Herring Gulls Larus Argentatus Research Articles

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.

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.

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.

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.

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.

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.

Effects of sodium heparin on δ13C, δ15N and δ34S values in avian whole blood

Anticoagulants are often added to avian blood samples immediately after collection to allow plasma to be extracted at a later time, but the effects of anticoagulants on stable isotope studies are not well understood. We use a Bayesian approach to assess the effects of sodium heparin, one of the most commonly used anticoagulants, on δ13C, δ15N and δ34S values in avian whole blood using Herring Gulls Larus argentatus and Great Black‐backed Gulls Larus marinus as study species. We found that the addition of sodium heparin only had a significant effect on δ34S values (−0.4‰) and that this effect did not meaningfully impact the estimated diet proportions of broad‐scale stable isotope mixing models, and only slightly affected the output of finer‐scale stable isotope mixing models. Our results highlight that researchers should be aware of the possible impacts of sodium heparin on measured stable isotope values in avian blood, particularly for δ34S, and that this effect should be carefully considered relative to the scale and particulars of the study (e.g. generalist versus specialist species and broad‐scale versus fine‐scale analyses).

Inter-colony variation in the foraging behaviour and resource selection of breeding Herring Gulls Larus argentatus

The resources available to breeding seabirds within their foraging ranges can influence productivity, either directly through the quality and quantity of food consumed by chicks, or indirectly by affecting the foraging behaviour and efficiency of parent birds. Where local resource availability is low, or the quality of resources are poor, species with flexible time-energy budgets can increase their foraging effort to provide adequate energy and nutrients to their chicks, although this may come at the expense of nest attendance. We investigated provisioning rates and nest attendance in European Herring Gulls Larus argentatus from seven colonies across southwest Scotland and Northern Ireland during two chick-rearing periods (2013 and 2014) in relation to the food resources used by these colonies. We observed variation in provisioning rates and nest attendance between colonies, and variation between years in nest attendance. We found no significant relationships between these behaviours and the proportion of intertidal prey consumed, suggesting that provisioning rate and nest attendance did not differ between resource types at the colony level. We also found no evidence that variation in behaviours was related to breeding success. Our results suggest that, within this region, the type of resources consumed had a greater influence on Herring Gull breeding success than differences in two proxies of foraging efficiency (provisioning rate and nest attendance), although other factors may also have influenced breeding success. Our work highlights the benefit of determining what food resources are provided to chicks, in addition to measuring foraging behaviours, to fully understand the consequences of consuming different resources on the breeding success of generalist foragers.

Inter-colony variation in the foraging behaviour and resource selection of breeding Herring Gulls Larus argentatus

Inter-colony variation in the foraging behaviour and resource selection of breeding Herring Gulls Larus argentatus

Factors associated with Herring Gulls Larus argentatus stealing food from humans in coastal towns

ABSTRACT Food stealing from humans by Herring Gulls Larus argentatus increased with human food availability but was not associated with any food preferences. Gulls obtained significantly more food when stealing than when scrounging, and the response of most people was neutral, suggesting that food stealing is a low-risk, high-reward strategy for urban Herring Gulls.

Differences in Trophic Level, Contaminant Load, and DNA Damage in an Urban and a Remote Herring Gull (Larus argentatus) Breeding Colony in Coastal Norway.

Herring gulls (Larus argentatus) are opportunistic feeders, resulting in contaminant exposure depending on area and habitat. We compared contaminant concentrations and dietary markers between two herring gull breeding colonies with different distances to extensive human activity and presumed contaminant exposure from the local marine diet. Furthermore, we investigated the integrity of DNA in white blood cells and sensitivity to oxidative stress. We analyzed blood from 15 herring gulls from each colony-the urban Oslofjord near the Norwegian capital Oslo in the temperate region and the remote Hornøya island in northern Norway, on the Barents Sea coast. Based on d13 C and d34 S, the dietary sources of urban gulls differed, with some individuals having a marine and others a more terrestrial dietary signal. All remote gulls had a marine dietary signal and higher relative trophic level than the urban marine feeding gulls. Concentrations (mean ± standard deviation [SD]) of most persistent organic pollutants, such as polychlorinated biphenyl ethers (PCBs) and perfluorooctane sulfonic acid (PFOS), were higher in urban marine (PCB153 17 ± 17 ng/g wet weight, PFOS 25 ± 21 ng/g wet wt) than urban terrestrial feeders (PCB153 3.7 ± 2.4 ng/g wet wt, PFOS 6.7 ± 10 ng/g wet wt). Despite feeding at a higher trophic level (d15 N), the remote gulls (PCB153 17 ± 1221 ng/g wet wt, PFOS 19 ± 1421 ng/g wet wt) were similar to the urban marine feeders. Cyclic volatile methyl siloxanes were detected in only a few gulls, except for decamethylcyclopentasiloxane in the urban colony, which was found in 12 of 13 gulls. Only hexachlorobenzene was present in higher concentrations in the remote (2.6 ± 0.42 ng/g wet wt) compared with the urban colony (0.34 ± 0.33 ng/g wet wt). Baseline and induced DNA damage (doublestreak breaks) was higher in urban than in remote gulls for both terrestrial and marine feeders. Environ Toxicol Chem 2022;41:2466-2478. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Fatty acid ecological tracers highlight the role of diet in perfluoroalkyl acid contaminant exposure in eggs of an omnivorous bird

