Distribution and Abundance of Breeding Birds in Boston Harbor PETER W.C. PATON 1,*, REBECCA J. HARRIS 1,2, AND CAROL L. TROCKI 1,3 Abstract - We surveyed birds during May and June, 2001–2003, on 26 islands and 1 mainland location in Boston Harbor, MA. We detected 136 species, 67 of which were suspected of breeding. Abundant breeding seabirds included Double-crested Cormorants (Phalacrocorax auritus), Herring Gulls (Larus argentatus), and Great Black-backed Gulls (Larus marinus). We found 73 Common Eider (Somateria mollissima) nests on Calf, Green, Middle Brewster, and Outer Brewster Islands in 2003, making Boston Harbor one of the largest, southernmost nesting areas for this species on the western Atlantic Ocean. We surveyed 7 wading bird colonies composed of Black-crowned Night-Heron (Nycticorax nycticorax), Great Egret (Ardea alba), Snowy Egret (Egretta thula), Glossy Ibis (Plegadis falcinellus), and Little Blue Heron (Egretta caerulea). We found a colony of Least Terns (Sterna antillarum), a state-listed species, on Rainsford Island. We estimated that 49 species of landbirds nested on Boston Harbor islands, but most islands had few species (mean = 9.8 [± 2.2 (SE)] species per island), presumably because many islands were small and dominated by non-native second-growth forests. The most widespread species were Yellow Warbler (Dendroica petechia), Song Sparrow (Melospiza melodia), and Red-winged Blackbird (Agelaius phoeniceus). We also detected over 50 species of migratory birds which did not nest on islands in the Harbor, including many species of shorebirds and warblers. Introduction Much is known about the spatial distribution and abundance of breeding birds in Massachusetts (Veit and Peterson 1993). Yet, surprisingly little has been published on the avifauna on islands in Boston Harbor, although it is located within the largest metropolitan area in New England. Hatch (1984) documented an increase in numbers of nesting Double-crested Cormorants (Phalacrocorax auritus (Lesson)) in the outer islands from 1972 to 1982. In 1994, Blodget and Livingston (1996) estimated numbers of nesting pairs of coastal waterbirds (cormorants, wading birds, waterfowl, gulls, shorebirds, gulls, and terns). These estimates included 13 pairs of Common Eiders 1Department of Natural Resources Sciences, University of Rhode Island, Kingston, RI 02881. 2Current address - Tufts Center for Conservation Medicine, Wildlife Medicine Building, Tufts University School of Veterinary Medicine, North Grafton, MA 01536. 3Current address - 95 Clinton Avenue, Jamestown, RI 02835. *Corresponding author - ppaton@uri.edu. Boston Harbor Islands National Park Area: Natural Resources Overview 2005 Northeastern Naturalist 12( Special Issue 3):145–168 146 Northeastern Naturalist Vol. 12, Special Issue 3 (Somateria mollisma (L.)), which were possibly descended from 175 chicks translocated from Portland, ME, to Penikese Island in the Elizabeth Island chain between 1973 and 1976 (Stanton 1977), or were pioneers from coastal Maine. Recently, Nove (2001) summarized some breeding records of waterbirds in the Harbor. The only comprehensive, long-term survey of birds in Boston Harbor, The Take a Second Look (TASL) program (see http://www.gis.net/~szendeh/tasl.htm), has monitored waterbirds during winter months since 1980. To our knowledge, however, no systematic surveys of passerines have taken place on islands in Boston Harbor, although the Massachusetts Breeding Bird Atlas project did survey some islands and the adjacent mainland areas from 1974 to 1979 (Veit and Petersen 1993). The objective of our research was to conduct a quantitative survey of the avifauna on lands administered cooperatively by the Boston Harbor Islands Partnership. Based on a pilot study in 2001, we used point counts to survey landbirds, boat- and land-based surveys to estimate numbers of gulls and cormorants, and intensive searches of selected islands to survey Common Eider, terns, and wading bird colonies during 2002 and 2003. From direct observations of nests and behavioral cues, we determined which species were likely nesting on each island. We used these avian surveys to recommend specific management guidelines. Methods Birds were surveyed on 26 islands and 1 mainland location (Worlds End) in May and June in 2002 and 2003 (Fig. 1). Islands ranged in size from 2 to 151 ha (5 to 373 acres) ( mean = 36.5 ± 7.1 ha (SE) [mean = 90 ± 17 acres]; Bell et al. 2002). All of the islands have a long history of human use; many islands still have structures, and some (e.g., Deer, Little Brewster, and Thompson) are still occupied with institutional uses. Thus, the vegetation, species composition, and structure on these islands are quite variable, with about 500 species of plants on 32 islands, of which 46% are non-native (Elliman 2005). Locations with the greatest plant species richness are in the inner harbor and are dominated by second-growth woodlands. These areas included the peninsula at Worlds End (300 species of plants) and Peddocks (224 species), Thompson (207 species), Bumpkin (182 species), and Grape (172 species) Islands. Widespread native trees in the harbor include gray birch (Betula populifolia Marshall), hackberry (Celtis occidentalis L.), eastern red cedar (Juniperus virginiana L.), big-tooth aspen (Populus grandidentata Michx.), quaking aspen (Populus tremuloides Michx.), and black oak (Quercus velutina Lam.). Native shrubs and vines include bayberry (Myrica pensylvanica), staghorn sumac (Rhus typhina L.), wild red raspberry (Rubus idaeus L.), and poison ivy (Toxicodendron radicans L.) (Elliman 2005). 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 147 Some of the islands are rocky outcrops, with steep cliffs and little woody vegetation (Middle Brewster, Shag Rocks, Little Calf, Green, and Hangman). Other islands in the outer harbor have steep cliffs with more herbaceous vegetation and shrubs in the center of the island (Calf, Outer Brewster, and Great Brewster). In the inner harbor, smaller islands consist of gradual, rocky beaches and some rocky outcrops with native and non-native trees in the center of islands (Sheep, Snake, Rainsford, Sarah, Langlee, Ragged, Button, and Slate). Georges, Gallops, and Lovells have a long history of human occupation by the military, and currently attract large numbers of visitors. Georges, in particular, with extensive lawns and a fort, has little natural vegetation. Spectacle Island is a capped landfill that was recently revegetated. In addition, in 2003 we surveyed a 9.2-m2 (10.9-yd2) platform off Spinnaker Island (formerly Hog) that was constructed as a nesting platform for Common Terns (Sterna hirundo L.) in 1984 (Hatch 2001). Figure 1. Locations of avian point count stations (circles), Common Tern colonies (squares), Least Tern colonies (cross), and colonial wading bird colonies (triangles) detected in Boston Harbor, 2002–2003. 