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Remote sensing has long been used to study wildlife; however, manual methods of detecting wildlife in aerial imagery are often time-consuming and prone to human error, and newer computer vision tec...

Eavesdropping on heterospecific alarm calls is a crucial source of information for many species (including corvids) and it is effective especially if these species form mixed-species flocks, have a similar spectrum of predators, and share habitat. Previous research on wild common ravens (Corvus corax) has shown that they react to the jackdaws’ alarm call. We tested their responses to the heterospecific alarm calls of various bird species differing in familiarity and taxonomical relatedness to ravens. Two other corvid species (the blue jay Cyanocitta cristata and the European jay Garrulus glandarius) and two non-corvids (the black-headed gull Chroicocephalus ridibundus and the laughing gull Leucophaeus atricilla) were presented. We played back the tested alarm calls to free-ranging ravens at a feeding site and observed the ravens’ responses to particular stimuli. We observed three behavioural responses made by the tested ravens: flying away, freezing (ceasing to move and crouching on the ground), and vigilance (observing the surroundings). The ravens responded to the Eurasian jay alarm call by freezing and flying away and to the blue jay alarm call by freezing and vigilance. The laughing gull alarm call induced mostly vigilance and the black-headed gull alarm call did not elicit any reaction. The responses to the alarm calls of both jays were similar to the responses to the playbacks of conspecific alarm calls, used as control (as well as to the response to a jackdaw alarm call from the previous study), which may point to the existence of a specific corvid characteristic in their alarm calls. The response to the alarm calls of both American species included vigilance, which suggests an uncertainty about the meaning of the call.

Mercury (Hg) and cadmium (Cd) concentrations in eggs of 8 seabird species inhabiting 5 coastal ecosystems in Sinaloa, Mexico were determined during 2 breeding seasons (2012 and 2013): blue-footed booby (Sula nebouxii), brown booby (Sula leucogaster), double-crested cormorant (Phalacrocorax auritus), magnificent frigatebird (Fregata magnificens), brown pelican (Pelecanus occidentalis), royal tern (Thalasseus maximus), laughing gull (Leucophaeus atricilla), and Heermann's gull (Larus heermanni). The interspecific differences found in the concentrations of both metals were attributed to the diet and foraging ecology of the species. The highest Hg concentrations were detected in piscivorous species (brown pelican, 0.42 µg/g; brown booby, 0.31 µg/g; blue-footed booby, 0.26 µg/g; and double-crested cormorant, 0.23 µg/g); whereas species with more varied diets presented the highest Cd concentrations (Heermann's gull, 0.31 µg/g; laughing gull, 0.27 µg/g; and magnificent frigatebird, 0.27 µg/g). Cadmium concentrations were significantly greater in 2013 than 2012 for most species, and brown pelican and laughing gull also had higher Hg concentrations in 2013 in Santa Maria Bay, suggesting a relationship as a result of the changes either in oceanographic conditions or in continental runoff. Mercury concentrations in brown pelican and Cd concentrations in Heermann's gull and laughing gull were above threshold levels for adverse effects on reproduction and survival. Environ Toxicol Chem 2016;35:2330-2338. �� 2016 SETAC.

Delaware Bay, US is the only documented location where influenza A virus (IAV) is consistently detected in a shorebird species, the Ruddy Turnstone (RUTU; Arenaria interpres morinella). Although IAV in shorebirds has been well studied at this site for decades, the importance of other species in the avian community as potential sources for the IAVs that infect RUTUs each spring remains unclear. We determined the susceptibility of Mallards (Anas platyrhynchos) and Laughing Gulls (Leucophaeus atricilla), to IAVs isolated from RUTUs in order to gain insight into the potential host range of these viruses. Captive-reared gulls were challenged with RUTU-origin H6N1, H10N7, H11N9, H12N4, and H13N6 IAV, as well as Mallard-origin H6N1 and H11N9. We challenged captive-reared Mallards with the same viruses, except for H13N6. At a biologically plausible challenge dose (10(4) 50% embryo infective doses/0.1 mL), one of five gulls challenged with both H6N1 IAVs shed virus. The remaining gulls were resistant to infection with all viruses. In contrast, all Mallards were infected and shed virus. The H12N4 Mallard challenge group was an exception with no birds infected. These results indicated that Mallards are permissive to infection with viruses originating from a shorebird host and that interspecies transmission could occur. In contrast, host adaptation of IAVs to RUTUs may compromise their ability to be transmitted back to gulls.

Rynchops niger (Black Skimmer) is a colonial-nesting seabird that nests on open, sandy or gravel beaches. In densely populated Pinellas County, FL, Black Skimmer colonies often occur on municipal beaches where there is relatively little mammalian predation, but intense predation by Corvus ossifragus (Fish Crow) and Leucophaeus atricilla (Laughing Gull). In 2013, a previously successful Black Skimmer colony experienced high egg-loss due to Fish Crow predation. To determine if effigies would decrease egg depredation in the middle of the breeding season, we monitored the number of crow-foraging passes over the colony and number of eggs taken before and after we placed 6 crow effigies among the nests. During 36 hours of monitoring, we observed 83 foraging passes and 28 eggs being taken by Fish Crows. Neither foraging passes nor eggs taken decreased after the placement of the effigies, and the Black Skimmers abandoned their nests. Future research should focus on other methods to limit nest predation a...

Laguna Cuyutlán (Colima, Mexico), an Important Bird Area, used to provide breeding habitat for ground-nesting waterbirds. During 2014 and 2015, nesting efforts of laughing gull, black skimmer, and royal, gull-billed and Forster's terns failed almost completely due to inundation, while least terns and snowy plovers fared the same during 2014. No anomalies in rainfall, tidal level, or coseismic subsidence explained such failure. Rather, the inundations were due to the enlarging of Canal Tepalcates that connects the lagoon with the sea, which was widened from 100 to 300 m and dredged to 17-m deep. Before this, the hydrodynamics were regulated by evaporation and runoff. Now, increased seawater volumes dominate the basin's hydrodynamics. The failure of Laguna Cuyutlán as a breeding habitat for these birds is an important threat for these species, as this lagoon held one of the < 20 colonies known for several of these species along the western coast of North and Central America. Documenting this demise of Laguna Cuyutlán for ground-nesting waterbirds transcends the regional scale as it emphasizes the little consideration still given to biodiversity vs. economic development, and is a warning for coastal projects in other developing areas of the world.

During the 2010–2011 and 2011–2012 breeding seasons (November to June), there were 21 colonies of 13 species, with at least 40,000 to 50,000 pairs of seabirds on six islands of Bahia Santa Maria-La Reforma in Mexico. Bahia Santa Maria maintains the largest breeding congregation of the west coast of Mexico for Laughing Gull (Leucophaeus atricilla; 22,000 pairs), Royal Tern (Thalasseus maximus; 11,000 pairs) and Black Skimmer (Rynchops niger; 1,500 pairs). In the past decade, most of the species that breed on El Rancho Island (coastal dune habitat) have increased their population size, apparently related to a combination of factors such as colonies recently established (and hence still expanding) and increased habitat availability. On the other hand, species breeding on islands with mangroves seem to be decreasing (in particular the Brown Pelican (Pelecanus occidentalis) population), but with no obvious reason to explain these low numbers of some species. Despite the small size of the islands used...

