Montana Public Radio

For Rocky Mountain Wood Ticks, Any Large Mammal's Blood Will Do

May 5, 2020

Spring has hit western Montana in full force. Days are longer than nights, temperatures are warming, and the snow is gone for the lower elevations. Animals that live here throughout the year, but become quiescent during the long, cold winters, are once again warm, active, and searching for their first meals of the spring. Such an animal is the Rocky Mountain wood tick, one of approximately 825 species of ticks known in the world, which as a group feeds solely on the blood of terrestrial vertebrates.

Their total dependence on blood, and the ability of many species of ticks to feed on humans, makes these very small arthropods both pests and potentially dangerous to us. Infectious agents such as bacteria, viruses, and protozoa may be circulating in the blood of wild mammals when larval and nymphal ticks feed on them. These agents are ingested by the ticks and then may be transmitted later in their saliva when the nymphal and adult ticks feed again on wild mammals or possibly humans. In the United States, Rocky Mountain spotted fever, lyme disease, Colorado tick fever, babesiosis, relapsing fever, and tularemia are some of the diseases that humans may develop after being infected by tick-bite.

Right now in western Montana, ticks are also out in full force as the unfed adult male and female wood ticks have become active after the long winter, thirsty for the blood of large mammals such as deer, elk, moose, and mountain goats. It is important for you to remember that if you go hiking, bird-watching, or camping during the next several weeks, you have a good chance of coming in contact with these ticks that may attempt to feed on you.

In the Bitterroot Valley one to 5 percent of these ticks are infected with the bacterium that causes Rocky Mountain spotted fever, a potentially fatal disease of humans but treatable with antibiotics if diagnosed early. Therefore, it is also important for you to check yourself frequently when you're in the woods and remove any ticks that you may have acquired from the surrounding vegetation. Simply flick the ticks off with a finger. If a tick has attached to your skin and begun to feed, remove it with tweezers as quickly as possible. Remember that the longer a tick feeds, the greater the chances that it will transmit a disease-causing agent to you if the tick is infected.

Although a tick is not an insect (an insect has 6 legs, adult ticks have 8), insect repellents that you use for mosquitoes or black flies may also help to repel ticks. Tucking your pant legs into your socks, and tucking your shirt into your pants, will also help prevent ticks from having easy access to your skin when they are walking on your clothing.

So don’t be afraid of ticks. They are actually fascinating animals, beautifully adapted to their own way of life. But be aware of them, especially right now, and when you are out enjoying this beautiful spring weather, don’t let the ticks feed on you.

In 2019, scientists at Rocky Mountain Labs in Hamilton, Montana published the results of a study of the prevalence of the Colorado tick fever virus on ticks in the Bitterroot Valley. Their findings: 6.6% of the ticks they analyzed carried the CTF virus.

"Field Notes" is produced by the Montana Natural History Center.

(Broadcast: "Field Notes,"  5/5/20 and 5/8/20. Listen weekly on the radio Tuesdays and Fridays at 4:54 p.m., or via podcast.)