Two years and 3 days ago, Penny and I rescued a, at the time, 8kg 6-year-old sulcata tortoise named Agnes. She is now a shade over 20kgs, and she’s just turned 8 years old. But it was not plain sailing from the word “go”. I originally constructed the paddock itself using 65 feet of fencing, giving approximately 260 square feet of space, a pond, several shaded areas and I also built a fully functional, thermostatically controlled all weather basking/hotbox with built in UV lighting. All on timers and self-contained – night time temperatures not dropping below 24 degrees Celsius – and UV’s turning off after 11 hours. Everything was set for this desert tortoise to come in and have a whale of a time eating all the grass and digging holes. That’s because as a grazing species, sulcatas are easy right….. yeah. That went well.
As I said, Sulcatas are a grazing species. Up to 90% of their diet is made up of grasses and grass hays. The remaining 10% of their diet is made up of every tortoises favourite – leafy greens and seasonal blooms (maybe a tiny bit of fruit…). So, what do you think Agnes did on her arrival? If you guessed - not eating the damn grass - then you are correct!
Before I rant, let me give you a little bit of back story on Agnes. She was rescued by a mediterranean tortoise specialist who, obviously, specializes in the rescue of the Testudo family of tortoises. Agnes, as a sulcata or African spur-thigh, is definitely not a mediterranean resident and she does not brumate during the winter months and grows a little larger than her European cousins. Agnes was originally from a public house in Stratford, Warwickshire. She was a loved pet, but at 14” long and 8kg she had outgrown her lodgings. The publican keepers sensibly got in touch with a tortoise rescue and made some enquiries into rehoming the baby behemoth that is Agnes.
Agnes was taken by the rescue who in turn made contact with me. They asked if I could help in any way, rehoming or making room for her as a resident at Shirley Aquatics. I opted for the former. And so, the building began….
Due to Agnes’ start in life, grass and hay were two things that had never appeared in her diet. Big on the romaine, loved the rocket, happy with lambs lettuce – but what she has biologically evolved to digest across evolutionary timescales? Not a chance. This was my first hurdle. Moving her over to a more suitable (and generally sustainable) food source. The game was on. I started chopping romaine lettuce and rocket and scattering it over the grasses right in front of her nose and, to be fair to Agnes, she was a quick study. By the end of week one, she was grazing tentatively. By the end of week two, she was doing her best lawnmower impression. By week three she was hand feeding treats and grazing throughout the day. I’d won that round!!
Now, I’d painstakingly dug a rough trench in Agnes’ original paddock to encourage her to dig as, according to all of the available research, both captive and wild specimens are fierce diggers and have been known to bulldoze metres underground to help thermoregulate and chase humidity levels. I was fully prepared for this, even down to a brand-new shovel so I could dig after her and drag her out if need arose. And Agnes, sweet Agnes, didn’t so much as knock any soil over on her adventures. I was left baffled by her behaviour so I started pouring over every single piece of documentation I could find on sulcata tortoises. Everything.Repeatedly, the literature returned to the same explanation:
“In the wild, Sulcata tortoises experience extreme environments. Daytime temperatures in their native African scrublands easily reach 35°C to 40°C so to survive this intense heat, they dig deep, underground burrows. The temperature in these burrows stays a comfortable 24°C to 29°C”.
So why wasn’t my Agnes digging? Why didn’t I have a veritable rabbit warren of tortoise burrows in her paddock? Turns out I was looking in the wrong place. Literally. Much of the literature I found drew from observations of wild specimens and captive keeping practices in warmer regions of the United States—particularly Florida. Florida and the UK differ vastly in many things: regional accents, roughly double the amount of people and slightly more interesting native reptiles. Not to mention – weather.
Temperature
- Florida: Summer highs frequently exceed 32°C (nearly 90°F) with very high humidity. Winter is warm, with average daytime highs ranging from 15°C to 21°C.
- UK: Summer highs average a modest 19°C to 22°C. Winter days are quite cold, generally averaging between 5°C and 9°C.
Sunshine and Rain
- Florida: Known as the "Sunshine State," it has long, sunny days. However, summer brings frequent, heavy afternoon thunderstorms.
- UK: Known for overcast, cloudy, and grey skies. Rain occurs all year and usually falls as light, persistent drizzle rather than heavy storms.
Humidity
- Florida: Summers are incredibly humid, with relative humidity frequently between 70–80%. Combined with sustained high temperatures, this creates prolonged warm, moisture-rich conditions.
- UK: Relative humidity is often high—particularly through autumn and winter—but lower ambient temperatures create very different environmental conditions compared with subtropical Florida. Warmth is generally less sustained and seasonal transitions are more pronounced.
Seasonal Differences
- Florida: Has two main seasons: a hot, wet summer from May to October, and a cooler, drier winter from November to April.
- UK: Has four distinct seasons (Spring, Summer, Autumn, Winter) with gradual temperature shifts.
