James D. Fraser

Prenesting use of intertidal habitats by piping plovers on South Monomoy Island, Massachusetts

JAMES D. FRASER,1 Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0321, USA SHANNON E. KEANE,2 Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0321, USA P. A. BUCKLEY, USGS Patuxent Wildlife Research Center, Box 8, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA

Nonbreeding bald eagle communal and solitary roosting behavior and roost habitat on the northern Chesapeake Bay

We studied roosting behavior and habitat use of nonbreeding bald eagles (Haliaeetus leucocephalus) on the northern Chesapeake Bay during 1986-89. In summer and winter, 11 and 13 communal roosts, respectively, and many solitary roosts were used simultaneously in the 3,426-km 2 study area. Radio-tagged eagles roosted solitarily with differing frequency by season (60, 21, 39, and 44% of 81 eagle nights in summer, fall, winter, and spring, respectively) (P<0.05). Roost trees, predominantly oaks (Quercus spp.) or yellow poplars (Liriodendron tulipifera) were larger in diameter and provided greater canopy cover than random trees (P<0.05). Roost sites had snags present more often than did random sites (P<0.01)

Substrate and Vegetation Selection by Nesting Piping Plovers

Abstract We studied substrate composition and vegetation cover at Piping Plover (Charadrius melodus) nests and paired random plots on New York beaches that had been widened by renourishment (deposition of dredged sand). Most nests (59.4%, n = 32) were in unvegetated plots, mean ± SE vegetative cover around nests was 7.5 ± 1.7%, and all plovers nested in <47% cover. Most nests (59.4%) were on pure sand and mean coarse grain cover (pebble and cobble-sized objects) on nest plots was 9.1 ± 2.6%. Nest plots were more likely to be vegetated than paired random plots. Coarse substrate also was of high relative importance in distinguishing nests and random plots. Beach management projects can reduce sparse vegetation and coarse substrate, which may affect Piping Plover nest site selection.

Residence Probability and Population Size of Red Knots During Spring Stopover in the Mid-Atlantic Region of the United States

Abstract Weekly counts of western Atlantic red knots (Calidris canutus rufa) at their Delaware Bay migration stopover site have suggested a major decline since the 1980s. We estimated red knot spring passage population size in the New Jersey Coast–Delaware Bay region (DENJ; 2004 and 2006) and Virginia (VA; 2006 and 2007), USA, by correcting weekly aerial counts for mean daily residence probability between counts in a Monte-Carlo simulation. We used daily telemetry relocations in mark–resight models to estimate mean daily residence probability. Average daily residence probability was approximately 1.0 in mid-May, 0.96–0.97 in the week of 22 May, and 0.64–0.77 after May 28 in DENJ in 2004 and 2006 and in VA in 2006. Average daily residency was approximately 0.88 in VA in 2007 from 22 May to 5 June. No birds moved from VA to DENJ in 2006 and only 2 birds (5.5%) moved in 2007. Stopover population sizes (±SE) in DENJ were 17,108 ± 1,322 in 2004 and 19,555 ± 831 in 2006, and in VA were 7,224 ± 389 in 2006 and 8,332 ± 718 in 2007, significantly greater than peak aerial counts. Years with similar peak counts had different residence probabilities; hence, adjustments for turnover should be used in the future to assess annual population changes. Our results suggest that VA can support a significant portion of this red knot subspecies during migration in at least some years. Managing red knots for recovery should entail improving our understanding of the use of other Atlantic Coast sites and protecting key coastal habitat from disturbance and development.

Differences in distribution of bleeding, nonbreeding, and migrant Bald Eagles on the Northern Chesapeake Bay

We compared the distributions of resident breeding, resident nonbreeding, and northern and southern migrant Bald Eagles (Haliaeetus leucocephalus) on the northern Chesapeake Bay from 1984-1988. Breeding eagles were dispersed throughout most of the study area and were resident all year. Dispersion of Chesapeake nonbreeding eagles was similar to the dispersion of breeding birds on the northern Chesapeake in summer and winter. Chesapeake nonbreeding eagles moved throughout most of the bay, 5 5% of radiotagged eagles were off the bay during any month. Radio-tagged northern migrants arrived in late fall (x = 21 December, n = 7, range = 61 days) and departed in early spring (. = 27 March, n = 14, range = 43 days). In contrast to local eagles, northern migrants were concentrated almost exclusively on Aberdeen Proving Ground, Maryland. Radio-tagged southern migrants arrived throughout April-August (x = 6 June, n = 11, range = 94 days) and departed from June-October (9 = 3 September, n = 22, range = 119 days). Southern migrants were more dispersed than the northern migrants but less dispersed than the resident eagles. Northern Chesapeake eagle abundance peaked twice annually; in winter (e.g., 261 eagles, December 1987), due to the presence of northern eagles, and in summer (e.g., 604 eagles, August 1988), due to the presence of southern birds.

