Effects of human activity on American Oystercatchers breeding at Cape Lookout National Seashore, North Carolina

Background/Question/Methods

As human populations and associated development increase, human-wildlife conflicts are occurring with greater frequency.  Anthropogenic noise is an often overlooked and poorly understood source of potential wildlife disturbance.  In this study, we seek to assess the effects of human noise on American Oystercatchers (Haematopus palliatus) nesting at Cape Lookout National Seashore.  The species is listed as a “Species of High Concern” by the U.S. Shorebird Conservation Plan and a “Special Concern” species by the State of North Carolina.  Human activities at Cape Lookout include military jet overflights, vehicles, and park visitors.  Our study is focused on the effects of various forms of anthropogenic activity on the behavior, physiology, reproductive success, and survival of American Oystercatchers at Cape Lookout.  We employ a variety of technologies including; audio recorders to monitor sound levels, video cameras to monitor oystercatcher behavior and beach activity, and microphones to monitor heart rates of incubating birds.  We are quantifying the incubating behavior, nest attendance, and heart rate of the incubating birds to assess the relative effects of human activity.  We are also comparing measures of productivity, such as nest survival, chick survival, and chicks fledged per pair, to assess the effects on reproductive success. 

Results/Conclusions

Nest survival for 58 nests was 0.259.  Chick survival and chicks fledged per pair were 0.467 and 0.451, respectively.  Preliminary results show a daily average of 26 anthropogenic activity events occurring near nests.  These initial results show a minimal behavioral response to aircraft.  Oystercatchers were on the nest 83% of the time both during military jet flyovers as well as 20 minutes before the flights.  The average sound exposure level during flights (79.70 dbA) is higher than before the flights (62.49 dbA).  The average military jet overflight lasts 74.41 seconds.  There is a potential behavioral response to vehicles: 28.7% of the time a vehicle drives by, the incubating bird is on the nest, as compared to 94.1% of the time 20 minutes before a vehicle drives by.  Average daily nest attendance was 92% (range: 73%-99%).  Preliminary results from heart rate monitoring show a small, but insignificant, physiological response to human activity (192 beats/min vs. 186 beats/min, p=0.7324).