When I read that wolves that had a parasite had a much higher chance of becoming the leader of the wolf pack, I was astounded.
A parasite affected the behavior of a mammal. How could that happen? I found it all rather interesting, and I think you will, too.
There is a microscopic organism that can only reproduce in cats, but it can thrive in most mammals.
That parasite is Toxoplasma gondii, and a study of 26 years of wolf data analyzed the blood of 229 wolves and found the disease in some of the wolves.
After reviewing all the blood data for 26 years, they concluded that presence of this parasite in wolves affected behavior. For example, the wolves that had Toxoplasma were 46 times more likely to become the leader of the pack.
Wolves that had Toxoplasma were the ones that were more likely to have territories overlapping with mountain lions.
Wolves that had Toxoplasma were 11 times more likely to disperse from their pack into new areas. Half of the wolves with Toxoplasma left their pack within six months.
Those without Toxoplasma didn’t leave the pack for 21 months.
And wolves with Toxoplasma often became pack leaders. This is important, because the leaders do the breeding, or most of it.
The leaders dominate the other wolves in the pack. They call the shots. They determine movement and feeding.
In essence, Toxoplasma in the wolf blood influences the ecosystem dynamics of the wolf.
It is suspected that Toxoplasma influences testosterone levels in the wolf, and this increases aggression.
Thus, this increases all the above traits infected wolves have. Infected wolves take higher risks, they become leaders, they disperse.
Yes, some die in doing so. Infected leaders take uninfected pack males into risky situations, such as moving into cougar territories. Some die. This shows that pack leaders influence their pack mates and this parasite influences all the wolves in that pack because the leader has it.
Cougars and wolves both compete for the same prey (deer, moose, and elk), so they often have overlapping territories. Remember Toxoplasma breeds in cats, so cougars can give it to other mammals including wolves.
When in a cougar territory, uninfected wolves may become infected through contact with cougar scat or pee. I noted above that some wolves die when they go into cougar territories. In fact since 2013 four radio-collared wolves have been killed by cougars in the state of Washington.
The fact that the researchers followed wolves and wolf packs for 26 years and sampled blood in hundreds of wolves, allowed them to draw the above conclusions. I do not know of another instance when a parasite in a warm blooded animal affected behavior, but I doubt that researchers have looked for that.
This study could trigger such work and we might be surprised to discover that a similar finding might be found for other parasites in other warm blooded animals.
Other wildlife happenings
Seagrass beds used by manatees for food are disappearing. This past year Florida officials provided lettuce to manatees, and it was just announced that they will continue to feed manatees this year. Save your old lettuce and feed the manatees.
The black-napped pheasant-pigeon was first described in 1882, but hasn’t been seen since. Here we are 140 years later and footage of this rare bird in Papua New Guinea was taken by researchers who went there to see if they could find this bird. Indeed after many days they found one and were able to film it.
The wildlife world is fascinating and always changing. Fun trying to keep up.
Dr. Dave Samuel is a retired wildlife professor from West Virginia University. His outdoor columns have appeared, and continue to appear, in Bowhunter magazine and the Whitetail Journal. If you have questions or comments on wildlife and conservation issues, email him at drdave4@comcast.net.
