Collars turn up new information about bears
Recent information from a study of two collared, female bears on the Chilkoot River suggests the animals can outgrow behaviors like stealing fish from anglers. Data also indicate that the Ferebee Valley may be an important mating area for brown bears.
The information is the latest from a state Department of Fish and Game study started in 2008 expected to help the agency and state land managers develop improvements to the popular bear-viewing area, such as raised platforms or roadway changes.
The data sample, however, is small and focuses only on bears habituated to people.
Fish and Game regional bear biologist Anthony Crupi leads research tracking “Speedy,” age 8, and “BMJ,” a 23-year-old “matriarch” and prolific breeder regarded as the river’s most dominant animal. BMJ has raised three sets of triplets in the past 12 years. A third bear, 233, was collared only between 2008 and 2010.
“Speedy” was named by tour guides for her habit of charging people along the river, and snatching whatever food they left behind. Collared in 2008 as a sub-adult, she matured out of her bad habits during the study, Crupi said.
A commonly held theory is that bears that learn to equate people with food will only become an increasingly dangerous nuisance.
“She proves that these are not necessarily lifelong habits,” Crupi said. “The two to three-year-old age is when they get into trouble, but as adults, they may straighten out.”
Emerging from the den when she did not have cubs, Speedy headed to the Ferebee, a valley three miles east of Chilkoot Lake. With cubs, she went straight to Chilkoot River, bolstering a theory that Ferebee serves as a mating ground, he said.
The average home range for the two bears was 135 square kilometers. The bears spent 42 percent of their time in closed forest, 14 percent in grassy areas, 13 percent in open forest (for example, avalanche chutes) and 12 percent in water. Aside from denning, the collared bears spent almost no time in alpine areas.
The bears concentrate along the river in September, when they spent 95 percent of their time within 500 meters of it, compared to 75 percent in August. They spend nearly all of late summer and fall moving between the river and nearby daybeds.
The average date of den entrance was Nov. 6 and the average date of den emergence was April 29. The mean elevation of the den was 2,800 feet on south or southwest facing slopes of 30 to 40 degrees.
Bear 233, collared as a 3-year-old, wandered all the way into town, behavior typical of a newly independent sub-adult bear that has not settled into a home range, Crupi said. In comparison, Speedy and BMJ have not gone closer to town than the old Army tank farm.
That suggests adult problem bears around town aren’t necessarily Chilkoot bears, as the research is increasingly showing that Chilkoot adults tend to stay close to the river, Crupi said.
Another projected use of the study is the reassessment of the local bear population. The Haines area brown bear population traditionally has been estimated at 400. Crupi believes that his study’s habitat use model may result in a lower estimate.
Fish and Game’s guideline harvest (including all bears killed) is set at 4 percent of the population estimate, or 16 bears, with a 60 to 40 male-to-female ratio. The local take has come in substantially above that estimate for the last two years: 25 bears killed in 2010 and 23 bears killed in 2011.
Overages of this magnitude could have a significant impact on population numbers in a relatively short time period, particularly if the population is smaller than the estimated 400, Crupi said.
Collars on Speedy and BMJ are programmed to release in the summer of 2013 and there are no plans for future collaring activities.
Crupi estimates that in an average year, five adults and five sub-adults use the Chilkoot River, not including cubs. All adult bears living along the lower Chilkoot River are females.
Crupi estimates about one third of the lower Chilkoot River bears are tolerant of human activities, but that “there are (also) bears that people will never see... bears that, at the first sound of the first car, hightail it for the woods.”
The rubber, 26-pound collars send a VHF signal to researchers with information regarding location, activity and temperature as frequently as every 20 minutes. Biologists use location information to develop habitat use and range models.
Crupi said great strides have been made in the management of the Chilkoot River resource since he first began studying bears there more than 12 years ago. The introduction of a bear monitor and a ban on overnight parking have reined in out-of-control encounters and reduced displacement of bears by fishermen and tourists, he said.
“There are so many people who come here to see a bear, but it has to be managed in a way that is sustainable... to make it a high-quality experience and let the bears feed enough to produce cubs... (including) the bears that are not tolerant of people.”
Crupi oversees brown and black bear studies across Southeast, including a large-scale project in Yakutat, where 40 brown bears are collared.