Elk herd health
Wednesday, March 14, 2012
MORTON, Wash. -- Pat Miller surveyed a table covered with oozing elk hearts, kidneys and other organs. He pointed out globs of white fat on some of the specimens.
“Your cardiologist doesn’t want to see a lot of this, but with wild animals, we want to see a lot of fat on the heart,” said Miller a wildlife biologist for the Washington Department of Fish and Wildlife. The more fat, the better an elk is able to get through the winter, when food sources are harder to find.
Cutting apart elk organs and measuring their fat content is one way biologists continue to measure the health of the Mount St. Helens elk herd. It’s been a focus for the department for the past six years, after hundreds of elk starved to death in the state’s wildlife area in the Toutle River Valley following severe winters.
This is the third year of the elk organs project. The past couple of years, the average fat content of Mount St. Helens cow elk has been less than ideal but not so low that it would reduce their chances of giving birth to calves.
To obtain material for their research, the biologists turn to hunters.
Last fall, hunters who drew cow tags for the Mount St. Helens herd were asked to leave body parts at state hatcheries and other drop sites. The bags of organs spent the winter in deep freeze.
“We send them a packet of illustrations of what we’re looking for,” Miller said. Most hunters do pretty well in their field dissections, though sometimes the biologists have to discard a stray bit of lung that comes along with a heart.
The hunters send along notes, too.
“The first one we looked at said he was doing it after dark in the pouring rain -- but he did get all of it,” Miller said.
Another note read: “I usually eat the heart. You owe me.”
One hunter shipped along the deformed hooves of an elk with hoof rot, though the team wasn’t set up to analyze that.
Two weeks ago, a group of 16 WDFW employees and volunteers assembled in a warehouse of the agency’s Cowlitz Wildlife Area in Morton to examine the body parts. The team included students from Washington State University and Portland State University.
The 148 returned bags of elk organs were laid out in neat rows in an unheated garage.
“We get our the best information from the heart, pericardium and kidneys,” Miller said.
The volunteers donned rain gear and rubber gloves for the messy work and compared each specimen to laminated photos of elk parts, numbered 1 to 20, depending on the amount of fat. Heart conditions varied from smooth and red to ones that were covered with fat deposits.
After hoisting a heart, the researchers first pulled off the pericardium. The membrane slips off fairly easily, like a floppy sleeve.
“These kidneys are pretty good,” said Scott McCorquodale, the statewide deer and elk specialist. “These are going to be on the high end.
“Let’s go 10 on the heart,” he added.
Another specimen didn’t score as high. “You can see this is kind of getting leathery,” McCorquodale said.
At another table, biologist Eric Holman examined a pericardium.
“There’s very little of this thing and you can see right through it,” he said. Holman gave it a “6” and tossed the specimen into a garbage can.
Hunters also sent in elk teeth. One from each animal is sent to a laboratory in Montana which photographs a cross-section.
“These animals will lay down a distinct ring for every year they’re alive,” McCorquodale said.
Hunters also were asked to supply the animals’ udders and reproductive tracts.
Madeline Jovanovich, a PSU undergrad, gently pulled a uterus away from the chunk of ice surrounding it to find a fetus about six inches long.
“This is probably the most exciting thing I’ve ever done -- seriously. It’s a great opportunity,” said Jovanovich, who hopes to become a wildlife biologist.
Fatter cows more likely to have calves
Though biologists have long used body fat as a gauge of wild animals’ health, research by Rachel Cook in 2001 made it much more precise, McCorquodale said. Cook, who was then at the University of Idaho, first observed and photographed the body organs, then had the entire elk rendered to get a precise body fat content.
“We can take those scores and get an estimate of what the animal’s body fat was on the hoof,” McCorquodale said.
“An elk making a really good living should be able to go into the winter at something above 20 percent,” he said. “Most don’t.”
Two years ago, the mean body fat for non-lactating cows in the St. Helens herd was 11.45 percent; last year it was 11.23 percent. Lactating cows had 8.5 and 9.34 percent fat; cows expend more energy if they’ve been nursing calves.
“I’m guessing they going to be pretty similar” this year, McCorquodale said. “We saw a few high-end conditions. We saw a lot in the mid-range. We saw some that were really lean.”
McCorquodale called the fat counts from past years “a bit on the lean side” though not dangerously low.
Cow elk that breed have a high chance of getting pregnant if their body fat is higher than 10 percent. “If it’s not above 5 percent, it’s almost nil,” McCorquodale said.
A similar body fat project was done for the Yakima elk herd from 2003 to 2007.
“St. Helens is lower pretty consistently,” which surprises some people who think the rainier, warmer part of the state is beneficial for elk, McCorquodale said. “Even though it’s drier on the East side, the nutrition levels tend to be higher,” he said.
So far, researchers haven’t made a formal comparison of the fat content of elk from different parts of the Mount St. Helens herd, which ranges from I-5 to the Cascade crest and from Highway 12 to the Columbia River.
Considering all the attention on elk on the Toutle valley mudflow, McCorquodale said more research is needed there.
WDFW gets additional body fat statistics from the mudflow area from another research project, in which live elk are tranquilized and examined.
“Some of the fattest elk we’ve seen are on the mudflow but so are some of the skinniest,” McCorquodale said.
However, nothing the elk fat research has shown suggests a need for a major revision of hunting regulations, he said. St. Helens cow tags have been increased since 2006 as WDFW tries to gradually reduce the herd size by 25 percent.
“I don’t see a big departure from that,” McCorquodale said.
Other elk projects underway
WDFW biologists get body fat statistics from live elk, too.
As part of ongoing work to develop a new technique for estimating herd size, biologists recently put radio collars on 30 elk near Mount St. Helens.
The biologists, working from helicopters, shot tranquilizer darts into the elk. Once on the ground, the researchers used an ultrasound device to check body fat and did pregnancy checks.
“They get a tooth pulled for aging,” Holman said.
The elk wake up in seven or eight minutes, Holman said. “The goal is no more than 10 minutes a piece” examining each animal, he said.
The February fat content in past years has ranged from 5 to 6 percent for non-lactators and 2.5 to 4 percent for lactators.
Elk have less body fat in February than they do in the fall.
“They should be getting pretty close to the bottom level of their condition,” McCorquodale said.