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2010 Drumming Survey Results

During the spring 2010 wild turkey hunting season, DEC conducted the fourth annual Ruffed Grouse Drumming Survey. This survey asks turkey hunters to record the number of grouse they hear drumming while afield. The primary purpose of the survey is to monitor the number of birds drumming per hour. Changes in the drumming rate should illustrate trends in the grouse population when viewed over a long period of time and will provide insight into statewide distributions for this popular game species as habitats change both locally and on a landscape scale.

We thank all the hunters that participated in the Ruffed Grouse Drumming Survey during the 2010 season.

Results from the 2010 Season

During the 2010 season, 148 hunters participated in the Ruffed Grouse Drumming Survey. Survey participants reported data from over 1,000 hunting trips across the state, from the lower Hudson Valley in the south, to the Adirondacks and St. Lawrence Valley in the north, and the Lake Plains and Allegheny Plateau in far western New York. They spent almost 4,000 hours afield and observed almost 800 grouse (about 0.2 birds/hour). Some general findings from the 2010 season include:

• Hunters participating in the survey averaged about 27 hours afield during the 2010 season. They took about 7 trips afield for the season and spent about 4 hours afield per trip (Table 1).
• Survey participants averaged about 5 grouse observed per hunter for the 2009 season and had to spend about 5 hours afield in order to observe one grouse drumming (Table 1).
• Over 40% of hunting effort (and thus, survey effort) took place during the first week of the season (May 1-7; Table 2); however, the drumming rate (grouse drumming/hour) was relatively consistent (0.25 birds/hour) for the first three weeks of May (Table 2).
• Overall, there was far more effort expended in the southern grouse season zone (about 86% of the total), but the drumming rate was higher in the northern season zone (0.37 vs. 0.21 grouse drumming/hour; Table 3).
• Significantly more effort was expended, and more grouse were observed, on private land than public land; however, private and public land had similar drumming rates (Table 4).
• Hunting effort was distributed across major geographic regions of New York State. About 34% of the hunting effort took place in western New York (13% DEC Region 8, 21% DEC Region 9), about 29% in central New York (DEC Region 7), about 24% in the southeastern portion of the State (10% DEC Region 3, 14% DEC Region 4), and 14% in northern New York (7% each in DEC Regions 5 and 6; Table 5). We observed the highest drumming rate in DEC Region 5 (0.42 grouse drumming/hour), but Regions 6 and 7 were also above the annual statewide average of 0.23 grouse drumming/hour (Table 5).
• The drumming rate was highest in the Adirondacks-Tug Hill Ecozone (0.62 grouse drumming/hour), followed closely by the St. Lawrence Valley Ecozone (0.59 grouse drumming/hour; Table 6, Figures 1 and 2). The Appalachian Hills & Plateau (0.26 grouse drumming/hour) and Champlain Valley (0.27 grouse drumming/hour) ecozones were close to the statewide average (0.23 grouse drumming/hour), and the remaining ecozones were below the statewide average (Table 6, Figures 1 and 2).

Comparing 2010 to Previous Seasons

• Overall, hunters spent fewer hours afield during 2010 than the previous year (3,998 vs. 4,793 hours), and they observed fewer grouse (787 vs. 1,177; Table 1). The drumming rate in 2010 was lower than the previous season (0.23 vs. 0.29 grouse drumming/hour) and the amount of time spent afield to hear one grouse increased from just over 4 hours to just over 5 hours (Table 1).
• By every measure - number of grouse drumming, grouse/hunter, grouse/trip, drumming rate (grouse/hour) - turkey hunters observed fewer grouse this spring than during the 2009 season (Table 1, Figure 1).
• Drumming rates decreased in six of seven ecozones from 2009 to 2010, with the exception being the Adirondacks-Tug Hill (Table 6, Figure 1). Declines ranged from 3% in the Lake Plains to almost 50% in the Catskills-Delaware Hills.
• Annual variation in grouse abundance is likely a result of variation in weather, including spring temperature and rainfall and winter snow conditions, and food availability during the summer and fall (e.g., hard and soft mast, insects). During spring and summer 2009 an above-average rainfall may have resulted in a poor hatch and fewer drumming males the following spring. In areas with a lack of the early successional habitats on which this species depends, grouse, their nests, and young are more vulnerable to predation and other limiting factors, thus we tend to observe lower drumming rates in these areas.

