Geology topics

Sara H. Schweitzer

Publications and source records attributed to Sara H. Schweitzer.

6 recordsLinked to original sources

USGS2015

Repeated count surveys help standardize multi-agency estimates of American Oystercatcher ( Haematopus palliatus ) abundance

The extensive breeding range of many shorebird species can make integration of survey data problematic at regional spatial scales. We evaluated the effectiveness of standardized repeated count surveys coordinated across 8 agencies to estimate the abundance of American Oystercatcher ( Haematopus palliatus ) breeding pairs in the southeastern United States. Breeding season surveys were conducted across coastal North Carolina (90 plots) and the Eastern Shore of Virginia (3 plots). Plots were visited on 1–5 occasions during April–June 2013. N -mixture models were used to estimate abundance and detection probability in relation to survey date, tide stage, plot size, and plot location (coastal bay vs. barrier island). The estimated abundance of oystercatchers in the surveyed area was 1,048 individuals (95% credible interval: 851–1,408) and 470 pairs (384–637), substantially higher than estimates that did not account for detection probability (maximum counts of 674 individuals and 316 pairs). Detection probability was influenced by a quadratic function of survey date, and increased from mid-April (~0.60) to mid-May (~0.80), then remained relatively constant through June. Detection probability was also higher during high tide than during low, rising, or falling tides. Abundance estimates from N -mixture models were validated at 13 plots by exhaustive productivity studies (2–5 surveys wk −1 ). Intensive productivity studies identified 78 breeding pairs across 13 productivity plots while the N -mixture model abundance estimate was 74 pairs (62–119) using only 1–5 replicated surveys season −1 . Our results indicate that standardized replicated count surveys coordinated across multiple agencies and conducted during a relatively short time window (closure assumption) provide tremendous potential to meet both agency-level (e.g., state) and regional-level (e.g., flyway) objectives in large-scale shorebird monitoring programs.

North Carolina, Virginia↗

USGS2008

Effects of human activity of breeding American Oystercatchers, Cumberland Island National Seashore, Georgia, USA

Abstract.-Increased human use of coastal areas threatens the United States population of American Oystercatchers (Haematopus palliatus), a species of special concern. Biologists often attribute its low numbers and reproductive success to human disturbance, but the mechanism by which human presence reduces reproductive success is not well understood. During the 2003 and 2004 breeding seasons, 32 nesting attempts of American Oystercatchers were studied on Cumberland Island National Seashore (CINS). Behavior was examined with and without human activity in the area to determine how human activity affected behavior. The oystercatchers' behavioral responses (proportion time) were analyzed with and without human or intraspecific disturbances using mixed models regression analysis. Proportions of time human activities were present (< 300 m from oystercatchers) during observations averaged 0.14 (N = 32, 95% CI = 0.08-0.20). During incubation, pedestrian activity near (< 137 m) oystercatchers reduced the frequency of occurrence of reproductive behavior, but pedestrian activity far (138-300 m) from oystercatchers had no effect. Vehicular and boat activities (< 300 m) had minimal effects on behavior during incubation. During brood rearing, an effect of pedestrian activity near oystercatchers was not evident; however, pedestrian activity far from oystercatchers increased the frequency of reproductive behavior. Vehicular and boat activity had no effects on behavior during brood rearing. Of 32 nesting attempts, two failed (<10%) because of human disturbance and were located in areas of greater human activity (south end). Managers on CINS should minimize pedestrian activity near nests (< 137 m) during incubation. During brood rearing, protection from pedestrian activity should be increased, when possible, to >137 m and vehicular activity should be minimized at current levels or less.

Waterbirds↗

USGS2006

Nest fate and productivity of American Oystercatchers, Cumberland Island National Seashore, Georgia

The American Oystercatcher (Haematopus palliatus) is listed as a species of high priority by the U.S. Shorebird Conservation Plan and is state-listed as rare in Georgia; however, biologists have not focused on identifying the causes of egg and hatchling losses. In 2003 and 2004, continuous video monitoring was used to document reproductive success of American Oystercatchers and identify causes of nest failure at Cumberland Island National Seashore, Georgia. The modified Mayfield method and program CONTRAST were used to determine and compare survival of eggs and nestlings. Eleven pairs made 32 nest attempts during two seasons. Nine attempts were successful, fledging 15 chicks. Daily survival of clutches was 0.973 (95% CI = 0.960-0.987) for 2003, 0.985 (95% CI = 0.974-0.995) for 2004, and 0.979 (95% CI = 0.970-0.987) for combined years. Daily survival was greater on the North End, than on the South End of the island (X21 = 7.211, P = 0.007). Eighteen of 20 nest failures during the egg stage and one of eight chick losses were documented. Egg predators included raccoon (Procyon lotor, N = 9), bobcat (Lynx rufus, N = 3), and American Crow (Corvus brachyrhynchos, N = 1). A ghost crab (Ocypode quadata) preyed on one chick. Other causes of nest failure were tidal overwash (N = 1), horse trampling (N = 1), abandonment (N = 2), and human destruction (N = 1). The North End of the island has one of the highest reproductive rates reported along the Atlantic coast. Predator control may be an effective means of increasing reproductive success on the South End of the island.