148 Northeastern Naturalist Vol. 12, Special Issue 3 Waterbird surveys We conducted a pilot study in 2001 to assess the logistics of surveying nesting seabirds on the outer islands and to conduct some preliminary landbird surveys in the inner harbor. We used several techniques to survey nesting seabirds. Because Double-crested Cormorants, Herring Gulls (Larus argentatus Pontoppidan), and Great Black-backed Gulls (Larus marinus L.) primarily nested on inaccessible cliffs on the outer islands, we used boat-based surveys to estimate the number of nesting pairs. Surveys for these three species were conducted during the last week of May in 2002 and 2003, which is just before the peak incubation period for these 3 species in southern Maine (Johnson and Krohn 2001). We used an 8-m (26 ft) landing craft to conduct these surveys, with a driver (who did not count birds or nests), one observer, and one recorder/observer. We circled the outer perimeter of each island from 10 to 50 m (33 to 164 ft) offshore, depending on water depth and visibility of cliff faces. At this distance, there was no evidence that nesting birds were disturbed by our presence, as we rarely observed birds flush off of nests. We drove the boat at approximately 5 km (3.1 miles) per hour, with surveys conducted only from 8:00 to 11:00 AM, without regard to tidal stage. During boat-based surveys, we assumed a nest was active when we observed (1) an adult in incubation posture, (2) an adult standing on or next to an obvious stick nest, or (3) a chick evident in a stick nest (Great Black-backed Gull nests only). Most nesting pairs appeared to be visible on the cliff faces, although we were unable to ground-truth nests due to the dangers associated with climbing cliffs where the birds nested. Since we could not ground-truth our boatbased surveys on most islands, we were unable to build a correction factor to more accurately estimate the number of nesting pairs of seabirds on each island. Our surveys probably underestimated the actual number of nesting pairs of seabirds because unattended nests and hidden nests were not tallied with our survey technique. In addition, Great Black-backed Gulls initiate nests earlier than Herring Gulls and Double-crested Cormorants (Johnson and Krohn 2001), thus we possibly underestimated the number of pairs of Great Black-backed Gulls nesting on each island due to failed nests or parents off nests to forage for their chicks. We also recorded the locations and numbers of American Oystercatcher (Haematopus palliatus Temminck) pairs while conducting these boat-based surveys. During the same time period in May 2002 on the more accessible islands (Calf, Great Brewster, Gallops, and Hangman), gull and cormorant nests were counted directly by two observers slowly walking swaths through the nesting areas. During these ground surveys, gull nests were identified based on nearby adults. We used two techniques to estimate the number of nesting Common Eider on outer islands. In 2001 (and for Green and Middle Brewster in 2002), we slowly circled each of the outer islands in a landing craft and 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 149 counted the number of young eiders (< 1-week-old chicks) on the water near each island. During the 2002 and 2003 field seasons, we conducted systematic surveys on outer islands we suspected had nesting eiders based on the presence of crèches of chicks offshore (in 2003 we visited all outer islands except Little Calf and Shag Rocks). Using 2–4 observers spaced 5 m (16 ft) apart, we walked a systematic grid system over each island (Calf: 22 May 2002, 21 May 2003; Great Brewster: 28 May 2002, 28 May 2003; Outer Brewster: 4 June 2002, 21 May 2003; Green: 28 May 2003). Incubating female eiders typically flushed when we were within 3 to 4 m (10 to 13 ft) of an active nest. In 2003, we used a GPS to record the UTM coordinates of each nest and counted clutch sizes. In 2002 and 2003, we estimated numbers of colonial wading birds nesting on selected islands. Based on observations of herons and egrets in flight, walking surveys of each island, and historical records (Andrews 1990, Blodget and Livingston 1996, Parsons et al. 2001), we determined where to search for potential colony sites. Once at a colony, we estimated the number of nesting pairs primarily by directly counting nests. In some inaccessible areas, we also used the presence of adults to count nests and assumed a 1:1 ratio of adults to each nest. Surveys of colonial wading nests took place from 21 May to 6 June, which is near the peak nesting dates for breeding in the region. Tern colonies on Snake and Rainsford were surveyed by one to two individuals walking through active colonies and counting all nests from 31 May to 26 June, which was longer than the Massachusetts Division of Fisheries and Wildlife tern census period of 5–20 June (Blodget and Melvin 1996). We were unable to survey nests directly at the Common Tern colony near Spinnaker Island because we could not climb up to the nest platform to count nests. Instead, we estimated the number of adults that flushed off the nest platform when we drove the boat into the area on 11 June 2003. Landbird surveys We used point counts to survey landbirds on selected islands (Fancy 2000, Ralph et al. 1995). To determine point count station locations, we overlayed a 250-m (820 ft) grid over a map of the islands using a GIS. Thus, stations were randomly located with respect to vegetation and placed 250 m apart. During point counts, observers recorded the number of birds heard or seen during a 5-minute period at each station. Surveys took place from dawn until a maximum of 4 hours after dawn and each station was surveyed 1–2 times in both 2002 and 2003. Surveys took place during June, when male passerines are typically singing on breeding territories (Veit and Petersen 1993). During point counts, we also noted behaviors that would indicate the species was nesting, including carrying nesting material, food or fecal sacs, feeding fledglings, or flying