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Gull-billed Terns (Gelochelidon nilotica) have historically demonstrated variability in nest-site selection and reproductive success throughout their breeding range. However, few studies have investigated the breeding parameters of Gull-billed Tern populations on barrier islands in the northern Gulf of Mexico, USA. The main objective of this study was to investigate annual variability of breeding population size, hatching success, and causes of nest failure during eight breeding seasons (2009–2016). Annual variation was observed in colony sizes (Range = 1–68 nests), colony locations (among five islands), and hatching success (0–93%). Mean hatching success was 56% and flooding was the main cause of failure, accounting for 64% of all failed nests. Additionally, nest site habitat characteristics were compared between successful and unsuccessful Gull-billed Tern nests. Nest substrate composition differed between successful and failed nests, and successful nests were also associated with higher eleva...

Coastal ecosystems are under increasing pressure from human activity, introduced species, sea level rise, and storm activity. Hurricanes are a powerful destructive force, but can also renew coastal habitats. In 2003, Hurricane Isabel altered the barrier islands of North Carolina, flattening dunes and creating sand flats. American Oystercatchers (Haematopus palliatus) are large shorebirds that inhabit the coastal zone throughout the year. Alternative survival models were evaluated for 699 American Oystercatcher nests on North Core Banks and South Core Banks, North Carolina, USA, from 1999–2007. Nest survival on North Core Banks increased from 0.170 (SE = 0.002) to 0.772 (SE = 0.090) after the hurricane, with a carry-over effect lasting 2 years. A simple year effects model described nest survival on South Core Banks. Habitat had no effect on survival except when the overall rate of nest survival was at intermediate levels (0.300–0.600), when nests on open flats survived at a higher rate (0.600; SE...

The Isles Dernieres Barrier Island Refuge in Louisiana, USA, constitutes a major colonial waterbird breeding site, and several restoration projects have been undertaken to sustain waterbird populations on the refuge. However, very little is known about food resources that colonial waterbirds depend on in the Gulf of Mexico. Royal (Thalasseus maximus) and Sandwich (T. sandvicensis) tern diet composition was investigated to determine important food resources during the breeding period. Regurgitated prey items in the 2013 and 2014 breeding seasons were used to compare diet composition, prey item frequency, and prey item mass among four groups: Royal Tern adults, Royal Tern chicks, Sandwich Tern adults, and Sandwich Tern chicks. The two most frequent prey items were Atlantic croaker (Micropogonias undulatus) and bay anchovy (Anchoa mitchilli). Royal Tern adults consumed significantly more Sciaenids than any other tern group, and Sandwich Tern adults consumed more Engraulids than any other tern group...

The availability of suitable breeding habitats is an important factor in explaining seabird demographic fluctuations. For ground nesting seabirds, such as Little Terns (Sternula albifrons), an essential characteristic in determining suitability of breeding habitats is vegetative cover. This study evaluated whether the long-term fluctuations (1979–2014) in Little Tern breeding numbers on sandy beach colonies of Ria Formosa, Algarve, Portugal, could be explained by changes in vegetation cover at each sandy beach colony, environmental variability (measured by the climatic North Atlantic Oscillation index), or a combination of both. The percentage of vegetation cover for each sandy beach was calculated from aerial photos of Ria Formosa barrier islands from 1976 to 2012, and related to breeding census data from the same period. The climatic variation measured by the North Atlantic Oscillation index did not show a significant relationship with the number of breeding pairs nesting on each sandy beach c...

Predicted sea-level rise and increases in the frequency and magnitude of storm surges are potential threats to waterbird nests and associated breeding habitat on low-lying landforms, such as barrier islands. Sea-level rise in Northumberland Strait of eastern Canada, predicted to rise by at least 0.50–0.60 m by 2100, could permanently flood large tracts of barrier island habitat. Potential impacts of higher sea levels on breeding habitat of Red-breasted Mergansers (Mergus serrator) were studied on three barrier islands at Kouchibouguac National Park, New Brunswick, Canada. Objectives of the study were to: 1) identify the range of dates for which nests (n = 189) were active and thus vulnerable to flooding; 2) determine elevation and distance to water for each nest; 3) examine whether birds selected nest sites that were relatively elevated and far from water; and 4) estimate the proportion of nests that could be flooded under four plausible sea-level rise and storm surge scenarios. Peak nesting occ...

