I’ve lost track of how many times I’ve been told that pumas target male mule deer (bucks) and, to a lesser extent, male elk (bulls). A ranch hand in Colorado once told me that if I walked out into the sagebrush, I’d stumble upon buck carcasses just about everywhere—gory evidence of what pumas prefer to eat.
This was a sensitive topic—because this man, like many of his coworkers, guided deer and elk hunters in the fall season as part of his revenue stream. People hired him specifically to find big bucks and bulls, and his success ensured more clientele and more money in the future. Pumas were competition, plain and simple, as far as he was concerned, and needed to be “controlled.”
The idea that pumas target male deer and elk is an ideology so pervasive, even if poorly tested, that it contributes to the current management strategies for large carnivores today. As Americans (and Canadians, too), we think reducing predators just might help us reach that elusive goal of increasing the deer and elk populations that we hunt ourselves (though most research shows that predator control does little to nothing to aid mule deer and elk populations long-term).
As a scientist charged with studying puma prey selection, I was especially taken with this ideology—because it can so easily be tested. Thanks to GPS collars and the legs that carry us, we record nearly everything pumas eat in our studies. We just needed to ask the question.
We documented 339 deer and elk killed by pumas in our Colorado study site—only six were bulls and 23, bucks. We documented 578 deer and elk killed by pumas at our Wyoming study site, also called Panthera’s Teton Cougar Project, 38 of which were bulls and 28, bucks. In terms of numbers, the influence of pumas on bulls and bucks was tiny—they were just 8.5% of the total deer and elk killed by pumas in Colorado, and 11.4% of the total deer and elk killed by lions in Wyoming.
The results of our preference analyses were more interesting. Overall in both Colorado and Wyoming, pumas went out of their way and targeted the youngest elk and deer, rather than the adult male animals prized by hunters. This should be a great relief to hunters. In fact, in both areas, pumas purposefully avoided adult elk, which are large and dangerous for pumas that are only a fraction an elk’s size.
Pumas did, however, show a very slight preference for bucks, which they primarily hunted during the rut when bucks were stressed, moved alone, and were highly distracted with courting females. This is also partly because there were so few bucks on the landscape as compared to other deer, so even a small number of bucks killed showed up as preferential feeding in our analyses.
Neither pumas nor human hunters in our study systems—or the combination of the two—decreased bulls or bucks to levels that hurt local populations. This is a testament to sound management in both areas, and also highlights the fact that killing pumas over competition for bulls and bucks is not justified.
We should instead focus management, media attention, and conservation science on disentangling the complex ecology driving local declines of mule deer and elk in the west. Many drivers of their declines are caused by humans and can be addressed.
Learn more about pumas, the threats they face in the wild, and Panthera’s efforts to protect them here.