Two separate approaches, a carcass sampling model and an exposure probability model, provided estimates of bird mortalities of 600 000 and 800 000, respectively, from the 2010 Deepwater Horizon MC 252 oil spill in coastal waters of the Gulf of Mexico. Monte Carlo simula- tion of parameter uncertainty led to respective 95% uncertainty intervals of 320 000 to 1200 000 and 160 000 to 1900 000. Carcass sampling relied on expansion factors multiplied by counts of bird carcasses retrieved in shoreline surveys, whereas exposure probability estimated bird deaths as a product of estimated coastal bird density, average oil slick size, slick duration, and proportionate mortality due to oiling. The low proportion of small-sized carcasses recovered, compared with considerably higher proportions of small live birds in coastal Gulf habitats, indicate an especially low probability of recovery for small birds after oil spills at sea. Most mortality affected 4 species: laughing gull Leucophaeus atricilla (32% of the northern Gulf of Mexico population killed), royal tern Thalasseus maximus (15%), northern gannet Morus bassanus (8%) and brown pelican Pele- canus occidentalis (12%). Declines in laughing gulls were confirmed by ~60% reductions in National Audubon Society Christmas Bird Count data for 2010−2013 along the Gulf coast. Popu- lation-level effects in apex predators of this magnitude likely had effects on prey populations that warrant careful assessment.

The Deepwater Horizon oil spill was an ecologically devastating event in the Gulf of Mexico, which saw the estimated release of over 4 million barrels of oil after flowing for three months in 2010. The US Fish and Wildlife Service provided a data set of 7,229 bird records. We aimed to illustrate the important features of the data set utilizing a blend of analytics and graphics executed through traditional and cloud-based software. It is concluded from the graphs that the areas containing the greatest concentration of birds were nearest to the coasts adjacent to New Orleans and the Deepwater platform. Moreover, the result of the logistic regression confirmed what is seen in bar charts, that the Laughing Gull and Brown Pelican, among many others, were most mortally impacted by the oil spill. Furthermore, additional investigation into the morbidity impact on birds over time indicates a lagging effect. A similar lag is present in the oiling of the birds where a separate time series shows the oiled/not visibly oiled birds alternating in frequency over the collection period.

Response of breeding waterbird communities to the effects of hurricanes remains poorly understood. The impact of two 2008 hurricanes on the breeding waterbird community was investigated at the Isles Dernieres Barrier Island Refuge in southern Louisiana using pre- and post-hurricane survey data. After the 2008 hurricanes, the breeding community was reduced from 44,042 breeding pairs in 2008 to 27,977 pairs in 2009 and to 23,544 pairs in 2010. Populations of the five most abundant species, Brown Pelican (Pelecanus occidentalis), Laughing Gull (Leucophaeus atricilla), Royal Tern (Thallasseus maximus), Sandwich Tern (Thallasseus sandvincensis), and Black Skimmer (Rynchops niger), decreased from 2008 to 2010. In contrast, populations of Roseate Spoonbill (Platalea ajaja), Sooty Tern (Onychoprion fuscatus), and Gull-billed Tern (Gelochelidon nilotica) increased from 2008 to 2009 but declined in 2010. The dramatic decline of total breeding pairs in the year following hurricanes demonstrates the vulnera...

The explosion of the Deepwater Horizon oil rig released, millions of gallons of oil into the environment, subsequently exposing wildlife, including numerous bird species. To determine the effects of MC252 oil to species relevant to the Gulf of Mexico, studies were done examining multiple exposure scenarios and doses. In this study, laughing gulls (Leucophaeus atricilla, LAGU) were offered fish injected with MC252 oil at target doses of 5 or 10mL/kg bw per day. Dosing continued for 27 days. Of the adult, mixed-sex LAGUs used in the present study, ten of 20 oil exposed LAGUs survived to the end of the study; a total of 10 of the oil exposed LAGUs died or were euthanized within 20 days of initiation of the study. Endpoints associated with oxidative stress, hepatic total glutathione (tGSH), oxidized glutathione (GSSG) and reduced glutathione (rGSH) significantly increased as mean dose of oil increased, while the rGSH:GSSG ratio showed a non-significant negative trend with oil dose. A significant increase in 3-methyl histidine was found in oil exposed birds when compared to controls indicative of muscle wastage and may have been associated with the gross observation of diminished structural integrity in cardiac tissue. Consistent with previous oil dosing studies in birds, significant changes in liver, spleen, and kidney weight when normalized to body weight were observed. These studies indicate that mortality in response to oil dosing is relatively common and the mortality exhibited by the gulls is consistent with previous studies examining oil toxicity. Whether survival effects in the gull study were associated with weight loss, physiologic effects of oil toxicity, or a behavioral response that led the birds to reject the dosed fish is unknown.

Gulls are the known reservoir for H13 and H16 influenza A viruses (IAV) but also host a diversity of other IAV subtypes. Gulls also share habitats with both ducks and shorebirds, increasing the potential for cross-species IAV transmission. We serologically tested laughing gulls (Leucophaeus atricilla) collected at Delaware Bay during May when they were in direct contact with IAV-infected shorebirds; both species feed on horseshoe crab (Limulus polyphemus) eggs on beaches during this month. From 2010 to 2014, antibody prevalence as determined by competitive blocking enzyme-linked immunosorbent assay ranged from 25%–72%. Antibodies to H13 and H16 were detected by hemagglutination inhibition (HI) tests in 12% and 24% of tested gulls, respectively. Results from virus microneutralization (MN) tests for antibodies to H1–H12, H14, and H15 varied among years but the highest prevalence of neutralizing antibodies was detected against H1 (24%), H5 (25%), H6 (35%), H9 (33%), and H11 (42%) IAV. The subtype diversity identified by serology in gulls was dominated by Group 1 HA subtypes and only partially reflected the diversity of IAV subtypes isolated from shorebirds.

The Laughing Gull (Leucophaeus atricilla) was extripated as a breeding bird from New York State by 1900. Recolonization of coastal New York by this colonial waterbird occurred in 1979 with discovery of 15 breeding pairs in Jamaica Bay (Queens County) New York, New York. We conducted a survey of Long Island salt marsh habitats in 2008 to document if other breeding colonies of Laughing Gulls existed. We identified 66 individual possible breeding areas and field surveys were conducted in each area during June 2008. Many areas appeared to provide suitable nesting habitat (i.e., large areas of salt marsh dominated by Spartina), but no evidence of Laughing Gull nesting was found. A better understanding of Laughing Gull populations within the northeast coastal region and the effects of ongoing gull control near New York airports is needed for their conservation.

Five new species of the genus Picobia are described and illustrated: 1) P. leucophaeus sp. nov. from the Laughing Gull Leucophaeus atricilla L. (Charadriiformes: Laridae) from Texas; 2) P. troglodytes sp. nov. from the House Wren Troglodytes aedon Vieillot (Passeriformes: Troglodytidae) from California; 3) P. cardinalis sp. nov. from the Northern Cardinal Cardinalis cardinalis (L.) (Passeriformes: Cardinalidae) from Texas; 4) P. carpodacus sp. nov. from the Purple Finch Carpodacus purpureus (Gmelin) (Passeriformes: Fringillidae) from California; and 5) P. psaltriparus sp. nov. from the Bushtit Psaltriparus minimus (Townsend) (Passeriformes: Aegithalidae) from Texas. Two avian species from the family Picidae (Piciformes) are recorded as new hosts for P. dryobatis (Fritsch, 1958): the Downy Woodpecker Picoides pubescens (L.) from Texas and the Ladder-backed Woodpecker Picoides scalaris (Wagler) from California. Additionally, all named species of the genus Picobia with their host associations and di...

