CHANGES IN THE NESTING POPULATIONS OF COLONIAL WATERBIRDS IN JAMAICA BAY WILDLIFE REFUGE, NEW YORK,

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1 CHANGES IN THE NESTING POPULATIONS OF COLONIAL WATERBIRDS IN JAMAICA BAY WILDLIFE REFUGE, NEW YORK, Author(s) :Kevin M. Brown, Julia L. Tims, R. Michael Erwin, and Milo E. Richmond Source: Northeastern Naturalist, 8(3): Published By: Humboldt Field Research Institute DOI: dx.doi.org/ / (2001)008[0275:citnpo]2.0.co;2 URL: full/ / %282001%29008%5b0275%3acitnpo %5D2.0.CO%3B2 BioOne ( is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne s Terms of Use, available at Usage of BioOne content is strictly limited to personal, educational, and BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit non-commercial publishers, academic use. institutions, Commercial research inquiries libraries, or and rights research and funders permissions in the common goal of maximizing access to critical research. requests should be directed to the individual publisher as copyright holder.

2 2001 NORTHEASTERN NATURALIST 8(3): CHANGES IN THE NESTING POPULATIONS OF COLONIAL WATERBIRDS IN JAMAICA BAY WILDLIFE REFUGE, NEW YORK, KEVIN M. BROWN 1,3, JULIA L. TIMS 1,4, R. MICHAEL ERWIN 2, AND MILO E. RICHMOND 1 ABSTRACT - The Jamaica Bay Wildlife Refuge (JBWR) represents the largest protected area for over 300 species of migratory and resident birds on Long Island (LI), New York, and occupies a key position along the Atlantic flyway. We identified changes in nesting populations for 18 species of colonial waterbirds in JBWR and on LI, during , to provide a basis for future wildlife management decisions in JBWR and also at nearby John F. Kennedy International Airport. None of the populations was stable over the past 25 years in JBWR or on LI. Some populations in JBWR increased (Laughing Gull L. atricilla Linnaeus, Great Black-backed Gull L. marinus Linnaeus, Forster s Tern Sterna forsteri Nuttall) while others decreased (Herring Gull Larus argentatus Coues, Snowy Egret Egretta thula Molina), but only Cattle Egrets (Bubulcus ibis Linnaeus) have disappeared from the refuge. Common Tern (S. hirundo Linnaeus), Least Tern (S. antillarum Lesson), Roseate Tern (S. dougallii Montagu), Black Skimmer (Rynchops niger Linnaeus), Black-crowned Night Heron (Nycticorax nycticorax Linnaeus) and Great Egret (Ardea alba Linnaeus) populations all increased on LI over the sampling period although the Common Tern colonies in JBWR have been declining since The continued protection of the colony sites, particularly saltmarsh islands, in JBWR will be important to the conservation efforts of many colonial waterbird populations on Long Island. The JBWR colonies may serve as a source of emigrants to other Long Island colonies, and in some cases, act as a sink for birds immigrating from New Jersey and elsewhere. INTRODUCTION The Jamaica Bay Wildlife Refuge (JBWR) provides nesting, migrating, and wintering habitats for over 300 species of shore-, land- and waterbirds (Buckley and Buckley 1980, Burger 1983). The refuge is part of the Gateway National Recreation Area and is managed by the National Park Service. Jamaica Bay is one of the few relatively unmodified greenscapes remaining in the New York metropolitan area and supports a variety of colonially nesting waterbirds including the only Laughing Gull (Larus atricilla Linnaeus) and Forster s Tern (Sterna forsteri Nuttall) colonies in New York State. Given the unusual biotic 1 USGS, New York Cooperative Fish and Wildlife Research Unit, Department of Natural Resources, Cornell University, Ithaca, NY 14853, kbrown@spartan.ac.brocku.ca; 2 USGS Patuxent Wildlife Research Center, Beech Forest Road, Laurel, MD 20708, USA; and Department of Environmental Sciences, Clark Hall, University of Virginia, Charlottesville, VA 22903, USA; 3 Current address: Department of Biological Sciences, Brock University, St. Catharines, Ontario, L2S 3A1, Canada; 4 Current address: Environmental Resource Management, Inc., 855 Springfield Drive, Exton, PA 19341, USA.

