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Attention Colockum and Yakima Elk Hunters – We need your help!
Scott McCorquodale, Ph.D, Deer and Elk Specialist

Heart with membrane (pericardium) cut away Heart covered by membrane and fat deposits Kidneys covered with fat Photos: Scott McCorquadal

When habitat conditions are good and a cow elk’s diet sufficiently nutritious, they can acquire the needed calories and other nutrients to successfully rear a calf. If abundant quality forage is available, they may also be able to store adequate energy reserves (fat) to assure breeding again that autumn. Research has indicated that the probability of successful breeding by cow elk declines rapidly as autumn body fat levels fall below 10%. At autumn fat levels below 5%, cow elk almost never successfully breed.

So, autumn fat levels among cow elk are a good predictor of the likelihood of successful breeding and of prevailing habitat quality. Researchers have found one very good, simple, and inexpensive method to assess autumn body fat is to examine harvested elk for fat levels deposited around specific internal organs… namely, the heart and kidneys. Research has established very good predictive equations providing a link between total body fat and the amount of fat covering the heart and kidneys in elk.

Every autumn, elk hunters take to the field and harvest cow elk These harvested elk can provide important information about elk population well-being and elk habitat quality. Biologists need help from hunters to collect information from harvested cows to make the needed assessment of body condition. Biologists need to examine the amount of fat covering both the heart and the membrane covering the heart (the pericardium), and they need to assess the amount of fat covering both kidneys (See photos). Two additional pieces of information are needed: it is helpful to know the cow’s age (was she prime-aged or senile?), and it is important to know if the cow nursed a calf the preceding summer (a skinny cow elk that nursed a calf all summer means something different than a skinny cow that was barren). A tooth from the harvested elk can be used to estimate it’s age, and a careful examination of the udder can determine whether the cow nursed a calf during the summer preceding harvest.

WDFW biologists are using just this approach to assess the nutritional status of elk from the Colockum and Yakima elk herds. For the last 2 years, biologists and volunteers have headed afield each autumn to locate successful cow elk hunters and collect data from their elk. Hunters not contacted in the field have been directed to provide the samples (heart, pericardium, both kidneys, an incisor tooth, and an assessment of the udder) at specific, signed drop-off locations. So far, some useful data have been acquired, but WDFW would like to increase sample collection. To date, only a few hunters have participated, and many samples received have been incomplete (for example, a heart but no kidneys…a heart, but no pericardium). Hunter cooperation is the key to success in this endeavor.

Most hunters can locate the heart and it’s covering membrane. Hunters can retain their elk hearts after examination by a biologist. The kidneys are slightly more difficult to locate for most hunters; they are found in the back of the body cavity, usually close to the liver. They are oblong, relatively firm organs about 5-6 inches long and are typically covered by considerable fat. Because the assessment requires examining fat surrounding the kidneys, it is critical that hunters do not trim fat off the kidneys. Locate the kidneys and carefully remove them with all attached fat. Then remove the 2 middle incisor teeth (front teeth, bottom jaw). Finally, either remove the udder for later examination or carefully pull on the teats (essentially like milking a cow) and watch for fluid, which may be milk-like or clear (report the nature of any fluid when you submit your sample). Hunters should look for signed drop-off barrels, contact any WDFW employee in the field, or call the Yakima Regional Office to report a sample. Although sample collection will require a little extra effort on your part, you will be helping to assure sound biological management of Washington’s elk herds. If you need more information, more detailed directions, or an organ location diagram, please call 509-575-2740 or 509-457-9322.