Laughing gulls (Larus atricilla) are commonly found in many areas of North America and little is known about their diet, particularly in coastal-urban interfaces where gull-aircraft collisions can be a serious concern. The objective of this study was to describe and quantify the consumption of terrestrial invertebrates by laughing gulls at a coastal-urban interface in the northeastern United States. We examined the stomach contents of laughing gulls (n = 1053) collected during wildlife damage management operations at John F. Kennedy International Airport during the summers of 2003 and 2004. Terrestrial invertebrates consumed by laughing gulls represented 2 taxonomic phyla, 4 classes, 15 orders and 40 families. Beetles (Coleoptera) and ants (Hymenoptera) were the most common terrestrial invertebrates consumed by laughing gulls. We found evidence of temporal (i.e., monthly) variation in the frequency of occurrence of terrestrial insects in laughing gull diets. Laughing gull gender and age did not...

We injected doses of methylmercury into the air cells of eggs of 26 species of birds and examined the dose-response curves of embryo survival. For 23 species we had adequate data to calculate the median lethal concentration (LC(50)). Based on the dose-response curves and LC(50)s, we ranked species according to their sensitivity to injected methylmercury. Although the previously published embryotoxic threshold of mercury in game farm mallards (Anas platyrhynchos) has been used as a default value to protect wild species of birds, we found that, relative to other species, mallard embryos are not very sensitive to injected methylmercury; their LC(50 )was 1.79 microg/g mercury on a wet-weight basis. Other species we categorized as also exhibiting relatively low sensitivity to injected methylmercury (their LC(50)s were 1 microg/g mercury or higher) were the hooded merganser (Lophodytes cucullatus), lesser scaup (Aythya affinis), Canada goose (Branta canadensis), double-crested cormorant (Phalacrocorax auritus), and laughing gull (Larus atricilla). Species we categorized as having medium sensitivity (their LC(50)s were greater than 0.25 microg/g mercury but less than 1 microg/g mercury) were the clapper rail (Rallus longirostris), sandhill crane (Grus canadensis), ring-necked pheasant (Phasianus colchicus), chicken (Gallus gallus), common grackle (Quiscalus quiscula), tree swallow (Tachycineta bicolor), herring gull (Larus argentatus), common tern (Sterna hirundo), royal tern (Sterna maxima), Caspian tern (Sterna caspia), great egret (Ardea alba), brown pelican (Pelecanus occidentalis), and anhinga (Anhinga anhinga). Species we categorized as exhibiting high sensitivity (their LC(50)s were less than 0.25 microg/g mercury) were the American kestrel (Falco sparverius), osprey (Pandion haliaetus), white ibis (Eudocimus albus), snowy egret (Egretta thula), and tri-colored heron (Egretta tricolor). For mallards, chickens, and ring-necked pheasants (all species for which we could compare the toxicity of our injected methylmercury with that of published reports where methylmercury was fed to breeding adults and was deposited into the egg by the mother), we found the injected mercury to be more toxic than the same amount of mercury deposited naturally by the mother. The rank order of sensitivity of these same three species to methylmercury was, however, the same whether the methylmercury was injected or maternally deposited in the egg (i.e., the ring-necked pheasant was more sensitive than the chicken, which was more sensitive than the mallard). It is important to note that the dose-response curves and LC(50)s derived from our egg injections are useful for ranking the sensitivities of various species but are not identical to the LC(50)s that would be observed if the mother bird had put the same concentrations of mercury into her eggs; the LC(50)s of maternally deposited methylmercury would be higher.

Seabirds and other colonial waterbirds nesting in the northern Bahamas are nearly undocumented. This study is the first complete inventory of seabirds and other colonial waterbirds nesting in the northern Bahamas (including the islands of the Abacos, Grand Bahamas, Biminis, and Berries). The survey found 20,267 nests of 19 species of seabirds and other colonial waterbirds at 113 colony sites. The over 40,000 seabirds and other colonial waterbirds found nesting in the northern Bahamas doubles population estimates previously published for The Bahamas as a whole, which included few of these sites. Sooty Tern (Sterna fuscata) was the most abundant species, having a nesting population of over 10,000 pairs. Next most abundant were the Bridled Tern (Sterna anaethetus), Laughing Gull (Larus atricilla), and Brown Noddy (Sterna stolidus). This paper documents the first nesting record in the Commonwealth of The Bahamas of the White Ibis (Eudocimus albus), the first recent nesting in northern Bahamas of the ...

Gull predation is an important source of egg and chick mortality for many seabirds. From 2003-2005, the effects of gull predation and a predator control program on tern nesting success were studied at Eastern Egg Rock, Maine. In 2003, gull predation was uncontrolled, and in 2004 and 2005, attempts were made to shoot Herring (Larus argentatus), Great Black-backed (L. marinus), and Laughing (L. atricilla) gulls that preyed on Common (Sterna hirundo), Arctic (S. paradisaea), and Roseate (S. dougallii) tern adults, eggs, and chicks. To evaluate the effectiveness of gull removal, daily watches were performed from an observation tower and tern hatching and fledging success were measured annually. Despite shooting efforts in 2004-2005, many known predators could not be removed. Great Black-backed Gull predation was a function of year, tidal state, and visibility, while Herring Gull predation depended only on the stage of the tern breeding cycle. Using disappearance of eggs and chicks from monitored nest...

Five lagoonal salt marsh areas, ranging from 220 ha to 3,670 ha, were selected from Cape Cod, Massachusetts to the southern DelMarVa peninsula, Virginia, USA to examine the degree to which Spartina marsh area and microhabitats had changed from the early or mid- 1900s to recent periods. We chose areas based on their importance to migratory bird populations, agency concerns about marsh loss and sea-level rise, and availability of historic imagery. We georeferenced and processed aerial photographs from a variety of sources ranging from 1932 to 1994. Of particular interest were changes in total salt marsh area, tidal creeks, tidal flats, tidal and non-tidal ponds, and open water habitats. Nauset Marsh, within Cape Cod National Seashore, experienced an annual marsh loss of 0.40% (19% from 1947 to 1994) with most loss attributed to sand overwash and conversion to open water. At Forsythe National Wildlife Refuge in southern New Jersey, annual loss was 0.27% (17% from 1932 to 1995), with nearly equal attribution of loss to open water and tidal pond expansion. At Curlew Bay, Virginia, annual loss was 0.20% (9% from 1949 to 1994) and almost entirely due to perimeter erosion to open water. At Gull Marsh, Virginia, a site chosen because of known erosional losses, we recorded the highest annual loss rate, 0.67% per annum, again almost entirely due to erosional, perimeter loss. In contrast, at the southernmost site, Mockhorn Island Wildlife Management Area, Virginia, there was a net gain of 0.09% per annum (4% from 1949 to 1994), with tidal flats becoming increasingly vegetated. Habitat implications for waterbirds are considerable; salt marsh specialists such as laughing gulls (Larus atricilla), Forster’s terns (Sterna forsteri), black rail, (Laterallus jamaicensis), seaside sparrow (Ammodramus maritimus), and saltmarsh sharp-tailed sparrow (Ammodramus caudacutus) are particularly at risk if these trends continue, and all but the laughing gull are species of concern to state and federal managers.

The foraging behavior of birds is often influenced by the development and dietary needs of their young. Laughing Gulls in New Jersey, USA, nest in highly productive salt marshes but adults commonly forage at inland sites when they have young in the nest. I monitored movements of individual Laughing Gulls using color-marking, banding and radio-telemetry combined with land-based and aerial surveys. I found that breeding adults were highly mobile and commonly flew inland to forage. Color-marked individuals were observed a mean of 16.6 km and a median of 11.0 km from the colony. Radio-tagged birds were located as far as 40 km inland. Laughing Gulls showed foraging site tenacity both within a given year and from year to year. Radio-tagged adults made as many as 11 foraging trips from the colony per day during both diurnal and nocturnal periods. Activity at the colony peaked during late evening and morning hours. Furthermore, Laughing Gull movement patterns changed with progression of the nesting seas...