Drumming Survey vs. Grouse Log

• Can we use results from the drumming survey to predict hunting success in the fall? At the statewide scale from 2007 to 2009, the drumming rate from the spring survey and the flush rate from the Grouse Hunting Log conducted during the fall are correlated (i.e., when we observe an annual change in the drumming rate, we see a similar change in the flush rate). Based on this, we anticipate that the flush rate during the upcoming 2010-11 season should be lower than last fall (1.2 grouse flushed/hour). However, when we attempt to link drumming rates with flush rates at smaller scales (e.g., WMU aggregates), the results are often inconsistent.
• Of the 20 WMU aggregates for which we have both drumming and flush data for the past three years (2007-2009), we observe similar annual changes in grouse abundance in only seven WMU aggregates. These WMU aggregates include the Tug Hill Transition, Champlain Valley, St. Lawrence Valley, and Oswego Lowlands in the northern part of the state, the Catskills and Neversink-Mongaup Hills in the southern tier, and the West Appalachian Hills in western New York. Similarly, at the larger ecozone scale, drumming and flush rates are correlated for only two of seven ecozones (Catskills-Delaware Hills, Lake Plains).
• Because of the inconsistencies at the WMU aggregate and ecozone levels, it is difficult to predict fall flush rates based on spring drumming data at these spatial scales. It is important to note that this is based on only three years worth of data and the results of these surveys may be correlated at the WMU aggregate or ecozone level over the long term.

^a Overall drumming rates are calculated as an average drumming rate for all days afield, not a simple division of the total number of grouse drumming by the total number of hours afield; SE = standard error.
^b A map illustrating Northern and Southern Season Zones for grouse.
^c A map illustrating DEC Regions.

^a WMU Aggregates are groupings of Wildlife Management Units. Ecozones are groupings of WMU Aggregates. The Coastal Lowlands Aggregate (NYC and Long Island) does not have a turkey season, thus is not listed.
^b Overall drumming rates are calculated as an average drumming rate for all days afield, not a simple division of the total number of grouse drumming by the total number of hours afield; SE = standard error.
^c There was an insufficient sample size in this WMU Aggregate. A minimum of 10 trips or 20 hours is needed for analysis.

Figure 1. Drumming rate (grouse drumming/hour) by ecozone based on the Ruffed Grouse Drumming Survey data, 2007-10. Ecozones are an aggregation of Wildlife Management Units. Abbreviations: Champlain Valley (CHVA), Adirondacks-Tug Hill (ADKS-TH), Catskills-Delaware Hills (CATS-DH), St. Lawrence Valley (SLV), Appalachian Hills & Plateau (APPH&PLT), Lake Plains (LKPL), Mohawk Valley-Hudson Valley-Taconic Highlands (MV-HV-TH). The Costal Lowlands Ecozone (New York City and Long Island) does not have a spring turkey hunting season, thus the drumming survey was not conducted there.

Figure 2. Drumming rate (grouse drumming/hour) by Wildlife Management Unit (WMU) aggregates from the Ruffed Grouse Drumming Survey, 2010. Only aggregates with >10 observations/records or >20 hours were included in the analysis. The statewide drumming rate for 2010 was 0.23 grouse drumming/hour. The St. Lawrence Valley, Tug Hill, and Northern Adirondacks aggregates had too few observations for analysis, and the Coastal Lowlands aggregate does not have a spring turkey hunting season, thus the drumming survey was not conducted there.