Larus Argentatus Research Articles

Young American Herring Gulls (Larus argentatus Subsp. Smithsonianus) Have the Opportunity for Social Development at the Breeding Colony

Young American Herring Gulls (Larus argentatus Subsp. Smithsonianus) Have the Opportunity for Social Development at the Breeding Colony

The influence of сestodes parasitizing in the small intestine of herring gull chicks on the activity of the host proteases

The activity of proteases and subclasses of proteases in small intestines of the herring gull (Larus argentatus (Pontoppidan, 1763)) chicks were determined. Changes of the protease activity in chicks infested by cestodes Tetrabothrius erostris (Loennberg, 1889) (Cestoda: Tetrabothriidae), Microsomacanthus ductilus (Linton, 1927) (Cestoda: Hymenolepididae), Wardium cirrosa (Krabbe, 1869) (Cestoda: Aploparaksidae), Arctotaenia tetrabothrioides (Loennberg, 1890) and Alcataenia larina (Krabbe, 1869) (Cestoda: Dilepididae) were studied. The activity of serine proteases decreased in the small intestine of gulls at the sites of cestode parasitism with high infestation values (M. ductilus in the proximal segment, W. cirrosa in the distal segment, A. tetrabothrioides, T. erostris and A. larina in the medial segment). The activity of cysteine proteases increased in the sites of localization of cestodes M. ductilus, W. cirrosa and A. larina. All the studied cestodes adsorbed proteases on the surface of the tegument, most of those were represented by serine proteases. Cestode homogenates of W. cirrosa, M. ductilus, A. tetrabothrioides, T. erostris and A. larina inhibited the activity of host proteases and the activity of commercial trypsin.

Visual fields, foraging and collision vulnerability in gulls (Laridae)

Wide variation in visual field configuration has been recorded among avian species and it is hypothesized that this variation is driven primarily by foraging ecology and predator detection. It has also been shown that visual field configurations can render some species more vulnerable to collisions with human artefacts that extend into open airspace, such as power lines and wind turbines. Visual fields have three main components: the monocular fields describe the extent of the world seen by each eye, the binocular field describes the region where the monocular fields overlap, and the blind area describes the region in which no vision is provided. Among birds, the topography of the binocular field, and the extent and position of the blind area, show considerable interspecific variation. Although Laridae (gulls, terns, skimmers) are a large and cosmopolitan taxon, visual field characteristics of only one species, Black Skimmer Rynchops niger, have been determined. However, skimmers are distinct from other Laridae species because they use a specialized foraging technique based upon tactile cues. We determined visual fields in three species of gulls (European Herring Gulls Larus argentatus, Lesser Black‐backed Gulls Larus fuscus, Black‐legged Kittiwakes Rissa tridactyla), and found that they show the key characteristics associated with visually guided foraging. However, the binocular field does not extend through the full height of the frontal field. This results in a blind sector, which can project in the direction of flight when gulls pitch their heads sufficiently far forwards to visually search the surface below. This could render gulls vulnerable to collisions with anthropogenic structures (power lines, wind turbines) that extend into the open airspace. Photographs show that gulls in level flight do pitch their heads forward sufficiently to render them almost blind in the direction of travel, and further work on the head positions adopted by gulls in flight are recommended. The visual field of skimmers differs markedly from those of gulls. Their binocular field topography is interpreted as functioning in the control of bill position when skimming (flying just above the water surface with the elongated, blade‐like, rhamphotheca of the mandible extending through the water surface). Skimmers also have a blind area, which projects forwards in the direction of travel when skimming. This can be associated with the vulnerability of skimmers to collisions with objects that extend just above the water surface.

