If you have pursued our state bird during the past few years, you must have been willing to expend more shoe leather than usual to even see a grouse. Ruffed grouse are in short supply, and according to a Pennsylvania Game Commission biologist, the population is at a historic low.
PGC grouse, dove and woodcock biologist Lisa Williams uses a combination of hunter data collected during the fall and winter, along with brood surveys conducted in June and July, to estimate grouse populations. Williams presented preliminary data at the September Pennsylvania Game Commission meeting, and an updated version was presented in a webinar broadcast Feb. 15.
During the 20th century, grouse populations seemed to cycle on roughly a five-year schedule. The population would hit a high about every five years, with a low year in between. When grouse populations headed southward this century, the finger was pointed at dwindling habitat. Ruffed grouse prefer young forest habitat and that is in short supply in the Keystone State.
Only recently did Williams begin to look at another potential factor — West Nile Virus. WNV was first detected in Pennsylvania in 2000, and by 2002, it was found in every county in the state. Coincidentally, 2002 and 2003 were poor years for grouse survival. Other severe years for the virus included 2004, 2005, 2012, 2013, 2016 and 2017. In most areas of the state, grouse populations decreased — sometimes dramatically — during those same years.
“Just because something looks like it is the cause, doesn’t mean that it is,” Williams said. “We needed more information. Are grouse susceptible to West Nile?”
In the spring of 2015, a challenge study was initiated. Pennsylvania grouse eggs, collected in the wild, were transported to a secure propagator in Idaho. After the eggs hatched and the chicks were four-to-five weeks old, they were transferred to a WNV lab at Colorado State University.
The chicks were inoculated with WNV, and after one week, 40 percent of the young grouse had died. At the end of week two, another 40 to 50 percent of the grouse demonstrated severe organ damage and probably would have died. Only 10 percent survived with no damage. This demonstrated that grouse mortality from WNV could be as high as 90 percent.
“These statistics were certainly grim for birds infected in the lab,” Williams said, “but what was happening in the wild?”
The findings sparked two additional studies. During 2015 and 2016, filter-paper strips were given to grouse cooperators — hunters who contribute samples and data to the commission each fall. Hunters collected and returned 418 blood samples from their harvested grouse.
“Of those, 19 percent had WNV antibodies, which means that they had been exposed to the disease, but survived, and were likely immune for life,” Williams said.
A second study focusing on the mosquitoes that transmit West Nile Virus was conducted last summer on State Game Lands 176 — the Scotia Barrens in Centre County.
“We found 25 different species of mosquitoes — eight of which could carry the disease and bite birds,” Williams explained. “I didn’t even know that there were 25 species of mosquitoes.”
From that study and looking at statewide Pennsylvania Department of Environmental Protection data, one mosquito species — Culex restuans — became the prime suspect.
Research and data collections are still on-going, and Williams has learned a lot during the past four years. She discovered that grouse living in better habitat handle WNV better than those living in poor habitat. The data suggest that grouse in the northern hardwood areas of Pennsylvania fare better than grouse in the southern oak-hickory habitat. She also was able to determine elevation thresholds — WNV appears to be less of an issue at elevations over 1,200 feet.
Two things will occur based on these discoveries. One, Williams has proposed the establishment of two grouse zones. The northern hardwood zone is made up of our seven most-northern wildlife management units. The southern zone, with generally poorer grouse habitat, contains the remaining 16 WMUs. Depending on certain criteria, she explained the two zones might be managed differently. The elevation-threshold discovery led her to ask that Game Commission grouse habitat work be concentrated at higher elevations.
Williams designed what she called a “consistent and transparent” responsive harvest framework to make recommendations regarding grouse season length. It will be based on hunter data from each zone, summer brood surveys and the prevalence of West Nile Virus during the previous summer.
Low grouse populations and high WNV will result in cancellation of the late grouse season, which is normally the day after Christmas through the third week of January. Favorable conditions will lead to Williams recommending a four-week season. If the factors fall somewhere in between, she will recommend that the late season be limited to one week.
In an effort to see more WNV-surviving grouse make it through to spring breeding, the late grouse hunting season was canceled this year. According to Williams, about one-third of the grouse harvest normally occurs during the late season. Closing or limiting late season hunting will hopefully keep more grouse in the breeding population.
“The summer of 2017 was one of the worst West Nile Virus years since we have been keeping records, and grouse populations are at historic lows,” Williams said. It should be no surprise that she again recommended that there be no late grouse season in either zone in December 2018 and January 2019.
“Grouse in Pennsylvania are in a pretty dangerous place,” she added.
Williams made her proposals to the Commissioners at their late January meeting, and they preliminarily approved a grouse season with no late season. The final approval could come in April. According to Williams, 58 percent of the hunters polled supported split management zones, and 72 percent of those responding supported closing the late season. Comments are welcomed by the Commission at firstname.lastname@example.org.
Free Nature Program
I would like to invite my regular readers to attend “The Flora and Fauna of Spring Creek,” a free nature program that I will be presenting at the March 1 meeting of the Spring Creek Chapter of Trout Unlimited. The informative program will cover a potpourri of nature subjects, including wildflowers, butterflies, birds, mammals, trees and others. The meeting begins at 7:30 p.m., and will be held at the Comfort Suites Inn, 132 Village Drive in State College. Seating is limited.
Mark Nale, who lives in the Bald Eagle Valley, is a member of the Pennsylvania Outdoor Writers Association and can be reached at MarkAngler@aol.com