Herring gulls (Larus argentatus) are generalist feeders; contaminant levels in their eggs reflect chemical exposure and uptake due to foraging in both aquatic and terrestrial environments. Hence, contaminant levels in their eggs provide insights into sources and relative importance of aquatic versus terrestrial pathways of chemical transfer. Here, perfluoroalkyl acids (PFAAs) known to be bioaccumulative were measured in individual herring gull eggs from one site on Lake Superior, Ontario, Canada. Thirteen perfluorinated carboxylates (PFCA, C4-C18) and four perfluorinated sulfonates (PFSA, C4-C10) were measured. Total PFCA and total PFSA concentrations varied 4- and 5-fold, respectively, among eggs. To understand these differences, stable carbon and nitrogen isotopes and fatty acid dietary tracers were measured in the same eggs. Stable isotopes were not useful in explaining inter-egg differences in PFAA concentrations. However, a variety of omega 3 (n-3) and omega 6 (n-6) fatty acid measures were correlated with C9-C13 PFCAs as well as the PFSAs: perfluoro-1-hexanesulfonic acid (PFHxS) and perfluoro-1-octanesulfonic acid (PFOS). In general, n-3 fatty acids were positively correlated with egg PFAA concentrations while only the n-6 fatty acids exhibited negative relationships with egg PFAA levels. Proportions of n-3 and n-6 fatty acids in eggs would be expected to increase and decrease, respectively, with increased aquatic food in the gull diet. Results indicate that increased use of aquatic food led to heightened PFAA exposure in these generalist consumers sampled in a relatively remote area. They also highlight the utility of employing a variety of dietary markers for understanding contaminant exposure and accumulation.

Lake Superior herring gulls benefit from anthropogenic food subsidies in a prey–impoverished aquatic environment

Herring gulls (Larus argentatus) are used as ecological indicators of the coastal Lake Superior ecosystem in Pukaskwa National Park, Ontario, Canada. Their populations have declined by 70 % over the last 40 years, suggesting changes in the park ecosystem. Previous studies highlighted declining prey abundance as a possible contributing factor to population declines. Here, we assess herring gull diets via stable isotope (nitrogen, carbon) and fatty acid indicators to investigate how diet may influence population trends through effects on physiology (stress-related hormones), reproduction (egg size) and behavior (nest attentiveness). Diets were variable among individual herring gulls. Gulls utilizing anthropogenic food sources exhibited reduced levels of stress-associated hormones, increased egg size, and increased nest attentiveness. Anthropogenic food sources are likely buffering the impacts of declines in aquatic food availability; however, populations are still declining. Understanding factors contributing to population trends in ecological indicator species is critical for species management and for identifying stressors that are likely affecting the broader ecosystem. Herring gulls are archetypal examples of the “canary in a coalmine” indicator but in an ecosystem context. Changes in their diets and in variables associated with their physiology, reproduction, and behavior point to very significant changes occurring in the Lake Superior ecosystem. Integrated research across the Great Lakes is required to understand the extent of this change and its implications for the sustainability of wildlife populations.

Conservation measures for the Caspian Tern Hydroprogne caspia at the largest colony in Sweden

We present conservation actions during 2007–2020 as part of the national Caspian Tern Hydroprogne caspia species action plan at Stenarna in the Björn archipelago, Uppland, the largest colony in Sweden. We applied a combination of monitoring, research, and management measures conducted within an adaptive approach framework, using both established and novel techniques. The implementation of conservation measures led to increased breeding success, from 0 fledglings per pair in 2007 to 1.3 in 2020. A surveillance video camera installed in 2009 aided in monitoring efforts and also revealed predation by Herring Gull Larus argentatus and White-tailed Eagle Haliaeetus albicilla, leading to species-specific control strategies. Management of the island and surrounding archipelago, including hunting of invasive American mink Mustela vison, vegetation removal, and habitat restoration after a severe storm, have also been instrumental to the success of the project. Implementation of projects such as this have the potential to improve conditions for continued viability of endangered species in a changing world and are likely to be useful to other conservation practitioners.

Accumulation of the Toxic Metal Mercury in Multiple Tissues of Marine-Associated Birds from South Florida.