to a nest. In addition, if a species was (1) heard singing, (2) had 150 Northeastern Naturalist Vol. 12, Special Issue 3 > 0.5 detections per point count station, (3) was within known breeding habitat, and (4) within its known breeding range based on Veit and Petersen (1993), we assumed that it was probably nesting on the island. Species that were detected only as they flew over point count stations were recorded separately because they were not directly associated with any habitats near survey stations. The primary objective of conducting point count surveys was to inventory avian species richness on each island. To determine the distribution and relative abundance of breeding landbirds on each island, we calculated the mean (± 1 SE) number of individuals detected at all point count stations on each island. We pooled data from 2002 and 2003 surveys for this descriptive analysis. Shorebird surveys While conducting waterbird and land surveys, we also recorded all incidental sightings of shorebirds. In 2002, shorebird surveys were extended beyond the breeding season (a minimum of 1 visit per month from May to October) on islands likely to be stopover points for migratory shorebirds based on habitat characteristics (mud flats and sandy or rocky beaches). During these shorebird surveys, we recorded the total number of individuals of each species present. Results Waterbirds We estimated 2032 and 1446 pairs of Double-crested Cormorants annually on 7 islands in Boston Harbor in 2002 and 2003, respectively (Table 1). Herring Gulls were the most abundant species of gull, with 1192 and 652 nesting pairs annually on 13 islands in 2002 and 2003. In comparison, we estimated 520 and 191 nesting pairs of Great Black-backed Gulls at 13 islands throughout the harbor. In addition, we detected more than 125 Common Eider chicks that were less than 1 week old on the water in 2001 and 2002 and found 73 Common Eider nests on 4 islands during 2003, with most (43 nests) found on the north end of Calf (Fig. 2). Mean eider clutch size was 4.5 (± 0.2) eggs per nest (range 2–9 eggs, n = 64). Eggs were hatching in four clutches on 28 May 2003. Mixed species colonies of wading birds were detected on 7 islands (Table 1). Black-crowned Night-Herons were the most abundant wading bird, with 194 pairs in 2003. Snowy Egrets (66 and 58 pairs in 2002 and 2003) were more abundant than Great Egrets (8 and 10 pairs). Glossy Ibis were uncommon, with 8 and 12 pairs nesting on Outer Brewster and Sheep in 2002 and 2003. A single Little Blue Heron was detected nesting on Sarah in 2003. The largest wading bird colony in the harbor was on Sarah, with an estimated 114 pairs of 4 species in 2003. 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 151 Two species of state-listed terns were detected in our surveys. A Common Tern colony on Snake had < 20 pairs in 2002 and 2003. A much larger (350–400 adults) Common Tern colony was detected in 2003 on an artificial nesting platform off Spinnaker Island. We also detected a colony of Least Terns (Sterna antillarum (Lesson)) on Rainsford, with a peak of 114 pairs 25 June 2003; 17 nests were counted on 6 June and 55 nests were found on 12 June 2003. Pairs of American Oystercatchers were detected on 14 islands, with 2 pairs each detected on 4 islands in 2003 (Peddocks, Rainsford, Sarah, and Snake) and single pairs found on the other islands. Spotted Sandpipers (Actitis macularia (L.)) were detected on 8 islands, with a concentration of up to 11 pairs on Rainsford. Landbirds We conducted point counts on 16 islands and at Worlds End, estimating that at least 49 species of landbirds nested on Boston Harbor Islands Partnership lands (Appendix A). The mean number of breeding landbirds on islands we surveyed with point counts was 9.8 (± 2.2) species. As would be expected, smaller islands tended to have fewer breeding landbirds, while larger islands had greater species richness (log 10 (species richness) = 0.545(log 10 (island area) ) + 0.272; Figure 2. Location of Common Eider nests (circles) in outer islands of Boston Harbor in 2003. 152 Northeastern Naturalist Vol. 12, Special Issue 3 Table 1. Number of breeding pairs of waterbirds surveyed on islands in Boston Harbor from 2001 to 2003. Islands not surveyed are depicted with a dash (-). BM = Bumpkin, BT = Button, C = Calf, GA = Gallops, GR = Grape, GB = Great Brewster, GN = Green, H = Hangman, LA = Langlee, LC = Little Calf, LO= Lovells, MB = Middle Brewster, OB = Outer Brewster, P = Peddocks, RG = Ragged, RN = Rainsford, S = Sarah, SG = Shag, SH = Sheep, SP = Spectacle, T = Thompson, W = Worlds End. Grand Species Year BM BT C GA GR GB GN H LA LC LO MB OB P RG RN S SG SH SN SP T W Total Double-crested 2002 0 0 2 0 0 0 256 0 0 376 0 842 131 0 0 0 254 171 0 0 0 0 0 2032 Cormorant 2003 0 0 55 0 0 0 187 0 0 157 0 714 125 0 0 0 80 128 0 0 0 0 0 1446 Great Egret 2002 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 6 0 0 0 0 0 0 8 2003 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0 0 0 0 0 0 10 Snowy Egret 2002 0 0 8 0 0 0 0 0 0 0 0 0 13 0 0 0 35 0 10 0 0 0 0 66 2003 0 0 0 0 0 0 0 0 0 0 0 0 33 0 0 0 17 0 8 0 0 0 0 58 Green Heron 2002 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 2003 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 4 Black-crowned 2002 0 0 13 0 0 0 0 0 0 0 0 - 21 0 0 0 86 0 11 1 0 3 0 135 Night-Heron 2003 0 0 24 0 0 0 0 0 0 0 0 14 66 0 0 0 87 0 3 0 0 0 0 194 Glossy Ibis 2002 0 0 0 0 0 0 0 0 0 0 0 0 8 0 0 0 0 0 1 0 0 0 0 9 2003 0 0 0 0 0 0 0 0 0 0 0 0 12 0 0 0 0 0 0 0 0 0 0 12 Canada Goose 2002 0 0 2 3 3 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0 1 1 0 16 2003 0 0 0 0 0 0 0 0 0 0 0 1 2 1 0 1 0 0 8 0 0 0 0 13 Mallard 2002 0 0 0 0 0 1 0 0 0 0 0 0 1 2 5 2 0 0 2 1 0 2 2 18 2003 2 1 0 0 0 0 0 0 0 0 1 1 0 0 0 1 0 0 0 0 1 0 0 7 American Black 2002 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 2 4 Duck 2003 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 2 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 153 Table 1, continued. Grand Species Year BM BT C GA GR GB GN H LA LC LO MB OB P RG RN S SG SH SN SP T W Total Common Eider* *2001 - - 70 0 0 - 4 0 - - 0 18 35 0 - 0 - 0 3 - 0 0 0 127 *2002 0 0 66 0 0 14 28 0 0 26 0 17 18 0 0 0 0 0 0 0 0 0 0 169 2003 0 0 43 0 0 0 9 0 0 0 0 13 8 0 0 0 0 0 0 0 0 0 0 73 American 2002 1 0 1 1 0 1 0 1 0 0 1 1 0 1 0 2 1 0 1 1 1 1 0 15 Oystercatcher 2003 0 0 1 1 0 1 0 1 0 0 0 1 0 2 0 2 2 0 1 2 1 1 0 16 Spotted Sandpiper 2002 0 0 4 0 0 3 0 0 1 0 0 0 1 