Black-headed Gull Colonies Research Articles

Position in the laying order has sex-specific consequences for reproductive success in adult black-headed gulls.

Mothers who produce multiple offspring within one reproductive attempt often allocate resources differentially; some maternally derived substances are preferentially allocated to last-produced offspring and others to first-produced offspring. The combined effect of these different allocation regimes on the overall fitness of offspring produced early or late in the sequence is not well understood, partly because production order is often coupled with birth order, making it difficult-to-separate effects of pre-natal maternal allocation from those of post-natal social environments. In addition, very little is known about the influence of laying order on fitness in later life. In this study, we used a semi-natural captive colony of black-headed gulls to test whether an offspring's position in the laying order affected its early-life survival and later-life reproductive success, independent of its hatching order. Later-laid eggs were less likely to hatch, but among those that did, survival to adulthood was greater than that of first-laid eggs. In adulthood, the laying order of females did not affect their likelihood of breeding in the colony, but male offspring hatched from last-laid eggs were significantly less likely to gain a breeding position than earlier-laid males. In contrast, later-laid female parents hatched lower proportions of their clutches than first-laid females, but hatching success was unrelated to the laying order of male parents. Our results indicate that gull mothers induce complex and sex-specific effects on both the early survival of their offspring and on long-term reproductive success through laying order effects among eggs of the same breeding attempt.

Multidrug-Resistant High-Risk Escherichia coli and Klebsiella pneumoniae Clonal Lineages Occur in Black-Headed Gulls from Two Conservation Islands in Germany.

Multidrug-resistant (MDR) Enterobacterales, including extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, not only emerge in healthcare settings but also in other habitats, such as livestock and wildlife. The spread of these pathogens, which often combine resistance with high-level virulence, is a growing problem, as infections have become increasingly difficult to treat. Here, we investigated the occurrence of ESBL-producing E. coli and K. pneumoniae in fecal samples from two black-headed gull colonies breeding on two nature conservation islands in Western Pomerania, Germany. In addition to cloacal samples from adult birds (n = 211) and their nestlings (n = 99) during the 2021 breeding season, collective fecal samples (n = 29) were obtained. All samples were screened for ESBL producers, which were then subjected to whole-genome sequencing. We found a total of 12 ESBL-producing E. coli and K. pneumoniae consisting of 11 E. coli and 1 K. pneumoniae, and including the international high-risk E. coli sequence types (ST)131, ST38, and ST58. Eight of the investigated strains had a MDR genotype and carried a large repertoire of virulence-associated genes, including the pap operon, which is important for urinary tract infections. In addition, we identified many genes associated with adherence, biofilm formation, iron uptake, and toxin production. Finally, our analysis revealed the close phylogenetic relationship of ST38 strains with genomes originating from human sources, underlining their zoonotic and pathogenic character. This study highlights the importance of the One Health approach, and thus the interdependence between human and animal health and their surrounding environment.

Great Crested Grebe (Podiceps cristatus) synchronies egg laying with protective species

Great crested grebes (Podiceps cristatus) are opportunistic breeders nesting in colonies or solitarily in different biotopes with varying nesting dates in different circumstances. On the northern coast of the Neva Bay in the eastern part of the Gulf of Finland, great crested grebes breed solitarily, in colonies situated in reed beds and in a colony on the open water in direct vicinity of a colony of black-headed gulls (Larus ridibundus) and black terns (Chlidonias niger). In the vicinity of the larid colony, grebes profit from the protecting behaviour of gulls and terns in a similar way as they do in their mixed colonies with larids. Despite the fact that small larids have a shorter incubation period than great crested grebes, the latter synchronize their beginning of incubation with the gulls and terns. The incubation of all three species in two adjoining open-water colonies started on the same dates. The incubation of grebes nesting in the reed beds began significantly later. The average clutch sizes did not differ significantly between the colonies situated on the open water near larids and those in the reeds. The average lowest distances between the nests of great crested grebes in the open water colony were larger than in the reed bed colonies. The ability to synchronize the beginning of incubation with a small protecting species helps great crested grebes to occupy otherwise unsafe habitats.