Hematocrit and protein concentration of Black Vulture and Turkey Vulture blood

Blood protein concentration and hematocrit (packed cell volume) values are easily obtained and can be useful in determining the health of trapped or captive birds (Hunter and Powers 1980, Duke and Redig 1984). However, if these parameters are to be useful, there must be baseline data for comparison. Bond and Gilbert (1958), Hunter and Powers (1980), and Gessaman et al. (1986) have provided data for a variety of raptors, yet information on vultures is lacking. Our purpose is to provide baseline data on the blood characteristics of the Black Vulture (Coragyps atratus) and the Turkey Vulture (Cathartes aura).

Effect of Great-Horned Owl Trapping on Chick Survival in Piping Plovers

ABSTRACT We studied the effect of great-horned owl (Bubo virginianus) removal on piping plover (Charadrius melodus) hatchling survival on Missouri River sandbars (2008–2009). Owl removal increased daily survival of piping plover chicks in 2008 (&bgr; = 2.03, 95% CI: 0.04–4.02), but this effect decreased with increasing age of the chick (&bgr; = -0.42, 95% CI: -0.81 to -0.03). Results for 2009 were similar in direction but not significant. Survival was higher in 2008 than in 2009, regardless of owl capture, indicating that even if owl capture consistently were effective at increasing survival, overall survival resulting from trapping may vary annually. Owl trapping was a successful means to raise chick survival on the Missouri River in ≥1 year and could be used at other sites experiencing depressed chick survival due to avian predators.

Winter Ecology of Piping Plovers at Oregon Inlet, North Carolina

Abstract Humans may modify winter habitat of the imperiled Piping Plover (Charadrius melodus), yet published accounts of the species’ winter ecology are rare. We studied Piping Plovers at Oregon Inlet, North Carolina from December 2005 to March 2006. Plovers used a 20.1 km2 area (100% minimum convex polygon home range) containing narrow barrier islands with ocean and sound-side beaches, and small shoals, dredged-material islands, and marsh islands in shallow-water sounds. Plover activity was concentrated in twelve areas totaling 2.2 km2 (95% fixed kernel home range). When plovers were on ocean beaches, they spent less time foraging (18%) than when on Sound Island beaches (88%) and islands (83%, P = 0.003). Sound island use increased and beach use decreased as the tide dropped (Logistic regression, P < 0.001). Plover use of dredged-material islands implied that habitat managers can create or restore attractive foraging sites where habitat may be declining or limiting. Wintering habitat management should aim to provide foraging opportunities during most of the day and across a range of tide conditions and ensure that foraging habitat is close to roost sites.

The effect of benthic prey abundance and size on red knot (Calidris canutus) distribution at an alternative migratory stopover site on the US Atlantic Coast

A population decline of the western Atlantic red knot (Calidris canutus rufa) has been linked to food limitation during the spring migratory stopover in Delaware Bay, USA. The stopover ecology at potential alternative sites has received little attention. We studied factors affecting red knot habitat selection and flock size at a coastal stopover site in Virginia in 2006–2007. The most common potential prey items were coquina clams (Donax variabilis) and crustaceans. Red knot foraging sites had more clams and crustaceans than unused sites in 2006. Prey abundance increased during the 2007 stopover period and remained high after the red knot peak. Red knot flock size in 2007 increased with mean clam shell length, and probability of flock presence decreased with increasing distance from night use locations. Our results suggest that red knots preferred coquina clams and that these clams were not depleted during the stopover period in 2007. Thus prey abundance did not appear to be a population-limiting factor at this coastal stopover site in Virginia in that year. Protection of coastal sites outside of Delaware Bay, many of which have been altered by human development, would likely benefit red knot population recovery, as they can apparently provide abundant food resources during at least some years.

Piping Plover Foraging-Site Selection on the Missouri River

Abstract Selection of a foraging site entails costs and benefits which are reflected in survival and reproductive success. We studied Piping Plover (Charadrius melodus) foraging-site selection during the breeding season (2001-2003) on the Missouri River and examined the relationship between site selection and invertebrate abundance indices within habitats. Foraging adult plovers selected protected shoreline (inter-sandbar channels, inlets, and backwater areas) more often than expected based on availability (use: 92% ± 3%; availability: 58% ± 5%). Invertebrate biomass and numbers along exposed shoreline did not differ among reaches. Along the protected shoreline, invertebrate biomass and numbers were higher below a dam with an epilimnetic release and a relatively constant release rate (epilimnetic reach) than at the other two reaches. On the epilimnetic river reach, invertebrate biomass and numbers were higher along the protected shoreline than on the main channel shoreline. On a reach below a dam with a hypolimnetic release and diel flow pulse (hypolimnetic reach) and a cold water reservoir, invertebrate indices were similar on the protected and exposed shoreline. Invertebrate numbers were higher in saturated and moist habitats than in vegetated and dry habitats (P < 0.05). At the epilimnetic and hypolimnetic reaches, foraging Piping Plover chicks used saturated and moist habitats more than vegetated and dry habitats, based on availability. On the Missouri River, protected shorelines were important foraging sites for Piping Plovers during the breeding season, and sandbars with low-lying moist habitat were important to foraging chicks. Piping Plovers will benefit from increased availability of these habitats on managed or created sandbars on the Missouri River.