Vehicles take a heavy toll on Kenai moose

Refuge Notebook

Early in the New Year, my daughter's swim coach, Luke, had his vehicle totaled in a collision with a moose. He came out of it with whip lash and embedded glass shards, but fortunately without serious injury. The loss of his 2010 Toyota Corolla, the threat to his life, and the couple weeks off from work became just another statistic -- a numerical contribution to the 250 or so moose that are killed in a typical year by collisions with trucks and cars on the Kenai Peninsula. While I'm really glad that Luke came out of this OK, as a wildlife biologist I gave some thought to the dead moose. What does this mortality mean to the Kenai moose population?

 

Over the last 30 years, the human population on the Kenai Peninsula has doubled, from 25,000 to 53,000. Traffic volume near Robinson Loop on the Sterling Highway, where the Alaska Department of Transportation maintains a permanent traffic counter, has almost quadrupled during this same period, increasing from 2,450 to 8,430 vehicles each day. Yet the rate of moose-vehicle collisions, while spiking during winters with deep snow, really hasn't changed much. Ranging from a low of 100 collisions in 1980 to a high of 366 in 1989, the 30-year average is 244 moose-vehicle collisions per year with no obvious trend. This translates to over 7,100 moose killed by vehicles on the Kenai since 1980!
Let's put this in some kind of demographic perspective. Over these same three decades, the number of moose harvested by hunting has also varied from year to year, ranging from a high of 884 in 1983 to a low of 388 in 1999. There's been a slight downward trend in harvest, but not as much as many hunters think -- the 30-year average of 576 moose harvested each year is not much different than the average of 516 moose harvested per year over the most recent decade.

What is remarkably constant over this period is that about a third (30 percent) of moose killed by humans every year is a result of vehicle collisions. For every two moose killed by a hunter on the Kenai, one is killed by a car or truck.

However, consider that death by a vehicle has a much greater impact on the health of the Kenai moose population than death by bullet or arrow. Hunting regulations restrict harvest to mostly bulls. In contrast, a 1991 study by Gino Del Frate and Ted Spraker found that most vehicle-killed moose on the Kenai are calves (55 percent) and cows (38 percent), a significant bite out of the annual reproductive cohort. And calves in that study were killed by vehicles at three times the proportion found in the general moose population in GMU 15A.

To make matters worse, vehicles kill more adult female moose than any other source of mortality. Ed Bangs and his colleagues tracked 51 adult female moose in the Kenai Lowlands between 1980 and 1986. Fifteen of his collared cows died from vehicles, translating to a mortality rate of 4 percent per year, the same rate as accidents, predation, hunting, and old age combined during their study. And unlike predation, which tends to take older adult females (9-plus years), vehicles were non-selective, taking moose which were in the same physiological condition as the general population and from different age classes.

In case you think that was then and this is now, Rick Ernst and his colleagues studied movements of 59 radio-collared adult female moose along MP58-79 of the Sterling Highway during 2005-07. Five moose died during this study, three due to collisions with vehicles, and two others that were being fed on by wolves so close to the highway that Ernst believes they were likely struck by vehicles first. A fourth collared moose was killed by a vehicle in 2010, three years after the study. Conservatively, 6 percent of cow moose died in moose-vehicle collisions during the 2-year study or 3 percent per year, statistics that are very similar to those measured during the 1980s when moose densities in GMU 15A were higher.

What's really alarming about these studies on the Kenai is that collisions with moose are under-reported to the State Troopers. Bangs found that only seven of the 15 moose killed by vehicles during their study were actually reported, suggesting that reported values may be 50 percent of the actual collision rate. A 1999 study in the Anchorage area similarly showed that the municipality recorded only 80 percent of the real number of moose killed by vehicles.

Even as far back as 1953 when highway traffic was much lower and slower, the first manager of the Kenai National Moose Range (predecessor to the Kenai National Wildlife Refuge) argued that moose road-kills were the "chief cause" of moose mortality other than legal hunting. Bangs similarly concluded that the most effective way to increase adult female survival on the Kenai was to reduce the number of moose-vehicle collisions. A public awareness program was initiated on the Kenai Peninsula in 1990 that included better data reporting, meat salvaging, signs that said "Give Moose A Brake," and other outreach efforts. However, given that road-kill statistics haven't changed for the better since then, I think it's fair to say there's room for improvement.

Why hasn't more been done? Frankly, it's expensive. Although there are some simple things that can be done like manipulating roadside habitat, the most effective long-term solutions involve putting in bottomless culverts or wildlife overpasses like those constructed in Banff National Park. The study that Ernst conducted on the 21-mile highway segment through the Refuge resulted in $14 million worth of recommended wildlife structures to permanently reduce collisions. That's hard on anybody's wallet.

On the other hand, consider that the Alaska Moose Federation estimates the average moose-vehicle collision costs $15,000 in property damage. A study published in 2006 estimated the average cost is $28,100 when medical costs and lost wages are included. Do the math yourself -- collisions with Kenai moose cost those unlucky individuals almost $7 million every year. Over the last 30 years, this translates to over $200 million, 7,100 dead moose (valued at $5,000 each), and the priceless loss of human lives!

As a final thought, remember that vehicles don't just kill moose. During 2000-07, in addition to 142 moose, Ernst tallied 24 black bears, 3 brown bears, and 5 caribou that were struck in his study area along the Sterling Highway. What a waste of wildlife and money. This has been a problem for decades and will continue to be one until we can agree on a path forward. In the meantime, as Luke learned the hard way, your only option is to drive slower and stay vigilant.

John Morton is the supervisory biologist at Kenai National Wildlife Refuge. You can find more information about the Refuge at http://kenai.fws.gov or http://www.facebook.com/kenainationalwildliferefuge.

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