0 0 11 1 0 0 1 1 0 0 23 2003 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 6 0 0 0 1 0 0 0 9 Willet 2002 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 3 2003 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 3 Great Black-backed 2002 0 0 62 53 0 24 37 106 1 36 0 47 52 0 0 3 90 3 6 0 0 0 0 520 Gull 2003 0 0 14 32 0 1 26 45 0 14 0 18 17 0 0 1 8 1 14 0 0 0 0 191 Herring Gull 2002 0 6 145 28 0 210 35 8 0 2 0 223 203 0 2 0 154 5 171 0 0 0 0 1192 2003 0 13 64 138 0 56 16 18 0 0 0 33 76 0 0 20 74 0 144 0 0 0 0 652 Common Tern** 2002 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 0 0 0 15 2003 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0 0 0 12 Least Tern 2002 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 41 0 0 0 0 0 0 0 41 2003 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 114 0 0 0 0 0 0 0 114 * Common Eider counts in 2001 and 2002 represent the total number of chicks seen on the water adjacent to each island. **In 2003, 350–400 adults were detected on an artificial nesting platform off Spinnaker Island. 154 Northeastern Naturalist Vol. 12, Special Issue 3 R2 = 0.77); we detected 1 possible breeding species on Button (0.25 ha) compared to 34 potential breeding species on Peddocks (74.6 ha) and 28 species on Thompson (54.2). Worlds End (104 ha) also had 34 breeding species of landbirds, but this area was somewhat of an outlier because it is a peninsula on the mainland (Fig. 1). Eight species of landbirds were widespread and detected on more than 6 islands during the breeding season (Appendix A): Song Sparrow (Melospiza melodia (Wilson)) (21 islands), Red-winged Blackbird (Agelaius phoeniceus (L.)) (16), Yellow Warbler (Dendroica petechia (L.)) (16), Gray Catbird (Dumetella carolinensis (L.)) (12), Barn Swallow (Hirundo rustica L.) (11), Common Yellowthroat (Geothlypis trichas (L.)) (9), Common Grackle (Quiscalus quiscula (L.)) (6), and European Starling (Sturnus vulgaris L.) (7). Birds associated with grassland habitats (e.g., Bobolink [Dolichonyx oryzivorus (L.)], and Eastern Bluebird [Sialia sialis (L.)]) were present at Worlds End, and the more widespread Savannah Sparrow (Passerculus sandwichensis (Gmelin)) was present on 7 islands, including an apparent nesting population in restored grasslands on Spectacle. We also detected 64 species that were probable migrants (Appendix B). Migrant landbirds included 15 species of warblers passing through on their way to breeding grounds: Nashville, Northern Parula, Chestnutsided, Cape May, Magnolia, Yellow-rumped, Black-and-white, Blackthroated Blue, Black-throated Green, Prairie, Blackpoll, Pine, Canada, Worm-eating, and Northern Waterthrush (Appendix B). Shorebirds Migrating shorebirds were detected on 16 islands, with the highest counts occurring on Snake, Rainsford, and Great Brewster Islands from late July through late August (Table 2). Twelve species were observed during fall migration, with the greatest species richness on Snake (10), but the greatest number of individuals on Rainsford. For example, on one day (21 August 2002), a total of 494 individuals of three species, Black-bellied Plover (Pluvialis squatarola (L.)), Semipalmated Plover (Charadrius semipalmatus Bonaparte), and Ruddy Turnstone (Arenaria interpres (L.)) were observed on the rocky/sandy beaches of Rainsford. During most sightings, individuals appeared to be resting rather than feeding, although some feeding activity likely occurred on the mudflats of Snake. Some shorebirds were also observed incidentally at other times during the season; for example, 32 Purple Sandpipers (Calidris maritima (Brünnich)) were noted on Green Island on 21 May 2002. Discussion Although Boston Harbor is adjacent to the largest metropolitan area in New England with 3.3 million people (US Census Bureau, 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 155 Table 2. Maximum number of shorebirds detected on various islands in Boston Harbor, 2002; - = not detected. BM = Bumpkin, BT = Button, C = Calf, D = Deer, GA = Gallops, GR = Grape, GB = Great Brewster, GN = Green, LA = Langlee, LC = Little Calf, LO = Lovells, MB = Middle Brewster, OB = Outer Brewster, P = Peddocks, RG = Ragged, RN = Rainsford, S = Sarah, SH = Sheep, SL = Slate, SN = Snake, SP = Spectacle, T = Thompson, W = Worlds End. Species BT C GA GB GN HA LA LC LO MB P RN SH SL SN SP T W Black-bellied Plover - - 7 5 - - - - 7 - 1 22 2 1 49 - 2 - Semipalmated Plover 1 - - 38 - - - - 14 - 2 241 - - 8 8 3 - Willet - - - - - 1 - - - - - - - - 78 - - - Greater Yellowlegs 1 - - - - - 1 - - - 1 - - - 83 - 2 11 Lesser Yellowlegs - - - - - - - - - - - - - - 11 - 1 - Whimbrel - - - 2 - - - - - - - - - 3 - - - - Ruddy Turnstone - - 12 33 - - - 2 7 1 14 116 2 - 9 - 2 - Purple Sandpiper - - - - 97 - - - - - - - - - - - - - Sanderling - - - 1 - - - - - - 3 - - - - - - - Semipalmated Sandpiper - 1 - 4 - - - - 43 1 1 35 - - 27 - 5 - Western Sandpiper - - - - - - - - 4 - - - - - 4 - - - White-rumped Sandpiper - - - - - - - - - - - - - - 5 - - - Dowitcher spp. - - - - - - - - - - - - - - 89 - 5 - 156 Northeastern Naturalist Vol. 12, Special Issue 3 2000 Census; www.census.gov), the diversity of birds nesting in Boston Harbor is high. Many species nest on islands throughout the harbor, with a broad array of migrants also using the area during spring and fall migration. Large numbers of seabirds nest on offshore islands in the harbor including Double-crested Cormorants, Herring Gulls, and Great Black-backed Gulls, and colonial waterbirds nest in several colonies throughout the harbor. Apparently there has been a major redistribution of cormorants nesting on some of the outer islands. In 1984, 885 cormorant nests were recorded on Shag Rocks and 94 nests on Middle Brewster (Andrews 1990), whereas now most cormorants nest on Middle Brewster (approximately 700–800 pairs) and we documented fewer than 200 nests on Shag Rocks. Yet the cumulative number of cormorants has remained relatively stable over the last 20 years (Hatch 1984). There has been an apparent decline in the number of gulls nesting in Boston Harbor since the mid-1980s. Gulls no longer nest on Spectacle, where 920 pairs of Herring Gulls and 36 pairs of Great Black-backed Gulls were recorded in 1984 (Andrews 1990). Presumably, gulls stopped nesting on Spectacle due to construction activities associated with capping the island’s landfill. We estimated approximately 650 (2003) to 1200 pairs (2002) of Herring Gulls in the entire Harbor, while