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 1974 - 1998, to provide a basis for future wildlife management decisions in JBWR and also at nearby John F. Kennedy International Airport. None of the popula- tions 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 1986. 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.

During the 1980s, the exponential growth of laughing gull (Larus atricilla) colonies, from 15 to about 7600 nests in 1990, in the Jamaica Bay Wildlife Refuge and a correlated increase in the bird-strike rate at nearby John F. Kennedy International Airport (New York City) led to a controversy between wildlife and airport managers over the elimination of the colonies. In this paper, we review data to evaluate if: (1) the colonies have increased the level of risk to the flying public; (2) on-colony population control would reduce the presence of gulls, and subsequently bird strikes, at the airport; and (3) all on-airport management alternatives have been adequately implemented. Since 1979, most (2987, 87%) of the 3444 bird strikes (number of aircraft struck) were actually bird carcasses found near runways (cause of death unknown but assumed to be bird strikes by definition). Of the 457 pilot-reported strikes (mean = 23 +/- 6 aircraft/yr, N = 20 years), 78 (17%) involved laughing gulls. Since a gull-shooting program was initiated on airport property in 1991, over 50,000 adult laughing gulls have been killed and the number of reported bird strikes involving laughing gulls has declined from 6.9 +/- 2.9 (1983-1990) to 2.6 +/- 1.3 (1991-1998) aircraft/yr; nongull reported bird strikes, however, have more than doubled (6.4 +/- 2.6, 1983-1990; 14.9 +/- 5.1, 1991-1998). We found no evidence to indicate that on-colony management would yield a reduction of bird strikes at Kennedy Airport. Dietary and mark-recapture studies suggest that 60%-90% of the laughing gulls collected on-airport were either failed breeders and/or nonbreeding birds. We argue that the Jamaica Bay laughing gull colonies, the only ones in New York State, should not be managed at least until all on-airport management alternatives have been properly implemented and demonstrated to be ineffective at reducing bird strikes, including habitat alterations and increasing the capability of the bird control unit to eliminate bird flocks on-airport using nonlethal bird dispersal techniques. Because the gull-shooting program may be resulting in a nonsustainable regional population of laughing gulls (>30% decline), we also recommend that attempts be made to initiate an experimental colony elsewhere on Long Island to determine if colony relocation is a feasible management option.

A field study was conducted to examine avian exposure to organophosphorus (OP) and carbamate (CA) pesticides applied to turf on a coastal South Carolina golf course. The number, distribution, and activity of birds on turfgrass were monitored from May 25 to August 27, 1993. Over 1,600 birds representing 23 species were counted on turfgrass during designated monitoring sessions and incidental observations. Most birds were observed during morning hours, on fairways, and on the back nine holes of the course. Foraging was the predominant behavior observed. Blood samples and footwashes were collected from red-winged blackbirds (Agelaius phoeniceus), common grackles (Quiscalus quiscula), and boat-tailed grackles (Quiscalus major) for measurement of plasma cholinesterase (ChE) activity and chemical residues, respectively. Reactivation of plasma ChE in 22 blood samples suggested CA exposure, but no overt signs of anti-ChE poisoning were observed in birds sampled. However, an incapacitated laughing gull discovered after an application of the CA bendiocarb (3.36 kg/ha) exhibited 87% depression of plasma ChE and displayed symptoms consistent with OP/CA intoxication. Pesticide exposure was confirmed by recovery of 50.33 μg bendiocarb in the footwash. Mole crickets (Scapteriscus spp.) that surfaced following the same chemical application contained bendiocarb residues and may have been ingested by foraging birds. Results of this study suggest a potential for avian exposure to OP and CA pesticides on the golf course, but few actual exposures and acute effects were observed.

Newly hatched laughing gulls, Larus atricilla , pecked at herring gull models more than at models of their own species, and preferred an unusual laughing gull model to a more conventional one. Chicks learned to peck preferentially at laughing gull models that fed them and to reduce their pecking at models that did not; they learned best when the model was unusual. Chicks were also able to learn to prefer a particular laughing gull mew call over a mew call recorded from a different laughing gull. When auditory cues were present during conditioning, the degree and importance of visual learning sharply declined.

Despite extensive studies of methylmercury (MeHg) toxicity in birds, molecular effects on birds are poorly characterized. To improve our understanding of toxicity pathways and identify novel indicators of avian exposure to Hg, the authors investigated genomic changes, glutathione status, and oxidative status indicators in liver from laughing gull (Larus atricilla) hatchlings that were exposed in ovo to MeHg (0.05–1.6 µg/g). Genes involved in the transsulfuration pathway, iron transport and storage, thyroid-hormone related processes, and cellular respiration were identified by suppression subtractive hybridization as differentially expressed. Quantitative polymerase chain reaction (qPCR) identified statistically significant effects of Hg on cytochrome C oxidase subunits I and II, transferrin, and methionine adenosyltransferase RNA expression. Glutathione-S-transferase activity and protein-bound sulfhydryl levels decreased, whereas glucose-6-phosphate dehydrogenase activity increased dose-dependently. Total sulfhydryl concentrations were significantly lower at 0.4 µg/g Hg than in controls. Together, these endpoints provided some evidence of compensatory effects, but little indication of oxidative damage at the tested doses, and suggest that sequestration of Hg through various pathways may be important for minimizing toxicity in laughing gulls. This is the first study to describe the genomic response of an avian species to Hg. Laughing gulls are among the less sensitive avian species with regard to Hg toxicity, and their ability to prevent hepatic oxidative stress may be important for surviving levels of MeHg exposures at which other species succumb. Environ. Toxicol. Chem. 2012; 31: 2588–2596. © 2012 SETAC

The assessment of secondary poisoning is an important consideration in the hazard evaluation of predator control agents and rodenticide baits. The selection of an appropriate test animal model is difficult because classiclaboratory species are frequently inappropriate, and the availability and reliability of wild species for testing is limited. The laughing gull (Larus atricilla) has demonstrated its usefulness as a secondary poisoning model in the laboratory and shown species sensitivity through case history documentation of secondary poisoning mortality in the field. A number of new candidate rodenticides are being developed throughout the world for control of rodent pests in domestic, industrial, and agricultural marketplaces. Because one or more of these rodenticides could have a wide variety of outdoor uses, the effects of these substances on the environment must be evaluated in terms of both their toxicity and their exposure. The portion of that evaluation which is to be considered in this paper concerns the assessment of secondary poisoning of birds. utilizing the laughing gull as a model for an avian predator.

Massachusetts Maritime Academy (MMA) conducted a study to evaluate the potential impact of the MMA wind turbine (Vestas V47-660 kW) on birds, including common terns (Sterna hirundo), which are protected at the state level, and roseate (S. dougalii) terns, which are protected at the federal level. We found that common terns were relatively abundant on the water adjacent to the wind turbine, especially during the post-breeding period (7 Aug-30 Sep). Roseate terns, however, were much less abundant than common terns, and their presence at the study site was nearly limited to the chick-rearing period (19 Jun-6 Aug). Both species were least abundant during the nesting period (24 Apr-18 Jun). During the study, we observed 253 terns passing through wind turbine airspace (i.e., within 50 m of the wind turbine). Most (n = 226) were common terns, 1 was a roseate tern, and 16 were unidentified to the species level. Terns (all categories) were most abundant in wind airspace during the chick-rearing period, especially during morning hours (0530-1100). However, their abundance was dependent upon the operational status of the wind turbine rotor. Terns were less abundant in wind turbine airspace when the rotor velocity was >1 rpm than when the rotor velocity was

Ornithodoros (Alectorobius) capensis Neumann, an ectoparasite of seabirds found circumglobally in the tropics and subtropics, has become established along the southeastern seacoast of the United States. The tick has been found feeding primarily on brown pelicans, Pelecanus occidentalis , but also has been found on the laughing gull, Larus atricilla , and the American oystercatcher, Haematopus palliatus . We report here the presence of O. (A.) capensis from New Hanover and Brunswick counties (near the mouth of the Cape Fear River) in North Carolina, to the Charleston Harbor area of South Carolina and thence south to Cumberland Island (a barrier island) in Camden County, Georgia, just north of the Florida state line.

