Wildlife biologists at Voyageurs National Park recently completed an aerial survey of the park's moose population in February and March. The 2014 population estimate for the Kabetogama Peninsula was 40 moose, similar to estimates from 2009-2013 of 41-51. The Kabetogama Peninsula is a 118-square mile roadless area that contains almost all of the park’s moose population. Fewer calves were observed in 2014 than in the previous 3 surveys, and the calf:cow ratio of 0.23 was also lower than estimates from 2010-2013 of 0.54-0.61. Two adult collared moose moved from the park into Ontario a few weeks before the survey began and another died during the survey. If those moose had been present during the survey, the 2014 estimate would have been inside the range of past counts. Biologists also confirmed the presence of at least 3 moose in the southern portion of the park.
The continued apparent stability of the low-density population in Voyageurs is corroborated through ongoing monitoring of GPS-collared moose. Only 1 of 14 collared adult moose has died since the last aerial survey was completed in 2013. Overall, mean annual mortality of adult moose in Voyageurs National Park has been 10% since monitoring began in 2010. By comparison, annual mortality of adult moose in the declining northeastern Minnesota moose population in recent years has been around 20%.
Voyageurs National Park is at the current southern extent of moose range in North America. Warmer annual and summer temperatures may be stressing moose populations in the region. The moose population declined by about 50% between 2006-2014 in northeastern Minnesota and several areas in adjacent Ontario have also documented recent declines. There are likely multiple factors involved in the observed declines including climate-related stresses on health and reproductive status, diseases and parasites, predation, and changes in habitat. Moose in Voyageurs experience all of these factors, including the brainworm parasites and high densities of wolves and bears. It is unclear if population dynamics in the park are indeed different from those in adjacent areas or if the park, at the western and southern edge of these other populations, will experience similar declines in the near future. Park biologists are continuing studies to understand the complex relationships that drive moose population dynamics in the park.
The National Park Service will continue to monitor the Voyageurs National Park’s moose population on an annual basis. In addition, Voyageurs National is investigating other aspects of moose ecology in collaboration with University of Minnesota-Duluth, Bemidji State University, Lakehead University, and other partners. Other studies include how moose behave in response to high temperatures and other weather events, how and why moose use wetlands for foraging and temperature regulation, and the interactions of moose, deer, beavers and wolves.
The 2014 Voyageurs National Park Moose Population Survey Report can be downloaded from the NPS website: http://irmafiles.nps.gov/reference/holding/493661.
For more information contact: Steve Windels, Wildlife Biologist, Voyageurs National Park, 218-283-6692, steve_windels@nps.gov
Moose photo by Walter Ezell. Licensed under CC BY 3.0 via Wikimedia Commons.