Plastic ingestion, accumulated heavy metals, and health metrics of four Larus gull species feeding at a coastal landfill in eastern Canada

The objectives of this research were to assess ingested plastics and accumulated heavy metals in four urban gull species. Additionally, the relationships between ingested plastics and selected demographic and health metrics were assessed. Between 2020–2021 during the non-breeding seasons, 105 gulls (46 American herring gulls (HERG, Larus argentatus smithsonianus), 39 great black-backed gulls (GBBG, Larus marinus), 16 Iceland gulls (Larus glaucoides), 4 glaucous gulls (Larus hyperboreus)) were killed at a landfill in coastal Newfoundland and Labrador, Canada, as part of separate, permitted kill-to-scare operations related to aircraft safety. Birds were necropsied, the upper gastrointestinal tract contents were processed using standard techniques, and livers were analyzed for accumulated As, Cd, Hg, and Pb. The relationships between ingested plastics, demographics, and health metrics were assessed in HERG and GBBG. Across all four species, 85 % of birds had ingested at least one piece of anthropogenic debris, with 79 % ingesting at least one piece of plastic. We detected interspecific differences in plastic ingestion and hepatic trace metals, with increased ingested plastics detected in GBBG compared with HERG. For GBBG, levels of ingested plastic were relatively greater for birds with higher scaled mass index, while HERG with more ingested plastic had higher liver lead concentrations.

Early-life diet does not affect preference for fish in herring gulls (Larus argentatus).

Urban populations of herring gulls (Larus argentatus) are increasing and causing human-wildlife conflict by exploiting anthropogenic resources. Gulls that breed in urban areas rely on varying amounts of terrestrial anthropogenic foods (e.g., domestic refuse, agricultural and commercial waste) to feed themselves. However, with the onset of hatching, many parent gulls switch to sourcing more marine than anthropogenic or terrestrial foods to provision their chicks. Although anthropogenic foods may meet chick calorific requirements for growth and development, some such foods (e.g., bread) may have lower levels of protein and other key nutrients compared to marine foods. However, whether this parental switch in chick diet is driven by chicks' preference for marine foods, or whether chicks' food preferences are shaped by the food types provisioned by their parents, remains untested. This study tests whether chick food preferences can be influenced by their provisioned diet by experimentally manipulating the ratio of time for which anthropogenic and marine foods were available (80:20 and vice versa) in the rearing diets of two treatment groups of rescued herring gull chicks. Each diet was randomly assigned to each of the 27 captive-reared chicks for the duration of the study. We tested chicks' individual food preferences throughout their development in captivity using food arrays with four food choices (fish, cat food, mussels and brown bread). Regardless of the dietary treatment group, we found that all chicks preferred fish and almost all refused to eat most of the bread offered. Our findings suggest that early-life diet, manipulated by the ratio of time the different foods were available, did not influence gull chicks' food preferences. Instead, chicks developed a strong and persistent preference for marine foods, which appears to match adult gulls' dietary switch to marine foods upon chick hatching and may reinforce the provisioning of marine foods during chick development. However, whether chicks in the wild would refuse provisioned foods, and to a sufficient extent to influence parental provisioning, requires further study. Longitudinal studies of urban animal populations that track wild individuals' food preferences and foraging specialisations throughout life are required to shed light on the development and use of anthropogenic resource exploitation.

Does social context influence neophobia in juvenile herring gulls (Larus argentatus)?

Does social context influence neophobia in juvenile herring gulls (Larus argentatus)?

First Documented Nesting of American White Pelicans (Pelecanus erythrorhynchos) in Ohio, USA

The discovery and documentation of a new breeding species in a defined area, such as a state, is a crucial first step in understanding the basic natural history of a species and its consequent needs for management and conservation. The American White Pelican has gradually expanded its breeding range from the prairies of North America into the Great Lakes region. While conducting a census on Herring Gulls (Larus argentatus) at least 4 nests of pelicans with either eggs or young were found. Further census showed a minimum of 12 almost fledged young. This report documents the first confirmed nesting of the American White Pelican in Ohio. This first nesting was observed in May 2023 on Turning Point Island, an artificial island in Sandusky Bay, Erie County, Ohio, in the western basin of Lake Erie. Continued nesting of pelicans in Ohio is expected in future years at this location and other suitable sites in the area. This species is likely to need future monitoring and management.

How do life history and behaviour influence plastic ingestion risk in Canadian freshwater and terrestrial birds?

