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Simple Summary: Each year, influenza infects millions of people, wildlife, and livestock, resulting in more than 30,000 deaths and a cost of more than USD 1 billion annually in the United States alone. In between the human flu seasons, the virus is maintained in wild bird populations, especially shorebirds and waterfowl. Much of the previous research has focused on ducks' role in this disease cycle; however, there is a growing realization that gulls may provide critical links across space due to their long annual migrations. Yet, little is known of how influenza circulates in gulls. In this work, we evaluate the prevalence of influenza in two species of gulls in Minnesota, USA. We found important differences between species and gull age classes, highlighting the variability in disease spread through wildlife populations, with consequences for how and when the virus might be transmitted to humans/livestock. Importantly, we consider not only ongoing infections, but also look for antibodies that indicate past infections, and which may provide some level of future protection from disease. We find this additional level of surveillance to be beneficial in understanding the spread of disease, especially when researchers are trying to make the most of limited sampling. Influenza A virus (IAV) is a multi-host pathogen maintained in water birds and capable of spillover into humans, wildlife, and livestock. Prior research has focused on dabbling ducks as a known IAV reservoir species, yet our understanding of influenza dynamics in other water birds, including gulls, is lacking. Here, we quantify morphological and environmental drivers of serological (antibody detection by ELISA) and virological (viral RNA detection by PCR) prevalence in two gull species: ring-billed (Larus delawarensis) and Franklin's (Leucophaeus pipixcan) gulls. Across 12 months and 10 locations, we tested over 1500 gulls for influenza viral RNA, and additionally tested antibody levels in nearly 1000 of these. We find substantial virus prevalence and a large, nonoverlapping seroprevalence, with significant differences across age and species classifications. The body condition index had minimal explanatory power to predict (sero)positivity, and the effect of the surrounding environment was idiosyncratic. Our results hint at a nontrivial relationship between virus and seropositivity, highlighting serological surveillance as a valuable counterpoint to PCR. By providing indication of both past infections and susceptibility to future infections, serosurveillance can help inform the distribution of limited resources to maximize surveillance effectiveness for a disease of high human, wildlife, and livestock concern. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a zoonotic protozoan parasite that infects most warm-blooded animals, including birds. Scavenging birds are epidemiologically important hosts because they can serve as indicators of environmental T. gondii levels. A rapid point-of-care (POC) test that detects antibodies to T. gondii in humans is commercially available. In this research, we assessed the ability of the human POC test to detect anti–T. gondii antibodies in 106 black vultures (Coragyps atratus) and 23 ring-billed gulls (Larus delawarensis) from Pennsylvania, USA. Serum samples were tested with the POC test and compared to the modified agglutination test (MAT) in a blinded study. Overall, anti–T. gondii antibodies were detected in 2.8% (3/106) of black vultures and 60.9% (14/23) of ring-billed gulls by the POC test. One false-positive POC test occurred in a black vulture that was negative by MAT. False-negative results were obtained in 2 black vultures and 4 ring-billed gulls that had MAT titers of 1:25 or 1:50. The sensitivity and specificity of the POC for both black vultures and ring-billed gulls combined were 95.7% and 95.5%, respectively. This is the first study using human POC tests to detect antibodies to T. gondii in birds. Further study of the rapid test as a screening tool for serological surveillance of T. gondii in birds is warranted. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

String-pulling is among the most widespread cognitive tasks used to test problem-solving skills in mammals and birds. The task requires animals to comprehend that pulling on a non-valuable string moves an otherwise inaccessible food reward to within their reach. Although at least 90 avian species have been administered the string-pull test, all but five of them were perching birds (passeriformes) or parrots (psittaciformes). Waterbirds (Aequorlitornithes) are poorly represented in the cognitive literature, yet are known to engage in complex foraging behaviours. In this study, we tested whether free-living ring-billed gulls (Larus delawarensis), a species known for their behavioural flexibility and foraging innovativeness, could solve a horizontal string-pull test. Here, we show that 25% (26/104) of the ring-billed gulls that attempted to solve the test at least once over a maximum of three trials were successful, and that 21% of them (22/104) succeeded during their first attempt. Ring-billed gulls are thus the first waterbird known to solve a horizontal single-string-rewarded string-pull test. Since innovation rate and problem-solving are associated with species' ability to endure environmental alterations, we suggest that testing the problem-solving skills of other species facing environmental challenges will inform us of their vulnerability in a rapidly changing world.

