Understanding all aspects of North American bird counts.
Whether we like to admit it or not, every upland hunter follows the bird counts of their favorite species in their favorite hunting areas. Pheasant hunters swarm to South Dakota when the numbers look good, and my home state of Minnesota gets pounded on years when the drumming counts are high.
We all look at these numbers, but do we really grasp what they mean? Do we consider how the numbers are acquired? Do we take into consideration that the numbers aren’t gathered during hunting season? Let’s explore some of these things, so we can all better understand bird counts.
How is the Data Acquired?
Every species is easier to find in different ways and in different areas. Prairie birds like to gather and dance, while pheasants and Hungarian partridge are most visible when they visit road edges during late summer. The ruffed grouse drums, and he drums a lot. Since each species does things a bit differently, the methods used to acquire data are a little different for each group.
Male ruffed grouse love to strut in the spring. After finding a good log, they pop up on it, puff out their chest and beat their wings so fast and with such vigor that their unique sound is a dead giveaway. Any uplander can spot the sound of a drumming grouse from a long ways off on a calm day.
Here in Minnesota, these drummers were first counted in 1949 and routes began to be documented. Over the next 30 years, more routes were added. By the early 1980s the current routes were set. Surveyors follow these exact routes, stopping to listen for drumming at certain spots along their routes. The amount of drumming heard at each stop is recorded, and all numbers are calculated after roughly five weeks of monitoring. That’s the short version of how ruffed grouse numbers are acquired.
Birds like the sharp-tailed grouse and greater prairie-chickens like to gather on dancing grounds (known as leks). Their dance can be observed and counted early in the morning with binoculars or from up close using a ground blind. However, with changes in habitat, leks can move from year-to-year, and some leks may not ever be found due to their remote locations.
In 1976 the lek survey methods were put into place, and data has been collected ever since. Volunteers and wildlife staff all participate in the surveys, recording how many males, females, and birds of undetermined sex are present at a lek during each visit.
Pheasants and Hungarian partridge are counted a little differently. These gallinaceous birds are notorious for hanging out on road edges, pecking at gravel early in the morning. Roadside counts are the norm for data collection.
In Minnesota, there are 172 routes that are each 25 miles long. Surveyors travel these routes once when conditions are predicted to be ideal. The numbers of birds as well as other common farmland wildlife are recorded.
When is the Data acquired?
Again, each species or group is a bit different. Since ruffed grouse and prairie birds are easiest to find during their mating season, counts are done in April and May. These surveys target adult birds, primarily males. The roadside counts are done between August 1 and August 15.
Possible Inaccuracies in Data collection
While the bird surveys are science-based, they are far from perfect science. When dealing with anything wild, there are far too many outside variables to set exact numbers. The slightest event can skew numbers one way or the other. Three key factors should be considered when thinking about surveys vs. sightings during hunting season.
If it’s cloudy, windy, or rainy during the entire survey time-frame, odds aren’t in the favor of the surveyor — they’re not going to observe or hear as many birds as they would on calm, sunny days. This goes for all species mentioned above, especially pheasants, as there’s only one day of surveying on each route.
Taking it a step further, since ruffed grouse and prairie grouse numbers are counted before nesting season, the numbers don’t reflect brood survival or adjust for weather events during nesting or post-hatch. Are those things taken into consideration? Yes, but survey data reflects conditions at the time of the survey, not future events.
Time of Year
Grouse hunters should keep this fact in mind: 4-1/2 to 5 months pass from the time the drumming counts are completed until opening day arrives. A lot can happen to a little bird in a big forest or open prairie in that time-frame. Bad nesting conditions, high predation, disease, severe weather events, poor food conditions and habitat loss can all play a factor in why drumming counts might be high but hunting success is low.
Pheasant and partridge hunters will see the roadside counts conducted in August, which is much closer to the season. However, there are still challenges with the time-frame of the survey. If a late hatch occurred, some birds may not be included in the count since young birds aren’t as visible and the roosters aren’t as distinguished in coloration.
Since the survey routes and stops are established and have changed very little since the surveys became concrete, there’s a significant chance that the habitat along the routes has changed drastically. Trees grow, crops cycle, the Conservation Reserve Program comes and goes, and human encroachment or sprawl is imminent. If the habitat along one of the routes is non-existent, it’s not skipped over as the data still needs to be collected.
It’s important to remember that the surveys are designed to capture the changes in habitat that occur through time. If the forest is cleared in one area, it is maturing in another area, and the routes are still representative of what is going on at a larger scale. The routes do get changed, however, when the habitat is not likely to come back or if conditions prevent a good survey, such as when the land is developed or traffic is so heavy that the birds can no longer be heard.
Possible Changes to the Surveys
In speaking with several people involved in these counts and surveys, one word rang true over-and-over: trends. Could the routes change with the habitat to show higher numbers? Most definitely. But as Charlotte Roy, Grouse Biologist from the Minnesota Department of Natural Resources explained, “If we change the way we collect data, it would be like starting from scratch. To be comparable, the methods have to be similar. Right now we have years and years of data, and we can compare years to figure out trends at a large scale over time.”
When I asked her if there were any considerations for different or alternative methods for collecting data being discussed, she again pointed out the importance of trends. “The primary new thing that’s been discussed is the new survey to collect data for spruce grouse population trends, which has never been done in Minnesota. It took four years to figure out a good way to collect the data. But now that we have it in place, we’ll do it similarly each year so that we can look at changes through time.”
When I posed this question to Nicole Davros, the Farmland Wildlife Research Supervisor for the Minnesota DNR, she stated, “There are some nuances to the roadside indices every year that can also require some interpretation. They have to do with understanding how weather (in winter, spring, and summer) might be affecting survival (over-winter hen survival, nest success, brood survival) and thus the numbers we get each year.
“For example, if our data shows that hen and brood indices are down from a previous year but the rooster index is up, then we start to think about whether it is a true decline in some numbers or if a late hatch due to spring weather can explain it.”
The Bottom Line
There are dozens, if not hundreds of volunteers, conservation groups, state workers, and birding enthusiasts who pour their time and efforts into collecting this data — not to figure out how many birds should be in the woods come hunting season, but rather to have a database to look back at which reflects trends in rough bird numbers based on things like weather, habitat changes, hunter participation, and so forth. These numbers aren’t a forecast for hunters. I know that some of us uplanders like to think that the bird world revolves around our dog’s noses, but I assure you, it does not.
The numbers shown in the surveys released every year are estimates, are in no way 100 percent accurate, and are not designed to show precise statistics. Too many hunters live and die by the bird counts, but the DNR warns that the numbers “should be interpreted cautiously.”
The bottom line is this: if you enjoy bird hunting, by all means do it. Don’t look at the drumming counts before deciding whether or not you’re going to buy a license. Look at yourself and decide if you enjoy a leisurely walk in the woods with a buddy, a family member or a furry friend. Ask yourself if you love the smell of a wet aspen forest floor, or running your fingers through thigh-prairie grass as the sun is burning the last bit of color from the sky.
I promise that you won’t find my bird dog sitting on the couch reading bird surveys. And the longer I hunt, the more I realize that I have a lot to learn from my bird dog.
Last modified: December 2, 2018