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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.

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.

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...

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.

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...

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.

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.

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.

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.

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.

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

Hailman reported that wild-reared laughing gull, Larus atricilla, chicks peck preferentially at models of laughing gulls over models of herring gulls, L. argentatus, but newly hatched chicks have no species preference, and respond equally well to an isolated red bill. The experiments reported here confirm these observations. They also suggest that the pecking of newly hatched chicks is guided by heterogeneous summation. A new working definition of heterogeneous summation is presented. Furthermore, the results suggest that species preference does not develop spontaneously with maturation or on the basis of imprinting, but rather from reinforcement and conditioned inhibition or habituation. It appears that learning can take place only to a model with high releasing value for pecking, and that the crooning call of adult laughing gulls has no major effect on pecking in newly hatched chicks.

Variation in the water, lipid, and nonlipid dry matter of eggs and newly hatched chicks of the Laughing Gull and Japanese Quail was related to variation in the size of the egg. Egg contents of the two species were, on average, very similar. Yolk size varied in direct proportion to egg size, but in the quail large eggs contained disproportionately low levels of lipid and high levels of nonlipid dry matter. The composition of the newly hatched gull chick closely resembled that of the newly hatched quail. With increasing egg size, and thus chick size, water level increased and lipid level decreased in the gull chick, whereas lipid level increased in the quail chick. Among body organs, the integument of the gull exhibited a disproportionate increase with an increase in egg size, owing mostly to the accumulation of water; in the quail, the legs were the only organs to increase out of proportion to increase in body size. Disproportionate decreases in body proportion with increasing chick size appeared mostly in the head, stomach, and intestine components of both species. Variation in proportions of lipid and water in the chick related to egg size is discussed in terms of (1) ecological requirements of newly hatched chicks, (2) sibling competition within broods, and (3) stage of development of the young at hatching.

The extensive efforts to analyze the size dependence of various parameters of thermoregulation in birds (King and Farner 1961, Lasiewski and Dawson 1967, Lasiewski et al. 1967, Herreid and Kessel 1967, Crawford and Lasiewski 1968, Aschoff and Pohl 1970) have been useful in defining certain physiological characteristics of these animals. However, the analyses have tended to obscure the fact that variation beyond that associated with general allometric relations can occur in these parameters within particular taxa. For example, House Sparrows (Passer domesticus) show geographic variation in heat resistance, thermal conductance, and metabolic responses to cold (Hudson and Kimzey 1966, Blem 1973, 1974, Kendeigh and Blem 1974). Horned Larks (Eremophila alpestris) in deserts surpass their counterparts from more mesic situations in thermoregulation in hot environments (Trost 1972). Basal metabolic rate of certain pigeons is inversely correlated with the degree of aridity of their respective environments (Dawson and Bennett 1973). Variation in thermoregulatory parameters is also evident among young of closely related species, judging by the results of Koskimies and Lahti (1964). These authors demonstrated that hatchling ducks of species breeding exclusively at arctic and subarctic latitudes tended to have better control of body temperature at cool ambient temperatures than those of species with wider and more southerly distributions. We feel that variation of this type within taxa may well reflect functionally significant adjustments. To evaluate the physiological role of these adjustments more precisely, we have studied the metabolism and thermoregulatory capacities of hatchling gulls in the genus Larus. This group is a particularly useful one for considerations of physiological variation, for it is represented by more than 30 species over a latitudinal span extending from the arctic to the sub-antarctic. Our initial study in this series (Dawson et al. 1972) concerned the Laughing Gull (Larus atricilla). We now report results obtained on the Ring-billed Gull (Larus delawarensis). This species nests predominantly on lakes at midlatitude in northern United States and southern Canada. It also breeds in maritime situations in Quebec and Newfoundland (A.O.U. Check-list 1957).

