We had an incredible sighting a few weeks ago as we trailed the two Gijima males responding to the distant roars of the Nwastishaka males. Watching the Gijima’s march toward our southern boundary on a cold winter’s morning and seeing their warm breath in the air really got me thinking. What are the ins and outs of a male lion’s caloric/energy expenditure, and I suppose more generally, how does temperature affect that?

I found after quite a dive into some academia that there is still so much we don’t know about the inner workings (think metabolic rate, calorie expenditure and thermoregulation) of these mammals. Having said that, there is still some information out there. Here are the findings I aggregated on how male lions balance their caloric burn, ‘male lion duties’, and the need to thermoregulate.

Lions | Built for Power

A mature male lion might weigh somewhere between 190 and 220 kg and require roughly 7,000 to 10,000 calories per day when mostly sedentary. That number rises quickly once territorial patrols, mating, conflict or hunting are added. It’s thought that these ‘busier’ days can cause a male lion’s energy expenditure to rise to a figure closer to 25,000 calories per day or more, which is astronomical. What fascinates me, though, is how carefully lions manage this expense.

A male may carry upwards of 70 kg of skeletal muscle, particularly concentrated through the shoulders, neck and forequarters. Muscle is expensive to use. Accelerating a body of that size, wrestling prey or covering territory burns calories rapidly. Which is why lions rest so much.

The light-maned Gijima male rests peacefully in the road. I almost fell out of my Land Rover trying to get eye level with him.

During winter, this becomes even more interesting. Even lying still, a lion continues burning energy to maintain body temperature. Heat production, circulation, muscle activity, and repair all continue quietly beneath the surface.

Energy Accountants

Suddenly spending most of the day resting feels far less like laziness and far more like smart accounting. Once you start to spend a lot of time with these big cats, you’ll start to pick up that they don’t operate on a neat daily schedule like humans. They seem to move in energy pulses.

An example would be several days (4 – 6 days) of lower levels of activity, 18 hours a day of sleeping, eating and taking in as many calories as possible. This is exactly why lions will gorge themselves to such a ridiculous level. For context, a male can consume between 40,000 and 60,000 calories or in other terms, about 20-30 kilograms of meat in one sitting.

After this ‘resting’ phase, you often get a day or two of heightened activity. This includes more vocalisations, more territorial behaviour (patrolling), which might include moving into spaces that are seen as fringe territories and finally conflict with neighbouring territorial males or nomadic ones.

Cold Mornings

Finally, I looked at how temperature affects these big cats specifically through their metabolic functions. For context its generally accepted that African Lions use the least energy to thermoregulate when temperatures range between 23 – 28 degrees Celsius. This is basically their optimum temperature (thermo neutral zone) to operate within.

With that being said its quite impressive how well these cats are adapted to dealing with colder conditions. Lions use a technique similar to humans, but are far better at it, namely vasocontriction. Vasoconstriction allows them to squeeze the blood vessels around their skin, forcing the blood to pool around their organs, keeping them warm. They also create quite a bit of heat in their digestive process, which is another way in which they stay warm. Finally, we all know how lions like to cuddle and while this has important social benefits its also a great way for them to share warmth!

So next time you see a lion sleeping the day away, remember you aren’t looking at laziness, you’re looking at survival math. Watching the Gijima males march into the cold winter morning, it’s clear they aren’t just kings because of their power. They are kings because they are brilliant at what they do.