Plastic ingestion presents many potential avenues of risk for wildlife. Understanding which species and environments are most exposed to plastic pollution is a critical first step in investigating the One Health implications of plastic exposure. The objectives of this study were the following: 1) Utilize necropsy as part of ongoing passive disease surveillance to investigate ingested mesoplastics in birds collected in Ontario and Nunavut, and examine the relationships between bird-level factors and ingested debris; 2) evaluate microplastic ingestion compared to ingested mesodebris in raptors; and 3) identify potential sentinel species for plastic pollution monitoring in understudied freshwater and terrestrial (inland) environments. Between 2020 and 2022, 457 free-ranging birds across 52 species were received for postmortem examination. The upper gastrointestinal tracts were examined for mesoplastics and other debris (>2 mm) using standard techniques. Twenty-four individuals (5.3%) retained mesodebris and prevalence varied across species, with foraging technique, food type, and foraging substrate all associated with different metrics of debris ingestion. The odds of ingesting any type of anthropogenic mesodebris was nine times higher for non-raptorial species than for raptors. For a subset of raptors (N = 54) across 14 species, the terminal portion of the distal intestinal tract was digested with potassium hydroxide and microparticles were assessed using stereo-microscopy. Although only one of 54 (1.9%) raptors included in both analyses retained mesodebris in the upper gastrointestinal tract, 24 (44.4%) contained microparticles in the distal intestine. This study demonstrates that a variety of Canadian bird species ingest anthropogenic debris in inland systems, and suggests that life history and behaviour are associated with ingestion risk. For raptors, the mechanisms governing exposure and ingestion of mesoplastics appear to be different than those that govern microplastics. Herring gulls (Larus argentatus) and ring-billed gulls (Larus delawarensis) are proposed as ideal sentinels for plastic pollution monitoring in inland systems.

An interspecific foraging association with polar bears increases foraging opportunities for avian predators in a declining Arctic seabird colony.

Interspecific foraging associations (IFAs) are biological interactions where two or more species forage in association with each other. Climate-induced reductions in Arctic sea ice have increased polar bear (Ursus maritimus) foraging in seabird colonies, which creates foraging opportunities for avian predators. We used drone video of bears foraging within a common eider (Somateria mollissima) colony on East Bay Island (Nunavut, Canada) in 2017 to investigate herring gull (Larus argentatus) foraging in association with bears. We recorded nest visitation by gulls following n = 193 eider flushing events from nests during incubation. The probability of gulls visiting eider nests increased with higher number of gulls present (β = 0.14 ± 0.03 [SE], p < .001) and for nests previously visited by a bear (β = 1.14 ± 0.49 [SE], p < .02). In our model examining the probability of gulls consuming eggs from nests, we failed to detect statistically significant effects for the number of gulls present (β = 0.09 ± 0.05 [SE], p < .07) or for nests previously visited by a bear (β = -0.92 ± 0.71 [SE], p < .19). Gulls preferred to visit nests behind bears (χ2 = 18, df = 1, p < .0001), indicating gulls are risk averse in the presence of polar bears. Our study provides novel insights on an Arctic IFA, and we present evidence that gulls capitalize on nests made available due to disturbance associated with foraging bears, as eiders disturbed off their nest allow gulls easier access to eggs. We suggest the IFA between gulls and polar bears is parasitic, as gulls are consuming terrestrial resources which would have eventually been consumed by bears. This finding has implications for estimating the energetic contribution of bird eggs to polar bear summer diets in that the total number of available clutches to consume may be reduced due to avian predators.

Ferramentas de identificação do Diplostomum spathaceum Rudolphi, 1819 (Diplostomida: Diplostomidae), um trematódeo parasita da gaivota de arenque (Larus argentatus)