Andrews (1990) estimated 1400 nests on Middle Brewster, 810 nests on Calf, and 17 nests on Shag Rocks in 1984. This reduction in Herring Gulls is similar to other regions in New England, where the species has been declining after reaching a peak in the 1970s and 1980s (Rome and Ellis 2004). Our estimates of numbers of Great Black-backed Gull nests in the Harbor, 200 (2003) to 500 (2002), were more similar to those from 1984, when Andrews (1990) reported 110 pairs on Middle Brewster, 149 nests on Calf, and 3 nests on Shag Rocks. In contrast to Herring Gull populations, regional trend estimates suggest that Great Black-backed Gull numbers are still increasing on the east coast of North America (Rome and Ellis 2004). One of our most surprising findings was the abundance of nesting Common Eiders on the outer islands. Calf, in particular, had 43 pairs at the northern end of the island, and we probably missed some nests during our survey. The Common Eider is an abundant migrant and winter resident along the coast of Massachusetts, but an uncommon breeder in the state (Veit and Petersen 1993). Prior to our study, the largest reported concentration of breeding pairs (13) was observed near Buzzards Bay, Elizabeth Islands, in 1983, where they had been introduced (Veit and Petersen 1993). Crèches of ducklings are commonly observed off Cuttyhunk Island, the southernmost of the Elizabeth Islands (S. Melvin, Massachusetts Division of Fisheries and Wildlife, pers. comm.). Additional records are scarce: 1 pair at Bird Island, near Marion, MA, in 1982 and 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 157 1 female eider with 3 chicks seen near Shag Rocks in Boston Harbor, also in 1982. There are no other records of breeding pairs within Boston Harbor (Veit and Petersen 1993). Thus, Boston Harbor now has probably the largest concentration of breeding Common Eiders at the southern end of their range in the Western Atlantic. Managers interested in protecting this species should keep the public away from nesting areas from April through June. Most eider nests we found were situated under staghorn sumac; thus, this shrubby vegetation should be maintained on the north end of Calf. Overhanging vegetation is frequently preferred as a microhabitat by eiders to make nests less visible to avian predators (e.g., Great Black-backed Gulls) (Goudie et al. 2001). In addition, once chicks hatched, we observed that they moved away from terrestrial nesting areas to protected coves, where they formed large crèches. Because it was early in the recreational boating season, we did not observe many boaters around the outer islands. Yet, the potential for disturbances to eider chicks by boaters, which in turn can result in increased predation on chicks by gulls, should be considered. Although we found some rather large wading bird colonies on several islands, the number of wading birds in the harbor has declined significantly over the past decade. In 1994, Parsons et al. (2001) estimated 725 nests on Sarah, with about 550 pairs of Black-crowned Night-Herons and 148 pairs of Snowy Egrets, which represented over 20% of the state’s nesting population (Blodget and Livingston 1996). In addition, the Black-crowned Night-Heron colony on Middle Brewster was much larger in 1985 with 124 pairs (Andrews 1990) and 207 pairs in 1994 (Blodget and Livingston 1996), compared to the 14 pairs we estimated in 2003. Small heronries were present on Spectacle before capping of the landfill (40 pairs of Snowy Egrets and 1 pair of Great Egret; Andrews 1990), and on Peddocks and Gallops until presumably driven away by increased visitation in the 1980s (Hatch 1982, Nove 2001). In 1978, three active colonies, consisting predominantly of Black-crowned Night-Herons, existed in Boston Harbor on Spectacle, Peddocks, and Middle Brewster (Osborn and Custer 1978). Reasons for these declines are uncertain, but negative population trends should be a management concern. We detected at least 16 pairs of American Oystercatchers on 14 islands during 2003 surveys. This suggests their population has increased significantly in the last decade, as only 1–2 pairs were recorded in Boston Harbor in 1989 (Veit and Petersen 1993), and in the early 1990s they were recorded nesting only on Slate, Lovells, and Snake (Nove 2001). The historic breeding range of the American Oystercatcher included the entire Atlantic Coast as far north as Labrador, but this species disappeared from the northern part of its range by the mid-nineteenth century (Mawhinney et al. 1999). Today it has reoccupied much of its historic breeding range from Virginia 158 Northeastern Naturalist Vol. 12, Special Issue 3 to Massachusetts (Mawhinney et al. 1999), and is an uncommon but widely distributed breeder in Massachusetts (Veit and Petersen 1993). Sightings in 1997 of a breeding pair in Maine and another in Nova Scotia suggest this species may be expanding its range even further (Mawhinney et al. 1999). Human disturbance to waterbird colonies can have detrimental effects on nesting success and juvenile survival (Carney and Sydeman 1999). Therefore, steps should be taken to ensure that human disturbance to these sites is minimized. Strong efforts should be made to stop the public from disturbing these colony sites during the breeding season from May through the end of July (Kushlan et al. 2002). Educational signage and symbolic fencing (i.e., single ropes tied between poles with warning signs) can be effective in tern nesting areas (Blodget and Melvin 1996), and should be implemented as a management strategy for tern colonies on Rainsford and Snake. The islands tended to have a low diversity of nesting landbirds. This is probably because the islands are small (the terrestrial area of 50% of the islands is ≤ 5 ha; Bell et al. 2002), and the forest structure is not well developed and is dominated by second-growth forests of non-native species (Elliman 2005); therefore, most forest specialists do not breed on the islands. Some species thrived in this environment (e.g., Song Sparrow, Red-winged Blackbird), but most species were found on only a few islands. Avian diversity could be increased on the islands with some focused management strategies. For example, grassland habitats could be enhanced on Spectacle by cutting down planted trees, and annual or biennial mowing could be conducted to prevent the encroachment of shrubs and trees. However, this mowing should not take place from 1 May to 31 July