LEWISTON, Idaho -- The same kind of exotic lice infesting deer at Riggins have been found on mule deer in a handful of other Idaho locations but at much lower densities and without causing hair loss to their hosts.
Deer with just a few lice have been found at Salmon, Elk Bend near Salmon, Emmett and the Andrus Wildlife Management area near Cambridge.
Idaho Fish and Game officials have documented that more than 90 percent of the deer living within the city limits of Riggins are invested with Bovicola tibialis, the exotic lice that causes hair loss and even death in some cases. Last winter the department killed about 60 deer at Riggins in an effort to control the outbreak.
State wildlife veterinarian Mark Drew of Caldwell said finding the lice in other places doesn't necessarily mean the lice that had previously been detected in western Oregon and Washington and parts of Northern California are moving. He and others who work for the Idaho Department of Fish and Game have been looking for the lice for the past few years.
In most of their searches, even those near, but not in, Riggins, no lice were found. When they have been found, Drew said it has been just a few lice and they have been found alongside native lice. The deer at Riggins have no native lice on them.
Drew now thinks it is possible the species has been present for a long time, perhaps decades, and something is causing its numbers to boom at places like Riggins and large swaths of coastal Oregon and Washington.
"I'm beginning to suspect, like lots of other people, this louse may have been introduced decades ago, probably on fallow deer, probably on the West Coast and other places, and it's kind of there on mule deer in low numbers, maybe in a general distribution, and there is something fueling this eruption of this louse in some places, and nobody knows what or why."
He said the louse may not have been found until now because nobody was looking for it.
"If it's not causing a problem in deer and you don't look at deer, does that mean it isn't there? If you look at deer with hair loss and find it, does that mean it's suddenly there or is something amiss in the system?"
That something could be a mineral deficiency, something related to nutrition or the unique conditions of deer living in high densities in a small area. Drew took blood and other samples from the 60 or so deer killed as part of the control operation. He expects to get full lab work back in the next few weeks and said that could yield some clues. The department is also experimenting with trying to treat some infested deer at Riggins.
Drew said 13 were marked, captured, treated and then released. Some time later six of the marked deer were recaptured and treated again. That effort will be repeated in a few weeks and then again next winter. At the same time, Drew said the state's effort to monitor deer and lice throughout the state will continue. He hopes to learn enough about the lice and what causes it to reach high numbers to control it.
"Maybe we can stem the tide, maybe we can't," he said. "We will know in nine months."
(c)2012 the Lewiston Tribune (Lewiston, Idaho)
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