ABSTRACT Specimens of the genus Diplostomum von Nordmann, 1832 (Trematoda, Diplostomidae) were collected from the intestine of the herring gull, Larus argentatus (Laridae), from El-Manzala Lake (Port Said City, Egypt). This parasite species was morphometrically, morphologically, and molecularly studied using the internal transcribed spacer (ITS1-5.8S-ITS2) gene region. The presence of a trematode species of Diplostomum spathaceum Rudolphi, 1819 (Diplostomidae) was observed in 70 % of the examined gull species. This species has generic features of the genus Diplostomum. Distinct criteria that discriminated this species from congeners were the division for body parts, the egg-shaped forebody with a smaller length than the hind body, the ventral sucker being smaller in size than the oral one, the position of the ventral sucker being near to the holdfast, vitellaria was compact and rarely extend anteriorly to the holdfast organ, and smaller egg size. Partial ITS1-5.8S-ITS2 sequences from diplosomite recovered in this study showed that they grouped with members of the genus Diplostomum and formed a monophyletic group supporting the morphological description. Findings obtained from molecular analysis are consistent with data from morphological classification where the parasite recorded was morphologically similar to Diplostomum spathaceum with a first record in Egyptian gulls.

Highly pathogenic avian influenza virus H5N1 infection in skua and gulls in the United Kingdom, 2022.

The reemergence of the highly pathogenic avian influenza virus (HPAIV) subtype H5N1 in the United Kingdom in 2021-2022 has caused unprecedented epizootic events in wild birds and poultry. During the summer of 2022, there was a shift in virus transmission dynamics resulting in increased HPAIV infection in seabirds, and consequently, a profound impact on seabird populations. To understand the pathological impact of HPAIV in seabirds, we evaluated the virus antigen distribution and associated pathological changes in the tissues of great skua (Stercorarius skua, n = 8), long-tailed skua (Stercorarius longicaudus, n = 1), European herring gull (Larus argentatus, n = 5), and black-headed gull (Chroicocephalus ridibundus, n = 4), which succumbed to natural infection of HPAIV during the summer of 2022. Cases were collected from Shetland, including Scatness (mainland), No Ness (mainland), Clumlie (mainland), Hermaness (island), Fair Isle (island), Noss (island), and the West Midlands, South East, and South West of England. Grossly, gizzard ulceration was observed in one great skua and pancreatic necrosis was observed in 4 herring gulls, with intralesional viral antigen detected subsequently. Microscopical analysis revealed neuro-, pneumo-, lymphoid-, and cardiomyotropism of HPAIV H5N1, with the most common virus-associated pathological changes being pancreatic and splenic necrosis. Examination of the reproductive tract of the great skua revealed HPAIV-associated oophoritis and salpingitis, and virus replication within the oviductal epithelium. The emergence of HPAIV in seabirds Stercorariidae and Laridae, particularly during summer 2022, has challenged the dogma of HPAIV dynamics, posing a significant threat to wild bird life with potential implications for the reproductive performance of seabirds of conservation importance.

Legacy contaminant trends in the Great Lakes uncovered by the wildlife environmental quality index

Since the 1970s, wildlife managers have prioritized the recovery of Great Lakes ecosystems from contamination by Persistent Organic Pollutants (POPs). Monitoring and quantifying the region's recovery is challenged by the diversity of legacy contaminants in the environment and the lack of benchmarks for their potential biological effects. We address this gap by introducing the Wildlife Environmental Quality Index (WEQI) based on prior water and sediment quality indices. The tool summarizes, in a single score, the exposure of wildlife to harmful levels of multiple contaminants – with harmful levels set by published guidelines for protecting piscivorous wildlife from biological impacts. We applied the new index to a combined Canadian and American dataset of Herring Gull (Larus argentatus) egg data to elucidate trends in wildlife for eight legacy industrial pollutants and insecticides in the Great Lakes. Environmental quality of the Great Lakes region (as indexed by WEQI) improved by 18% between 2002 and 2017. Improvement came from reductions in both the scope of contamination (the number of guideline-exceeding contaminants) and its amplitude (the average size of guideline exceedances) at bird colonies. But recovery was unequal among lakes, with Lake Erie showing no improvement at one extreme. Weakly- or non-recovering lakes (Erie, Ontario, Huron) were marked by inconsistent improvement in scope and amplitude, likely due to ongoing loading, sediment resuspension and other stressors reported elsewhere. Fast-recovering lakes (Superior and Michigan), meanwhile, improved in both scope and amplitude. Contrasting trends and contaminant profiles (e.g., exceedances of PCBs versus DDTs) highlight the importance of lake-specific management for equalizing recoveries. Lower environmental quality at American than Canadian colonies, particularly in Lake Huron, further suggest uneven success in – and opportunities for – the binational management of wildlife exposure to legacy contaminants.