Laughing Gulls (Larus atricilla) were studied in a tidal salt marsh located in Brigantine, New Jersey and on an island in the Gulf of Mexico to determine how nesting gulls respond to conspecific intruders. Gulls were observed in Texas and at Brigantine during the pre-egg stage. In Texas, Laughing Gulls set up pairing territories in the sand beach area next to the colony, and defended these areas against conspecifics. In New Jersey, pairing territories were often located on Spartina mats within the colony area. Twelve pairs of gulls were marked, sexed, and observed for eight to fourteen hours per day during the incubation period. An intruder was defined as any gull other than the nesting pair which landed within three meters of the nest. The interactions between the nesting pair and intruders were recorded for 1145 sequences. Eighty-five percent of all intruders were responded to with the following patterns: Long Calls (18%), Intruder Displays (45%), and Chases (22%). Long Calls and Intruder Displays were given by an incubating bird, while Chasing was performed by the mate standing nearby. Gulls flying over the nest were usually reacted to with a Long Call although Intruder Displays were sometimes given. Intruders landing within one meter of the nest were always given an Intruder Display by the incubating bird and were frequently chased by its mate. Intruders landing from one to two meters from the nest were usually given the Intruder Display: those landing two to three meters from the nest were usually chased. Gulls landing over three meters from the nest were usually ignored. The probability that an intruder was responded to decreased as the distance from the nest increased. The behavior of intruders was as follows. Fifty-three percent of the intruders landing within a meter of the nests were rapists or potential rapists. These intruders remained on the nest longer than did other intruder, and sometimes evoked pecking and attack from the incubating bird. Nest-material stealers (18%) remained on the nest for less time. Neighbors (7%) infrequently landed on the wrong nest but quickly flew to their own nest. In 22 percent of the cases the activities of the intruders could not be determined, since they were quickly repelled.

Most of this paper is a description and analysis of the hostile behavior patterns of adult Ring-billed Gulls and Franklin's Gulls on the ground or water. Both species have elaborate repertories of these patterns, including a variety of unritualized reactions and an even larger number of ritualized displays. The causation of these patterns is analyzed in terms of their motivation. All of them appear to be produced by simultaneous activation of the attack and escape drives; each pattern being produced by its own particular combination, i.e. relative and actual strength, of these drives, (with the addition of other drives, such as sex, in some cases). An attempt is also made to trace the derivation and social signal function(s) of the display patterns. A few of the corresponding patterns of the California Gull and Bonaparte's Gull are described very briefly. The comparative, evolutionary, implications of some of the displays are discussed at greater length, as they seem to be particularly suggestive, (more so than most of the aerial hostile patterns). The non-aerial hostile repertory of adult Ring-bills is very reminiscent of the other "typical Larus" gulls; but it does include a few peculiar features which have not been found in either the Herring Gull or the Common Gull. The California Gull is also very similar; and some of its displays are almost exactly intermediate in form between the homologous displays of the Herring Gull and the Ring-bill. The adult non-aerial hostile displays of Franklin's Gull are more distinctive. They are most reminiscent of the Laughing Gull; but the repertories of the two species are strikingly different in several important features. The repertories of the Ring-bill and Franklin's Gull are rather more similar than would be expected in view of the great morphological and ecological differences between the two species. This might suggest that the displays they hold in common are primitive in the family Laridae, (and the arrangement of these displays may also be primitive). It is possible, in fact, to make a tentative and hypothetical reconstruction of the probable complete hostile repertory, both aerial and non-aerial, of the ancestral gull, based upon comparison of the adults of all species whose behavior has been described in this and other publications.

Im Endothel der Kapillaren des Pecten der Augen von Haustaube und Lachmowe (Larus ridibundus) lassen sich lichtmikroskopisch alkalische und saure Phosphatase sowie Aminopeptidase nachweisen. Bernsteinsauredehydrogenase und verschiedene Esterasen fehlen dagegen.

