Each summer, ODFW biologists across the state enter the field to conduct upland game bird production inventories. These inventories are typically conducted the last half of July or the first half of August. The timing varies with wildlife district and area of the state. Many of the routes surveyed by the biologists are the exact same routes surveyed for many years. Biologists record the species observed, the gender of birds observed (if possible), number of chicks observed, and number of chicks in complete broods.
These survey techniques detect an unknown proportion of the population; consequently the numbers cannot be used to provide an estimate of the total population. However, the data collected can be used to generate population trends, especially over many years, and likely detect large changes in the population from year to year. The greater the increase of birds for a given year, the more likely the biologists will count more birds. Except for some of the forest species which are difficult to observe, such as ruffed grouse and mountain quail, these surveys indicate the relative size of the fall population. During 2005, there was a sharp and detectable increase in the number of birds on the routes. Predictably, hunters during the fall of 2005 encountered some of best upland game bird populations in many years.
For species such as sage-grouse and Columbian sharp-tailed grouse, which gather on dancing grounds (called “leks”), the dancing ground counts are also used to determine the trend in the population. Biologists also examine the wings (and sometimes tails) to learn more about certain upland game bird species - particularly those species, such as blue grouse, ruffed grouse, and mountain quail which are difficult to detect on survey routes.
More about how biologists use hunter returned wings (pdfs)
Biologist estimate abundance by the number of birds they see, on average, for every 10 miles of route that is surveyed. Thus, “#/10 MI” equals the average number of birds observed per 10 miles of survey route. Production is estimated by the number of chicks observed per hen or per adult (if the sexes can’t be distinguished). Thus, “CH/hen or CH/AD” equals the average number of chicks observed per hen or adult. The abundance index and production index is plotted on the following charts for 5 of Oregon’s most popular upland game birds species.