One of the best studied global "hot spots" for ecological mercury (Hg) contamination is south Florida (USA), where elevated Hg concentrations in environmental media and regional wildlife were first described over thirty years ago. While Hg contamination has lessened in this region, it is still critical to monitor Hg uptake and potential risks in south Florida wildlife, especially in marine-associated birds, which are known to accumulate potentially toxic Hg levels. In this study, total Hg (THg) concentrations were measured in liver, kidney, muscle, and feathers of 101 individuals from seven species of south Florida birds: brown pelican Pelecanus occidentalis, double-crested cormorant Phalacrocorax auratus, herring gull Larus argentatus, laughing gull Leucophaeus atricilla, northern gannet Morus bassanus, royal tern Thalasseus maximus, and osprey Pandion halietus. A sizeable proportion of individuals (> 40%) were found to contain THg concentrations in internal tissues that exceeded estimated toxicity thresholds for Hg-related effects. Certain species, especially osprey, were found to exhibit a higher rate of threshold exceedances than others and should continue to be monitored for Hg-related effects in future studies. Feather THg concentrations exhibited a lower rate of toxicity threshold exceedances (12%) and were not significantly correlated with those in internal tissues in most cases, suggesting that they may not be well suited for monitoring Hg exposure in these species unless sources of data variation can be better understood. The results of the present study contribute significantly to our understanding of trends in Hg accumulation and Hg-related health risks in south Florida marine-associated birds.

City Living: Nest-Site Selection Preferences in Urban Herring Gulls, Larus argentatus

Herring gulls (Larus argentatus) are declining globally, but there are populations who are taking advantage of the new foraging and nesting opportunities afforded to them by urban landscapes. Nest-site selection (NSS) in urban environs is understudied, despite its critical role in supporting planning policy, biodiversity conservation and the management of human–wildlife conflict. The aim of this study was to assess the contribution of anthropogenic habitat features to NSS in urban populations of L. argentatus at different hierarchical levels in Fingal County, Ireland. We used generalised linear models with a logit function to investigate the relationship among nest sites, building features, street furniture (i.e., streetlights and refuse bins), landscape features, and presence of conspecifics at three different hierarchical levels, including the county, town, and colony levels. L. argentatus preferentially chose buildings that were closer to streetlights and food sources at the colony level, while avoiding streetlights when considered in isolation. Conspecific attraction at the county and colony levels indicated that individuals avoided neighbouring nest sites, yet this relationship was inverted at the town level, suggesting preference. Moreover, 75% of nests were within 30 m of each other (the average road width in the study area) when measured at the county level. Various relationships with different food sources were identified, suggesting within-population variation among preferences for nest sites. There appears to be a substantial population variation among preferences for nest sites, which does appear to be driven by the cross-scale decisions involved in nest-site selection.

Age Dynamics of Helminth Fauna of the Herring Gull (Larus argentatus) in Kola Bay, Barents Sea

Age Dynamics of Helminth Fauna of the Herring Gull (Larus argentatus) in Kola Bay, Barents Sea

Foraging habitat selection by breeding Herring Gulls (Larus argentatus) from a declining coastal colony in the United Kingdom

Individual foraging specialisms among generalist species can have important consequences for demographic rates. We investigated the habitat preferences of breeding Herring Gulls (Larus argentatus) at South Walney, a declining coastal colony in the UK, comparing results to a previous assessment made three decades before, when the breeding population was higher, which indicated substantial use of terrestrial, intertidal and anthropogenic resources. We used a two-stage Resource Selection Function (RSF) analysis to assess the habitat selection of 21 Herring Gulls fitted with GPS tags over three breeding seasons (2014–16). By generating pseudo-absences within the minimum convex polygon surrounding individual level GPS fixes, we first used logistic regression models to relate presence/absence for each individual to habitat. Selection for mussel bed areas was also modelled specifically as a function of phase of tide, time of day, period within the breeding season, year as well as individual covariates of mass, sex and hatching success. Second, individual RSF coefficients were extracted from the logistic regression models and used as response variables in linear models.Herring Gulls significantly selected for mussel beds and other coastal habitats (75% of all fixes away from the colony occurring in these habitats). Selection for mussel bed sites was significantly greater during the first half of the breeding season, March–May, compared with June–August, while there was also significant positive selection for this habitat between −3 and −2 m tide height (ordnance datum).There has been an apparent reduction in the range of food resources utilised by Herring Gulls at South Walney in recent years with a greater propensity for intertidal specialists within the tracked sample and, in particular, little use was made of urban and landfill areas. Therefore, better understanding of the intertidal resources available and considered management will be beneficial to balance the needs of conservation and commercial and social interests of the nearby shellfisheries.

COVID-19 and the opportunities for research: The lockdowns' impacts on wildlife, ecology and conservation biology, and the humanities.

The ongoing lockdowns provide ideal conditions to study the relationship between wildlife and humans but among humans themselves.