3 276 Northeastern Naturalist Vol. 8, No. 3 richness of this urban refuge and the potential of birds to interfere with aircraft operations at nearby John F. Kennedy International Airport (Buckley and McCarthy 1994, Burger 1985, Dolbeer et al. 1993), knowledge of the distribution, abundance, and population trends of gulls and other waterbirds in JBWR is important to airport authorities, wildlife managers, recreational bird watchers, and the public. Since 1974 the National Park Service and other cooperating researchers and agencies have conducted periodic surveys of colonial waterbird populations in JBWR as either part of the Long Island Colonial Waterbird and Piping Plover Survey (Peterson et al. 1986, Sommers et al. 1994, Sommers and Alfieri 1998) or for other wildlife management related issues (Buckley and Buckley 1980, 1984a; Griffin and Hoopes 1992; Dolbeer et al. 1993, 1997). In this paper, we report the results of our JBWR surveys in 1997, and compile these 25 years of census data in an effort to identify any changes in JBWR and Long Island populations of colonial waterbirds. This information will help provide a basis for future wildlife management decisions in JBWR and also contribute to the on-going development of the Bird Hazard Reduction Program at Kennedy airport (U.S. Dept. of Agriculture 1994, Brown et al. 2001). FIELD SITE DESCRIPTION AND METHODS Jamaica Bay Wildlife Refuge is located at the southern end of Long Island and within the limits of New York City (Kings and Queens counties; 40 o 36 N, 73 o 50 W). The bay itself, approximately 3600 ha, is a shallow tidal lagoon (<3m at low tide except for dredged channels) with one inlet. Major habitat types include salt-marsh islands (approximately 374 ha of Spartina alterniflora and 213 ha of S. patens), six upland islands created from dredge fill, tidal mudflats (142 ha at low tide), and several man-made fresh and brackish water ponds (Burger 1983). John F. Kennedy International Airport (JFKIA) is located immediately adjacent to the northeastern boundary of JBWR (Fig. 1.). Surveys of Gull and Heron Colonies On 6 June 1996 and 28 May 1997, we surveyed the bay from a helicopter to locate nesting populations of all colonial waterbirds as a preliminary step to ground surveys. Between 18 and 23 May 1997, we conducted ground counts of nests at five of the six Herring and Great Black-backed Gull (L. argentatus Coues and L. marinus Linnaeus) colony sites in JBWR: Subway Island (upland area approximately 112 ha), Little Egg Marsh (10 ha), Ruffle Bar Island (34 ha), Elder s Point Marsh (0.3 ha) and Duck Point Marshes (0.2 ha). At Canarsie Pol Island, we did not count nests because of the island s large size (96 ha) and thick vegetation; we estimated the number of adult gulls on nesting areas during the helicopter survey in Ground counts coincided with mid- and late-incuba-

4 2001 K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond 277 tion periods of Herring and Great Black-backed Gulls, respectively. At each colony, active nests (contained eggs and/or chicks) were counted by a team of 5-10 people walking parallel transects, about 3m apart, through nesting area(s). Each active nest was marked with a flag to avoid recounting and missing nests. To distinguish species of gull nests, we used the width of the largest egg within a clutch as a discriminator between Herring (<53mm) and Great Black-backed (> 53 mm) Gull nests (J.L.T. unpubl. data). Most wading birds were observed nesting in multi-species heronries on Canarsie Pol Island. On 14 May 1997, a team of three investigators conducted a survey by foot of these heronries. We estimated the total numbers of adults of each species that flushed from their nests as we walked around the nesting areas. All vegetated areas of the island were included in the survey. Figure 1. Map of Gateway National Recreation Area, Jamaica Bay Wildlife Refuge, and John F. Kennedy International Airport, in the Boroughs of Brooklyn and Queens, New York City (map courtesy of P. A. Buckley). Jo Co Marsh, located next to the airport, is marked A.

5 278 Northeastern Naturalist Vol. 8, No. 3 Historical Waterbird Data Historical data on distribution and abundance of colonial waterbirds in Jamaica Bay and on Long Island (Appendices 1 and 2) were compiled from peer-reviewed manuscripts (Buckley and Buckley 1980, 1984a; Dolbeer et al. 1997), technical reports to the National Park Service (Griffin and Hoopes 1992) and Port Authority of New York and New Jersey (Dolbeer and Bernhardt 1997, Dolbeer and Bucknall 1997, Dolbeer and Chipman 1998), Long Island Colonial Waterbird and Piping Plover Survey(s) (Peterson et al. 1986; Sommers et al. 1994, 1996; Sommers and Alfieri 1998), and personal communications (P. A. Buckley and F. G. Buckley, unpublished data). Census techniques varied among studies, species, and years, and included helicopter surveys of numbers of adults (Buckley and Buckley 1980), aerial photography of nests (Dolbeer et al. 1997), and ground counts of active nests (this study). Surveyors recorded either estimates of numbers of adults present at colony sites and/or the number of nests. Constructing population trends from historical data is often fraught with difficulties (Ogden 1978, Frohring et al. 1988). A number of factors are known to affect the accuracy and the precision of census data and to confound interpretation of population trends including: scale, inconsistencies in counting methods within and among sampling sites, inherent biases associated with the various aerial (visual counts, photographs, video) and ground (temporal errors) surveying techniques, observer variability (experience, skill, effort), detectability (white vs dark species), incomplete surveys (missed colonies), different units of measure and conversion factors, and statistical limitations (non-independence and pooling of data; for examples, see Bennetts et al. 1999, Buckley and Buckley 1984b, Dolbeer et al. 1997, Erwin 1981, Ewins et al. 1995, Frederick et al. 1996, Kendall et al. 1996, Sadoul 1997). We believe, however, that count data were obtained using sufficient sampling effort and represent reasonable estimates of actual numbers because (1) waterbird colonies are conspicuous and often found in traditional locations, and (2) considerable effort has been given to improve the accuracy (identify/correct sources of error) and precision (standardized technique) of colonial waterbird census data since the mid-1970s (Buckley and Buckley 1984b, Kushlan 1997). We excluded data from incomplete surveys in JBWR and, to attempt to achieve standardization, converted nest and adult counts to an estimate of breeding pairs (1 nest = 1 pair; 1 adult gull or wader = 1 pair; 1 adult tern = 0.9 pair (Erwin 1979, Peterson et al. 1986)). Count data were log-transformed to reduce heteroscedasticity (Zar 1996). We used linear and quadratic regression models to determine fit (based on highest r 2 value) of transformed count data to year for each species during (Table 1). We reject the null hypothesis (no trend) if P < 0.05 and report the mean ±1SD population size.

