Sunday 21 July 2019

Being Top Cat

If you happen to own a cat, especially an un-neutered male, you may have noticed that they sometimes pee on things. Shocking, I know.

Spraying is just one way that cats leave scent marks, whether to warn other cats away from 'their' territory, or to advertise their availability to members of the opposite sex. And, as we'd reasonably expect, this is as much true of large wild cats as it is of the domestic moggy. Indeed, we have a reasonable understanding of how some wild cats use these markings. For instance, we know that, just as in the domestic animal, male North American cougars spray more than females, both to mark their territory and to advertise for females.

Different cat species are likely to behave in different ways, depending on their particular needs, but there may also be differences in behaviour even within species. The term "cougar" for instance, is really just one North American word for an animal (Puma concolor) known by an unusually large number of different names, and that's found across a particularly wide stretch of the Americas. One could argue that the northern subspecies are "cougars", while the southern one are "pumas", but scientists tend to use the latter word for both. For that matter, the northern subspecies is the one found in Central America where everyone also calls them "pumas".

So far as I'm concerned they're puma/cougar/mountain lions, and those are just the three most popular names. But, for today, I'll stick with "puma".

But here's the thing. Might pumas living in the tropics behave differently than those in North America? You might think not, but, leaving aside the different climate, which might not have much of an effect, there are reasons to think otherwise.

In North America, puma/cougar/mountain lions are the largest pure predators outside of the Arctic. Admittedly, there are bears, but these aren't really direct competitors, having a rather different diet. But in South and Central America, that's not true, because there's an even larger predator there that's very much a direct threat. That, of course, is the jaguar (Panthera onca) and, being cats, they also leave scent marks. Jaguars and pumas really don't like one another and, since there's nothing to stop them sniffing each other's scent marks, it's entirely plausible that the pumas might modify this behaviour for reasons of personal safety, if nothing else.

One advantage with trying to see how pumas leave scent marks in the wild is that they don't simply urinate on a tree and then leave. Instead, they scrape up leaves and soil on the ground to leave a visible marker that other pumas can identify and then sniff. So, to try and judge how tropical pumas communicate using scent marks, scientists simply walked along some old trails through the jungle and looked for the scrapes.

This study was conducted in a wildlife sanctuary in Belize. Established in 1986 largely to help protect the local jaguar population, it is also home to a number of pumas, and many other animals besides, and has man-made trails largely because of the extensive logging that used to occur there before the sanctuary was established. These walking trails, no longer used by vehicular traffic, have been co-opted by large animals to help them move through the jungle, so it was also possible to place camera and video traps along them to see which big cats were in the area, and perhaps even catch them in the act of leaving a mark.

In the five months or so of the study, 22 different jaguars and 16 pumas passed by the camera traps, as identified by their coat markings or specific patterns of scars. They left hundreds of scrape marks along the trails, each of which could last up to a month before no longer being visible, indicating that these are relatively long term messages.

One finding, which supports earlier studies, is that the great majority of scrape marks were left on nights when no jaguar was seen walking down the trail in question. Furthermore, almost every time that a cat was seen actually leaving a scrape mark on a video image, the cat was a puma. Jaguars, it seems, do occasionally leave similar marks, but they much prefer to either roll around the ground when they want to leave a scent, or they just spray some prominent piece of rock of foliage. And, yes, in almost all cases, judging from the footage, it's the males who are doing this.

In fact, it wasn't even all of the males, with a number being seen passing through the area without any subsequent indication that they had left scent marks. However, these were not repeat visitors, but rather males passing through on the way to somewhere else. Not only would they have had no territory to mark, but advertising their presence might well have annoyed the local - and probably older and larger - males whose territory they were encroaching on. Occasionally, such passing visitors would scent mark when a female had passed through just before, evidently hoping that she was close enough that they would have time for quick mating before the local male could spot them, but otherwise, they kept quiet.

Similarly, the only time the females marked was to add their own signal to one that had male had recently left. In general, female pumas seemed to visit the trails only for a few nights at a time before leaving again; possibly, this was when they were in heat. Female jaguars were more regular visitors, so maybe they just found the trails too useful to ignore even when they weren't looking for love. Or perhaps they scent marked themselves when the cameras weren't around - since jaguars prefer spraying to scratching, there isn't necessarily a visible sign for humans to spot.

But what about the possibility that scent marks might be apparent to other species than the one they were intended for? With two kinds of large predatory cat in the area, did they take advantage of each other's scents? Obviously, this is harder to know, but the video traps did capture footage of one puma examining a scent mark left by a jaguar. For the puma, this may well have been a handy warning to stay away from the area, lest the much larger jaguar take exception to the competition.

The puma wasn't alone. A couple of ocelots were seen examining both jaguar and puma scents, which makes sense, given that they're smaller than either. A few other animals did the same, most notably a number of peccaries, which would have had very good reason not to want to be around any sort of animal that might eat them.

A tayra - a sort of tree-dwelling wolverine-like animal - was even seen rubbing its head in a pile of puma dung. It's something they've been seen doing before, possibly in the hope that if they smell like something even scarier than they are, larger predators will leave them alone.

Jaguars, on the other hand, didn't examine anybody else's scent so far as the study could tell. They're the top predators in the area, and, apparently, they know it.

[Photo by Charles J. Sharp, from Wikimedia Commons.]

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