Barrier islands in Louisiana and elsewhere in the northern Gulf of Mexico region provide valuable breeding habitat for numerous waterbird species; however, these islands are also deteriorating at an alarming rate. Management and conservation of waterbird species in these dynamic environments require a better understanding of the breeding biology for northern Gulf of Mexico populations. Productivity parameters were investigated for Royal (Thalasseus maximus) and Sandwich (T. sandvicensis) terns at the Isles Dernieres Barrier Island Refuge in Terrebonne Parish, Louisiana, during the 2009 and 2010 breeding seasons. Mean hatching success for Royal Tern was 77% (n = 169 nests), while Sandwich Tern hatching success was 75% (n = 130 nests). For both Royal and Sandwich terns, the estimated probability that a chick survived from hatching to fledging age was 55% (n = 630 nestlings). Overall, estimated breeding success for Royal and Sandwich terns was 42.3% and 41%, respectively. Chick growth rates were si...

North America's northernmost, sizable colony of Caspian Terns (Hydroprogne caspia) is located on the Copper River Delta of south-central Alaska, USA. The colony was monitored in June during 2008-2016 and in July during 2009-2013. This 9-year period coincided with reduction of Caspian Tern nesting habitat at East Sand Island in the Columbia River estuary, Oregon, USA, one of the world's largest Caspian Tern breeding colonies. The number of active nests on the Copper River Delta more than doubled during the early study period from 209 in 2008 to 423 in 2013. However, there was a steady decline in the number of nests during 2014 (281) to 2015 (115) and the colony failed in 2016. These declines were likely due to warm sea surface temperature anomalies across the northeastern Pacific Ocean in those years. Based on resightings of banded individuals, colony connectivity was documented between the Copper River Delta and other colonies, ranging from southeast Alaska (215 km) to central California, USA (> 3,000 km). The East Sand Island colony was the most important source of immigrants to the Copper River Delta. While the Copper River Delta now serves as important natural breeding habitat for Caspian Terns, increased flooding and severe storms associated with climate change will likely limit colony size and productivity in the long-term.

Barrier islands provide numerous ecosystem functions and services, including critical breeding habitat for many waterbird species. Louisiana's barrier islands are experiencing rapid land loss and habitat degradation. Restoration of barrier islands has become a high priority in Louisiana and barrier island degradation has increased waterbird reliance on restored dredge material islands. To improve restoration and management of barrier islands, we investigated the hatching success of Black Skimmer (Rynchops niger) and determined important habitat characteristics for their hatching success. Nest monitoring and nest habitat characteristics were measured at breeding colonies on the Isles Dernieres Barrier Island Refuge, Louisiana, in 2009 and 2010. Hatching success varied greatly for Black Skimmers (1–84%). Predation, flooding, and competition were the three main causes of nest failure. Habitat modeling identified nest elevation relative to the high-tide line and distance to high-tide line as importa...

Long-jump migrant shorebirds have brief windows during spring stopover to acquire the energy needed to complete migration. Red Knots (Calidris canutus) refueling on Horseshoe Crab (Limulus polyphemus) eggs in Delaware Bay can meet their energy needs foraging only by day. In nearby Virginia, thousands of Red Knots stop over, but primarily low-quality, hard-shelled prey are available. One tactic Red Knots may use to meet their energy demands with such prey might be to extend their foraging time by feeding at night. To estimate the length of the foraging day in Virginia, daylight feeding was studied during three spring stopover periods (2008 to 2010), and night feeding was studied in 2010. Red Knots foraged 76 ± 3 SE% of the time in 2008 and 2009 combined, and 59 ± 3% of the time in 2010, during 3-minute observations. In 2010, Red Knots foraged 51 ± 7% of the time during a continuous 7-h daytime observation and 77 ± 5% of the time during a continuous 8-h night time observation on the same island. G...

Previous studies documented that Black Skimmers, Rynchops niger; tend to forage at night but did not examine which environmental variables explain nocturnal foraging. Foraging frequency and environmental variables were studied at a large breeding colony of skimmers on an urbanized barrier island on the west coast of Florida, USA. To determine which variables influenced foraging, the number of skimmers departing to forage was counted for 120, one-hour periods through the day and night from 30 May–29 August, 2007. Using generalized linear models, factors were most associated with skimmers departing to forage were identified. These models included: light level, temperature, wind, wind direction, relative humidity, tide height, tide stage (incoming, outgoing, or slack) and status of the colony (mostly eggs, chicks, or fledglings). Light level was the only factor to significantly influence the amount of foraging (Wald = 9.40, d.f. = 1, p = 0.002). The relationship was negative, as light levels decrea...