Waterbirds↗

USGS2005

A simple, inexpensive video camera setup for the study of avian nest activity

Time-lapse video photography has become a valuable tool for collecting data on avian nest activity and depredation; however, commercially available systems are expensive (>USA $4000/unit). We designed an inexpensive system to identify causes of nest failure of American Oystercatchers ( Haematopus palliatus ) and assessed its utility at Cumberland Island National Seashore, Georgia. We successfully identified raccoon ( Procyon lotor ), bobcat ( Lynx rufus ), American Crow ( Corvus brachyrhynchos ), and ghost crab ( Ocypode quadrata ) predation on oystercatcher nests. Other detected causes of nest failure included tidal overwash, horse trampling, abandonment, and human destruction. System failure rates were comparable with commercially available units. Our system's efficacy and low cost (<$800) provided useful data for the management and conservation of the American Oystercatcher.

Georgia↗

USGS2005

Evaluation of the landscape surrounding northern bobwhite nest sites: A multiscale analysis

Implementation of the Conservation Reserve Program (CRP) altered the interspersion and abundance of patches of different land-cover types in landscapes of the southeastern United States. Because northern bobwhites ( Colinus virginianus ) are experiencing significant population declines throughout most of their range, including the Southeast, it is critical to understand the impacts of landscape-scale changes in habitat on their reproductive rates. Our objective was to identify components of landscape structure important in predicting nest site selection by bobwhites at different spatial scales in the Upper Coastal Plain of Georgia. We used a Geographic Information System (GIS) and spatial analysis software to calculate metrics of landscape structure near bobwhite nest sites. Logistic regression was used to model the relationship of nest sites to structure within the surrounding landscape at 4 spatial scales. We found that patch density and open-canopy planted pine were consistently important predictor variables at multiple scales, and other variables were important at various scales. The density of different patch types could be increased by thinning rows of pines in large monotypic stands of closed-canopy planted pine stands. Thinning and creating openings in CRP pine plantations should provide increased nesting opportunities for bobwhites. We interpret the support for other variables in our analysis as an indication that various patch configuration lead to different combinations of landscape structure that provide an acceptable range of habitat conditions for bobwhites.

Journal of Wildlife Management↗

USGS1999

Nesting habitat of least terns (Sterna antillarum athalassos) on an inland alkaline flat

We measured habitat characteristics in colony sites and at nest sites of endangered least terns ( Sterna antillarum athalassos ) on an expansive alkaline flat at Salt Plains National Wildlife Refuge, Oklahoma, in 1992 and 1993. Least terns nested in 12 colony sites on the alkaline flat during 1992 and 1993. Number of nests per colony site ranged from 5–25 and density of nests ranged from 0.1–0.75 nests/ha. Density of least terns in colony sites ranged from 0–2.1 terns/ha and was not correlated with soil color (P = 0.66) or soil texture (P = 0.12). Only a small percentage of ground cover was provided by vegetation (0.0–1.2%), driftwood (0.0–0.4%) and debris (0.0–1.1%) in colony sites. Least terns selected nest sites with coarser soil (loamy sand to sandy loam) than that of random points (P ≤ 0.0003). The coarser soils were lighter in color (P = 0.0001). Least tern nests were closer to driftwood or debris than random points (P = 0.0001). Internest distances in active colony sites ranged from 21.4 to >100 m. Nearest-neighbor analyses indicated that nests were distributed randomly in 58% and uniformly in 42% of active colony sites. Nests were distributed uniformly in small active colony sites and randomly in large active colony sites. No differences in densities of nests were noted relative to size of colony sites. Increasing availability of coarse light-colored soils in areas of ≥20 ha on alkaline flats may enhance recovery of least terns by improving nesting habitat and recruitment.

Oklahoma↗