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One of the easiest ways to monitor species decline is to do surveys. The largest survey of birds in the United States and Canada is the Breeding Bird Survey. Every five years in the state of New York a Breeding Bird Atlas is published using data from these surveys. The current point count surveys are conducted in June from about 30 min before dawn and continue for 4-5 hours into mid-morning (United States Geological Survey, 1998). These techniques are somewhat biased toward the detection of diurnal bird species and may not collect accurate data on the abundance of crepuscular and nocturnal species such as owls and nightjars. This paper includes a survey of calls of two crepuscular species of nightjar (Caprimulgiformes): the Eastern Whip-poor-will (Antrostomus vociferus) and the Common Nighthawk (Chordeiles minor). Both are severely declining bird species in the state of New York and Species of Special Concern in many areas of North America. Estimates suggest that whip-poor-will populations in North America have declined 69% and nighthawk populations have declined 58% in the last 50 years (Rosenburg et al., 2016). Calling is important for these birds because they call to find mates, for communication, and sometimes when feeding (Brigham et al., 2011, Cink et al., 2017). Two graduate students at Western Michigan University, Amy Janik and Joanna Sblendorio, under the direction of Dr. Sharon Gill, collected audio recordings at 16 locations on military base Fort Drum, New York in May and June of 2017. I used these recordings to conduct my study. First, I randomly selected days and times of recordings to determine the time of day when both species were more likely to be detected. Then I reviewed recordings from three days (May 16, May 26, and June 11) around the time the Breeding Bird Surveys begin. I detected whip-poor-wills between 04:00-5:00 (Eastern Standard Time) at 12 out of the 16 locations over the three day survey. I also detected nighthawks at all but five of the locations. Both species were more likely to be detected in mid-to-late May, suggesting that this time might be better to survey for whip-poor-wills and nighthawks than in June, when detection of nightjars was lower. I suggest that autonomous recorders may be helpful for surveying nocturnal and crepuscular bird species, which may be missed entirely or miscounted by traditional day-time surveys.
Brooks, Sydney, "An acoustic survey of Fort Drum, New York, for severely declining nocturnal birds" (2018). Honors Theses. 3031.