2009 Piping Plover Nest Count at Cape Lookout National Seashore Down Slightly, But Fledglings High
When it comes to piping plovers, a threatened species, the nesting habitat at Cape Lookout National Seashore is some of the best in North Carolina. That's evidenced by the fact that in 2009 the 37 nests counted at the seashore represented 70 percent of all piping plover nests in North Carolina. While the tally reflected a slight decline from 2008's record high of 46 nests, the number of chicks that fledged was a record high.
The Portsmouth Flats and the aptly named Plover Inlet/Ophelia Inlet area between mileposts 23 and 24 on the seashore proved the most popular for nesting plovers, with 12 and 11 nests, respectively, counted in those areas, the seashore's annual plover census noted. Overall, "24 of the nests hatched and 30 chicks were fledged from 17 different broods," the report said. "The average clutch size was 3.29 eggs and 83 of 145 eggs hatched."
While the fledgling success rate of 0.83 per nesting pair seems low, the report noted that that actually marked fourth-highest success rate recorded at the seashore, trailing only the 2004 (0.92), 2005 (0.85) and 2006 (0.88) nesting seasons. "Though the nesting pair count dipped this year, productivity was high. The actually number of chicks fledged, 30 fledglings, is the highest on record for Cape Lookout," it noted.
The drop in nesting pairs could be traced to low fledglings in 2007 and 2008, the report said. "The fledging success was only 0.24 (11 fledglings) in 2007 and 0.20 (9 fledglings) in 2008. The pair losses primarily occurred at Plover Inlet on the north end of SCB (South Care Banks) which lost 7 pairs from 2008. The area has revegetated since the scouring effects of Hurricanes Isabel (2003) and Ophelia (2005). It appears that the habitat can no longer support the density of pairs it did in 2007 and 2008," noted the document.
Additionally, nesting success last year was down.
"Only 53 percent of the nests and 57 percent of the eggs hatched successfully. The ten weather-related nest losses accounted for 48 percent of total losses," the report noted. "These weather losses were primarily related to strong winds in May that buried nests in sand or flooded nests. Predation took five (24 percent) nests, three were ghost crab predation and two were raccoon predation. One (5 percent) nest was abandoned. Five (23 percent) nest losses were recorded as unknown."
And yet, 2009 was a record year for the number of chicks that successfully fledged.
The majority of the fledglings were produced from North Core Banks at two sites, Portsmouth Flats and New Drum. Typically unproductive, Portsmouth Flats had a record year with the highest fledge success in the last 12 years. These chicks foraged primarily on open wet sand flats near pools of water. Weather may have played a role at this site and others this year. 2009 was a cool and wet nesting season. Not too wet to completely flood the flats, but wet enough to support abundant prey for the chicks. The relatively cool weather may also have reduced the heat stress level. The timing of weather events in the reproductive cycle is important and may have aligned just right for the chicks at Portsmouth Flats.
This same weather pattern negatively effected the growing nesting population at Old Drum Flats. Two nests were flooded out by the cool north winds that pushed soundside water against the banks. For much of the summer the soundside mudflats were flooded by north winds. This may explain the increased foraging use of the ocean intertidal zone at Plover Inlet in 2009, in addition to the marsh vegetation crowding.
Given the unpredictable weather patterns and piping plover breeding behavior monitoring and management should allow for these dynamic changes. Further study of the environmental/weather’s role in reproductive success is needed.
Despite the bird's threatened status, seashore officials noted that "(P)osted closures for bird nesting areas were not always respected by park visitors. In 2009 a record of violations was maintained by natural resource staff in order to enter these records into the case incident system. There were 53 records of pedestrians or footprints within bird closures and 20 records of vehicles or tracks within bird closures. These numbers are conservative since footprints and tire tracks disappear, before they are recorded, after moderate wind, tide changes, and or rain. Law enforcement rangers issued 1 citation for pedestrian in bird area and 6 citations for vehicles in bird areas."