Ever wonder how biologists count moose? These massive but elusive animals don’t make it easy. But it turns out the key to good population surveys starts with a good snowfall. Snowy days are essential to conducting annual moose surveys across northern and central Ontario, as far south as Haliburton and the Kawarthas.
The inventories—done by low-flying aircraft—help the Ontario Ministry of Natural Resources and Forestry (MNRF) estimate populations for long-term management—an increasingly important task as climate change and host of other factors have imperilled moose in southern portions of their range.
The aerial counts are done using a standard protocol that’s used across North America: between 10 AM and 2 PM from December through mid-February, within 72 hours of a fresh snowfall of at least 30 cm (to make tracks more visible) and temperatures less than minus 5ºC (since moose are more active in the cold).
“The Ontario moose population has decreased 20 percent since 2004,” says Amanda Rantala, the administrative assistant to the regional director with the Northeast Region MNRF in Timmins. “Exact causes of population declines are not always clear, but multiple factors likely play a role including habitat, parasites, hunting, climate and predators. The ministry is exploring the potential for further science efforts to examine the impacts of some of these factors more closely.”
Rantala says the most significant declines have occurred in parts of northeastern and central parts of the province, including most of Ontario cottage country. But it’s not just here; similar patterns are occurring elsewhere along the southern fringes of moose habitat. Minnesota’s moose population has decreased by more than 50 per cent since 2006, in part because of increasing numbers of white-tailed deer, which carry a brainworm parasite that’s lethal to moose. In Maine, warmer winters are being blamed for eruptions of winter ticks, which threaten the survivorship of young moose by causing hair loss.
Aerial surveys are conducted on a rotational basis in Ontario Wildlife Management Units (WMU) known to support moose. Based on aerial observation of moose signs in the surveys, biologists make population estimates for low-, medium- and high-moose density habitat, which can then be extrapolated across the entire WMU. Aerial surveys also allow biologists to estimate the number of bulls, cows, and calves within an area.
Ultimately, moose aerial estimates are plotted against management goals to allow biologists to assign hunting quotas for various parts of the province. Rantala says moose in Ontario’s cottage country are within population objective ranges, with about 1,300 moose in the Parry Sound area, 339 in Muskoka and 458 in Haliburton. The moose population for the entire province is around 91,000—about the same as the number of moose hunters.