Four years of field data collection on the Wisconsin experimental elk herd was completed on 17 May 1999 but it was decided to determine elk productivity and monitor calf survivorship during the 1999 calving season to bolster the annual increment data base. Between 21 and 25 calves are destined to be born this year, depending upon the unknown pregnancy rate of yearling cows. A goal of radio-tagging 10 calves was established by the elk research team in consultation with the Wisconsin Elk Project Advisory Committee that was formed by The Rocky Mountain Elk Foundation. Approximately 50% of the calves that were born in the past 2 years have also been radio-tagged. Approximately one half of the elk mothers of 1999 are radio-tagged at this time. Some transmitters have failed (life expectancy = 3 years) and about 50% of the cows that were born in Wisconsin were not captured. Verifying births of the untagged cows will require much field-work; a final tally will not be available until late summer.
Pregnant radio-tagged cows, usually in small groups, are monitored daily during the calving season that reaches a peak during the first week in June after a 250-day gestation period. The cows have 20-day estrous cycles during the rut in mid-September with most being bred during the first cycle. A cow will isolate herself from others when she is ready to freshen. After 1 to 2 days of isolation they are cautiously approached in hopes of finding them near the calf. That area is searched diligently to find and hand-capture the camouflaged, immobile, and usually well hidden calf. It is quickly tagged, measured, weighed, and released at the capture site; the mother is never very far away.Ten births have been confirmed thus far this year and 10 calves (5 females, 5 males) have been captured or tagged. Other calves most certainly have also been born to untagged mothers during the past 2 weeks and calves that were conceived during the second estrous cycle last fall are destined to be born within this coming week. The remainder of the 1999 summer will be devoted to monitoring survivorship of radio-tagged calves and determining productivity of untagged cows. Wisconsin Department of Natural Resources (DNR) personnel have been present daily for calf capturing and tagging along with many volunteers and The Wisconsin Conservation Corp.
[Image: Courtesy of Flickr user Larry1732]