This was the point where I realized my original assumption had a limitation.
I had built for the species, but not necessarily for the context.
Much of the husbandry information available for sulcata tortoises understandably draws on observations from their native range and from regions where outdoor keeping is common, particularly warmer parts of the United States. Those environments differ substantially from the UK—not just in peak temperatures, but in the duration of heat exposure, substrate temperatures, humidity patterns and seasonal consistency.
If a wild sulcata experiences sustained daytime temperatures of 35–40°C and relies on burrows that remain closer to 24–29°C, digging becomes an effective thermal and hydration strategy.
But in the UK, our challenge is often the opposite.
Outdoor temperatures are lower, extremes are shorter-lived, and in managed environments we frequently provide heated shelters, dry refuge areas and controlled gradients. That made me start asking a different question:
Was Agnes failing to express natural behaviour—or had I misunderstood what environmental conditions normally drive that behaviour in the first place?
I spoke with breeders, private keepers and local collections and found surprisingly little documented evidence of routine outdoor burrowing behaviour in UK-kept sulcatas outside reproductive digging. That doesn’t mean it does not happen—it almost certainly does in some individuals—but it made me wonder whether digging in captive UK sulcatas may be more facultative than inevitable.
In other words, perhaps burrowing is not simply a species trait—it may be a response to environmental demand.
Existing guidance often draws appropriately from natural history, but observed behaviour under UK climatic conditions may not always mirror expectations formed in hotter regions.
Look at that. Agnes had accidentally become Head of Research for PRO Herpetology. Works out well for me really—the job sucks.
The next dilemma to arise was winter. Specifically, our wet and miserable winter months. How would a tortoise commonly found in the African savannah cope with our harsh, cold and wet climate? As I’ve already mentioned – Agnes has a house. Reclaimed wood, Perspex top, pond liner finish on an overhang all around the roof itself, insulated interior, raised off the ground to prevent moisture creeping in, ventilation points and thermostat control on both temperature and UV exposure. So, the house is good. I can regulate temperature and UV exposure and there’s even a temperature gradient in there. Evening temperatures don’t drop below 24°C, allowing for overnight cooling while maintaining environmental stability and avoiding excessive thermal demand. What’s the issue I hear you ask?
Snow, sleet, freezing rain, frost, ice, blistering wind, temperatures in the negatives and, quite importantly for Agnes, very little grass to graze. What was the answer for this one?
Thankfully, Agnes herself provided the answer.
Inside her shelter I used a mix of topsoil, sand and fibre-rich bedding topped with timothy hay. I have generally preferred hay over straw for tortoise species over the years—straw tends to be coarser, more abrasive and, when very dry, can break down into dust and chaff that may irritate eyes and airways.
Hay, meanwhile, tends to function as both furnishing and forage.
What I did not expect was quite how enthusiastically Agnes would demonstrate this.
Once grazing opportunities reduced outdoors during winter, she began feeding directly from the hay layer inside the shelter. Supplementary greens remained available several times per week, but her feeding behaviour shifted noticeably compared with summer.
This sent me down another rabbit hole.
Winter feeding guidance for sulcata tortoises is widely available, but quantitative information on actual intake appears limited—particularly under UK conditions. Most recommendations focus appropriately on maintaining access to fibre-rich forage and suitable environmental conditions but measured seasonal consumption data appears scarce.
So, we did the next best thing and monitored.
Agnes maintained body weight throughout the colder period without excessive feeding. We initially offered approximately 3% of body weight daily and gradually adjusted based on leftovers, behaviour and weight stability.
Eventually the system became surprisingly simple:
Unlimited access to hay.
Supplementary greens and seasonal treats.
Regular weight checks.
Minimal intervention.
Interestingly, reduced activity and lower food intake did not appear pathological—it simply looked seasonal.
Wild sulcatas naturally experience seasonal variation in forage quality, moisture availability and environmental conditions across their native range. While they are not adapted to prolonged cold exposure, changes in feeding intensity and activity under appropriately maintained captive conditions may represent behavioural adjustment rather than necessarily indicating poor health. In Agnes’ case, stable body condition, continued grazing behaviour and access to controlled environmental conditions suggested adaptation rather than decline.
Nature, once again, had quietly solved a problem before I finished overcomplicating it.
So that’s it.
Over two years I learned more from one 20kg rescue tortoise than I expected to learn from any number of care sheets.
Agnes challenged assumptions I didn’t realise I was making—not just about temperature and environmental design, but diet, seasonal behaviour and the way natural history translates into captive care.
And perhaps that was the biggest lesson.
Understanding what an animal evolved to do is essential—but understanding the conditions that allow that behaviour to emerge in captivity may matter just as much.
Good husbandry begins with natural history.
It improves through observation.
And occasionally, if you are particularly lucky, you get schooled by a 20kg armour plated toddler who refuses to read the literature.
Add comment
Comments