Field Methods

The NNF Bird Survey took place typically during the second weekend in June each year. Participants worked in teams, consisting of one or more group leaders who are experts in bird song identification. Other team members participated as timekeeper, navigator, audio recorder operator, or data recorder. Each team was assigned a group of approximately 6-10 sites for the morning surveys. Some sites were located along roads, while others required a short hike into the target habitat. The northern and southern halves of the NNF were surveyed every other year, which ended up being approximately 150 sites annually, though a total of 522 sites were surveyed across the 30-year span of this effort. Survey locations and road markers can be viewed in an online map viewer.

Bird data were collected using standardized 10-minute, unlimited-distance point count surveys (Knutson et al. 2008), in which a bird expert recorded all birds seen or heard from a stationary point during a 10-minute period regardless of how far away the bird was to the observer. Bird observers recorded birds during the surveys using a standardized bird point Census Form, which also includes noting the minute and distance a bird was detected and basic habitat and weather information. The census was designed to maximize compatibility with other bird census methods and to encourage documentation of all information obtained during the count.

Bird Survey Locations

Click on the map below to view the NNF Bird Survey survey locations and road markers. You may also download these geospatial coordinates as MS Excel spreadsheets (survey locations; road markers).

Bird Audio Recordings
For the last 8 years of the NNF Bird Survey, bird teams collected audio recordings of every point count survey conducted each year. These recordings can be used for future analyses of observer bias, for example. Take a listen to a few recordings that document the beautiful bird choruses that field teams enjoyed during point count surveys in June 2016.

Site 503, located in swamp conifer. You can hear a nice variety of bird species, including Golden-crowned Kinglet, Rose-breasted Grosbeak, Winter Wren, and Nashville Warbler, among many others. Listen to the clip.

Site 508, located in a hemlock-dominated forest stand. Take a listen for some of the NNF's most common species, such as Red-eyed Vireo, Black-throated Green Warbler, and Ovenbird. You may also hear Yellow-bellied Sapsucker, Blue Jay, and others. Listen to the clip.

Site 630, located in dry, upland shrubs. White-throated Sparrow, Nashville Warbler, Black-capped Chickadee, and Yellow-rumped Warbler sing quite loudly throughout the bird survey. Listen to the clip.