Author(s): Barras, Scott C.; Dolbeer, Richard A.; Chipman, Richard B.; Bernhardt, Glen F. | Abstract: We evaluated bird and small mammal use of two mowed (15 to 25 cm height) and two unmowed vegetation plots (40 to 88 ha) at John F. Kennedy International Airport (JFKIA), New York, in 1998 to 1999 to determine which management strategy would best reduce wildlife use of the airport. We counted more birds per 5- minute observation period in unmowed plots than mowed plots in both 1998 (9.0 versus 7.9) and 1999 (11.7 versus 8.6). Maximum vegetation height was greater (Pl0.05) for unmowed areas than mowed areas after mowing commenced in 1998 and 1999 for each two-week monitoring period. In 1998 to 1999, vegetation density was also higher (Pl0.05) for unmowed plots for 13 of 14 sampling periods. The species composition of vegetation differed (X2=20.54, df=3, (Pl0.01) among mowed and unmowed plots. Mowed plots contained a higher percentage of grasses (81% versus 68%), and a lower percentage of forbs (16% versus 25%) and woody plants (1% versus 4%) than unmowed plots. Vegetation was generally sparse in both unmowed and mowed plots, a consequence of the poor, sandy soils on much of the airport. We captured 33 small mammals from three species in unmowed plots and 12 individuals of one species in mowed plots in 1999. Small mammal populations increased seasonally in unmowed plots, but remained constant in mowed plots over the same time period. We recommended JFKIA switch from the unmowed vegetation management regime in place since 1986 to a regime of maintaining vegetation mowed at 15 to 25 cm height. This management strategy should reduce bird and small mammal use of grassland areas at JFKIA. Further research should examine use of alternative vegetation types to improve ground cover and vegetation density at JFKIA while minimizing attraction to wildlife.

On 15 May 2000, I observed a Laughing Gull (Larus atricilla) nest parasitized by a Black-bellied Whistling-duck (Dendrocygna autumnalis). The nest contained three Laughing Gull eggs and three Black-bellied Whistling-duck eggs and was located in a colony of 56 Laughing Gull nests.

This is the 33rd annual report from the Norwegian Rarities Committee (NSKF). The majority of records treated here are from 2008, but more than 100 older records are also included. The Norwegian rarities committee follow advises given by the Taxonomic Advisory Committee (TAC) of the Association of European Records and Rarities Committees (AERC) on issues concerning taxonomy and nomenclature. The systematic list of accepted records is set out in the following system: (1) The bird's Norwegian name, (2) scientific name, (3) the numbers in brackets, e.g. (2, 30/32, 1), refers respectively to the ( i ) total number of records/total number of individuals up to and including 1974, ( ii ) total number of records/total number of individuals from 1975 (the foundation year of NSKF), except ( iii ) records/individuals in 2008, (4) any breeding, (5) year, (6) county, (7) number of individuals, age (1K = first calendar year etc.), sex (if known) and sometimes circumstances («rm.» means that the bird was ringed, «sy.» indicates a singing male), (8) site and municipality, (9) date, (10) * indicates if the record was complemented by positive evidence, and type of the evidence (F = photo, V = video-recorded, L = tape-recorded), (11) observers' names in brackets, main observer(s) is specified first and emphasized with *, (12) roughly gives the species' distribution and (13) comments concerning the records. Species and subspecies new to the Norwegian list Two new species were accepted to the Norwegian Category A list from 2008. Both of these were Nearctic waders, namely a Hudsonian Godwit Limosa haemastica from Rostlandet on June 24 th and a Western Sandpiper Calidris mauri from Jaeren on July 12th-13th. In addition there were three new subspecies accepted: Buff-bellied Pipit Anthus rubescens japonicus (Karmoy, January to April), Yellow Wagtail Motacilla flava feldegg (Utsira, 3rd to 5th June) and White Wagtail M. alba leucopsis (Lista, 1st-2nd November). General trends Record numbers for Norway was recorded for Grey Phalarope Phalaropus fulicarius (14/23) during 2008. Also the following species showed an occurrence above average during 2008: Great White Egret Ardea alba , Black Kite Milvus migrans , Pectoral Sandpiper C. melanotos , Red-rumped Swallow Cecropis daurica , Citrine Wagtail M. citreola , Blyth's Reed Warbler Acrocephalus dumetorum and Rose-coloured Starling Sturnus roseus . Also published here are the 6th Egyptian Goose Alopochen aegyptiaca (Cat. C), 3rd Lesser Scaup Aythya affinis , 8th Harlequin Duck Histrionicus histrionicus , 5th to 7th American Golden Plover Pluvialis dominica , 4th Laughing Gull Larus atricilla , 6th Franklin's Gull L. pipixcan , 6th and 8th Oriental Turtle Dove Streptopelia orientalis , 8th Blyth's Pipit A. godlewskii , 2nd Siberian Rubythroat Luscinia calliope , 5th Isabelline Wheatear Oenanthe isabellina , 10th Lanceolated Warbler Locustella lanceolata , 4th Melodious Warbler Hippolais polyglotta , 3rd Eastern Bonelli's Warbler Phylloscopus orientalis and 4th and 7th Steppe Grey Shrike Lanius meridionalis pallidirostris .

Methylmercury is the predominant chemical form of mercury reported in the eggs of wild birds, and the embryo is the most sensitive life stage to methylmercury toxicity. Protective guidelines have been based mainly on captive-breeding studies with chickens (Gallus gallus), mallards (Anas platyrhynchos), and ring-necked pheasants (Phasianus colchicus) or on field studies where whole eggs were collected and analyzed and the effects of the mercury were measured based on the reproductive success of the remaining eggs. However, both of these methods have limitations. As an alternative, we developed a technique that involves extracting a small sample of albumen from a live egg, sealing the egg, returning the egg to its nest to be naturally incubated by the parents, and then relating the hatching success of this microsampled egg to its mercury concentration. After first developing this technique in the laboratory using chicken and mallard eggs, we selected the laughing gull (Larus atricilla) and black-necked stilt (Himantopus mexicanus) as test subjects in the field. We found that 92% of the microsampled laughing gull eggs met our reproductive endpoint of survival to the beginning of hatching compared to 100% for the paired control eggs within the same nests. Microsampled black-necked stilt eggs exhibited 100% hatching success compared to 93% for the paired control eggs. Our results indicate that microsampling is an effective tool for nonlethally sampling mercury concentrations in eggs and, as such, can be used for monitoring sensitive species, as well as for improving studies that examine the effects of mercury on avian reproduction.