IN both gulls and terns (Laridae) evidence suggests that individual recognition of offspring by parents develops more or less coincident with the onset of brood mobility. Evidence that individual recognition of parents by young also develops at the same time has been obtained for the Crested Tern (Sterna bergii) (Davies and Carrick, 1962), Ring-billed Gull (Larus delawarensis) (Evans, 1966), and Laughing Gull (L. atricilla) (Beer, 1969). As individual recognition is an important means of maintaining family unity (Alley and Boyd, 1950; Ramsay, 1951), particularly after the onset of extended brood mobility in or near a congested colony (Bateson, 1966), such recognition might be expected to be particularly well-developed at an early age in colonial species whose young leave the nest and form flocks soon after hatching. The primary objective of the present study was to test this hypothesis by studying the ontogeny of parental recognition by chicks of the Black-billed Gull (L. bulleri), a highly colonial species (Black, 1955; Beer, 1965), whose relatively precocial young may leave the nesting area, often to intermingle with other broods, within 1 to 2 days after hatching (Beer, 1966). Studies of parental recognition by young Ring-billed Gulls (Evans, 1966) had indicated that chicks were able to recognize the call the parents gave repeatedly when feeding them; in the present study, the parental calls given in this context were therefore selected to test for parental recognition by the young. In Black-billed Gulls, chick feeding is typically preceded or accompanied by a soft, staccato purring that has been described as a "soft crooning sound" of 1.5 to 2 seconds duration and may be transcribed "Chrrrrrooooooo" with a smooth decrease in pitch (Beer, 1966, compare with Figures 1, 2). Comparison with the vocalizations given in similar situations by the Herring Gull (L. argentatus) (Tinbergen, 1953: 105, 135, 225; Moynihan, 1955: 143), the Black-headed Gull (L. ridibundus) (Moynihan, 1955: 45, 95), the Ring-billed Gull (Moynihan, 1958a: 111; 1958b: 121), and various other gull species (Moynihan, 1955, 1962) suggests that this call is similar in function, and possibly homologous to the "mew call" characteristic of other Larus gulls. This call in the Blackbilled Gull differs strikingly to the human ear from the comparable call of the Herring Gull that Tinbergen (1953) named the "mew call." The name "mew call" is adopted here following the usage of Moynihan (1958a: 112) who described it as "the least confusing, if not the most descriptive, of the possible alternatives."

THERE are scattered records in the literature showing that the weights of consecutively laid fresh eggs or their measured lengths and maximum diameters may either decrease or increase in different species. In a statistical analysis of 20 clutches in the Laughing Gull (Larus atricilla), Preston and Preston (1953) showed that the length measurement did not differ significantly either among the eggs of the same clutch or between the eggs of different clutches. On the other hand, in three-egg clutches the third egg laid had a significantly smaller diameter than the first two. In two-egg clutches, the second egg appeared to resemble the third more than the second in the three-egg clutches, but the small number of measurements available did not permit definite conclusions. Since a large series of data had been collected at the Baldwin Bird Research Laboratory, near Cleveland, Ohio, between 1925 and 1938, on the eggs of the House Wren (Troglodytes aedon), we decided to determine whether or not there were any consistent changes in dimensions and weight with sequence of laying in this passerine species.

The effects of environmental contaminants on the reproductive success of olivaceous cormorants (Phalacrocorax olivaceus), laughing gulls (Larus atricilla), and black skimmers (Rhynchops niger) nesting in Galveston Bay, Texas were investigated from 1980 through 1982. Populations of cormorants and gulls have remained stable in recent years, but skimmer numbers may have declined. Cormorants produced 1.9 to 2.8 young per pair in nests that remained active throughout the season. Gull and skimmer reproduction was seriously limited by storms and predation. DDE and polychlorinated biphenyl (PCB) residues in carcasses and eggs generally were below levels associated with chronic poisoning and reproductive problems in most species of birds. Possible exceptions were four black skimmer carcasses with DDE concentrations that ranged from 20 to 92Μg/g and one olivaceous cormorant carcass with 20Μg/g DDE. The generally low levels of dieldrin, chlordane, HCB, toxaphene, and heptachlor epoxide were below those know to affect avian reproduction and survival. Mean DDE residues in cormorant and gull eggs were less than 1.8Μg/g. The mean DDE residue in skimmer eggs was less than 3.3Μg/g; 12% of the skimmer eggs contained at least 12Μg/g DDE, a level known to cause reproductive problems in some avian species. DDE in the eggs of all species declined from 1.5- to 7-fold over the past decade. Polychlorinated biphenyl was detected in all gull and skimmer eggs and in 90% of the cormorant eggs. Residues of PCB in cormorant and skimmer eggs in 1980–82 were lower than in 1970, but the frequency of occurrence in gull eggs increased. Polychlorinated styrenes were recovered in 45% of the cormorant carcasses at levels below 1Μg/g. Eggshell thicknesses in all three species were similar to those of eggshells collected before the widespread use of DDT.

