Fall Migration and Vehicle Disturbance of Shorebirds at South Core Banks, North Carolina.

• Main Author: Tarr, Nathan Moloney
• Other Authors: Kenneth H. Pollock, Committee Member, Jaime A. Collazo, Committee Member, Theodore R. Simons, Committee Chair
• Language: unknown
• Published: 2008
• Subjects: habitat use; ORV; OHV; migration; stopover; shorebirds; disturbance; BACI; Barrier Island; Swash; Arenaria interpres; Calidris alba; Calidris canutus
• Online Access: http://www.lib.ncsu.edu/resolver/1840.16/983

Anthropogenic disturbance has been implicated as a factor related to declines in shorebird populations because they depend upon coastal stopover sites, where human recreation is concentrated, for resting and refueling between long, energetically-expensive migration flights. We examined the use of South Core Banks, a barrier island on North Carolina’s Outer Banks, by migrating shorebirds and recreationists during fall and measured the effects of vehicle disturbance on shorebird behavior and habitat use. To describe spatial, temporal, and tidal patterns in shorebird and vehicle abundance, we performed weekly surveys of birds and vehicles from all-terrain vehicles, recording the species, numbers, and microhabitat locations (i.e. surf, swash zone, dry sand, and wet sand) of all individuals within half-mile ocean beach segments. We summarized survey data by week, tide, beach section, and daylight hour in order to identify patterns in abundance. Shorebird densities on South Core Banks were similar to those reported for other sites on the Outer Banks, and their numbers decreased slightly throughout the season, but peaked several times. Gull and vehicle numbers increased throughout the fall while tern numbers decreased. As a group, shorebirds were more or less evenly distributed along the southeast facing beach, but individual shorebird species showed unique spatial patterns in abundance. Several species, including Sanderlings (Calidris alba), Black-bellied Plovers (Pluvialis squatarola), Semipalmated Plovers (Charadrius semipalmatus), Red Knots (Calidris canutus), and Ruddy Turnstones (Arenaria interpres), were more abundant on the ocean beach during high tide than during low tide. They used a sand spit and a portion of the ocean beach on the southern half of the island as roosting sites at high tide. Shorebirds were abundant in areas where vehicle abundance was also relatively high, but their distribution among microhabitats was opposite that of vehicles; vehicles were primarily located on dry sand while shorebirds ...