A brief history of the genus Parorchis Nicoll, 1907 (Philophthalmidae: Parorchiinae) is provided along with the description of 3 new species: Parorchis catoptrophori n. sp., distinguished by a bipartite pharynx with a larger, anterior, muscular primary pharynx, followed by a smaller posterior nonmuscular secondary part composed of 2 smaller posterior extensions; Parorchis longivesiculus n. sp., distinguished by an external seminal vesicle that overreaches the acetabulum posteriorly, extending into the hindbody to about midway between the testes and the acetabulum; and Parorchis ralli n. sp., distinguished by an external seminal vesicle, the posterior third of which is tubular and coiled. The preoccupied junior homonym Paratrema Dronen & Badley, 1979 (Parorchiinae) is replaced by Stenomesotrema nomen novum, and a rediagnosis of the genus is given wherein Stenomesotrema numenii n. comb. is assigned as the type species in the genus, and Stenomesotrema asiaticus n. comb. is proposed as a second species in the genus. Species of Parorchis are divided into 2 basic body types. The first type contains those species with a barbell-like or hourglass body shape, a rudimentary head collar, symmetrical to tandem testes, 2 rows of corner spines on the head collar, a preequatorial acetabulum, and a forebody that is wider than the hindbody. The second body type, called the “Parorchis body type”, contains those species with a pyriform body shape, a well-developed head collar, symmetrical testes, a single continuous row of circumoral spines on the head collar, and an equatorial acetabulum. There appears to be 2 subtypes of the Parorchis body type: subtype 1 containing those species possessing smooth to slightly irregular testes (not deeply lobed) and an esophagus lacking diverticuli; and subtype 2 containing those species having irregular and deeply lobed testes and an esophagus possessing lateral diverticuli. A comparative analysis of museum-deposited specimens of P. acanthus revealed as many as 9 possible additional species of Parorchis. This suggests potential problems in using measurements of structures alone without differences in additional corroborating specific features to separate species of Parorchis. Along with measurements, the number and size of spines on the circumoral collar, the presence or absence of a prepharynx, an intertesticular space, and esophageal diverticula as well as the extent of the posttesticular space, the length of the metraterm, egg size and the ratios of the width of the oral sucker to the width of the acetabulum and the width of the pharynx to the width of the oral sucker appear useful in distinguishing species of Parorchis.

This is the 30th annual report and the 31 st announcement from the Norwegian Rarities Committee (NSKF). The majority of records treated here are from 2005, but some older records are also included. Norway follows taxonomic advises given by the Taxonomic Advisory Committee (TAC) in the Association of European Record and Rarities Committees (AERC). The systematic list of accepted records is set out in the following system: (1) The bird's Norwegian name, (2) scientific name, (3) the numbers in brackets, e.g. (2, 30/32, 1), refers respectively to the ( i ) total number of records/total number of individuals up to and including 1974, ( ii ) total number of records/total number of individuals from 1975 (the foundation year of NSKF), except ( iii ) records/individuals in 2005, (4) any breeding, (5) year, (6) county, (7) number of individuals, age (1K = first calendar year etc.), sex (if known) and sometimes circumstances («rm» means that the bird was ringed), (8) site and municipality, (9) date, (10) * indicates if the record was complemented by positive evidence, and type of the evidence (F = photo, V = video-recorded, L = tape-recorded, D = found dead), (11) observers' names in brackets, main observer(s) is specified first and emphasized with *, (12) roughly gives the species' distribution and (13) comments concerning the records. General trends With 260 accepted records presented in this report, 2005 was one of the best years in the his- tory of NSKF. A total of 62 accepted records from previous years complete the status of rare birds on the Norwegian Bird list. There are 17 records presented that have been shelved. Two thirds of these concerns presumed hybrid Herring x Glaucous Gulls or first year «Eastern Yellow Wagtails». These records have been shelved due to the lack of identification knowledge in the literature for such birds. Also presented are 46 records that for some reason have not been accepted. Record numbers for Norway was recorded for the following species during 2005: White-rumped Sandpiper Calidris fuscicollis (four records involving five birds), Barn Owl Tyto alba (three records), Desert Wheatear Oenanthe deserti (five records), Black-throated Thrush Turdus ruficollis atrogularis (four records) and Arctic Warbler Phylloscopus borealis (11 records involving 15 birds). Also, 2005 was the first year ever with multiple records of Ross's Gull Rhodostethia rosea (two records), Pallid Swift Apus pallidus (two records involving three birds) and Steppe Grey Shrike Lanius meridionalis pallidirostris (two records). Four records of «Eastern» Stonechat Saxicola torquatus maurus/stejnegeri were also an all time high. Species and hybrids new to the Norwegian list Two new species to the Norwegian category A list are presented in this report. This brings the official Norwegian bird list to 474 species. Included in this list are accepted records in category A-C. The new species were Siberian Rubythroat Luscinia calliope and Brown Shrike Lanius cristatus . Both were found at Utsira, Rogaland in early October. Hybrid Mallard Anas platyrhynchos x Gadwall Anas strepera at Innfjorden, Rauma, More og Romsdal and Mallard x American Black Duck A. rubripes at Surnadal, More og Romsdal were also new for Norway. Also published here are the 2nd & 3rd Egyptian Goose Alopochen aegyptiaca for Norway, 3 rd American Black Duck Anas rubripes , 3rd American Golden Plover Pluvialis dominica , 3rd Baird's Sandpiper Calidris bairdii , 3rd Upland Sandpiper Bartramia longicauda , 6th Spotted Sandpiper Actitis macularius , 5th Wilson's Phalarope Phalaropus tricolor , 3rd Laughing Gull Larus atricilla , 5th Franklin's Gull Larus pipixcan , 1st-2nd & 5th-6th Yellow-legged Gull Larus michahellis , 9th Caspian Gull Larus cachinnans , 4th Roseate Tern Sterna dougallii , 10th Calandra Lark Melanocorypha calandra , 5th-7th Blyth's Pipit Anthus godlewskii , 10th Pallas's Grasshopper Warbler Locustella certhiola , 2nd Thick-billed Warbler Acrocephalus aedon , c. 8th Booted Warbler Hippolais caligata , c. 3rd Western Bonelli's Warbler Phylloscopus bonelli , 9th & 10th record of Penduline Tit Remiz pendulinus and 4th & 5th Steppe Grey Shrike Lanius meridionalis pallidirostr is .

The δ13C, δ15N, and δ34S stable isotopic values of feathers from pre-fledged Laughing Gulls (Larus atricilla) in coastal Virginia and Jamaica Bay, New York were used to examine dietary variation during the nestling period. The tip portions of the feathers were used to indicate diet during the initiation of primary feather growth, whereas the base portions indicated diet during the period immediately prior to fledging. The results indicate that diets of the nestlings in Virginia moved to a higher trophic level during the period prior to fledging, however the New York nestlings did not appear to undergo any appreciable dietary change during this period. Overall, nestlings from both colonies consumed proportionately more foods of marine origin than freshwater or terrestrial. Therefore, the results do not support those of earlier studies that suggested that partially developed salt glands in young gulls might restrict the diet to more terrestrial or freshwater prey in the early stages of nestling growth.

We studied seven species of waterbirds that nested on Isla Montague, Mexico, at the mouth of the Colorado River, during the 1993 and 1994 breeding seasons: Great Blue Heron (Ardea herodias), Snowy Egret (Egretta thula), Black-crowned Night Heron (Nycticorax nycticorax), Laughing Gull (Larus atricilla), Least Tern (Sterna antillarum), Gull-billed Tern (Sterna nilotica), and Black Skimmer (Rynchops niger). Breeding occurred along several tidal channels of the Estero del Chayo and on shell mounds near the lighthouse. There were low levels of predation, by at least one Coyote (Canis latrans), and unknown, but likely avian, predators. Tidal inundation was the major factor affecting the nesting of the birds, as it destroyed almost all nests, eggs and chicks on at least five occasions during one breeding season. It seems likely that the pattern of inundations we recorded does not happen all years. Received 21 August 2000, accepted 20 March 2001.