Tool use (i.e., the use of a moveable, inanimate, noninternally manufactured object to facilitate the acquisition of a goal; McGrew et al. 1975) has been documented for many avian species (van LawickGoodall 1970) including several corvids (Orenstein 1972, Jones and Kamil 1973, Powell and Kelly 1975, Janes 1976). I report here two observations of corvids, a Fish Crow (Corvus ossifragus) and a Common Raven (C. corax), attempting to displace nesting gulls by using objects. Fish Crows and Common Crows (C. brachyrhynchos) prey extensively on the eggs of Laughing Gulls (Larus atricilla) and Clapper Rails (Rallus longirostris) in the marsh of the Brigantine National Wildlife Refuge, New Jersey (Montevecchi 1977), often taking advantage of human disturbances in the nesting areas. On 6 June 1974, a Fish Crow with a 10cm stalk of dried salt marsh grass (Spartina alterniflora) in its beak flew directly toward an incubating Laughing Gull near an observation blind in which I was working. The crow hovered about 5 m above the nest, and then, passing the stalk from its beak to its feet, descended to about 3-4 m. The gull, focusing intently on the hovering crow, became progressively more aroused; it called loudly, erected its plumage, and arose from the eggs. The crow dropped the stalk toward the gull. Owing to a brisk breeze, the stalk landed about 1 m from the gull, who remained on the nest. The crow flew off and did not return for the remainder of the observation period (90 min). Had the stalk struck (or landed nearer) the gull, the highly agitated bird probably would have fled the nest. No predation occurred at this nest during the subsequent week when it was checked, and I saw no similar behavior by crows. On 12 June 1977, on Baccalieu Island, Newfoundland, I observed a Common Raven on a cliff perched about 1 m above a Black-legged Kittiwake (Rissa tridactyla) sitting on a nest. The raven called loudly at the aroused kittiwake, who behaved like the Laughing Cull described above. After about one minute, the raven pulled a tuft of dried grass from sod on the cliff face and dropped it on the gull. When the grass hit the kittiwake, the bird took flight, and the raven jumped down and rummaged through the empty nest. Ravens on Baccalieu Island frequently supplant nesting kittiwakes by suddenly approachi g them closely while calling loudly, or sometimes by physical attack. Ravens often pull grass from the cliff face, though I only once saw a raven drop the grass on a gull. Janes (1976) reported a raven dropping rocks on human intruders near its nest. If hunting tactics such as those reported here are successful, it is likely that they will be used more frequently and may be rapidly adopted by other corvids hunting in the same places (see Hinde and Fisher 1951).

The development of gull chicks is typically considered semi-precocial, because the birds remain in or near the nest for some days after hatching and depend on parental care, but hatch with downy coverings and possess some thermoregulatory ability (Drent 1967; Palokangas and Hissa 1971; Dawson et al. 1972, 1976; Dunn 1976; Dawson and Bennett 1980, 1981). Newly hatched chicks of several gull species in the genus Larus have been studied with respect to thermoregulatory function. These studies suggest that the heat transfer coefficient (conductance) is not correlated with climatic conditions in the breeding area, whereas the thermogenic ratio (maximum increase in metabolism during cold-exposure) seems to show some correlation with breeding distribution (Dawson and Bennett 1981). Thus, chicks of the Common Black-headed Gull (L. ridibundus) and the Ring-billed Gull (L. delawarensis) can double their metabolic rate above the basal rate (BMR) when exposed to cold (Palokangas and Hissa 1971, Dawson et al. 1976), whereas those of the Laughing Gull (L. atricilla), which breed in warmer climates, are able to increase their metabolic rate by only 50% (Dawson et al. 1972). The Black-legged Kittiwake (Rissa tridactyla) has a circumpolar holarctic distribution, breeding in tundra, boreal, and temperate climatic zones (Voous 1960). Since the kittiwake thus breeds farther north than most other gulls, one could hypothesize that the chicks have special thermoregulatory capabilities. To test this, we studied body temperature regulation in newly hatched chicks of kittiwakes breeding at 79"N latitude.