Does the vicinity of the Black-Headed Gull colony (Chroicocephalus ridibundus) increase the breeding success of the Common Tern (Sterna hirundo) on the islands of the middle Vistula?

We conducted our study in the Common Tern colony (STH) located on an island in the middle Vistula River course, at the height of the city of Dęblin (km 393–394 of the waterway), in 2017. Our goal was to investigate some aspects of the biology and reproductive ecology of this species. Due to the fact that STH breeds both in single-species as well as in two- or multi-species colonies, in associations with Little Terns (Sternula albifrons), Black-Headed Gulls (Chroicocephalus ridibundus) (LAR) and/or Mew Gulls (Larus canus), we wanted to investigate whether the neighborhood of other species (in this case LAR) affected hatching success and chick survival in STH. Our results clearly show that the presence of breeding terns in the neighborhood of the LAR colony was not accidental and/or caused by the lack of space on the island and/or the possibility of nesting elsewhere. The height of nesting site, type of nesting habitat, clutch size, mean egg volume and mean egg mass of these STH pairs did not differ significantly from those that formed a single species colony, on the same island but several hundred meters away. However, STH nests in the neighborhood of the LAR colony were established much earlier and both the hatching success and chick survival of STH during the early-chick stage were twice as high. Thus, we can conclude that the LAR colony could provide an effective protection against predation of crows, magpies and gulls, dangers which accounted for the vast majority of STH nest failures in the year of our study.

Collapse of a protector species drives secondary endangerment in waterbird communities

Interactions and dependence between species can transmit the effects of species declines within and between trophic levels, resulting in secondary endangerments and, in some cases, extinctions. Many mixed-species avian breeding aggregations commonly have a protector species whose aggressive nest defense is used by other species to defend their nests. Disappearance of the protector species may have population demographic consequences on the dependent species. Aggressive nest defense behavior of small colonial gulls, such as the black-headed gull (Chroicocephalus ridibundus), is used by many waterbird species to gain protection against predators. We used data from 15 local waterbird communities in Finland to study long-term changes and dynamics of breeding numbers of other waterbirds as a response to long-term changes and dynamics of black-headed gull colonies. We found that breeding numbers of many species tracked long-term changes in the size of black-headed gull colonies. This was true even after controlling for a common trend in the size of the black-headed gull colony and the breeding numbers of the other species. The trend-controlled positive temporal association with black-headed gull was relatively stronger in species that nest in similar habitats of a lake as the black-headed gull, and in species that have a more critical conservation status due to drastic population decline. Our results suggest that the overall decline of black-headed gull colonies has resulted in secondary endangerment of many other species in waterbird communities.

Födosök hos skrattmås Chroicocephalus ridibundus under häckningstid

During the 1990s, I compared the feeding habitat use during the breeding time of two Black-headed Gull colonies in south-western Sweden, a small urban colony (<100 pairs; Skövde city) and a large rural colony (>2000 pairs; Hornborgasjön), 20 km apart. Randomly selected roads were patrolled and gulls were counted and allocated to the observed feeding habitat (within 7.5 km of the small and within 15 km of the large colony). Refuse dumps were used by both colonies, but studied only for the rural colony with up to 30% of the birds counted at the dump. In spite of this apparent importance, the dump was not critical as closure of it did not affect colony size. With the dumps excluded, the birds from the urban colony used predominantly lawns (c. 70%) and those from rural colony bare soil (43%), newly sawn fields (20%) and pasture (14%). When feeding young the gulls collected food at a larger distance than during incubation: 2.7 vs. 1.6 km for the urban and 9.9 vs. 8.4 km for the rural colony.