6 2001 K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond 279 RESULTS Herring and Great Black-backed Gulls Since the mid-1970s, the Herring Gull population in JBWR has declined 23 percent from 3,319 ± 743 pairs/year ( , n = 5 years) to 2,549 pairs in 1997 (linear regression, P = 0.033, Fig. 2a). In contrast, estimates of Great Black-backed Gulls have increased eight fold from 49 pairs in 1974 to 401 pairs in 1997 (linear regression, P < 0.001, Fig. 2b). On average, Herring Gull has declined 63 pairs/year and Great Blackbacked Gull has increased 15 pairs/year. In 1997, most (99%) nests were distributed among four large colonies on Canarsie Pol Island (900 Herring and 100 Great Black-backed Gull nests), Ruffle Bar Island (880, 111), Little Egg Marsh (271, 92), and Subway Island (488, 96). On Long Island, the Herring Gull population has declined over 50 percent since 1985 from about 24,000 to 11,000 pairs in 1995 (Sommers Table 1. Regression models that best describe patterns of colonial waterbird populations nesting in Jamaica Bay Wildlife Refuge, and on Long Island, between 1974 and Species Period Regression model (log y =) 1 r 2 df F P Jamaica Bay Wildlife Refuge Population Laughing Gull x x Herring Gull x Great Black-backed Gull x Common Tern x x Forster s Tern x x Black-crowned Night Heron x Yellow-crowned Night Heron x x Glossy Ibis x Great Egret x x Snowy Egret x Cattle Egret x Tricolored Heron x x Long Island Population Laughing Gull x x Herring Gull x x Great Black-backed Gull x x Common Tern x x Forster s Tern x Least Tern x x Roseate Tern x x Gull-billed Tern x Black Skimmer x Black-crowned Night Heron x x Yellow-crowned Night Heron x Glossy Ibis x x Great Egret x x Snowy Egret x Cattle Egret x x Tricolored Heron x Little Blue Heron x x Green Heron x x Linear or quadratic regression models (where x equals the year code, 1974 was set as zero) that yielded the highest r-square value (line of best fit) and the corresponding P-value; statistics were computed from log-transformed data (Y = log [Y + 1]).

7 280 Northeastern Naturalist Vol. 8, No. 3 et al. 1996). Our quadratic model ( ), suggesting an increase followed by a decrease, approached statistically significance (P = 0.091, Fig. 2a). During the late-1970s and 1980s, Great Black-backed Gull increased from about 1,500 to 9,700 pairs in 1988, declining thereafter to 6,600 pairs in 1995 (quadratic regression, P < 0.001, Fig. 2b). Laughing Gull. Laughing Gulls colonized Jo Co Marsh in JBWR in 1979 (Post and Riepe 1980). The nesting population increased exponentially to 7,629 pairs in 1990 and spread over about 400 acres of saltmarsh islands. Since 1991, when a gull-shooting program began on Kennedy airport property (Dolbeer et al. 1993, U.S. Department of Agriculture 1994), the population has declined 32 percent to 5,203 ± 852 pairs/year ( , N = 7 years). A quadratic regression model fit this pattern (P < 0.001, Fig. 3a). Figure 2. Estimates (nesting pairs, y-axis) of (A) Herring and (B) Great Black-backed Gulls nesting in the Jamaica Bay Wildlife Refuge (solid boxes), and on Long Island (open boxes), from 1974 to The lines represent the regression models that best fit these data (P < 0.05).

8 2001 K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond 281 In 1978, one nest was found on the Line Island complex in Great South Bay, near Jones Beach (Buckley et al. 1978). In 1990 and 1991, up to four pairs nested on North Cinder Island, Town of Hempstead, and two pairs nested on Young s Island, Smithtown, in 1995 (Sommers et al. 1994, 1996). These sites were abandoned after one or two years of nesting attempts, and Laughing Gulls do not currently nest elsewhere on Long Island. Terns and Skimmers. Common Tern (S. hirundo Linnaeus) colonies are widely distributed on Long Island. Between 1974 and 1983, colonies were found at 115 different sites, with as many as 50 marsh colonies in a given year (Buckley and Buckley 1980, 2000). In JBWR, Common Terns nest sympatrically with Forster s Terns and Laughing Gulls, mostly on saltmarsh islands. Occasionally, pairs of Common Terns have Figure 3. Estimates (nesting pairs, y-axis) of (A) Laughing Gulls and (B) Common Terns nesting in the Jamaica Bay Wildlife Refuge (solid boxes), and on Long Island (open boxes), from 1974 to The lines represent the regression models that best fit these data (P < 0.05).