Diet Specialization in an Insular Population of Coastal Peregrine Falcons

Individual diet specialization is known to occur in populations of generalist predators, where specific individuals develop specialist feeding strategies. Diet specialization has been reported in many raptor species and it may be an important driver of intraspecific population structure. Here, we quantify the diet of Peregrine Falcons Falco peregrinus from five breeding territories on an island determined from prey remains collected over four breeding seasons. Three prey species accounted for 69.8% of total prey frequency, with Manx Shearwater Puffinus puffinus being the primary prey accounting for 47.3% by frequency and 40.8% by biomass. European Herring Gull Larus argentatus was the second most important prey species by frequency (13.8%) and biomass (29.8%) followed by Feral Pigeon Columba livia (frequency: 8.7%, biomass: 7.0%). Prey frequency on specific prey groups varied substantially between breeding pairs and months. Two pairs specialized on Manx Shearwater, one pair specialized on Herring Gull and Manx Shearwater, with the remaining two pairs having a relatively generalist diet of Manx Shearwaters, Feral Pigeon and small passerines. Prey frequency on Manx Shearwaters increased throughout the breeding season with a peak in total diet frequency of 63.8% in July, with a concurrent decrease in Herring Gull prey frequency. Higher percentage of Manx Shearwater in the diet explained 87% of the variation in a narrower dietary breadth for the Peregrine pairs. Our results suggest individual diet specialization may be one of multiple factors important for understanding population density in insular raptor populations.

Limited Outbreak of Highly Pathogenic Influenza A(H5N1) in Herring Gull Colony, Canada, 2022.

In summer 2022, highly pathogenic influenza A(H5N1) virus reached the herring gull (Larus argentatus subspecies smithsonianus) breeding colony on Kent Island, New Brunswick, Canada. Real-time monitoring revealed a self-limiting outbreak with low mortality. Proactive seabird surveillance is crucial for monitoring such limited outbreaks, protecting seabirds, and tracing zoonotic transmission routes.

The applicability of human mobility scaling laws on animals-A Herring Gull case study.

With the development of sensors, recording and availability of high-resolution movement data from animals and humans, two disciplines have rapidly developed: human mobility and movement ecology. Addressing methodological gaps between these two mobility fields could improve the understanding of movement processes and has been defined as the Integrated Science of Movement. We apply well-known human mobility metrics and data processing methods to Global Positioning System (GPS) tracking data of European Herring Gulls (Larus argentatus) to test the usefulness of these methods for explaining animal mobility behavior. We use stop detection, spatial aggregation, and for the first time on animal movement data, two approaches to temporal aggregation (Next Time-Bin and Next Place). We also calculate from this data a set of movement statistics (visitation frequency, distinct locations over time, and radius of gyration). Furthermore, we analyze and compare the gull and human data from the perspective of scaling laws commonly used for human mobility. The results confirm those of previous studies and indicate differences in movement parameters between the breeding season and other parts of the year. This paper also shows that methods used in human mobility analysis have the potential to improve our understanding of animal behavior.

Peri‐urban systems alter trophic niche size and overlap in sympatric coastal bird species

