Pumas are Better for our Health

You read that correctly, pumas are better for our health! How can a wild animal like a mountain lion be better for our health? We have all heard about the web of life. All things are connected, and there is a natural balance within an ecosystem. Pumas show us how removing part of that system shifts that balance, creating a system that is harmful to people.

Web of Life

Let’s first look at the web of life that a puma lives in:

Cougars are better for our health

The web of life for a Puma (very simplified)

In this very simplified (though accurate) system, pumas play two roles as the top predator in the ecosystem. They feed primarily on deer, and they keep coyote numbers in check. One one hand, this leads to a normal sized deer population for the ecosystem. On the other it means that there are more foxes in the system, because there are less coyotes predating them. This leads to mouse numbers that are also at normal levels for the system. Ticks feed all the animals within the system.

Now let’s compare the above system to that of the east coast of the United States, where pumas are no longer found.

Pumas are Better for our Health

Web of Life without the Puma

Without the pumas, deer numbers have increased tremendously, causing vegetation to diminish due to overgrazing. More importantly, coyote numbers have increased, causing there to be fewer foxes, in turn leading a much higher number of deer mice. In this system there are a lot more deer for adult ticks to feed on and a lot more mice for larval ticks to feed on.

This is where the health aspect comes in. Ticks carry disease, including Lyme disease. Ticks get Lyme disease when they feed on mice, who are hosts to the disease causing bacteria. With more ticks present, there may not be a larger percentage of ticks that carry Lyme disease but there will be a larger number of individuals that are vectors of it. Due to the fact that cougars are not controlling deer or indirectly mouse numbers on the east coast, more Lyme disease carrying ticks are around, which leads to a higher rate of incidence for the disease in the area.

Tick and Lyme Maps

Let me illustrate the point with some maps.

Tick species ranges that carry Lyme disease in the US

Tick species ranges that carry Lyme disease in the US

In the US, both the Black-legged Tick (Ixodes scapularis) and the Western Black-legged Tick (Ixodes pacificus) carry and transmit Lyme disease.

This is the area in which Lyme disease has the highest incidence rate (or, where it happens the most):

The fifteen states with the highest incidence rate of Lyme disease in the US

The fifteen states with the highest incidence rate of Lyme disease in the US (see Lyme Disease Association Analysis) — the darker the red the higher the number of incidences

As you can clearly see, the highest chance of infection is limited to the east Coast.

Now let’s look where Pumas currently live in accordance with the above data:

Mountain Lion presence and their relation to Lyme disease infection

Mountain Lion presence and their relation to Lyme disease infection

Even though Lyme disease and their vectors are present on the west coast of the US, mountain lions keep the tick numbers low (by keeping the deer and mouse numbers lower), therefore creating an overall healthier system for people. More mountain lions eventually means a lower chance of getting Lyme disease.

Is there space for pumas on the east coast?

Historically, cougars used to occupy the east coast where Lyme disease is so prevalent now, but they were extirpated from the region in the early 1900’s. Could a case be made for re-introducing cougars to the east coast? Now that they have been gone from the region for hundreds of years? Is there even space for them? Even though the western United States has greater areas of fully protected land, the eastern states still have plenty of habitat for pumas as well.

US population density - Copyright Ian Offord

US population density – Copyright Ian Offord

The population density map shows that cougars have no space left on the actual east coast. Nor would you want them to wander into New York City or Boston. Once you are more inland however, the population density is low enough where you can have successful co-existence between these cats and people. Having an re-introduction plan would help of course but even naturally, pumas are moving more and more east as time passes. Maybe sooner than later, Lyme disease will be less of an issue in the States, and all due to a wild cat.


Why Saving All Endangered Species Matters

This is a some-what of a follow up to the previous blog post about politician Joe Baca introducing a bill that would certainly bring the Delhi Sands Flower-loving Fly to extinction. I wanted to stress how important it is to save not only species that we can easily fall in love with like the endangered Sea Otter, or Giant Panda but also species that we might not even recognize what it exactly is.

The reason for this is quite simple, all species are connected ecologically, removing one species from the system will have some kind of impact on the rest of it. This can lead to devastating effects, even for us humans. A prime example of this (and I am very much simplifying it here) is the connection between the bacteria Borrelia burgdorferi, Black-legged Ticks (Ixodes scapularis), Western Fence Lizard (Sceloporus occidentalis), and us humans. Black-legged Ticks can carry the above mention bacteria which is the agent of Lyme disease. If a tick buries itself into a human it has the potential of passing on the bacteria and disease leading to potentially debilitating effects for the person later in life. Enter the all important Western Fence Lizard, it has been shown that when nymphal Black-legged Ticks feed on Western Fence Lizards the disease carrying bacteria is destroyed by a protein in the lizard’s blood — aka the tick no longer has the potential of spreading the disease to us humans. The fact that the lizard is only found on the west coast might be the exact reason that only 2-4 percent of adult Black-legged Ticks carry the disease here compared to up to 50% in the north east of the US. Here is a map for a quick view.

Western Fence Lizard and California Poppies

Western Fence Lizard and California Poppies

Now we are lucky that the Western Fence Lizard is not endangered, but what if it was, we would start caring a lot more about it. My guess is there are a lot of these kinds of examples out there in the natural world, many of which we don’t even know about yet, many of which involve endangered species. So yes, let’s save the Blue Whale and Polar Bear but let’s give equal attention to less charismatic endangered wildlife.

*If you are interested in purchasing any of the pictures displayed in this post, please check out my fine prints page for pricing.*