9 282 Northeastern Naturalist Vol. 8, No. 3 nested on sandy substrates on Little Egg Marsh (1986, 1998) and Canarsie Pol islands (1989); we estimated 100 pairs on Little Egg Marsh in In JBWR, the Common Tern population increased from about 400 to 1500 pairs between 1975 and 1985 but declined to about 320 pairs in 1996 (quadratic regression, P = 0.002, Fig. 3b). Although we did not conduct a formal survey of terns in 1997, we did estimate that about 450 adult Common and Forster s Terns (8:1 ratio) flushed from nests at Jo Co Marsh and East High Meadow. Similarly, the Long Island Common Tern population increased from about 11,000 to 27,000 pairs between 1974 and 1987 but declined to 21,000 pairs in 1996 (quadratic regression, P < 0.001, Fig. 3b). The largest portion (40-80%) of the Long Island population nest on Great Gull Island (Sommers et al. 1994, 1996). Forster s Tern was first reported as a breeding bird on Long Island in 1989 and in JBWR in Except for a few (< 5) pairs each year, most of the Long Island population nested in JBWR (55 ± 18 pairs, Figure 4. Estimates (nesting pairs, y-axis) of (A) Least (open boxes) and Roseate (solid boxes) Terns and (B) Black Skimmers nesting on Long Island, from 1974 to The lines represent the regression models that best fit these data (P < 0.05).

10 2001 K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond ). The increasing trend was significant for Long Island (P = 0.012) but not for JBWR (P = 0.163). Since 1974, the Least Tern (S. antillarum Lesson) population on Long Island has increased 49 percent from 1,719 to 2,560 pairs in 1997 (linear regression, P = 0.029), but a quadratic regression analysis indicated that this population has been declining, from a peak of 3,800 pairs, since 1983 (P = 0.006, Fig. 4a). In contrast, the Roseate Tern (S. dougallii Montagu) population decreased 53 percent between 1974 and 1986 but has since recovered to 2,055 pairs in 1997 (quadratic regression, P = 0.03, Fig. 4a). Neither species has been reported nesting in JBWR. Each year since 1975, one to four pairs of Gull-billed Tern (S. nilotica Gmelin) have nested on Long Island (mode = 2 pairs/year). A Gull-billed Tern was flushed from a nest on Silver Hole Marsh in 1976 and as many as three pairs were observed at the East and West Ponds from 1976 to 1979 but no nests were found (Buckley and Buckley 1980). Figure 5. Estimates (nesting pairs, y-axis) of (A) Black-crowned Night Heron and (B) Glossy Ibis nesting in the Jamaica Bay Wildlife Refuge (solid boxes), and on Long Island (open boxes), from 1974 to The lines represent the regression models that best fit these data (P < 0.05).

11 284 Northeastern Naturalist Vol. 8, No. 3 The Black Skimmer (Rynchops niger Linnaeus) population on Long Island has increased 58 percent from 339 pairs in 1974 to 536 pairs in 1997 (linear regression, P = 0.05, Fig. 4b). In JBWR, a single pair nested on Subway Island in 1985 only. Herons and Egrets In 1997, we estimated that about 800 pairs of wading birds nested at heronries on Canarsie Pol Island. In addition, we observed a few pairs of Great Egret (Ardea alba Linnaeus) and Black-crowned Night Heron (Nycticorax nycticorax Linnaeus) on nests at Ruffle Bar Island; Glossy Ibis (Plegadis falcinellus Linnaeus) were also seen nearby but no nests were found. Prior to 1986, small numbers of Great and Snowy (Egretta thula Molina) Egrets, Black-crowned and Yellow-crowned (Nyctanassa violacea Linnaeus) Night Herons, and Glossy Ibis also nested at a heronry located on the west side of the East Pond on Rulers Bar Hassock Figure 6. Estimates (nesting pairs, y-axis) of (A) Great and (B) Snowy Egrets nesting in the Jamaica Bay Wildlife Refuge (solid boxes), and on Long Island (open boxes), from 1974 to The lines represent the regression models that best fit these data (P < 0.05).

