Why Are Beetles Destroying Western Forests?

Recently Susan visited Colorado for a vacation where she has been many times before to visit family. She always enjoys getting out of the city to experience the beauty of the Rocky Mountains. But this time, she was truly alarmed by the sight of dead trees everywhere. She asked me to look into this and write a post about it.

Dead Trees due to Pine Beetle in Bristish Columbia

Courtesy azimuthproject.org

The culprit is the native mountain pine beetle, an insect about the size of a grain of rice, which has been destroying trees in British Columbia, Canada, and across Colorado and Wyoming.

The mountain pine beetle is a predator of many western pine trees, particularly mature lodgepole pines. It must kill the trees in order to successfully reproduce. The beetle typically kill trees already weakened by disease or old age. But even a healthy tree isn’t able to fight off the beetles when they are at epidemic levels.

The beetles attack pines in late summer, dispersing a chemical signal that attracts other beetles to mass-attack the tree. When the beetles bore through the bark of the tree, they introduce blue-stain fungus, which can work quickly to kill the tree. The beetles form tunnels and lay eggs underneath the bark, which hatch into larvae. The larvae spend the winter underneath the bark and emerge as adults in the summer, beginning the cycle again.

The U.S. Forest Service estimates that by 2012, the majority of lodgepole pines in northern Colorado and southern Wyoming will be killed by the beetle. Extensive beetle kill has resulted in ecosystem-wide impacts such as increased potential for wildfires and some loss of other tree species such as Douglas fir.

What has caused this infestation? It appears that global warming is a major factor in the infestation. The beetle eggs, pupae, and young larvae are the most susceptible to freezing temperatures. According to a British Columbian government site, in the winter, temperatures must consistently be below -35 Celsius to -40 Celsius (-31 to -40 degrees Fahrenheit) for several straight days to kill off large portions of beetle populations. In the early fall or late spring, sustained temperatures of -25 Celsius (-13 degrees Fahrenheit) can freeze mountain pine beetle populations to death.

Amy Nicholas, a  U.S. Fish and Wildlife Service biologist in Rock Springs, Wyoming,  says: “Because of warming temperatures, scientists are now seeing significant beetle impacts even in the high elevation sites occupied by whitebark pine. These sites are usually quite cold and unfavorable for epidemic levels of mountain pine beetle. That no longer seems to be the case.”

In addition to global warming, other factors, such as extended droughts and dense forests, have created a “perfect storm” for the infestation.

Lodgepole pine forests dominate the forested ecosystems of western North America and can provide breeding and foraging habitat for many coniferous wildlife species, including song birds, woodpeckers, and red squirrels.

Research by biologists with the U.S. Fish & Wildlife Service aims to determine which alternative stand types may best support wildlife species until lodgepole stands can regenerate after the ongoing infestation.

Unfortunately the spread of the beetle and its deadly fungus reminds us at Frogs Are Green of another disease linked to climate change, the chytrid fungus, that is wiping out populations of frog species worldwide.

Most of the information for this post came from a press release issued by U.S. Department of Fish and Wildlife, Wyoming: Perfect Storm Fuels Mountain Pine Needle Epidemic


Big Chill Helps Mountain Yellow-Legged Frog

One of the most endangered amphibians in North America—the mountain yellow-legged frog—might have some hope this spring due to the collaborative work of researchers at the San Diego Zoo’s Institute for Conservation Research, along with the help of biologists at the U.S. Forest Service, U.S. Geological Survey, and the U.S. Fish and Wildlife Service.

Courtesy of UC Berkeley, www.crcd.org

As reported in the Press-Enterprise (Riverside, California), researchers from the San Diego Zoo’s Institute for Conservation Research, which has a captive breeding program for the frogs, discovered that three months hibernation in near-freezing water is what gets these frogs in the mood for love. In the wild, frogs hibernate in icy, high-elevation streams, not in 55-degree aquariums. To mimic these cool temperatures, they were placed in clear plastic shoe boxes called “Valentine’s Day retreats” and stored in the refrigerators.

When they were removed from the refrigerators in April, they displayed breeding behavior within a few days. According to the institute’s Research Coordinator Jeff Lemm, “It has been wildly successful, and as a result, we could reintroduce about 500 eggs into the San Jacinto Mountains.”*

Only 200 individual mountain yellow-legged frogs exist in the wild. Once common in Southern California’s mountain streams, the frog species is almost extinct due to fungal infections, pollution, habitat loss, and predatory trout introduced for fishing. Researchers hope to re-establish wild populations with the captive-bred frogs.

Kudos to students, researchers, and biologists who are helping to save the mountain yellow-legged frog from extinction!

Please see the video below to learn more about efforts to save the mountain yellow-legged frog. This frog species was also featured in the episode Yosemite in the recently rebroadcast PBS documentary The Thin Green Line, about the amphibian decline, which you can watch online.

*As reported on the University of California’s Natural Reserve System site.


The Froglog: A Frog-Friendly Invention

Last summer we received a wonderful photograph taken by Mary Lascelles for our photo contest of a frog (whom she named Fritz) who hung out on the filter line in her pool sunning himself. Luckily, Fritz never fell in the pool.


Unfortunately many frogs do fall in pools and are poisoned by chlorine, which is absorbed into their bloodstream through their permeable skin. Recently on the Mother Nature Network blog, I read about a new invention, called a froglog, that helps frogs and other small animals escape from pools.

The froglog was created by Rich Mason, a wildlilfe biologist with the U.S. Fish and Wildlife Service, who was disturbed that so many frogs and other animals were dying in pools. The froglog is a thick foam tile with angled edges that allow frogs to climb out of the pool. The froglog can also be used in hot tubs, spas, fountains, and backyard ponds.

As Mason writes on his website, due to suburban sprawl, pools are now often built close to the natural habitats of amphibians. He mentions a friend with a pool in Maryland who found over 50 animals trapped in his pool in one night.

Check out this video of frogs and turtles using the froglog escape ramp. And if you have a pool and live in an area with lots of wildlife, definitely consider getting a froglog!