Effects of harbour and ship channel construction on breeding seabirds

Bird population changes were studied during the construction of the new Vuosaari Harbour in 2001–2011 (Helsinki, Finland, N60°14.52' E25°9.07'). Part of the monitoring programme was to determine the possible impacts of harbour and ship channel construction on breeding seabird populations. The study revealed that the population trends of most species showed no substantial difference between islets close to harbour and channel and more distant reference islet. A Black-headed Gull colony was destroyed by landfill but that was deliberately and with permission. The trends of Ruddy Turnstone and Great Black-backed Gull populations were more negative in near than in distant islets. In the surrounding archipelago, the Barnacle Goose, Mew Gull and Common Black-headed Gull clearly increased during the study years. The European Herring Gull decreased distinctly, which was probably caused by the removal of individuals from the rubbish dumps around Helsinki. There were some differences between the restricted-and open-access islands. The population of Herring Gull was higher and the decline stronger in the restricted areas, while the Common Ringed Plover population simultaneously increased.

An Assessment of the Effectiveness of Straw as an Algal Inhibitor in an Upland Scottish Loch

The control of algal blooms caused by a colony of black-headed gulls in an upland loch in central Scotland was attempted using bales of barley straw. The initial evidence suggests that the release of the inhibitory substance commenced 6-10 months after placement of the bales and was sustained for at least 18 months. The moored bales provided a useful substrate for benthic invertebrates, acting as a shelter and detritus trap. Algal diversity appeared not to be affected by the bales, but the cell numbers of the main species were affected.

Radionuclides and the birds at Ravenglass

Since 1983, concern has been expressed about the apparent decline in numbers of birds in the Ravenglass estuary in west Cumbria, particularly of the black-headed gull colony on the Drigg dunes, and suggestions have been made that this decline might be due to excessive radiation in the birds' food and their general environment. Twelve species of marine invertebrates from Ravenglass, most of them known to be important foods for birds, were analysed, and further samples were taken from sites along the west Cumbrian coast. None of these samples showed excessive contamination with any of the radionuclides analysed. Analysis of a sample of bird carcasses from the areas showed oystercatchers ( Haematopus ostralegus) and shelduck ( Tadorna tadorna) to have some of the highest concentrations of 137Cs in their tissues; yet their breeding success and populations were not affected. Black-headed gulls, on the other hand, were found to be feeding mainly inland, and were the least contaminated with radionuclides of all the birds at Ravenglass, yet this species and its breeding success were in decline. Calculations of the total dose equivalent rate to the whole body of the most contaminated black-headed gull amounted to 9·8 × 10 −4 mSvh −1 ( ⋍8·4 × 10 −4 ) mGh h −1, whole body absorbed dose rate), and the background exposure dose was of the order of 8·3 × 10 −4 mGy h −1. As a minimum chronic dose of 1000 mGy day −1 has been found necessary to retard growth of nestling birds, and 9600 mGy over 20 days of incubation to cause the death of 50% of embryos in black-headed gulls' eggs, the concentrations of radionuclides in the foods, body tissues and general environment were at least three orders of magnitude too low to have had any effect. The more likely cause of the desertion of the gullery was the combination of an uncontrolled fox population, the severest outbreak of myxomatosis amongst the rabbits since 1954 and the driest May–July period on record, all in the same year (1984).

Food information in the Black-headed Gull, Larus ridibundus

The ‘information-centre’ hypothesis suggests that bird colonies function as sources of information about good feeding sites, to which unsuccessful birds may follow foragers. One assumption of the hypothesis is that unusually successful foragers are followed by other colony members when returning to a newly found, rich food source. We tested this assumption in a colony of Black-headed Gulls (Larus ridibundus). Parents feeding their young from a rich, artificial food source were observed on their return trips to the feeding site. In none of 50 cases did other colony members follow them to the newly found food. However, the gulls were attracted to groups of foraging conspecifics. In experiments with paired food piles and a group of model gulls at one pile in each pair, Black-headed Gulls always alighted first at the piles with models. Hence the information-centre mechanism was refuted, but the gulls did acquire food information from each other in another way.

