We determined the distribution of staging red knots along the Virginia barrier islands using a series of low-altitude aerial surveys from the last week of April through the first week of June 2006–2009. Each survey began on Assateague Island (Virginia/Maryland border) and followed the outer beaches south to Fisherman Island. The surveys included all active beach zones of the outer barrier system (approx. 141 km of open beach). We flew 6 survey flights each year beginning the last week of April and ending the first week of June. We conducted flights on a falling tide initiated around half stage. The decision to conduct surveys around low tide reflects our interest in the impact of peregrines on the distribution of foraging rather than roosting knots.

We conducted all surveys from a Cessna 172 (Cessna, Wichita, KS), high-wing aircraft flying 25–30 m above the ground at an air speed of approximately 140 km/hr. We used low altitude flights to temporarily flush birds to ease identification and numerical estimation. We believe that disturbance was minimal as flocks flushed circled and resettled in seconds. We flew a line on the outer edge of the surf zone to encourage birds to flush inland. Surveys were a collaborative effort between 2 observers (the same 2 observers conducted all surveys). The first observer identified bird species and estimated flock sizes while the second observer mapped flocks on aerial photographs. We mapped each flock and gave each a unique code to cross-reference with survey data. We recorded all survey data in digital audio files and later transcribed them to data sheets. Work with red knots was observational only and no Institutional Animal Care permit was required.

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