The Hermann’s tortoise (Testudo hermanni) is one of the most popular tortoise species in the world, thanks in large part to the species’ manageable size.
Unlike sulcatas (Centrochelys sulcata), leopard tortoises (Stigmochelys pardalis), or other gigantic species, which present significant housing challenges, it’s relatively easy to provide a Hermann’s tortoise (or even a small group of them) with sufficient space.
When it comes to owning a Hermann’s tortoise, especially from the hatchling stage onwards, it’s worth being equipped with details about their growth rate and how long it takes for them to become fully grown so that keepers can get ahead of the curve when to comes to understanding how fast they grow and at what point they will require a full-sized enclosure.
In this article, I’ll be explaining everything you need to know about the growth rate of Hermann’s tortoises and also sharing some factors that influence their growth rate too.
Sex and Subspecies Considerations
Before delving into the growth rate of these tortoises, it’s important to note that there are two things that strongly influence their size: their sex and the subspecies to which they belong.
Subspecies Size Disparities
Hermann’s tortoises differ markedly across their range. In fact, there are currently two different subspecies recognized, and each tends to reach a different size range.
Western Hermann’s Tortoise (T. h. hermanni)
Found along the coast of Italy and into France and Spain, this subspecies typically remains smaller than the eastern subspecies, with a maximum size of about 7 inches.
Some individuals never even exceed 4 inches in length. Many keepers find that these tortoises grow slightly slower than their eastern counterparts.
Eastern Hermann’s Tortoise (T. h. boettgeri)
These animals are found throughout much of the Balkans and along the eastern shores of the Adriatic Sea. These tortoises grow much larger and much faster than their western counterparts and occasionally reach 11 inches in length or more.
Sex-Based Size Disparities
Like many other reptiles, Hermann’s tortoises are sexually dimorphic in terms of size. This means the females typically grow larger than males – sometimes significantly so.
For example, the females from the eastern portions of the species’ range may reach 9 to 11 inches. Meanwhile, males from the same locations may only reach 6 inches or so.
Individuals from western portions of their range also exhibit this size discrepancy, but because they’re smaller, the differences are less pronounced. Western subspecies females often reach 5 to 6 inches, while males usually reach 4 to 5 inches in length.
Typical Hermann’s Tortoise Growth Rates: Size by Age
While the growth rates of individual tortoises can certainly vary, the following sizes and ages provide a good starting point for keepers to expect.
Hatchlings
Hatchling Hermann’s tortoises are quite small and generally measure between 1 and 2 inches in length, though that varies a bit based on the subspecies. Most weigh about 10 to 12 grams, though outliers exist.
Juveniles (1 to 3 Years of Age)
By the time Hermann’s tortoise has reached its first birthday, it will usually measure between 2 and 3 inches, depending on how large it was at the time of hatching (as well as the other factors I’ll explain in more detail below). They generally weigh between 40 and 60 grams at this point, though some may reach 80 grams or more.
By the time they’re in the 2- to 3-year-old range, most Hermann’s tortoises will have reached the 3-inch mark, with a handful of individuals reaching 3.5 inches. Tortoises in this age bracket will generally weigh 100 to 200 grams, though this can vary pretty widely.
Young Adults (4 to 6 Years of Age)
Growth rates vary quite a bit during this time frame, though most Hermann’s tortoises are approaching maturity (approximately 5 to 6 inches in length) by their sixth birthday. At this time, the tortoises should usually weigh approximately 500 grams, though specimens measuring closer to 7 inches may weigh nearly 1 kilogram.
Mature Adults (7 Years of Age or More)
Once Hermann’s tortoises reach full maturity, their growth rate slows drastically. While daily or weekly weight fluctuations may occur based on the amount of food or water they’ve recently consumed, their weight will tend to remain constant over the long term.
Similarly, they won’t increase in length very much, though you may see them grow an inch or so over incredibly long time frames (a decade or more).
Factors Influencing the Growth Rate of Hermann’s Tortoises
There are a variety of things that will influence your tortoise’s growth rate. Some of the most important factors influencing your pet’s growth are discussed below.
Overall Health
Your tortoise’s general health may strongly influence his growth rate in a variety of ways.
For example, parasites may be “stealing” some of his calories, resulting in reduced growth. Viral or bacterial infections may also cause his body to divert resources that should be allocated to growth and funnel them toward his immune response. For that matter, chronic stress can suppress growth.
Given the influence poor health can have on your tortoise’s growth rate, you’ll want to discuss the issue with your vet if you find that your pet is not growing as fast as most Hermann’s tortoises do.
Amount of Food Consumed
Like all animals, tortoises break down food and use it to fuel their activity and growth. So, tortoises who don’t eat as much as other tortoises simply cannot grow as fast. Note that this difference may be caused by the amount of food the tortoise is offered or by the individual tortoise’s appetite — some tortoises simply have stronger appetites than others.
It’s also important to consider the nutritional value of the food your tortoise consumes; not all foods are created equally. Additionally, some keepers elect to provide their tortoise with more animal-based protein than others. This is generally not recommended for your pet’s long-term health, but it will generally result in more rapid growth.
Husbandry
Tortoises who receive proper husbandry will generally outgrow those who’re provided with poor husbandry. In many respects, this is because the caliber of husbandry provided influences a tortoise’s health and stress level. In fact, tortoises who become stressed or sick may not only grow slower than healthy individuals, but they may never reach the size that healthy individuals do.
Additionally, things like appropriate temperatures and light quality can affect your tortoise’s appetite and the efficiency with which he digests his food.
Genetics
While there isn’t much empirical evidence to establish that genetics influence the growth rate of Hermann’s tortoises, it is quite likely that your tortoise’s parents will have a strong influence on his eventual size and the rate at which he grows.
There isn’t much you can do to alter this, though it may be helpful to inquire about the growth rate of your tortoise’s parents, when having initial discussions with the breeder.
Brumation Duration
The length of time you allow your tortoise to brumate will also influence his growth rate, as growth essentially stops during this period of inactivity. Aside from the slowed metabolic rate that occurs during this time, your tortoise won’t be eating.
So, if you were to brumate one tortoise for two months and a sibling for three months, the former will likely demonstrate more growth over time than the latter.
Citations
- Oecologia – When carapace governs size: variation among age classes and individuals in a free-ranging ectotherm with delayed maturity
- PubMed – Effects of two dietary vitamin and mineral supplements on the growth and health of Hermann’s tortoise (Testudo hermanni)
- Northampton Reptile Centre – Hermann’s Tortoise Care Sheet