Colony and Nest Site Selection in Laughing Gulls in Response to Tidal Flooding

-We examined colony and nest site selection in Laughing Gulls (Larus atricilla) from 1976 to 1979 in Barnegat Bay, New Jersey. Laughing Gulls nested predominantly in Spartina alterniflora on low salt marsh islands. In 1978, the gulls shifted colony locations to higher islands that contained a higher percentage of S. patens and Phragmites. The gulls nested on spoil areas which were slightly higher in elevation. Differential nesting success occurred as a function of habitat because of high tides in early July which wiped out all nests in S. alterniflora and most of those in S. patens. Chick survival varied as a function of vegetation type. We propose that all larid species exhibit site tenacity because they return to former sites even if they eventually shift locations. Further, we suggest that each species chooses from a wide range of potential colony and nest sites depending upon local conditions and proximate environmental cues. Many species of gulls and terns exhibit remarkable colony site tenacity in that they occupy the same places for decades or longer. This is particularly true of colonies situated in stable habitats such as rocky islands or cliffs: Black-legged Kittiwake (Rissa tridactyla) colonies use the same cliffs every year (Coulson and White 1956, 1958, 1960) and Glaucous Gulls (Larus hyperboreus) often nest on the same rocks in tundra lakes year after year (Snyder 1940). A colony of Black-headed Gulls (L. ridibundus) has remained at Ravenglass in England since the 1600's, nesting amid sand dunes and marram grass (Patterson 1965). Colony site tenacity has also been shown for the Herring Gull (L. argentatus; Tinbergen 1961, Ludwig 1963), Silver Gull (L. novaehollandiae; Murray and Carrick 1964), Glaucous-winged Gull (L. glaucescens; Vermeer 1963), Ring-billed Gull (L. delawarensis; Southern 1967), Black-headed Gull (L. ridibundus; Beer 1961), and Laughing Gull (L. atricilla; Stone 1937, Noble and Wurm 1943). Species that nest in unstable habitats, on the other hand, shift colony locations when habitats become unsuitable. Notable examples of such species are the Blackbilled Gull (L. bulleri, Beer 1966), Franklin's Gull (L. pipixcan, Burger 1974a) and Brown-hooded Gull (L. maculipennis, Burger 1974b). The first species nests on sand bars in the middle of rivers, and the latter two nest in marshes that suffer sporadic changes in water levels (Weller and Spatcher 1965). The apparent dichotomy between species nesting in stable habitats versus those in unstable habitats prompted McNicholl (1971, 1975) to postulate that colony tenacity relates to habitat stability. Colony site tenacity may not differ among species, but may relate to the conditions that particular members of each species face. A colony of kittiwakes might shift quickly if their cliff suddenly fell into the sea. Similarly, Laughing Gulls, usually considered to show a high degree of colony site tenacity (Bongiorno 1970, Nisbet 1971), may abandon colony sites when these become temporarily unsuitable. In this paper we report on colony and nest site selection in Laughing Gulls under normal tidal conditions (1976, 1977, 1979) and under unusually high tidal conditions (1978). At the beginning of the study, we did not know when flooding tides would occur, but planned to continue the study until we encountered these conditions. We wished to determine if Laughing Gulls would respond to exceptionally high tides by changing colony sites, changing nest ites, or both. Laughing Gulls nest from the Gulf of Mexico and the Caribbean to the northern Atlantic, although few colonies exist farther north than New Jersey. Along the middle Atlantic coast they nest in tidal salt marshes (Burger and Beer 1975), while south of the Carolinas they nest on sandy islands (Stone 1937, Buckley and Buckley 1972, Dinsmore and Schreiber 1974).

A Census of Black-headed Gull Colonies

Probably over 100,000 pairs of Black-headed Gulls now breed in England and Wales, about double the total in 1958. The two largest colonies hold more than a quarter of ,the total, and probably a half of the population is now concentrated on the shores of the Solent and Wash. inundation by high tides is the greatest hazard, but despite this the coastal colonies have shown spectacular increases.

Census of Black-Headed Gull Colonies in England and Wales, 1958

Census of Black-Headed Gull Colonies in England and Wales, 1958

Census of Black-headed Gull colonies in Scotland, 1958

Census of Black-headed Gull colonies in Scotland, 1958

Census of Black-headed Gull colonies in England and Wales, 1958

Census of Black-headed Gull colonies in England and Wales, 1958

Observations and experiments on egg-laying in the black-headed gull ( Larus ridibundus L.)