We examined diversity measures of the colonial-nesting waterbird community in Galveston Bay Estuary from 1973-1990 to determine if trends were apparent at three levels of ecological organization (i.e., community, assemblage, and population), each representing a different level of data aggregation. The community was dominated numerically by the Laughing Gull (Larus atricilla), a species with the lowest annual variability. In general, species that exhibited high annual variability also had low mean abundances [e.g., Anhinga (Anhinga anhinga) and Yellowcrowned Night-Heron (Nycticorax violaceus)]. White Ibis (Eudocimus albus) and Sandwich Tern (Sterna sandvicensis) were unusual in that they were both highly variable and abundant. Trend analyses of the abundances of individual species showed that Roseate Spoonbill (Ajaia ajaja), Snowy Egret (Egretta thula), and Black Skimmer (Rynchops niger) declined significantly. Neotropical Cormorant (Phalacrocorax brasilianus) and Sandwich Tern increased significantly, and the remaining 13 species showed no statistical change. A classification analysis identified five species assemblages. Two assemblages increased significantly in abundance, one assemblage decreased significantly, and two assemblages showed no change. At the community level, none of the indices we examined showed a significant change over the 18-year period. We hypothesized that loss of coastal marsh vegetation and the development of favorable feeding conditions outside of Galveston Bay may have caused some of the population changes we identified. Our ability to identify trends was affected by the level of data aggregation. Community measures were less sensitive to change than were assemblage and population-level data. Received 17 November 1997; accepted 24 February 1998.

We evaluated aerial photography (full coverage, using fixed-wing aircraft) and aerial video (transects, using helicopter) surveys to estimate the population of Laughing Gull (Larus atricilla) nests in Jamaica Bay, New York, duringJune 1992-1995. We counted 4,920 nests in the colony using aerial photography and estimated 5,367 nests using aerial video in 1992. In 1993-1995, we respectively counted 5,691, 5,095, and 6,126 nests in the colony using aerial photography, and estimated from ground plots that our counts differed from the actual number of nests by means of-9% to 1%. Overall (1993-1995) correction factors (by which to multiply the aerial photography nest counts) to estimate the mean and 95% lower and upper CI range of the nest population were 1.04, 0.96 and 1.13, respectively. Ninety-seven percent of nests identified using aerial photography or video had >1 adult Laughing Gull present or within 1 m of the nest. The aerial video survey was less expensive ($2,100 United States currency) than the aerial photography survey ($4,000). The estimated cost of a total count of nests from the ground is $6,700$9,600. The aerial video survey provided an accurate estimate of the number of nests. Full-coverage aerial photography also provided an accurate estimate of nests in addition to habitat, nest distribution and nest density data. Received 13 June 1996, accepted 3 October 1996.

After the eggs hatch, about 63% of the large eggshell fragments can be found near laughing gulls' nests. For the shells that were found, the mean distance from the rim of the nest was less than 80 cm at three study sites. The removal distance was positively correlated with the size of the nest platform, which suggests that birds often walk to the edge of the platform and simply drop the shell. Within the colony, eggshells have a natural variation in darkness that is related to the range of darkness of the nest material. In preference tests we have matched shell models to the darkness of the eggs in the nest. When both natural shells and orange shells pegged to the ground were presented simultaneously, gulls preferentially attempted to remove the orange shell. The strength of the preference for the pegged orange shell varied from site to site within the colony, so the results were validated in a separate experiment by placing shells in the nest bowl one at a time to be removed in as natural a manner as possible. Orange was stiff preferred; fear of the orange model seemed to promote the removal response. Contrary to the expectations from prior studies, the natural model was also no stronger stimulus than a solid white model in pegged shell tests. Control tests with white, grey, and black models indicate that brightness plays a very weak role, so the removal preference must be based on colour. When pegged models of any colour were on the nest and the bird engaged in nest building, the nest building was usually biased toward the models, but not precisely directed at them. Our results suggest that removal behaviour can be elicited via different perceptual mechanisms. One mechanism specifically recognizes the egg-shell, while the other mechanism is stimulated by a broad range of foreign objects that contrast with the nest background. In the laughing gull, the contrast mechanism appears to be at least as strong as the recognition mechanism. This may be related to the low level of predation experienced by these gulls.

The intertidal flats of the Cape May, New Jersey shore of Delaware Bay are populated by large numbers of laughing gulls and migrating shorebirds during the spring and early summer. Exclusion of birds from a shallow slough and a sand bar had only minor effects on the infaunal benthic invertebrate assemblage at either site. The Cape May beaches provide a rich source of food in the form of horseshoe crab ( Limulus polyphemus ) eggs; foraging on this item may be more profitable than probing the sediment for infauna. Gemma gemma , a small, thick-shelled bivalve, composed over 98% of the benthic infauna at both sites in 1980, and this species may be resistant to predation by certain shorebirds, as suggested by Schneider (1978) .

1. The nesting strategy as determined by nonrandom variation in environmental features at laughing gull (Larus atricilla) nests in a salt marsh was studied (Fig. 3). Gulls tended to nest on mats in tall grass that grows on low ground (just above high tides) near water (Figs. 4–7). Grass height was inversely related to ground elevation and distance to water (Fig. 8). Throughout the season, gulls selected nest sites in grass about 35 cm in height; due to continued grass growth, early breeders had taller grass around nests (Fig. 9). Pairs in the colony center nested earlier and in taller grass than pairs in a peripheral area. 2. Mats apparently stabilize nests during flooding, and by settling on mats gulls may conserve energy in the collection of nest material. Tall grass around nests afforded chicks protection from predators and weather, and held floating nests in place during flooding. 3. Gulls spend about 4 weeks (two spring tidal cycles) on the nesting grounds before egg laying. During this time they perform virtually no nest building and probably gain important information about nest site suitability. 4. Tidal flooding, the greatest threat to reproductive success—destroying 70–100% of the nests in the colony — occurred on average once every 2 years over 10 years. Floods occurred during spring tides accompanied by sustained NE winds. 5. Following a flood that destroyed 70% of the nests in the colony, it was shown that a significantly greater proportion of successful pairs nested on mats and in significantly taller grass than unsuccessful pairs. Grass height, especially that on the SW side of the nest, was the most important predictor of success during flooding. 6. More pairs in the central area were successful than those in the peripheral one: the result of nesting in taller grass and the greater protection of the central area from tides and winds. Though not differing among successful and unsuccessful nesters, females in the peripheral area laid smaller eggs and clutches, and laid later than females in the central area (over 3 years), suggesting that females in the peripheral area were on average younger than females in the central area. It was speculated that, on average, younger pairs will experience during flooding lower reproductive success as a result of nesting inexperience and nesting in suboptimal habitat. The smaller reproductive investments of younger pairs in eggs and clutches can be interpreted as an adaptation to conserve energy during a period of the life cycle when new behavioral adjustments and nesting areas are being explored.

