Sampling coyote populations is an inexact science
Wildlife managers in North Dakota and Minnesota use a variety of surveys to gather population indices for coyotes and other furbearers. The surveys tally trends rather than population estimates.
Stephanie Tucker, furbearer biologist for the North Dakota Game and Fish Department in Bismarck, said the department conducts three surveys to get a statewide perspective on coyotes:
• A rural mail carrier survey, in which Game and Fish asks rural mail carriers across the state to record every coyote they see on their mail route for three consecutive mornings. The survey generally is conducted in April and covers about 100,000 miles, Tucker said. "We've done research to show this is a really great way to get an index of coyote trends in North Dakota," she said.
• A survey of hunters and trappers to gather harvest information.
• A survey of fur buyers. The survey provides insight into the minimum harvest, at the very least, but is highly dependent on pelt prices, Tucker said.
John Erb, furbearer biologist for the Department of Natural Resources in Grand Rapids, Minn., said the DNR gets the bulk of its "formal" information from two animal track surveys. They also collect harvest data, Erb said, but the information isn't reliable for determining population trends.
• "Scent station" surveys feature tracking stations of sifted soil along a road or trail with a fatty-acid scent tablet placed in the middle to attract furbearers. The stations are placed at .5-kilometer intervals on alternating sides of a road or trail. Each route features 10 survey stations and is checked daily during the four-day survey period. Surveyors then check for tracks of furbearer species at each station. The DNR in 2015 completed 268 survey routes.
• "Winter track" surveys involve checking for carnivore tracks after a snowfall in the northern part of the state. Each route is 10 miles long and follows secondary roads or trails on 57 track-survey routes across northern Minnesota. Besides coyotes, the survey provides information on timber wolves, fishers, marten and red fox.