One of our goals as keepers is to provide animals with opportunities to express the behaviours they evolved to perform.
It's one of the fundamental principles of modern welfare science. Animals should have the opportunity to bask, climb, burrow, forage, explore, court, hunt and hide if those behaviours form part of their natural behavioural repertoire.
It's a philosophy I completely agree with.
But there's one question I rarely hear asked.
At what cost?
Every behaviour costs something.
Basking costs time.
Climbing costs energy.
Digging costs effort.
Even standing still isn't free.
Every decision an animal makes carries a metabolic cost, an opportunity cost or a degree of risk.
And that's exactly how evolution intended it.
Evolution has never selected behaviours because they're enjoyable. It has selected behaviours because, on balance, they improve an individual's chances of surviving long enough to reproduce.
A behaviour only persists if the benefit outweighs the cost.
Agnes gives us a wonderful example of a behavioural trade-off.
Sulcata tortoises are grazing specialists, with the vast majority of their diet consisting of grasses and hays. Nutritionally, these are relatively dilute food sources, meaning Agnes can't simply eat a small meal and spend the rest of the day sleeping in the sunshine. To obtain enough energy, she has to invest energy.
She has to walk.
She has to graze.
She has to keep looking.
Grazing is expensive. It costs time, movement and calories.
But evolution decided that the return on that investment was worth paying.
Giving Agnes a huge plate of salad with a side of healthy weeds and seasonal flowers would seem to be the most responsible thing to do as a keeper. By doing that, I'm fulfilling her nutritional needs and removing all the walking and foraging from her day.
But by doing that, I'm also removing the behavioural cost.
Some behaviours evolved to solve a problem.
If we remove the problem...
Have we accidentally removed part of the animal as well?
At the other end of the energy equation, we have Pleb.
Pleb is a ferocious predator and will attempt to eat almost anything he can fit in his mouth. But he does this in a way that conserves as much energy as possible. As a dwarf pixie frog, Pleb is a classic ambush predator. He doesn't actively search for food. Instead, he'll sit and wait for something of an appropriate size to wander past before launching an explosive strike. That split second of astonishing violence is the only significant energy investment he has to make.
Evolution has done the rest.
So, as seen all over the internet, many keepers remove their pixie frogs from the enclosure and place them into a bare feeding tub. It certainly makes feeding easier for the keeper.
But I found myself wondering...
If a sulcata tortoise benefits from having to graze because grazing is part of its evolved behavioural repertoire, are we asking an ambush predator to behave unnaturally by making it actively search for its food?
I don't know the answer.
But I think it's an interesting question.
An ambush predator has evolved to conserve energy until the precise moment it's needed. Every unnecessary movement has a cost. If we ask that animal to spend several minutes actively hunting around a feeding tub, are we increasing behavioural cost in a way evolution never intended?
Or...
Is the energetic cost so small that it makes no meaningful difference at all?
Either way, it highlights an important principle.
Husbandry isn't just about what we feed.
Sometimes it's also about how we feed.
I'm not suggesting feeding tubs are wrong. They may have genuine practical benefits in some situations, from monitoring food intake to preventing accidental substrate ingestion. But I do think they're worth thinking about from the animal's perspective as well as the keeper's.
If we remove every behavioural cost, are we also removing some of the behavioural opportunities that evolution spent millions of years refining?
Perry gives us another fascinating example. Climbing is expensive. It requires muscle, coordination and energy. It exposes a royal python to potential predators and increases the risk of injury. So why climb at all?
Because evolution has already done the maths.
If the reward—whether warmth, security or access to resources—outweighs the cost, climbing becomes a worthwhile investment.
Greebo approaches the same problem from a completely different angle.
Every spring he transforms from an otherwise sensible bearded dragon into what can only be described as a brightly coloured, head-bobbing romantic with absolutely no sense of self-preservation.
His beard turns jet black.
His body inflates.
He repeatedly head bobs with the enthusiasm of a drummer who's had far too much coffee.
Every one of those behaviours costs energy.
But reproduction is one of the greatest evolutionary rewards there is.
The cost is enormous.
The potential benefit is even greater.
At first glance, Perry climbing and Greebo displaying appear to have nothing in common.
One is searching for opportunity.
The other is advertising himself to it.
Yet both are solving exactly the same biological equation.
Is the reward worth the cost?
Perhaps good husbandry isn't about removing every behavioural cost. Perhaps it's about understanding which costs evolution considered worth paying... and giving our animals the opportunity to decide the rest.
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