to prevent mortality of eggs or unfledged chicks. Savannah Sparrows have apparently already become established at the restored landfill on Spectacle Island. The importance of selected islands (particularly Snake, Rainsford, and Great Brewster) as shorebird habitat during migration is evident, both from our study and from previous studies. Although little regular monitoring of the islands for shorebirds has taken place, some records do exist for some islands, such as Snake. The TASL group also conducted surveys for shorebirds during fall 1996–1998 (Soheil Zendeh, pers. comm.). In addition, sporadic counts by various groups reported to the International Shorebird Surveys (ISS) and Manomet Center for Conservation Sciences took place primarily on Snake Island from 1972 to 2000 (ISS, unpubl. data). The absence of historical shorebird surveys on many islands points to the importance of regular monitoring of shorebirds in the future on many more of the islands in Boston Harbor. A notable high count from ISS and TASL data is an estimate of 5647 individuals of 15 species on 20 July 1980, including 5000 Semipalmated 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 159 Sandpipers (Calidris pusilla (L.)) on Snake Island (compared to our high count of 27 in late July 2002). Eleven species seen in the ISS censuses on Snake were not seen on any islands during our counts in 2002 including Hudsonian Godwit (Limosa haemastica (L.)), Marbled Godwit (L. fedoa (L.)), Piping Plover (Charadrius melodus Ord.), Least Sandpiper (Calidris minutilla Vieillot), Dunlin (C. alpina (L.)), and Red Knot (C. canutus (L.)). Over nine years, ISS counts varied widely from zero to thousands of individuals, without a readily apparent trend over time. Such fluctuations may reflect the irregular nature of shorebird migrations; however, several species have not been reported to ISS or noted by TASL since the mid-1980s, and were not present in our counts. The current absence of certain species in the harbor may also reflect altered nutrient availability due to changing effluent regimes since the late 1990s (Rex et al. 2002), and/or actual declines of some species that have been observed worldwide (e.g., Red Knots; Harrington 1996). Such declines point to the pressing need for undisturbed migration habitat that has a minimum of human disturbance (Pfister et al. 1992), such as at Snake Island, to provide potential refugia along an increasingly developed coastline. Acknowledgments We thank Lisa Cavallaro for assistance with establishing point count stations before the 2002 field season and help with report writing. Deb DiQuinzio and Marc Albert (National Park Service) provided excellent logistical support. Russ Bowles, Frank Frazier, and John Cotter (Universtiy of Massachussets–Boston) provided boat support and transportation on the water. Bradley White conducted point counts during the 2003 field season. Polly Stevens shared her time and knowledge of the islands. Brian Harrington and the International Shorebird Surveys (Manomet Center for Conservation Sciences) provided ISS data and Soheil Zendeh made TASL data available. Sara Stevens provided database support and Beth Johnson (both with NPS Inventory and Monitoring Program) assisted this project in numerous ways. We thank the US Coast Guard, Massachusetts Department of Environmental Management, Massachusetts Water Resources Authority, Metropolitan District Commission, Massachusetts Port Authority, City of Boston, Boston Redevelopment Authority, Thompson Island Outward Bound Education Center, The Trustees of Reservations, Island Alliance, and Boston Harbor Islands Advisory Council for access to islands. Financial support for this project was provided by the National Park Service Inventory and Monitoring program. Literature Cited Andrews, R. (Compiler). 1990. Coastal Waterbird Colonies: Maine to Virginia 1984–1985. US Fish and Wildlife Service, Newton Corner, MA. 429 pp. Bell, R., M. Chandler, R. Buchsbaum, and C. Roman. 2002. Inventory of intertidal habitats: Boston Harbor Islands, a national park area. Technical Report NPS/NERBOST/NTR–2004/1, National Park Service, Northeast Region, 15 State Street, Boston, MA. 138 pp. 160 Northeastern Naturalist Vol. 12, Special Issue 3 Blodget, B.G., and J.E. Livingston. 1996. Coastal colony-nesting waterbirds: The Massachusetts status report 1994–1995. Massachusetts Wildlife 4:10–20. Blodget, B.G., and S.M. Melvin. 1996. Massachusetts Tern and Piping Plover Handbook: A Manual for Stewards. Massachusetts Division of Fisheries and Wildlife, Westborough, MA. Carney, K.M., and W.J. Sydeman. 1999. A review of human disturbance effects on nesting colonial waterbirds. Waterbirds 22:68–79. Ehrlich, P.R., D.S. Dobkin, and D. Wheye. 1988. The Birder’s Handbook: A Natural History of North American Birds. Simon and Schuster, Inc., New York, NY. 785 pp. Elliman, T. 2005. Vascular flora and plant communities of the Boston Harbor Islands . Northeastern Naturalist 12(Special Issue 3):49–74. Fancy, S.G. 2000. Guidance for the design of sampling schemes for inventory and monitoring of biological resources in national parks. Unpubl. Final Report. National Park Service, Washington, DC. 10 pp. Goudie, R.I., G.J. Robertson, and A. Reed. 2001. Common Eider (Somateria mollissima). In A. Poole and F. Gill (Eds.). The Birds of North America, No. 618, The Birds of North America, Inc., Philadelphia, PA. Harrington, B. 1996. The Flight of the Red Knot: A Natural History Account of a Small Bird’s Annual Migration from the Arctic Circle to the Tip of South America and Back. W.W. Norton and Co., New York, NY. 192 pp. Hatch, J.J. 1982. The cormorants of Boston Harbor and Massachusetts Bay. Bird Observer of Eastern Massachusetts 10:65–73. Hatch, J.J. 1984. Rapid increase of Double-crested Cormorants nesting in southern New England. American Birds 1984:984–988. Hatch, J.J. 2001. Tern nesting in Boston Harbor: The importance of artificial sites. Bird Observer 29:187–193. Johnson, C.M., and W.B. Krohn. 2001. The importance of survey timing in monitoring breeding seabird numbers. Waterbirds 24:22–33. Kushlan, J.A., M.J. Steinkamp, K.C. Parsons, J. Capp, M. Acosta Cruz, M. Coulter, I. Davidson, L. Donay, N. Edelson, R. Elliot, R.M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler, and K. Wohl. 2002. Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Waterbird Conservation for the Americas, Washington, DC. 78 pp. Mawhinney, K., B. Allen, and B. Benedict. 