12 2001 K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond 285 (Buckley and Buckley 1980); this site was abandoned circa 1987 (Sommers et al. 1994). Since the mid-1970s, the Black-crowned Night Heron population on Long Island has quadrupled from about 450 to 1,800 pairs in 1995 (linear regression, P < 0.001, Fig. 5a). In JBWR, estimates have been variable ranging from 0 to 238 pairs in 1997 (56 ± 60 pairs/year, N = 14 survey years; linear regression, P = 0.501). The Yellow-crowned Night Heron population on Long Island has fluctuated around 23 ± 8 pairs/ year (N = 15 survey years) since It was first recorded nesting in JBWR in 1986 (2 pairs at East Pond) and then again at Canarsie Pol in 1993 and During the past 25 years, Glossy Ibis has been the most abundant wading bird nesting in JBWR although their numbers have fluctuated (112 ± 112 pairs/year, N = 14 survey years) and none was recorded in 1989 and 1992 (Fig. 5b). We estimated 306 adults in Similarly, Figure 7. Estimates (nesting pairs, y-axis) of (A) Cattle Egret, (B) Tricolored Heron and (C) Little Blue Herons nesting in the Jamaica Bay Wildlife Refuge (solid boxes), and on Long Island (open boxes), from 1974 to The Green Heron population on Long Island is shown in C (solid boxes). The lines represent the regression models that best fit these data (P < 0.05).

13 286 Northeastern Naturalist Vol. 8, No. 3 the Long Island population has fluctuated around 703 ± 145 pairs (N = 15 survey years) between 1974 and Since the JBWR surveys began in 1974, Great Egret numbers have fluctuated around 28 ± 33 pairs (N = 14 survey years). We estimated 127 pairs in On Long Island, Great Egret declined slightly during the mid-1970s and increased during the 1990s (quadratic regression, P = 0.001, Fig. 6a). Snowy Egret and Cattle Egret (Bubulcus ibis Linnaeus) also declined in JBWR between 1976 and 1993; none were recorded in 1989 and 1992 (linear regressions, P = and 0.021, Figs. 6b and 7a, respectively). In 1997, we estimated that about 130 pairs of Snowy Egrets nested on Canarsie Pol Island, about half of that recorded from 1976 to 1978, but we did not find any Cattle Egrets. On Long Island, Snowy Egret numbers fluctuated (904 ± 325 pairs) between 1974 and 1995 while Cattle Egret increased to 350 pairs in 1985 (N = 351 pairs) but decreased thereafter to 42 pairs in 1995 (quadratic regression, P < 0.001). During a few surveys since 1985, small numbers (< 10 pairs) of Green Heron (Butorides virescens Linnaeus), Tricolored Heron (E. tricolor Muller) and Little Blue Heron (E. caerulea Linnaeus) were also observed at the Canarsie Pol heronry (see Appendix 1). On Long Island, the Tricolored Heron has doubled since the mid-1970s (linear regression, P = 0.083, Fig. 7b) while both Green and Little Blue Herons increased during the 1980s and declined during the early 1990s (quadratic regressions, P = 0.03 and 0.008, respectively, Fig. 7c). DISCUSSION Populations of none of these 18 colonial waterbird species were stable over the past 25 years in JBWR or on Long Island. Some JBWR populations increased (Laughing and Great Black-backed Gulls, Forster s Tern), some decreased (Herring Gull, Common Tern, Glossy Ibis, Snowy Egret) while others (Cattle Egret) disappeared from the refuge. Below, we provide possible explanations for a few of these changes and discuss implications to gull management. Several hypotheses have been proposed to explain the recent declines of Herring Gull populations on the Atlantic coast including: (1) improved sanitation practices and the closing of landfills (Buckley and Buckley 1984b); (2) displacement from optimal breeding sites and depredation of eggs and chicks by the larger-bodied Great Black-backed Gull (McGill-Harelstad 1985; Tims 1999); and (3) reduction in commercial fishing activities (Pierotti and Good 1994). The closing of three landfill sites, located next to JBWR, in 1985 and 1991 has probably contributed to the decline of Herring Gulls by lowering the carrying capacity of the environment, especially in winter. The colonization and exponential growth of the Laughing Gull colonies in JBWR during the 1980s coincided with a near doubling of the