Two hundred and ninety-five nests of a Black-headed gull colony were inspected for eggs once, twice or three times daily from 14th April till 6th May, and at irregular intervals later. In 196 nests first clutches appeared over a period of more than three weeks. In the first week only 13 per cent. of the birds started laying. Darling's (1938) suggestion that discrete parts of a big colony behave as he thought isolated colonies did, could not be verified. Slightly more a-, b- and c-eggs are laid during the day than during the night but the differences are not significant. No significant difference was found for the number of eggs laid in the afternoon and in the morning. Of 184 clutches 70 per cent. consisted of 3 eggs. This figure is almost certainly too small, because it does not include the clutches which had been robbed before they were inspected. The most common interval between the laying of successive eggs of a clutch is 1 1/2–2 days. The mean interval between the laying of the a- and b-eggs is not significantly different from the mean interval between the b- and c-eggs. The Black-headed gull lays its clutch in a shorter time than do Common and Herring gulls. If the a-egg was removed within 12 hours after it was laid the ♂ laid a d-egg 2 days after the c-egg. If both a- and b-eggs or all 3 eggs were removed immediately after each was laid protracted laying occurred in a number of cases. In one nest 7 eggs were obtained from one ♂. Therefore, the Black-headed gull also is an indeterminate layer as Salomonsen (1939) and Paludan (1951) proved for the Herring gull and the Lesser Black-backed gull. Reducing the number of eggs had no effect on egg-laying if one egg was left in the nest. It is thus not the size of the clutch but the gull's brooding which causes the cessation of egg-laying. Removing both eggs immediately after the b-egg was laid caused protracted laying in a number of cases. If, however, all eggs were removed after the c-egg was found no further egg was laid immediately but a full second clutch appeared after 8–13 days. By adding eggs several days before the gulls laid it was possible to suppress egg-laying completely or partially: 13 pairs never laid though many brooded our wooden eggs for 2 months. In 4 nests one egg was laid after 5–7 days' sitting, in 13 nests we found 2 eggs and in 4 nests where the birds had only sat for one day all 3 eggs appeared. Five ovaries were inspected at various times during the egg-laying cycle. Around the time the first egg is laid, the second and third are successively smaller and a tiny fourth follicle was found, apart from the still smaller reserve eggs. In two birds killed after the b-egg had been laid this d-egg was degenerating. It is concluded, as it was for the Herring gull ( Paludan, 1951 ), that incubating has an inhibitory influence on the growth of follicles and causes them to degenerate as long as they have not reached a certain stage of maturity. This limits the number of eggs to be laid after the gull has begun to sit.

British Trust for Ornithology

THE fifth annual report of the British Trust for Ornithology reveals the remarkable progress made in the co-ordination of field studies in Britain in recent years, and much space is given to the results of these field investigations. They include the lapwing habitat inquiry, and that of the distribution of the corncrake, which is to be continued this year. In 1938, 1200 completed returns were received referring to the corncrake and noting its decreasing numbers, most marked in Ireland and least in Scotland; efforts are being made to get information from the Continent, where the species is also decreasing. The survey of black-headed gull colonies had 150 observers, and shows that few coastal counties have been colonized in the past twenty-five years, but there has been a marked inland spread. the sample census of heronries shows an incroase of breeding stock in many places, and three heronries in England now have between 120 and 150 nests. The bridled guillemot inquiry shows that few of this variety are in the English and Welsh colonies, but the percentage increases from about lat. 56° N. The woodcock inquiry showed by ringing that occasional British woodcock accompany the winter migrants when they return to their native breeding haunts. the woodland bird inquiry gave special attention to the British sub-species of birds, which can be divided into four groups showing thirty-soven distinctive races of bird entirely confined to Britain. A now inquiry on the redshank is planned for 1939–40 and a hatching and fledging inquiry will extend nationally the work started at Whipsnade Bird Sanctuary.