1999. Status of the American Oystercatcher, Haematopus palliatus, on the Atlantic coast. Northeastern Naturalist 6:177–182. Nove, J. 2001. Birding the Boston Harbor Islands. Bird Observer 29:173–186. Osborn, R.G., and T.W. Custer. 1978. Herons and Their Allies: Atlas of Atlantic Coast Colonies, 1975 and 1976. Biological Services Program, US Fish and Wildlife Service. FWS/OBS-77/08. 209 pp. Parsons, K.C., S.R. Schmidt, and A.C. Matz. 2001. Regional patterns of wading bird productivity in Northeastern US estuaries. Waterbirds 24:323–330. Pfister, C., B.A. Harrington, and M. Lavine. 1992. The impact of human disturbance on shorebirds at a migration staging area. Biological Conservation 60:115–126. 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 161 Ralph, C.J., S. Droege, and J.R. Sauer. 1995. Managing and monitoring birds using point counts: Standards and applications. Pp. 161–168, In Ralph, C.J., S. Droege, and J.R. Sauer (Eds.). Monitoring Bird Populations by Point Counts, USDA Forest Service, Pacific Southwest Research Station, General Technical Report PSW-GTR-149. Rex, A.C., D. Wu, K. Coughlin, M. Hall, K.E. Keay, and D.I. Taylor. 2002. The state of Boston Harbor: Mapping the harbor’s recovery. Massachusetts Water Resources Authority Technical Report No. 2002-09, Boston, MA. 41 pp. Rome, M.S., and J.C. Ellis. 2004. Foraging ecology and interactions between Herring Gulls and Great Black-backed Gulls in New England. Waterbirds 27:200–210. Stanton, P.B. 1977. Eider duck transplant experiments on Penikese Island. Transactions of Northeast Fish and Wildlife Conference 34:65–70. Veit, R.R., and W.R. Petersen. 1993. Birds of Massachusetts. Natural History of New England Series. Massachusetts Audubon Society. 514 pp. 162 Northeastern Naturalist Vol. 12, Special Issue 3 Appendix A. Mean (± SE) number of landbirds detected per station during point counts in late May and June, 2002–2003, on islands in Boston Harbor. Counts from both years are combined. Boldface indicates islands where species is suspected of breeding; P = present, < 0.05 individuals per station; F = flying over only; B = probably breeding on island, but < 0.05 individuals per station. BM = Bumpkin, BT = Button, C = Calf, D = Deer, GA = Gallops, G = Georges, GR = Grape, GB = Great Brewster, LA = Langlee, LO = Lovells, OB = Outer Brewster, P = Peddocks, RG = Ragged, RN = Rainsford, S = Sarah, SL = Slate, SN = Snake, SP = Spectacle, T = Thompson, W = Worlds End. # Islands Species Breeding BM BT C D GA G GR GB LA LO OB P RG RN S SL SN SP T W Osprey 1 0 0 0 0 0 0 0 0 0 0.1 0 0 0 0 0 0 0 0 B 0 (0.1) Red-tailed Hawk 0 0 0 0 0 0.2 0 0 0 0 0.1 0 F 0 0 0 0 0 F 0 F (0.2) (0.1) American Kestrel 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 F 0 0.1 (0.1) Ring-necked Pheasant 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.3 0 (0.1) Northern Bobwhite 0 0 0 0 0 0 0 0 0 0 0 0 B 0 0 0 0 0 0 0 0 Rock Dove 0 0 0 0 1.1 0 2.3 0 0 0 0.1 0 0 0 0 0 0 0 0 0.1 0 (0.4) (1.2) (0.1) (0.1) Mourning Dove 3 0 0 0 0 0 0.8 0.1 0.3 0.3 0.2 0 0.5 0 0 0 0 0 0 0.6 0.3 (0.5) (0.1) (0.3) (0.3) (0.2) (0.1) (0.1) (0.1) Great Horned Owl 0 P 0 0 0 0 0 0 P 0 0 0 0 0.3 0 0 0 0 0 0 0 (0.3) Chimney Swift 2 0 0 0 0 0 0 0.1 0 0 0 0 P 0 0 0 0 0 0.1 0.1 0 (0.1) (0.1) (0.1) Downy Woodpecker 3 B 0 0 0 0 0 P 0 0 P 0 B 0 0 0 0 0 0 B 0.3 (0.1) Belted Kingfisher 1 0 0 0 0 0 0 0 0 0 0 0 0.1 0 0 0 0 0 0 0 0 (0.1) 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 163 # Islands Species Breeding BM BT C D GA G GR GB LA LO OB P RG RN S SL SN SP T W Northern Flicker 3 0.3 0 0 0 0 0 0.1 0 0 0 0 B 0 0 0 0 0 0 0.1 0.1 (0.3) (0.1) (0.5) (0.1) Eastern Wood-Pewee 2 0 0 0 0 0 0 P 0 0 0 0 B 0 0 0 0 0 0 0 B Willow Flycatcher 4 0.5 0 0 0 0 0 0.5 0 0 0 0 0.1 0 0 0 0 0 0.1 0.1 0 (0.3) (0.2) (0.1) (0.1) (0.1) Eastern Phoebe 3 0 0 0 0.1 0 0 0 0 0 B 0 B 0 0 0 0 0 0 P B (0.1) Great Crested 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 P Flycatcher (0.1) Eastern Kingbird 3 0 0 0.3 0 0 0 0 P 0 0 0 B 0 0 0 0 0 0.1 0 0.2 (0.3) (0.1) (0.1) Warbling Vireo 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.2 (0.1) Red-eyed Vireo 1 P 0 0 0 0 0 0 0 0 0 0 0.1 0 0 0 0 0 0 0 0.1 (0.1) (0.1) Blue Jay 4 0.3 0 0 0.1 0 0.2 0 0 0 0.1 0 0.2 0 0 0 0 0 0 0.2 0.2 (0.3) (0.1) (0.2) (0.1) (0.1) (0.1) (0.1) Brown Thrasher 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 0 (0.1) American Crow 3 1.0 P 0.8 0.3 P 0 0.7 1.3 P 0.7 F 0.7 4.3 0.3 0 0.3 0 0.2 1.3 0.3 (0.4) (0.5) (0.1) (0.3) (1.3) (0.1) (0.2) (3.8) (0.3) (0.3) (0.1) (0.3) (0.1) Tree Swallow 3 0 0 0 0 0 0.1 0.1 0 0 0 0 0.1 0 0 0 0 0 0 0.5 0.1 (0.1) (0.1) (0.1) (0.2) (0.1) Northern Rough- 3 0 0 0 0.9 F 0 0 0 0 0 0 B 0 F 0 0 0 0 0.4 0 winged Swallow (0.3) (0.3) Bank Swallow 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.2 0 0 (0.2) Barn Swallow 11 0 0 F 2.1 F 4.6 0 2.0 0 2.4 F 0.5 0 B 0 0 1.5 0.2 0.2 0 (0.5) (1.2) (1.0) (1.0) (0.2) (1.5) (0.1) (0.1) 164 Northeastern Naturalist Vol. 12, Special Issue 3 # Islands Species Breeding BM BT C D GA G GR GB LA LO OB P RG RN S SL SN SP T W Black-capped 6 0.3 0 0 0 0 0.1 0.2 0 0 0 0 0.1 0 0 0 0 0 P 0.1 0.7 Chickadee (0.3) (0.1) (0.1) (0.1) (0.1) (0.3) Tufted Titmouse 1 0 0 0 0 0 0 0 0 0 0 0 P 0 0 0 0 0 0 0 0.3 (0.1) White-breasted 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 Nuthatch (0.1) House Wren 3 P 0 0.3 0 0 0 0 0 0 0 0 B 0 0 0 0 0 0 0 B (0.3) Eastern Bluebird 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 B American Robin 2 0 0 0 0.1 0 0 0 0 0 0 0 0.6 0 0 0 0 0 0 1.3 0.3 (0.1) (0.1) (0.3) (0.1) Gray Catbird 12 2.5 0 P 0 0 0.1 2.8 B 1.0 1.0 P 0.7 1.3 0.3 0 1.5 0 0 1.0 1.0 (1.2) (0.1) (0.5) (0.6) (0.3) (0.1) (0.3) (0.3) (0.5) (0.2) (0.2) Northern Mockingbird 3 0 0 0 0.2 0 0.3 0 P 0 0.1 0 0.1 0 0 0 0 0 0 0.3 0.1 (0.1) (0.2) (0.1) (0.1) (0.1) (0.1 ) European Starling 7 0 0 0 6.3 0 1.4 0 B 0 5.8 0 1.0 0 0 0 0 0 3.9 3.9 0.8 (1.9) (0.7) (3.4) (0.3) (2.7) (0.8) (0.4) Carolina Wren 5 0 0 P 0 0 0 0.1 B 0 0.1 0 0.5 0 0 0 0 0 0 0 0.2 (0.1) (0.1) (0.1) (0.1) Cedar Waxwing 1 0.5 0 0 0 0 0 0.4 0 0 0.5 0 1.0 4.0 0 0 0 0 0.2 0.6 0.3 (0.5) (0.2) (0.3) (0.3) (2.3) (0.1) (0.2) (0.2) Yellow Warbler 16 2.0 0 0.8 0 B 0.1 1.8 1.3 0.7 1.3 0 1.1 0.7 0.7 0.5 0.75 1.5 0 0.9 0.9 (1.4) (0.3) (0.1) (0.2) (1.3) (0.7) (0.4) (1.1) (0.3) (0.3) (0.5) (0.2) (0.2) Common Yellowthroat 9 1.5 0 0.3 0 0.2 0 0.4 0.7 0 0.3 B 0.4 0 0 0 0.5 0 0 0.5 0.3 (0.3) (0.3) (0.2) (0.1) (0.3) (0.1) (0.1) (0.3) (0.1) (0.1) American Redstart 1 P 0 P 0 0 0 0 P 0 0 0 0.1 0 0 0 0.3 0 0 0 0.2 (0.1) (0.3) (0.1) Scarlet Tanager 