14 2001 K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond 287 Laughing Gull population in New Jersey (from 30,730 in 1977, to 52,914 in 1979 and 58,797 in 1989, Jenkins et al. 1990), despite competition with Herring Gulls for nest sites (Burger and Shisler 1978). While populations in Florida and Texas declined 20 and 35 percent during this period (Belant and Dolbeer 1993), the total North American population remained relatively unchanged (249,000 pairs in 1977, 259,000 in 1990) suggesting that the expansion of northeastern population was initially driven by emigration of adults from colony sites to the south. The most recent ( ) estimates of Common, Least and Roseate Terns, and Black Skimmer populations on Long Island were 30 to 40 percent higher than during the mid-1970s. These species have likely benefitted from increased protection of terneries and Piping Plover nesting habitat on barrier beaches from human encroachment and disturbance. Common Tern numbers appear to track bluefish (Pomatomus saltatrix) numbers in Long Island Sound, with increases in the 1980s, followed by declines in the 1990s (Safina and Burger 1985, 1988). In JBWR, heron numbers increased during the mid-1970s and declined during the mid-1980s and early 1990s. Similarly, most wading birds have been declining on Long Island since the mid-1970s, except for Black-crowned Night Heron, Tricolored Heron, and Great Egret (Buckley and Buckley 1980, Sommers and Alfieri 1998). In 1997, however, Glossy Ibis, Great Egret, and Black-crowned Night Heron were at least as numerous as they were during the mid-1970s although our estimate of Snowy Egret was about half that recorded between 1976 and Only the Cattle Egret has disappeared from the bay which may be related to the abandonment of the large Connecticut colony at Chimon Island (unpubl. data, R. M. Erwin). The 800 total pairs nesting on Canarsie Island in 1997 represents one of the three largest heronries (> 500 pairs) on Long Island; the other two include Isle of Meadows, Richmond County, and North and South Brother Islands, Bronx County (about 800 and 700 pairs in 1995, respectively; Sommers et al. 1996). Determining the reasons for these local (JBWR) changes was problematic for most species, considering that a metropolitan New York metapopulation of 4-5 colonies has existed for more than a decade. Gull Management The increasing numbers of gulls in JBWR during the 1980s, and birdstrikes with aircraft at Kennedy airport led to concerns for human safety and to the implementation of a gull-shooting program at the airport in 1991 (Dolbeer et al. 1993, U.S. Department of Agriculture 1994). Since then ( ), 50,521 Laughing Gulls have been shot as they tried to fly over or past the airport, and the JBWR colonies have declined 32 percent (5,203 ± 852 pairs/year, ; Dolbeer and Chipman 1998). Similarly, the Laughing Gull population in New Jersey also decreased about 20,000 pairs between 1989 and 1995 (Jenkins et al and unpublished data). While band return data identify JBWR and several colony sites in

15 288 Northeastern Naturalist Vol. 8, No. 3 New Jersey as the natal origins of some Laughing Gulls shot at the airport (Dolbeer and Bucknall 1997), it remains uncertain if culling was the cause of these declines, i.e., the airport may be acting as a population sink. Upon evaluation of band recovery data from a 15-year culling program at two Herring and Lesser Black-backed (L. fuscus) Gull colonies in Great Britain, Coulson (1991) concluded that the cull acts as a sink by removing recruited birds (70% immigrants) from as far as 500 km from the colonies. The continued protection of colony sites in JBWR will be important to the conservation efforts of many colonial waterbird populations on Long Island. While the closing of landfills and reduced fisheries waste have been identified as important causes of the recent declines of Herring Gull populations along the northeastern Atlantic coast (Buckley and Buckley 1984b, Pierotti and Good 1994), there is clearly a need for scientific evaluation of the impacts of culling programs on local and regional gull populations. The JBWR colonies may serve as a source of emigrants to other Long Island colonies, and in some cases, act as a sink for birds immigrating from New Jersey and elsewhere. ACKNOWLEDGMENTS We are grateful to and thank the numerous contributors to the Long Island Colonial Waterbird and Piping Plover Survey(s): Tim Carroll, Andrea Coppola, Dawn Davis, Bruce Davis, Brian Eyler, Denis Macrae, Chris Olijnyk, Diane Pollar, Don Riepe, Leo Viana, and John Zuzworsky for their contributions in the field; P. A. and F. G. Buckley for providing raw data from their Long Island colonial waterbird surveys from 1974 to 1978, and 1983; staff at Jamaica Bay Wildlife Refuge, at U.S.G.S. Patuxent Wildlife Research Center and at Cornell University for logistical support; and F. A. Servello (Guest Editor) and two anonymous reviewers for useful comments that improved this manuscript. This research was funded under the Natural Resources Protection Program (NRPP) of the Biological Resources Division, U.S.G.S. Patuxent Wildlife Research Center, with a Cooperative Agreement (No ) to the New York Cooperative Fish and Wildlife Research Unit at Cornell University (Research Work Order no. 34). The views and conclusions contained in this paper are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Government. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Government. LITERATURE CITED BELANT, J.L., and R.A. DOLBEER Population status of nesting laughing gulls in the United States American Birds 47: BENNETTS, R.E., W.A. LINK, J.R. SAUER, and P.W. SYKES Jr Factors influencing counts in an annual survey of snail kites in Florida. Auk 116: BROWN, K.M., R.M. ERWIN, M.E. RICHMOND, P.A. BUCKLEY, J.T. TANACREDI, and D. AVRIN Managing birds and controlling aircraft in the Jamaica Bay-Kennedy airport complex: the need for hard data and soft opinions. Environmental Management (in press). BUCKLEY, F.G., M. GOCHFELD, and P.A. BUCKLEY Breeding laughing gulls return to Long Island. Kingbird 28:

16 2001 K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond 289 BUCKLEY, P.A., and F.G. BUCKLEY Population and colony-site trends of Long Island waterbirds for five years in the mid 1970s. Transactions of the Linnaean Society, New York, no. 9: BUCKLEY, P.A., and F.G. BUCKLEY. 1984a. Expanding double-crested cormorant and laughing gull populations on Long Island, New York. Kingbird 34: BUCKLEY, P.A., and F.G. BUCKLEY. 1984b. Seabirds of the north and middle Atlantic coast of the United States: their status and conservation. Pp , In J. P. Croxall, P. G. H. Evans, and R. W. Schreiber, (Eds.). Status and conservation of the seabirds of the world. I.C.B.P. Technical Publication No. 2, Cambridge, The University Press. BUCKLEY, P.A., and M.G. McCARTHY Insects, vegetation, and the control of laughing gulls (Larus atricilla) at Kennedy International Airport, New York City. Journal of Applied Ecology 31: BUCKLEY, P.A., and F.G. BUCKLEY Patterns of colony-site use and disuse in saltmarsh-nesting Common and Roseate terns. Journal of Field Ornithology 71: (in press). BURGER, J Jamaica Bay studies III: Abiotic determinants of distribution and abundance of gulls (Larus). Estuarine, Coastal and Shelf Science 16: BURGER, J Factors affecting bird strikes on aircraft at a coastal airport. Biological Conservation. 33:1-28. BURGER, J., and J. SHISLER Nest site selection and competitive interactions of herring and laughing gulls in New Jersey. Auk 95: COULSON, J.C The population dynamics of culling Herring Gulls and Lesser Black-backed Gulls. Pp , In C.M. Perrins, J-D. Lebreton, and G.J.M. Hirons (Eds.). Bird Population Studies: Relevance to Conservation and Management. Oxford University Press Inc., New York. 683 pp. DOLBEER, R.A., and G.E. BERNHARDT Aerial photography to estimate populations of laughing gull nests in Jamaica Bay, New York, Port Authority of New York and New Jersey, Special Report. 16 pp. DOLBEER, R.A., and J.L. BUCKNALL Shooting gulls to reduce strikes with aircraft at John F. Kennedy International Airport, Port Authority of New York and New Jersey, Special Report. 33 pp. DOLBEER, R.A., and R.B. CHIPMAN Shooting gulls to reduce strikes with aircraft at John F. Kennedy International Airport, Port Authority of New York and New Jersey, Special Report. 32 pp. DOLBEER, R.A., J.L. BELANT, and J.L. SILLINGS Shooting gulls reduces strikes with aircraft at John F. Kennedy International Airport. Wildlife Society Bulletin 21: DOLBEER, R.A., J.L.BELANT, and G.E. BERNHARDT Aerial photography techniques to estimate populations of laughing gull nests in Jamaica Bay, New York, Colonial Waterbirds 20:8-13. ERWIN, R.M Coastal waterbird colonies: Cape Elizabeth, Maine to Virginia. U.S. Fish and Wildlife Service, FWS/OBS - 79/10. ERWIN, R.M Censusing wading bird colonies: an update on the flight-line count method. Colonial Waterbirds 4: EWINS, P.J., D.V. WESELOH, and H. BLOKPOEL Within-season variation in nest numbers of double-crested cormorants (Phalacrocorax auritus) on the Great Lakes: implications for censusing. Colonial Waterbirds 18: FREDERICK, P.C., T. TOWLES, R.J. SAWICKI, and G.T. BANCROFT Comparison of aerial and ground techniques for discovery and census of wading bird (Ciconiiformes) nesting colonies. Condor 98:

17 290 Northeastern Naturalist Vol. 8, No. 3 FROHRING, P.C., D.P. VOORHEES, and J.A. KUSHLAN History of wading birds in the Everglades: a lesson in the use of historical information. Colonial Waterbirds 9: GRIFFIN, C.R., and E.M. HOOPES Birds and the potential for bird strikes at John F. Kennedy International Airport. Final Report to Nat. Park Service. 102 pp. JENKINS, C.D., L.J. NILES, and J. WESSEL Survey of colonial nesting waterbirds on the Atlantic coast of New Jersey New Jersey State Department of Environmental Protection, Woodbine, NJ. 42 pp. KENDALL, W.L., B.G. PETERJOHN, and J.R. SAUER First-time observer effects in the North American breeding bird survey. Auk 113: KUSHLAN, J.A The conservation of wading birds. Colonial Waterbirds 20: MCGILL-HARELSTAD, P.A Mechanisms and consequences of interspecific interactions among gulls. Ph.D Thesis, Cornell University, Ithaca, NY. OGDEN, J.C Recent population trends of colonial wading birds on the Atlantic and Gulf Coastal Plains. In Wading Birds, A. Sprunt IV, J.C. Ogden and S. Winckler (Eds.). New York: National Audubon Society Research Report 7, pages POST, P.W., and D. RIEPE Laughing gulls colonize Jamaica Bay. Kingbird 30: PETERSON, D.M., T.S. LITWIN, D.C. MACLEAN, and R. LENT Long Island colonial waterbird and piping plover survey. Cornell University, Laboratory of Ornithology, Seatuck Research Program, Ithaca, NY. 158 pp. PIEROTTI, R., and T.P. GOOD Herring gull (Larus argentatus). In The Birds of North America, No. 124, A. Poole and F. Gill (Eds.). The Academy of Natural Sciences; Washington, DC. The American Ornithologists Union, 28 pp. SADOUL, N The importance of spatial scale in long-term monitoring of colonial Charadriiformes in southern France. Colonial Waterbirds 20: SAFINA, C., and J. BURGER Common tern foraging: seasonal trends in prey fish densities and competition with bluefish. Ecology 66: SAFINA, C., and J. BURGER Prey dynamics and the breeding phenology of common terns (Sterna hirundo). Auk 105: SOMMERS, L.A., R. MILLER, K.J. MESKILL, and M. ALFIERI Long Island colonial waterbird and piping plover survey. New York State Department of Environmental Conservation, Stony Brook, NY. 79 pp. SOMMERS, L.A., M.L. ALFIERI, K.J. MESKILL, and R.L. MILLER Long Island colonial waterbird and piping plover survey. New York State Department of Environmental Conservation, Stony Brook, NY. 209 pp. SOMMERS, L.A., and M.L. ALFIERI Long Island colonial waterbird and piping plover survey. New York State Department of Environmental Conservation, Stony Brook, NY. 149 pp. TIMS, J.L Aspects of the nesting ecology and effects of vegetation manipulations on herring (Larus argentatus) and great black-backed (L. marinus) gulls in Jamaica Bay, New York. M.S. Thesis, Cornell University, Ithaca, NY. 120 pp. U.S. DEPARTMENT OF AGRICULTURE Gull hazard reduction program at John F. Kennedy International Airport. Final Environmental Impact Statement. USDA, Animal Damage Control Unit, Pittstown, New Jersey. ZAR, J.H Biostatistical analysis (third edition). Prentice Hall, NJ.

