Moose Calf Survey Completed
Moose calves were counted in Lake and Cook counties as part of an ongoing cooperative moose research project in northeastern Minnesota. Biologists from Fond du Lac Band, 1854 Authority, the Minnesota Department of Natural Resources (DNR), and the U.S. Geological Survey cooperated on the aerial calf survey that was flown May 24 and 25.
The survey was intended to determine which of the radio-collared cow moose had given birth.
"This is the first calf survey of its kind in northeastern Minnesota," said Mike Schrage, Fond du Lac Band biologist. "We want to get an idea of calf production and survival. The annual aerial population survey done in early winter gives us a cow to calf ratio for January. We have little information on how many calves are hitting the ground in May or surviving to adulthood."
The survey crew found that single calves accompanied half of the cows, twins accompanied three cows, and one cow had triplets.
"The triplets were a real surprise," said Mark Lenarz, the DNR biologist on the study. "We occasionally see twins during the January surveys, but never triplets. Very few cases of triplets in moose have ever been reported."
"So far, adult mortality has been higher than expected among collared cow moose in the study," Lenarz said. "With high adult mortality, bringing calves into the adult population becomes more important in maintaining our population."
The helicopters, flown by DNR pilots, were used to locate radio-collared cows and then find and count their newborn calves.
"The flights were timed to coincide with peak calving but before extensive green-up occurred in the study area," said Andy Edwards, the biological services director for the 1854 Authority.
Peak calving is May 15 to June 1. The study area is near Isabella.
"We weren?t sure this calf survey was going to work," Edwards said. "We do most moose counts when there?s snow on the ground so that the moose stand out against a white background. We had no idea if it was going to be possible to find newborn calves against a brown springtime background even if their moms were wearing radio collars."
Survey crews visually located 31 of 33 collared cows during the survey, after homing in on them using radio telemetry, according to DNR pilot John Heineman.
"It was just a matter of persistence and working back and forth at low levels until we found them," Heineman said. "Cows with calves were tight together. The cows either stood their ground or moved off slowly with their calves toward more overhead cover."
Biologists said they were pleased with first-year results. It is likely that not all cows had dropped calves by the start of the survey. Follow-up survey flights will shed light on that aspect.
Moose biologists will likely see some of these cows during normal weekly telemetry tracking and the winter survey, which will allow them to document additional reproduction. Moose calves remain with their mothers until the following spring when the cow is ready to give birth again.
Another calf survey is planned for late winter/early spring 2005 to confirm how many calves documented in the spring of 2004 have made it to adulthood.