This is a series I wanted to write for a long time but I finally got the time to lay out how I want to discuss this. The aim of the series is to tackle misconceptions about predators but mostly to teach ranchers, farmers etc how a predator functions biologically in the hopes that they can avoid any common pitfall traps that lead to livestock loss. So with that in mind let's break this down.
In case you don't know calories are essentially the energy you put into your body. Your body needs a certain number of calories(which changes depending on activity, weight etc) to maintain it's weight and activity. More calories than your body need results in weight gain and fewer calories than your body need result in weight loss. So if your body needs 50 calories a day to survive and you give it 100, the remaining 50 will be converted into extra fat and thus weight. If however, you give it 20, your body will take the remaining calories it needs from fat reserves.
Now that we got that out of way let's focus on a predator. Most predators like a lifestyle often referred to as "feast or famine" that means there are periods where these animals are starving or when they are doing very well and eating a lot. Some lucky predators can get a constant intake of prey and don't live this lifestyle but those usually aren't the focus when it comes to livestock depredation.
Now why is it important to understand a predator's lifestyle and the calorie intake? For two main reasons.
1) As animals, predators are hardwired to prefer fatty or high-calorie foods. The same way that we prefer something high in fat or calories, the same reason predators will. This leads to an association where predators easily learn that a cow, sheep etc is often fattier than a deer and will put up less of a chase. It's important to understand that this is not a conscious decision on behalf of the predator. No cougar decides they will have lamb or goat today. Instead, if they have had enough lamb or goats, they make the unconscious decision that this anima is fattier and higher in calories and will, therefore, pursue it if they have the option.
When predators hunt they use calories so it is important that these calories are regained and then some. I often equate it to hiking in the mountains for eight hours and having jerky for dinner versus hiking in the mountains for one hour and then having a big burger and fries. If you could choose one of the two options, more often than not the burger would be preferable. So once predators make the association that a particular livestock is fattier and taken down easier than game animals, they won't hesitate to try again. This is the fundamental reason why canines in particular insist on livestock predation once they start. Now it's not all doom and gloom and there are ways to break the association and the habits and I intent to touch those in the future.
2) Surplus killing. Despite popular belief, there is no actual evidence of predators killing for "sport". Hunting is a dangerous undertaking for a predator. They could lose their prey which results in calorie loss or even worse injuries. For an animal whose life depends on their hunting ability, an injury can be a pretty big deal(I plan to talk about injuries more extensively later). So why do some animals hunt when they have just eaten or why do we hear stories of wolves killing 120 sheep? The reality can be a bit complicated but here's a simple way to think about it.
You have been starving for 4 days now, eating almost nothing. A friend invites you to a free an all-you-can-eat buffet. Will you or will you not overfill your plate and definitely eat more than you need? What if I told you that you can take home however much food you want? That's the predator's mindset. Surplus killings occur when predators stumble upon a great hunting opportunity. They kill because they think that no one will remove those carcasses and they will be able to cache or eat them. This often happens during a period of starvation in predators but can happen at any time. This is why it is important to always monitor a habitat and getting an idea of what game species are present and how skinny local predators are.
The search for food is everpresent for wild predators. Unlike humans, they will take any opportunity they can to kill and eat because most predators do not know when their next meal is. Also since predators like to cache or stash their food by burying it or placing it somewhere they can revisit it, it is likely that they will kill with the intent to eventually revisit.
There isn't much you can do to stop surplus killing apart from standard deterrents. The surrounding area could be plentiful in prey animals but the predator could be a bad hunter or injured or has just arrived at the area starving. That being said fostering the land and ensuring that prey is available for predators will likely reduce the likelihood of a surplus killing but will not guarantee it.
That's pretty much the basics on calories and how they are associated to predators and their behavior. Next article I plan to visit the hunt and what it means to predators.