size-Specific Fecundity of the Desert Tortoise (Gopherus agassizii)
- Canadian Journal of Zoology — Egg size and shape, clutch dynamics, and reproductive effort in European tortoises
- Turtle Conservancy — Huge Clutch of Eggs Excavated