Three statewide surveys in South Carolina for American Oystercatchers, Haematopus palliatus, were conducted during the breeding season from 2001-2003. A mean of 1,105 oystercatchers were recorded each year. In 2002, 407 breeding pairs were documented and in 2003, 397 pairs. There were 378 nonbreeding oystercatchers in 2002 and 383 in 2003. The Cape Romain Region supported a majority of South Carolina’s breeding pairs and nonbreeding flocks. Oystercatchers nested, on average, closer to each other on estuarine islands, (specifically made of shell) and farthest apart on edge shell mounds. Although historically oystercatchers may have nested primarily on front beaches, this study documented only 28% of the breeding pairs on barrier island beaches, 27% on estuarine islands and 45% on edge shell mounds. Twenty-four percent of all pairs in South Carolina were on edge shell mounds adjacent to the Atlantic Intracoastal Waterway (AIWW). Nesting on shell mounds may become increasingly important as beaches b...

The nest survival of the Black Skimmer (Rynchops niger) in coastal Mississippi was modeled to better understand their breeding biology and suggest management strategies for protecting nesting colonies. During the 2004 and 2005 breeding seasons a total of 301 nests was monitored and hatching success was 67% in 2004 and 39% in 2005. Mean clutch size differed between years, although mean incubation length did not differ between years or between colonies on the mainland and barrier islands (P = 0.70). Nest survival was influenced by year, seasonal variation within year, clutch size, and colony. Nest survival was greatest in 2004, and within years nest survival followed a seasonal pattern where it was high from May through late June and then decreased through early August. Large clutches had greater survival than small clutches. There was considerable inter-colony variation in nest survival, and it appeared that low survival was correlated with disturbance risk at many colonies. This study provides th...

Colonially nesting wading birds (herons, egrets, and ibis) are a highly visible, biologically significant component of the mid-Atlantic coastal avifauna. Populations of these species were decimated by extensive market hunting in the late nineteenth century, recovered, and additional species colonized the region. Herein, we summarize changes in species, numbers of breeding pairs, and colony sites for ten species of wading birds surveyed four times over a 26-year period (1977 to 2003) within the Chesapeake Bay and Atlantic coastal barrier island region. Over the period of surveys, wading bird breeding colonies increased 246% (to 537) and numbers of breeding pairs increased 67% (to 26,589). Expansion among Great Blue Herons (Ardea herodias), Great Egrets (Ardea alba), Yellow-Crowned Night-Herons (Nyctanassa violacea) and Glossy Ibis (Plegadis falcinellus), primarily accounted for the dramatic increase, while declines were recorded for Snowy Egrets (Egretta thula), Cattle Egrets (Bubulcus ibis) and B...

The conservation status of the American Oystercatcher (Haematopus palliatus palliatus) along the Chesapeake Bay, coastal bays, and barrier island shorelines of Maryland and Virginia has been investigated in detail in recent years. The region supports approximately 700 breeding pairs with more than 80% occurring on the east coast of the Delmarva Peninsula and less than 20% occurring along the shorelines of the Chesapeake Bay. The number of breeding pairs in Maryland appears to have been stable or to have increased slightly during the past 20 years. The overall trend of the breeding population in Virginia is less clear, but recent evidence suggests that numbers on the barrier islands are increasing after more than two decades of a declining trend. The coastal bays and barrier islands typically support between 1,500 and 2,000 wintering birds with most occurring on the east coast of the Virginia portion of the Delmarva Peninsula. The shorelines of both states together play an important role in suppor...

From 1986-2005, Virginia supported between 6% and 13% of the federally threatened Atlantic Coast Piping Plover (Charadrius melodus) breeding population with an annual average of 111 nesting pairs (SD ± 25.0, range = 84-192 pairs). The statewide population remained relatively static from 1986-2003 (x = 104.4 pairs, SD ± 12.0, range = 84-127 pairs). In 2004, the population increased to 152 pairs and in the following year grew to 192 pairs. Over 95% of the state’s Piping Plover breeding activity occurred on the barrier islands. From 1986-1997, five pairs or less were observed at Craney Island, a dredge material deposition site in Portsmouth and at Grandview Nature Preserve, a high-use recreation area located in the City of Hampton. Predators and human disturbance likely account for the present-day absence of nesting pairs from both inland sites. From 1990-2002, annual productivity studies revealed an annual average of 1.14 fledged young per pair (SD ± 0.4, range = 0.59-1.65). The 2003 breeding seas...