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 B 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 165 # Islands Species Breeding BM BT C D GA G GR GB LA LO OB P RG RN S SL SN SP T W Chipping Sparrow 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 B Savannah Sparrow 1 0 0 P 0 0 0 0 P 0 0 P P 0 0 0 0 0 0.2 P P (0.1) Song Sparrow 21 3.3 1.5 1.8 0.2 0.8 0.9 2.9 2.3 03.0 2.4 B 1.6 3.0 2.0 2.0 1.0 0.5 1.6 1.7 1.2 (0.3) (1.5) (0.8) (0.1) (0.2) (0.3) (0.4) (1.3) (0.0) (0.5) (0.2) (0.6) (0.6) (0.0) (0.4) (0.5) (0.3) (0.1) (0.2) Northern Cardinal 6 0.3 0 P 0 0 0.1 0.5 P B 0.2 0 0.4 B 0 0 0.3 0 0 0.6 0.4 (0.3) (0.1) (0.1) (0.2) (0.1) (0.3) (0.2) (0.1) Indigo Bunting 1 0 0 0 0 0 0 0 0 0 0 0 B 0 0 0 0 0 0 0 0 Bobolink 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.7 (0.2) Red-winged Blackbird 16 0.3 0 1.0 0.8 0.2 2.7 0.1 1.7 0 0.8 B 0.9 0 1.7 0 0 4.0 6.3 1.1 3.5 (0.3) (0.6) (0.4) (0.2) (0.9) (0.1) (0.9) (0.4) (0.3) (2.0) (1.4) (0.2) (0.6) Common Grackle 7 0.5 1.0 0.3 0.3 0.2 0.6 1.4 0.3 0.7 0.3 P 1.2 0.7 0 1.0 0.3 1.5 0.3 2.6 1.2 (0.3) (1.0) (0.3) (0.3) (0.2) (0.2) (0.7) (0.3) (0.3) (0.2) (0.3) (0.7) (1.0) (0.3) (0.5) (0.1) (0.6) (0.3) Brown-headed Cowbird 5 0 0 0 0 0 0 0.7 0 0 0.1 0 P 0 0 0.5 0 0 0 0.2 P (0.3) (0.1) (0.5) (0.1) Orchard Oriole 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.2 (0.1) Baltimore Oriole 2 0 0 0 0 0 0 0 P 0 0 0 0.1 0 0 0 0 0 0 0 0.2 (0.1) (0.1) House Finch 3 0 0 0 0.2 0 0.4 0 0 0 0 0 0.3 0 0 0 0 0 0 0.1 B (0.2) (0.2) (0.2) (0.1) American Goldfinch 6 0.8 0 P 0.1 0 0.9 2.41 1.3 0 2.1 0 1.0 F 4.3 0 2.5 1.0 0.2 0.9 0.9 (0.5) (0.1) (0.6) (0.7) (1.3) (0.4) (0.2) (0.3) (0.4) (1.0) (0.1) (0.2) House Sparrow 2 0 0 0 0.9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.4 0.2 (0.4) (0.3) (0.1) Total number of breeding species 7 1 5 7 4 9 12 9 4 11 4 35 4 5 1 3 3 10 28 34 166 Northeastern Naturalist Vol. 12, Special Issue 3 Appendix B. Migratory birds detected in Boston Harbor during summer months in 2001–2003 that apparently do not nest in the Harbor. P = present, OW = on water near island, F = flying over area, - = not detected. BM = Bumpkin, BT = Button, C = Calf, D = Deer, GA = Gallops, GR = Grape, GB = Great Brewster, GN = Green, LA = Langlee, LC = Little Calf, LO = Lovells, MB = Middle Brewster, OB = Outer Brewster, P = Peddocks, RG = Ragged, RN = Rainsford, S = Sarah, SH = Sheep, SL = Slate, SN = Snake, SP = Spectacle, T = Thompson, W = Worlds End. Species BM BT C D GA GR GB GN LA LC LO MB OB P RG RN S SH SL SN SP T W Common Loon - - OW - - - - - - - - - - - - OW - - - - - - - Red-throated Loon - - - - - - - - - - - - - OW - - - - - - - - - Wilson’s Storm-Petrel - - - OW - - - OW - - - OW OW - - OW - - - - OW - - Northern Gannet - - - - - - - - - - - OW - OW - - - OW - - - - - Tricolored Heron - - - - - - - - - - - - - - - - - - - - - - P Brant - - - - - P P P - - - P - - - - P - - - P - - Black Scoter - - - - - - OW - - - - - - - - - - - - - - - - White-winged Scoter - - - - - - P - - - - - - - - - - - - - F - - Long-tailed Duck - - - - - - - - - - - - - - - OW - - - - - - - Bufflehead - - - - - - - - - - - - - OW - - - - - - - - - Red-breasted Merganser - - - - OW - - - - OW - - OW - - - - - - - - - - Black-bellied Plover - - - - P - P - - - P - - P - P - F P P - P - Semipalmated Plover - P - - - - P - - - P - - F - P - - - P - P - Greater Yellowlegs - P - - - - - - P - - - - P - - - - - P - P P Lesser Yellowlegs - - - - - - - - - - - - - - - - - - - P - P - Whimbrel - - - - - - P - - - - - - - - - - - F - P - - Ruddy Turnstone - - - - P - P - - P P P - P - P - P - P - P - Purple Sandpiper - - - - - - - P P - - - - - - - - - - - - - - Sanderling - - - - - - P - - - - - - F - - - - - - - - - Semipalmated Sandpiper - - P - - - P - - - - P F P - P - - - P - P - 2005 P.W.C. Paton, R.J. Harris, and C.L. Trocki 167 Species BM BT C D GA GR GB GN LA LC LO MB OB P RG RN S SH SL SN SP T W Western Sandpiper - - - - - - - - - - P - - - - - - - - P - - -White-rumped Sandpiper - - - - - - - - - - - - - - - - - - - P - - - Dowitcher spp. - - - - - - - - - - - - - - - - - - - P - F - American Woodcock - - - - - - - - - - - - - P - - - - - - - - - Laughing Gull - - P - - - P - - - F - - P - P - - - P P P - Bonaparte’s Gull P - - - - - P - - - - - - P - - - - - P - P - Ring-billed Gull P P - - - - - - - - P - - P - P - - - - - P - Royal Tern - - - - - - - - - - - - - - - - - - - - - P - Turkey Vulture - - - - - - - - - - - - - - - - - - - - - - F Cooper’s Hawk - - - - - - - - - - - - - - - - - - - - - - F Sharp-shinned Hawk - - - - - - - - - - - - - - - - - - - - - - F Peregrine Falcon - - - - - - - - - - - - - - - - - - - - F F - Razorbill - - - - - - - - - - - - OW - - - - - - - - - - Black Guillemot - - - - - - - - - - - - OW - - - - - - - - - - Red-bellied Woodpecker - - - - - - - - - - - - - - - - - - - - - - P Fish Crow - - - - - - - - - - - - - - - - - - - - - - P Red-breasted Nuthatch - - - - - - - - - - - - - - - - - - - - - - P Wood Thrush - - - - - - - - - - - - - - - - - - - - - P - Swainson’s Thrush - - - - - - - - - - - - - P - - - - - - - - - Nashville Warbler - - - - - - - - - - - - - - - - - - - - - - P Northern Parula - - - - - - - - - - - - - - - - - - - - - P P Ruby-crowned Kinglet - - - - - - - - - - - - - - - - - - - - - P P Chestnut-sided Warbler P - - - - - - - - - - - P - - - - - - - - - P Cape May Warbler - - - - - - - - - - - - - - - - - - - - - - P Magnolia Warbler - - P - - - - - - - - - - P - - - - - - - - P Yellow-rumped Warbler - - - - - - - - - - - - - P - - - - - - - P P 168 Northeastern Naturalist Vol. 12, Special Issue 3 Species BM BT C D GA GR GB GN LA LC LO MB OB P RG RN S SH SL SN SP T W Black-and-white Warbler - - - - - - - - - - - - - - - - - - - - - - P Black-throated Blue Warbler - - - - - - - - - - - - - P - - - - - - - - P Black-throated Green Warbler - - - - - - - - - - - - - P - - - - - - - - P Prairie Warbler - - - - - - - - - - - - - - - - - - - - - - P Blackpoll Warbler - - P - - - - - - - - - - P - - - - - - - P P Pine Warbler - - - - - - - - - - - - - - - - - - - - - - P Canada Warbler - - P - - - P - - - - - - - - - - - - - - - - Worm-eating Warbler - - - - - - - - - - - - - P - - - - - - - - - Northern Waterthrush - - - - - - - - - - - - - - - - - - - - - - P Swamp Sparrow - - - - - - P - - - - - - - - - - - - - P - - White-throated Sparrow - - - - - - - - - - - - - P - - - - - - P P P Dark-eyed Junco - - - - - - - - - - - - - P - - - - - - - P - Purple Finch - - - - - - - - - - - - - - - - - - - - - - P