Pennsylvania Game News - April 2019 - 7

each of the 10 game lands we've studied.
n We know Culex restuans populations rise and fall largely due to temperature and rainfall. WNV transmission
benefits from above-average spring and
autumn temperatures, because warm temperatures prolong the mosquito-breeding
and the WNV-transmission season.
Unfortunately, we also know WNV is
not going away. High-prevalence years
are becoming more frequent. Eight of the
past 10 years exhibited extremely high
WNV prevalence.

What we know now
As the discoverer of West Nile virus
impacts on ruffed grouse, I hear from a
lot of frightened grouse hunters and frustrated colleagues.
Once WNV infiltrates grouse populations, the tendency is to give up. I hear it
from Pennsylvania hunters and I've seen
the nothing-we-can-do-now mentality
attached to a lot of reports from across
the country.
But I reject such statements outright.

avid grouse hunter, as well as the Southeast
Cooperative Wildlife Disease Study and a Penn
State student to examine internal roundworms
of grouse. We found that grouse are commonly
infected with two roundworms - Ascarids, and
Heterakis. Neither are likely to be sources of
disease at the level of infection we observed
in harvested grouse.
Blackhead - While Heterakis can cause relatively mild disease in domestic poultry, the primary concern of this roundworm in wild birds
is the role it plays in the disease commonly
called blackhead. In this parasite-within-aparasite disease, the Heterakis gallinarum
cecal worm can harbor another parasite inside
of it - Histomonas meleagridis, which causes
blackhead. Through collaborative research,
we found grouse are commonly infected with
APRIL 2019

I understand the shock people experience as they grapple with the idea of this
virus suppressing grouse populations. But
the day we give up is the day we lose.
To safeguard grouse, the Game Commission in 2017 shortened grouse season
for the first time since 1960.
Closing the post-Christmas season is
designed to decrease the removal of birds
from the population in mid-winter, and
correspondingly increase the number of
birds entering the breeding population.
Even though the late season is a favorite among grouse hunters, over 70 percent
of the more than 300 season-related
written comments received since 2017
supported the closing.
Recognizing grouse-population
declines, Pennsylvania's passionate
grouse hunters have been willing to give
up days afield to help restore populations.
A structured framework now recommends season length based on grouse
population levels. This is a consistent and
transparent system that provides a mechanism for the season to lengthen as grouse
populations recover. A competing-models

Heterakis roundworms, but they harbor a different species that, to date, is not known to be
infected with Histomonas meleagridis. While
further research is needed to understand the
impacts of blackhead on ruffed grouse, this
preliminary research is additional good news.
Genetics - Working with East Stroudsburg
University, we have done an initial assessment
of genetic diversity among hunter-harvested
grouse. We are now comparing that level of
diversity with historic samples collected prior
to the arrival of West Nile virus. These data
will provide a baseline on genetic diversity of
Pennsylvania grouse that can be compared
with historic and future data. Genetic findings
also might reveal important information about
survivors, as well as the impact of West Nile
virus on population genetics and resilience.
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Pennsylvania Game News - April 2019

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