Surveys of the American Oystercatcher (Haematopus palliatus) were conducted in all suitable nesting habitat in coastal Virginia, USA during the 2003 breeding season. The total of 588 pairs more than doubles previous estimates for the state, and provides a benchmark for the comparison of future surveys. These results suggest that Virginia supports the largest number of oystercatchers in the breeding season relative to other east coast states. Previous surveys in Virginia focused only on one coastal area, the barrier islands. Over two hundred pairs recorded in the seaside lagoon system of the Delmarva Peninsula in 2003 accounted for the large discrepancy between previous estimates for the state and the results of this survey. Over 89% of the total number of pairs was observed on the islands and in the lagoon system of the Delmarva Peninsula. Approximately 87% of the pairs were on land that is managed or regulated to some degree for the conservation of nesting birds by federal, state, municipal and ...

American Oystercatcher (Haematopus palliatus) numbers along the east coast of the United States are declining in some areas and expanding in others. Researchers have suggested that movement from traditional barrier beach habitats to novel inland habitats and coastal marshes may explain some of these changes, but few studies have documented oystercatcher reproductive success in non-traditional habitats. This study compares the reproductive success of the American Oystercatcher on three river islands in the lower Cape Fear River of North Carolina with that of birds nesting on barrier island beach habitat of Cape Lookout National Seashore. There were 17.6 times more oystercatcher breeding pairs per kilometer on the river island habitat than barrier beach habitat. The Mayfield estimate of daily nest content survival was 0.97 (S.E. ± 0.0039) on river islands, significantly higher than 0.92 (S.E. ± 0.0059) on barrier islands. The primary identifiable cause of nest failure on the river islands was flood...

Many birds feed on bivalve molluscs, but only oystercatchers (Haematopus spp.) are known to prise open the shells. Brown Teal (Anas chlorotis), a dabbling duck endemic to New Zealand, were observed opening Common Cockles (Austrovenus stutchburyi) on Great Barrier Island. The teal jackhammered into the open shells of feeding cockles and quickly scooped out the flesh. Despite having the bill morphology of a typical dabbling duck, they were adept at this feeding method.

Raccoons (Procyon lotor) are important predators of ground-nesting species in coastal systems. They have been identified as a primary cause of nest failure for the American Oystercatcher (Haematopus palliatus) throughout its range. Concerns over the long-term effects of raccoon predation and increased nest success following a hurricane inspired a mark-resight study of the raccoon population on a barrier island off North Carolina, USA. Approximately half of the raccoons were experimentally removed in 2008. Nests (n = 700) were monitored on two adjacent barrier islands during 2004–2013. Daily nest survival estimates were highest for 2004 (0.974 ± 0.005) and lowest for 2007 and 2008 (0.925 ± 0.009 and 0.925 ± 0.010, respectively). The only model in our candidate set that received any support included island and time of season, along with a diminishing effect of the hurricane and a constant, 5-year effect of the raccoon removal. For both hurricane and raccoon removal, however, the support for island-specific effects was weak (β = -0.204 ± 0.116 and 0.146 ± 0.349, respectively). We conclude that either the raccoon reduction was inadequate, or factors other than predation cause more variation in nest success than previously recognized. A multi-faceted approach to management aimed at reducing nest losses to storm overwash, predation, and human disturbance is likely to yield the largest population level benefits.

Information on demographic parameters needed to inform conservation strategies for American Oystercatchers (Haematopus palliatus) is lacking. The population dynamics of American Oystercatchers in Virginia, USA, were examined using a multi-state analysis framework that modeled movement of American Oystercatchers into and out of the State. Change in breeding status, age-specific survival rates, and age at first breeding were investigated for three geographically distinct study sites. Non-breeding American Oystercatchers originating from Virginia readily moved in and out of the State among years. The immigration rate for birds breeding on barrier islands was 6% Emigration rates were 6% for the barrier island breeding population and 17% for the seaside lagoon population. Stage-specific annual survival rates were 0.66, 0.95 and 0.91 for juvenile, sub-adult and adult stages, respectively. Age at first breeding peaked in the fourth year for both the barrier island and seaside lagoon breeding populations. Movement and recruitment rates suggested that the barrier islands may provide the highest quality breeding habitat among the three study sites. This study showed that Virginia's American Oystercatcher population is linked with other Atlantic Coast populations, and these links should be considered when evaluating local population trends and management targets.

We report the northernmost breeding record of the Reddish Egret (Egretta rufescens) along the North American Atlantic Coast. Nesting activity was first seen in late May 2004, and on 6 July 2004 a nest was discovered with two young chicks on Marsh Island, a barrier island located within Cape Romain National Wildlife Refuge, South Carolina, USA. Reddish Egret nestlings were last observed within 1 m of the nest on 30 July 2004. This represents a northward extension of ca. 450 km in the breeding range of this species and, for the U.S. Atlantic Coast, the only recorded instance of nesting north of Florida.