Confirming previous observations in the gull-colony the parental attraction-call 'crooning' selectively enhanced activity while the alarm-calls 'kow' and 'uk-uk' suppressed activity and vocalizations, even in the absence of additional visual clues. These calls may have had the observed effects in part because of certain acoustic characteristics to which chicks preferentially respond and in part because of specific experiences that chicks may have had with these calls prior to testing. Some of the difference between experiment (a) and (b) in the performance towards 'uk-uk' calls may have been due to the fact that the chicks in (b) were tested later in the season than the chicks in (a). Later hatching chicks may have been physically less well developed and thus less responsive than earlier hatched chicks, or they may have had differential kinds or amounts of auditory experience before they were tested. The present results differ from findings of an earlier pilot-investigation (BEER, 1973) in which recordings of single adult birds evoked no clearcut responses in chicks. However most of those chicks had been several days old and in other experiments it was shown that responsiveness to calls of adults changes with age (BEER, 1970b).Observations. Adult Laughing Gulls utter several distinct calls during the incubation of their eggs and the raising of their chicks. One call referred to as 'uhr' call is frequently heard during incubation in conjunction with rising from the eggs or resettling, and in response to the mate's activities near the nest. 'Crooning' is heard during mate-reliefs in incubation. After hatching this call functions to attract the young to the parent. `Uk-uk' and 'kow' alarm-calls are both uttered when the colony is disturbed by a potential predator, but 'kow' calls can also be heard in purely conspecific disturbances. Experiment I . The responses of day-old chicks, reared by their parents, were investigated towards recordings of some of these calls. Confirming observations in the wild, `crooning' selectively enhanced activity and elicited approach; 'uk-uk' suppressed activity and vocalization and elicited crouching; 'kow' calls had similar effects but to a lesser extent. Experiment 2. Chicks collected at hatching from nests in the gull-colony were compared with chicks hatched in an incubator in order to discover whether the prenatal conditions affected early postnatal responsiveness to 'crooning'. It was found that parent-hatched chicks showed increased activity in the presence of 'crooning' and some of them approached the speaker, whilst incubator-hatched chicks were not activated by these calls. Experiment 3. Younger chicks were compared with older chicks (all hatched in the incubator) for the purpose of finding out to what extent their responsiveness to 'crooning' would change with postnatal age. The results showed that to parentally inexperienced chicks this call increasingly acquires the effects of alarm-calls in that it suppresses vocalization and activity and elicits crouching. Experiment 4. The role of parental calls as experienced in the wild during incubation was examined experimentally. During the last 2 1/2 to 3 days of incubation eggs were repeatedly exposed to different types of calls (or no calls at all), in order to see to what extent and with what degree of selectivity such exposures would affect responsiveness to 'crooning' and 'kow' calls in newly hatched chicks. It was found that prenatal exposure to 'crooning' leads to enhancement of activity and vocalization in the presence of such calls postnatally. Effects of prenatal experience with disyllabic 'uhr' call point into the same direction. Prenatal experience with 'kow' calls does not lead to early postnatal activation in response to 'crooning'. Responsiveness to 'kow' calls was only affected by prenatal exposure to these calls. Discussion. Some previously published studies in this field of research are briefly reviewed and compared with the present findings. The relative contribution of prior experience of parental and filial vocalizations to later responsiveness to parental calls is discussed. Earlier research in the Laughing Gull had shown that parentally inexperienced embryos are selectively activated by 'crooning' till close to hatching. In the present study it was shown that repeated prenatal experience with 'crooning' leads to its attractiveness after hatching. Therefore repeated prenatal (and maybe early postnatal) exposure to this call and related calls seems to function to maintain and. consolidate responsiveness to this call in the neonate. In contrast to 'crooning', 'kow' alarm-calls heard prenatally do not enhance nor suppress motility. Prior exposure to this call does not maintain this apparent indifference, but merely reduces the extent to which it acquires activiy suppressing effects.

Lead concentrations were measured in eggs, prefledgings and adult laughing gulls collected near Galveston, Texas. No lead was found in eggs. Prefledgling and adult birds had lead ranging from zero to 16 mug/g wet tissue. Liver had the greatest lead concentrations followed by brain, heart and skeletal muscle. There were no significant differences in lead concentrations between fledglings and adults or between males and females.

The adaptive significance of hatching asynchrony was investigated in the laughing gull ( Larus atricilla ). Staggered hatching of the brood is frequently correlated with reduced survival in the later-hatching chicks, and the phenomenon has therefore been the subject of speculation about adaptive function. The relative timing of hatching within the brood was experimentally manipulated in order to compare the effects of synchrony versus asynchrony on parental reproductive success. The average number of young fledging per nest was significantly higher in the asynchronous group. Staggered hatching of the brood is hypothesized to be a parental strategy offering the option of brood reduction under conditions of food shortage. The possibility is discussed that asynchronous hatching benefits parents independently by reducing sibling rivalry over parental investment and minimizing wasteful competition.

Ring-necked Pheasant (Phasianus colchicus) chicks exposed to a hen incubation vocalization during the final week of incubation showed stronger attraction to feeding and caution calls than expected by chance when tested one, three and five days post-hatching. Control chicks incubated in silence did not differ from chance in response to the caution call. Largest differences between experimental and control chicks for positive responses to the caution call occurred at one and three days post-hatching. Differences for positive response to the feeding call were greatest at one and five days post-hatching. Correct pecking behavior in response to feeding calls was greater at all test ages in chicks exposed to incubation calls than in control chicks. However, when tested on the caution call, control chicks responded with correct hiding behavior more often than experimentals at one day of age. Correct behavior in response to the caution call greatly increased in experimental chicks at three days post-hatching but not in controls. By five days post-hatching, experimentals and controls were nearly equal. Calls by the incubating hen pheasant act to sensitize and predispose embryonic chicks for proper responses to calls that they will hear after hatching. Stages of post-hatching development and learning possibly have some modifying influence on the timing of responsiveness to post-hatching calls. Kuo (1921, 1932) was the first to suggest that at least some features of apparently innate behavior of neonatal animals might be the result of experiences that occurred during late embryonic stages. Exposure of developing embryos to various sounds including self-auditory stimulation, sound stimulation by siblings and extra-egg sound sources has been shown to affect recognition of parent calls after hatching (Gottlieb 1965, 1971, 1974, 1975a, b, c, 1978) in domestic chickens (Gallus gallus var. domesticus), domestic Pekin ducks (Anas platyrhynchos var. domesticus) and Wood Ducks (Aix sponsa). Mallard (Anas platyrhynchos) ducklings also show post-hatching recognition of, and attraction to, calls heard during the late embryonic stage (Hess 1972, 1973). Bailey and Ralph (1975) found increased attraction for and movement toward sounds heard during late incubation in Ring-necked Pheasant chicks (Phasianus colchicus). Semi-precocious Laughing Gull (Larus atricilla) chicks respond to calls of the natural parents, but not to strange parents, if the chicks have had prior experience with the calls of their parents (Beer 1970, Impekoven 1976). Early post-hatching exposure of Ring-billed Gull (Larus delawarensis) chicks to feeding vocalizations of adults increases recognition of individual adults (Evans 1980). Perinatal exposure to parental calls in Common Murre (Uria aalge) chicks determines recognition of the parents and enhances preference for the parent-specific calls in choice tes s (Tschanz 1968). However, in these studies, whether prenatal, perinatal or postnatal expos re to calls, preference and recognition was for the same sound heard during initial exposure and might be considered as associative learning (Bailey and Ralph 1975). Incubating Ring-necked Pheasant hens vocalize throughout most of the 23-day incubation period with a variety of low-frequency, low-intensity calls. Field observations and recording of incubating hen pheasants revealed an increase in some of these calls and a decrease in others as hatch approached. The call most frequently given by incubating hens during the final week of incubation can be described as a "mew" sound of low frequency, relatively long duration and modulated downwards (Fig. la). Pheasant chicks are brooded on the nest for 24 to 48 h before the hen leaves and vocalizes to the chicks, who then follow. The calls that he hen gave during incubation are replaced by other calls, which were never given during in ubation. These post-hatching calls-a feeding or brood-gathering call (Fig. 1b) and caution call (Fig. 1 c)-are obeyed correctly by the chicks the first time the hen gives them (Simmons 1975). Heinz and Gysel (1970) have documented the various adult pheasant calls including feeding and caution calls. Heinz (1973) found, in the laboratory, that day-old pheasant chicks were attracted equally to the feeding call (brood gathering call) and the caution calls. However