Unraveling Pennsylvania’s Ruffed Grouse Decline

Photo by Susan Drury

Grouse hunting in Pennsylvania is a tradition for many. The northern tier of the state particularly housed robust but variable populations of ruffed grouse. The thrill has always been getting to hear the characteristic thump, thump, thump of a drumming bird. Pennsylvania grouse hunting is a completely different thrill. Harvesting one means pulling up on a flushed bird in dense cover and making a difficult shot. These situations, however, are becoming much rarer in the state.

The ruffed grouse decline the Keystone state has been experiencing for decades is coming to ahead. Hunters are noticing it more and so are land managers. Regardless of if you hunt grouse, hunted them years ago, or are simply an interested outdoors person, the current state and future for this bird is concerning.

“Decline” and “trouble” are serious words but are being used more and more to describe ruffed grouse populations in Pennsylvania. It is not just Pennsylvania either. Most Northeast and Midwest states like Maryland, Minnesota, and West Virginia are all showing seriously declining grouse populations. Pennsylvania is coming up on the last year of a 10-year grouse management plan aimed at addressing the issue. Although, the situation looks much different than it did back in 2011.

Grouse Numbers and Our Current State

Grouse hunting in Pennsylvania was traditionally split into two seasons. Grouse would open in the fall alongside squirrel hunting and other small games species. Even though there were several weeks available in the fall Pennsylvania grouse season, hunters relished the late-season opportunity. These weeks after Christmas were ideal to sneak through dense thickets in the big woods or for running dogs to flush birds. But based on the increasing decline in grouse numbers, the late-season opportunity has been closed since 2017.

Grouse populations are always in flux. Across their entire North American range, their numbers tend to rise and fall in 5- to 10-year cycles. Biologists to a lesser extent understand why the 5- to 10-year cycles occur compared to more short-term swings in numbers.

Many factors affect population numbers. Generally, a cold, damp spring combined with a prolonged cold winter lowers grouse populations in the state. These conditions influence adult female survival and decrease the chances a young grouse will make it through to next spring. Like other animals, causes of mortality also include predation, disease, accidents and environmental factors such as floods and habitat loss.

Exact grouse numbers are difficult to estimate. Instead, the Pennsylvania Game Commission (PGC) uses sightings, harvests, and hunter survey data to assess grouse populations year-over-year and compile long-term trends. In the most recent data from 2018 (available from the PGC), a flush rate of 0.88 flushes per hour (f/hr) was overserved. This was a 6% decrease from the previous year and the lowest since 1965. For comparison, the long-term average is 1.37 f/hr. In addition, sight surveys are down 33% from the previous year and down 49% from the short-term average. These figures are based on surveys from grouse hunters (or cooperators) inside and outside of Pennsylvania grouse seasons. Clearly, the ruffed grouse decline that first was observed in the early 1980s is continuing to propagate itself.

Video: Award-winning and comprehensive look at Pennsylvania grouse from the PGC.

Two Factors Affecting the Ruffed Grouse Decline

The ruffed grouse decline can be attributed to two factors. The first, habitat loss, has always played a role in grouse numbers across their entire range. Aging forests are increasing and thus young forests, which grouse thrive in, are harder to find. It was not until 1999 when the second factor appeared. The impacts to grouse from the West Nile virus (West Nile) are only exemplified with habitat loss.

Habitat Needs of Grouse and Implications of Losing It

The primary habitat requirement of grouse is cover. Grouse use dense cover for all aspects of their life cycle including feeding, breeding, and shelter. Young forests provide these ideal conditions, however, aging Pennsylvania forests offer less suitable habitat. Also, population growth has fragmented what once were large contiguous tracts of forests. Grouse do not adapt well to changing habitat conditions and increased interaction with people.

Vegetation like mountain laurel, young pines and hemlocks, and new growth of hardwoods such as aspen are key elements to productive grouse habitat. Birds will eat buds of young growth during winter and feed on greenbriers, witch-hazel, and grapes during warmer months. All of which grow infrequently in older timber stands.

Multi-age forests have been dwindling through natural attrition over time since the large-scale logging that took place at the beginning of the 20^th century. This continued loss reduces the habitat needed particularly for breeding and rearing young. The ruffed grouse decline is a direct result of decreased young forests in the state.

West Nile’s Threat

West Nile virus began running its course in Pennsylvania between 2001 and 2003. Mosquitoes can transmit the virus to humans, animals, and birds. The health impacts have been known as it relates to humans, but less is understood when it comes to birds. Birds have shown symptoms and even mortality, especially in crows and jays. Recently, grouse have been studied and observed to have effects related to West Nile.

Research has begun to show just how much of a threat West Nile is to grouse populations in Pennsylvania. More robust population segments, which occur in high-quality habitats, have a greater chance of surviving West Nile. These segments are able to rebound faster after years where West Nile is more prevalent. When small populations in poor habitats experience widespread West Nile prevalence, it is more likely they will experience higher than average mortality and further decline.

In summary, the ruffed grouse decline is not an either-or but rather a combination of less than optimal habitat in conjunction with higher incidents of West Nile.

Planning to Save the Ruffed Grouse’s Legacy in Pennsylvania

The state has proactively been addressing the ruffed grouse decline for decades but more rapidly since the development of the statewide ruffed grouse management plan in 2001.

One-step undertaken has been the use of a framework for Pennsylvania grouse season recommendations. Grouse hunting in Pennsylvania was reduced beginning in 2017 to close the late-season. Even though hunting is a minor factor in grouse survival, closing the after Christmas season ensures that even more birds made it to the next breeding season.

Similar to other wildlife species, habitat is key. Creating and maintaining high-quality grouse habitat supports existing populations and helps them be more resilient against outbreaks from West Nile. Grouse management is being incorporated in the strategic planning for forest harvesting on state lands. Programs are also being implemented to support private forest landowners in an effort to expand acreage and connectivity of a good habitat.

Finally, additional research is being conducted to assess the impacts of West Nile. The focus is on looking at factors that can limit the transmission of the virus and at what thresholds of infection grouse are most vulnerable. Information like this would be used to prioritize habitat work that will have the most benefit on existing and future grouse populations in Pennsylvania.

The good news is we have an example where this is possible. The state of elk in Pennsylvania is thriving due to accomplishments in creating habitat and intensive management. Grouse can be the next success story with a lot of focused effort.

Hunting grouse in Pennsylvania is in many ways a dying tradition. The changing hunter demographic but more so the ruffed grouse decline has been a major contributing factor. However, hunters will need to play a major role in the path ahead to solving this issue. They are key in assessing populations and helping to manage large tracts of public and private land for which Pennsylvania is known for. The future of the state bird and beloved game species is most certainly a concern. Yet optimistically, much has been and more is being done to change the declining path grouse have been on.