Tuesday, October 16, 2012

Refuge tracking surveys show evidence of Canada lynx in Vermont

This post is part of a series running all week about the work done on national wildlife refuges to help with threatened and endangered species recovery. Today, you’re hearing from Rachel Cliche, a wildlife biologist at the Nulhegan Basin Division of the Silvio O. Conte National Fish and Wildlife Refuge, about winter tracking surveys to document the presence of Canada lynx in Vermont.

Are Canada lynx here to stay in Vermont, or just passing through? 

The answer will determine the role of management for this species at the Nulhegan Basin Division of the Silvio O. Conte National Fish and Wildlife Refuge. 

Canada lynx (Lynx canadensis) are medium-sized cats that live in spruce-fir forests and are highly dependent and adapted to hunt snowshoe hare. They were federally listed under the Endangered Species Act as a threatened species in 2000. 

Canada lynx
The Canada lynx range extends from Alaska, through much of Canada, to the
boreal forests in the northeastern U.S., Great Lakes, Rocky Mountains
and Cascade Mountains. Credit: USFWS

Vermont is at the southern end of the lynx's range, and while Canada lynx were never common in Vermont, they have been considered absent from the state for some time. Therefore, recent evidence of lynx in the vicinity of the Nulhegan Basin warranted an  in-depth look. 

In the winter of 2012, the Vermont Fish and Wildlife Department led an effort to conduct a snow tracking survey on the Silvio O. Conte National Fish and Wildlife Refuge’s Nulhegan Basin Division. The 26,000-acre division in northeast Vermont is an area where lynx sightings have been confirmed. 

A concentration of spruce-fir habitat, an abundance of snowshoe hare and the snowmobile access made Nulhegan Basin an ideal location to implement the first systematic survey of lynx in the state. 

Snowmobiles are driven slowly along transects as technicians search for lynx tracks (note the tracks along
the edge of the trail to the right of the snowmobile). Credit: Vermont Fish and Wildlife Department.

Refuge and state technicians used snowmobiles to survey about 71 kilometers of predefined areas (called transects) for lynx tracks. They followed survey methods similar to those used in Maine:
  • Surveys conducted within 48 hours of a snowfall to allow the animals time to travel and lay down tracks for possible detection. 
  • Transects included groomed snowmobile trails and unmaintained trails closed to snowmobile recreation. 
  • The survey area was divided in half, and four technicians (two per snowmobile) surveyed these transects for lynx tracks. 
  • Each lynx track that was “intercepted,” or crossed a transect, was measured, logged into a GPS and photographed, and the direction of travel was recorded. 
  • If time allowed, other species were also noted, including bobcat, fisher, and snowshoe hare. 
  • A fifth technician retraced the lynx tracks at each intercept and searched for potential DNA material, like scat or hair. 
  • The survey was completed within 10 hours, thereby ensuring optimum conditions for tracking and DNA collection. 

Lynx track
In deep snow, you will see the furred heel of the lynx
(more pronounced in the right track), and the track will
appear to float on top of the snow. Credit: Vermont Fish and
Wildlife Department.
A total of eight lynx track intercepts were recorded during two survey efforts in February and March. The track patterns and genetic analysis indicated three to five distinct individuals, some of which were traveling together. The individuals traveling together likely represented an adult female and her kittens, which stay with the female for a full year before dispersing on their own in late winter. 

The detection of a family group indicates that a breeding population may be present in northeast Vermont. 

Future survey efforts by the state will focus on similar habitat south and west of the Nulhegan Basin Division to further understand lynx distribution. Monitoring will continue on the refuge in an attempt to better understand lynx use and how management of refuge habitats can benefit this species.


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