AbstractUrban habitats can create empty trophic niche space by providing abundant alternative dietary resources, allowing some generalist species to either shift or expand their trophic niches. Resulting changes to trophic niche size may consequently affect interspecific interactions and competition, although trophic impacts are less clear in peri‐urban systems, where both natural and urban resources are readily accessible to highly mobile species. We combined stable isotope (δ13C, δ15N, δ34S) data with GPS tracking of two sympatric coastal bird species (Larus argentatus, L. marinus) across four study sites on the east coast of the United States, ranging from a study site in New York City (the most populous city in the United States) to less‐urban sites off Massachusetts. We quantified the trophic niche size and trophic niche overlap in three‐dimensional isotopic space and assessed spatial overlap in foraging habitat between species at both peri‐urban and less‐urban study sites. We found that for both species, birds at peri‐urban study sites had significantly larger trophic niches than birds from the less‐urban sites. Furthermore, for study sites where both species occurred, we found that overlap in trophic niche space and foraging habitats between species was lower at the peri‐urban study site than at the less‐urban site. These results suggest that peri‐urban environments may facilitate trophic niche expansion and decrease niche overlap in mobile generalist species, contrasting with previous studies showing increased trophic niche overlap in more isolated urban populations. Following further analysis, we found that trophic niche expansion was facilitated by both within‐ and between‐individual differences in foraging strategies. We posit that peri‐urban environments, particularly along coastal areas, can reduce interspecific competition between sympatric species by providing access to a variety of natural and anthropogenic diet items, especially for highly mobile generalist consumers that can access both natural and urban foraging areas. Research assessing how and at what scale peri‐urban systems influence wildlife is key to understanding how further global urbanization will shape ecosystem structures.

The eyes have it: the response of European Herring Gulls Larus argentatus to human eye-gaze

ABSTRACT Using a novel method for testing the effect of gaze direction on flight initiation distances of European Herring Gulls Larus argentatus, we found that distances were significantly shorter for an averted gaze treatment than for a direct gaze. There was no difference between adult and immature gulls in their response, suggesting that from an early age Herring Gulls consider the orientation of a human’s eye in their anti-predator responses.

An ethogram identifies behavioural markers of attention to humans in European herring gulls (Larus argentatus).

Herring gulls (Larus argentatus) are one of few species thriving in anthropogenic landscapes. Their history of urbanisation and familiarity with people makes them a good target for studies of human-wildlife interactions. Previous research highlights a connection between food-stealing behaviour, success in anthropogenic areas, and increased attention towards humans, raising questions about the exact extent of a gull's knowledge of human food cues. To explore these, behavioural responses to human cues in a food-related context were investigated and presented in a systematic ethogram, which identified three distinct markers of attention. Head turns, approaches, and angular body position all differed significantly between control and food conditions, showing that attention towards humans in a food-related context was upregulated and reflected in behaviour. In food condition trials, head turns occurred more often and gulls faced more towards the experimenter with occasional approaches that were never seen in control conditions. Acoustic and behavioural human food-like cues alone seemed insufficient to elicit these responses, indicating that gulls specifically paid attention to the details of human behaviour or had specific knowledge of anthropogenic food items. These results show situation-dependent attentional modulation in gulls and provide a description of attentive behaviours that can be used in further study.

First person – Franziska Hacker

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping researchers promote themselves alongside their papers. Franziska Hacker is first author on ‘ An ethogram identifies behavioural markers of attention to humans in European herring gulls (Larus argentatus)’, published in BiO. Franziska conducted the research described in this article while a Master of Research student in Professor Paul Graham's lab in the School of Life Sciences, University of Sussex, Brighton UK. She is now a scientific manuscript editor and aspiring PhD candidate with a strong interest in mammal and seabird cognition, behavior, sociality, communication, and conservation research.

Inter-species stimulus enhancement: herring gulls (Larus argentatus) mimic human food choice during foraging.

Herring gulls (Larus argentatus) are one of few species that thrive in anthropogenic landscapes, and their familiarity with people makes them an excellent target for studies of inter-species social cognition. Urban gulls pay attention to human behaviour in food-related contexts and, thus, we set out to investigate whether such cues can influence a gull's attention to and choice of potential food items in their environment. Herring gulls were given free choice of two differently coloured anthropogenic food items in the presence of a demonstrator, who was either sitting still or eating food from an item that matched one of the presented ones. We found that a demonstrator eating significantly increased the likelihood of a gull pecking one of the presented items. Furthermore, 95% of pecks were directed toward the presented food item that colour-matched the demonstrator's food item. The results showed gulls were able to use human cues for stimulus enhancement and foraging decisions. Given the relatively recent history of urbanization in herring gulls, this cross-species social information transfer could be a by-product of the cognitive flexibility inherent in kleptoparasitic species.