18 Appendix 1. Estimates (nesting pairs) of colonial waterbirds nesting in the Jamaica Bay Wildlife Refuge from 1974 to Laughing Gull (LAGU), Herring Gull (HERG), Great Black-backed Gull (GBBG), Common Tern (COTE), Forster s Tern (FOTE), Black-crowned Night Heron (BCNH), Yellowcrowned Night Heron (YCNH), Glossy Ibis (GLIB), Great Egret (GREG), Snowy Egret (SNEG), Cattle Egret (CAEG), Green Heron (GRHE), Little Blue Heron (LBHE), Tricolored Heron (TRHE) 2. Year LAGU HERG GBBG COTE FOTE BCNH YCNH GLIB GREG SNEG CAEG GRHE LBHE TRHE Conversion of survey data to estimate of the number of nesting pairs is described in the text 2 Laughing Gull data from: 1979 (Post and Riepe 1980); (Buckley and Buckley 1984); (Sommers et al. 1994); 1990 (Griffin and Hoopes 1992); (Dolbeer et al. 1997); (Dolbeer and Bernhardt 1997); 1998 (Dolbeer and Chipman 1998). All other species data from: , 1983 (Buckley and Buckley 1980, P.A. Buckley and F.G. Buckley, pers. comm.); (Sommers et al. 1994; Sommers and Alfieri 1997); 1997 (this study) K.M. Brown, J.L. Tims, R.M. Erwin, and M.E. Richmond 291

19 Appendix 2. Estimates (nesting pairs) of colonial waterbirds nesting at colony sites on Long Island from 1974 to Laughing Gull (LAGU), Herring Gull (HERG), Great Black-backed Gull (GBBG), Common Tern (COTE), Forster s Tern (FOTE), Least Tern (LETE), Roseate Tern (ROST), Gull-billed Tern (GBTE), Black Skimmer (BLSK), Black-crowned Night Heron (BCNH), Yellow-crowned Night Heron (YCNH), Glossy Ibis (GLIB), Great Egret (GREG), Snowy Egret (SNEG), Cattle Egret (CAEG), Green Heron (GRHE), Little Blue Heron (LBHE), Tricolored Heron (TRHE) 2. Year LAGU HERG GBBG COTE FOTE LETE ROST GBTE BLSK BCNH YCNH GLIB GREG SNEG CAEG GRHE LBHE TRHE Conversion of survey data to estimates of the numbers of nesting pairs is described in the text. 2 Laughing Gull data from: 1978 (Buckley et al. 1978); 1979 (Post and Riepe 1980); (Buckley and Buckley 1984); (Sommers et al. 1994); 1990 (Griffin and Hoopes 1992); (Dolbeer et al. 1997); (Dolbeer and Bernhardt 1997); 1998 (Dolbeer and Chipman 1998). All other species data from: , 1983 (Buckley and Buckley 1980, P.A. Buckley and F.G. Buckley, pers. comm.); (Sommers et al. 1994); Sommers and Alfieri 1998); 1997 (this study). In Sommers and Alfieri (1998), the total estimate of Common Terns on Long Island in 1997 did not include Jamaica Bay colonies and so we added the estimate for Jamaica Bay in 1996 (323 pairs) to the Long Island total for Northeastern Naturalist Vol. 8, No. 3