The eggs of Herring Gulls (Larus argentatus) and several other marsh nesting species undergo periodic flooding. We conducted an experiment to test the effects of simulated tidal flooding on Herring Gull and domestic chicken (Gallus gallus) eggs. Experimental variables were salinity, temperature, length of immersion, and state of incubation when immersion occurred. In general, Herring Gull eggs had a higher hatching success after immersion and at lower temperatures than did chicken embryos. Herring Gull embryos equally survived immersion during the first and third week of development, whereas more chicken embryos survived immersion during the first week. There were no significant differences between species with respect to the duration of the immersion. Herring Gulls (Larus argentatus) have recently begun breeding in salt marshes of New Jersey that are subject to tidal flooding (Burger 1977), and presently most of their colonies are located on coastal salt marshes or salt marsh islands (Kane and Farrar 1977). Herring Gulls prefer to nest under Iva bushes on the higher parts of the islands, but in the last few years many gulls have nested in lower Spartina alterniflora areas that are subject to tidal flooding (Burger 1977, Burger and Shisler, unpubl.). Immersion of eggs during tidal flooding in the breeding season may result in the death of embryos, but the eggs of bird species that are normally subject to inundation may be more resistant to harmful effects of flooding. For example, many species of ducks have eggs with water-repellent surfaces (Welty 1975), which probably help resist the entry of water. Inundation of Clapper Rail (Rallus longirostris) nests by high tides has no apparent effect on hatching success (Mangold 1974). In New Jersey, Laughing Gulls (Larus atricilla) normally nest in salt marshes that are subject to saltwater flooding (Bent 1921, Bongiorno 1970) and Burger (1979) found that Laughing Gull eggs have a 63% hatching success even after being immersed in salt water for two hours during the third week of incubation. In order to determine effects of flooding on survival of embryos, we immersed Herring Gull and domestic chicken (Gallus gallus) eggs and varied four factors that we thought might be related to death of embryos. The factors studied were salinity and temperature of the water, duration of immersion, and stage of incubation. MATERIALS AND METHODS Field research was conducted on Clam Island, a salt marsh island in Barnegat Bay, New Jersey (39045'N, 74'08'E). The vegetation of Clam Island is primarily Spartina alterniflora and S. patens grass with scattered Iva frutescens and Baccharis halimifolia bushes. The island is divided into four sub-islands, three of which contained 1,200 pairs of nesting Herring Gulls during this study. The majority of the Herring Gulls nested in the higher bush areas of the island. Two hundred pairs of Laughing Gulls nested on the fourth sub-island. The island was checked for nests and eggs one to three times per week from 16 April until 15 May 1978, when it was checked every other day until 10 July. New nests were marked with flags and numbered with metal tags; eggs were numbered with a black felt-tip marker when first discovered. Nests and contents were checked until 10 July, when the fate of all eggs could be determined. When clutches were at the right stage of incubation we collected eggs and randomly assigned one of eight treatments for that stage of incubation to the group of eggs. Eggs removed from a nest for treatment were replaced with an egg from another nest so that the parents would continue to incubate and not vacate the nest. We marked the eggs removed for treatment with a black felt-tip marker so that they could be returned to their original nest. All of the eggs were taken from nests which initially had three-egg clutches, and 89% of the nests had three eggs when treated. We treated only eggs from nests whose date of clutch completion with three eggs was known and we considered the time of clutch completion to be the beginning of the first week of incubation. Eggs within the same nest always received the same treatment and were treated only once. We treated eggs by immersing them completely for the prescribed time in a bucket of water of the chosen salinity and temperature. The levels of the four factors that we used for immersion treatments were as follows: for salinity, ocean water taken from Barnegat Bay and fresh water; for water temperature, 7-90C and 26-280C; for duration of immersion, half an hour and two hours; and for stage of incubation, the first and third weeks of incubation.

Philophthalmus hegeneri sp. n. is described from adults reared from megalurous cercariae developing in the marine snail, Batillaria minima (Gmelin, found infected at numerous shore localities along the Gulf of Mexico from Dunedin to Key West, Florida. Metacercariae in flask-shaped cysts were infective orally and ocularly to various experimental birds including domestic chickens and pigeons, Mute Swan (Cygnus olor), Western Gull (Larus occidentalis), and the Southern Chachalaca (Ortalis ruficauda). Natural avian hosts include the Royal Tern (Thalasseus maximus), Yellow-crowned Night Heron (Nyctanassa violacea), Laughing Gull (Larus atricilla), and the Willet (Catoptrophorus semipalmatus). The genus Ophthalmotrema is considered a synonym of Philophthalmus. This is the first time a marine gastropod has been implicated in the biology of any member of this genus. A marine-acquired species of Philophthalmus which reached maturity under the nictitating membrane of a variety of experimental avian hosts has been mentioned by Penner and Fried (1961), Fried and Penner (1961), and Fried (1962a, b, c). The adult flukes were noted as related to the lucipetus group of 4 of the 23 species previously described in having follicular rather than tubular vitellaria. These were P. lucipetus, P. lachrymosus, P. offlexorius, and P. skriabini. Because our material from both experimental and natural infections differs from all previously described species of Philophthalmus, it is necessary to report the species as new. All measurements are in millimeters. Philophthalmus hegeneri sp. n.