Organisms escape consumers using a variety of behaviors and structural or physiological defenses (e.g., toxins and irritants). Portuguese men o’ war (Physalia physalis) rely on nematocysts to immobilize or kill their prey, chiefly fish, but the nematocysts can also be painful or deadly to predators. Consequently, few species are known to approach, let alone consume, P. physalis. During an opportunistic birding excursion in coastal Texas, ~5 Ring-billed Gulls (Larus delawarensis) were observed picking up beached P. physalis, taking them to the water’s edge, and thrashing them in the water briefly before consuming them, or at least parts of them. These are among a very limited number of records of birds consuming P. physalis.

The population of ring-billed gulls in the upper Midwest has increased exponentially in recent decades leading to a variety of conflicts including property damage, negative economic impacts, threats to human safety, and potential threats to human health. Some studies have suggested a link between gull fecal droppings and elevated Escherichia coli levels, which result in swim advisories and bans on public beaches. The objectives of the Chicago ring-billed gull damage management project were to reduce the local production of ring-billed gulls, to evaluate the affects limiting gull production has on gull use of beaches, and to reduce the severity of conflicts with gulls including the issuance of swim advisories and swim bans. Between 2007 and 2009, we applied corn oil to 52 - 80% of nests in 2 large gull colonies in Chicago and successfully reduced hatching success and subsequent fledging of 18,000 - 42,000 gulls per year without causing colony abandonment. Fewer hatch year gulls were observed in 2009 on Chicago’s beaches compared to 2007. The reduction in the number of gulls using Chicago beaches has contributed to a reduction in conflicts with gulls, including a decrease in the frequency of swim advisories/bans on Chicago’s beaches in comparison to 2006.

A 20-year-old female mute swan (Cygnus olor) originally in a flock of free-living swans on a Long Island, New York, lake, was presented for facial swelling and decreased appetite. An adult male ring-billed gull (Larus delawarensis) was also presented to the same wildlife rescue center for bilateral lameness of 1-week duration. Once referred for veterinary evaluation and care, both species were diagnosed with septic arthritis and osteomyelitis caused by Chryseobacterium indologenes and treated with orbifloxacin until complete recovery. Chryseobacterium indologenes is infrequently diagnosed as an opportunistic pathogen in human medicine, and less so in veterinary medicine. In human patients, this bacterium is the cause of various infections, including meningitis, pneumonia, and implant failure. However, in veterinary medicine its pathogenicity has only been reported in fish, and sporadically mentioned as a culture result in tree frogs and turtles, where it was generally considered insignificant. In this report a clinical presentation, diagnosis, treatment, and outcome of osteomyelitis and septic arthritis caused by C indologenes is described in 1 anseriforme and in 1 charadriiforme species. [ABSTRACT FROM AUTHOR]

We evaluated the effectiveness of Allsopp Helikites® as a gull (Larus spp.) deterrent at loafing and nesting areas and as a bird deterrent in a sunflower field. In 1998, a 10-day trial was conducted at two 0.5-ha ponds at the Erie County, Ohio landfill (EC) and a 2-week trial on two 0.1-ha plots on the Tru-Serv Corporation (TSC) warehouse roof in Cuyahoga County, Ohio. Also in 1998, a 5-week trial in a sunflower field was conducted in Erie County, Ohio. In 1999, a 24-day trial was conducted at the Service Liqueur Distributors (SLD), Inc. warehouse roof, 1.6 km from the Albany, NY landfill. At the EC landfill the mean number (±SE) of ring-billed (L. delawarensis) and herring gulls (L. argentatus) on the treated pond decreased (P < 0.05) from 421 ± 292 to

Toxoplasma gondii is a zoonotic protozoan parasite that infects most warm-blooded animals, including birds. Scavenging birds are epidemiologically important hosts because they can serve as indicators of environmental T. gondii levels. A rapid point-of-care (POC) test that detects antibodies to T. gondii in humans is commercially available. In this research, we assessed the ability of the human POC test to detect anti-T. gondii antibodies in 106 black vultures (Coragyps atratus) and 23 ring-billed gulls (Larus delawarensis) from Pennsylvania, USA. Serum samples were tested with the POC test and compared to the modified agglutination test (MAT) in a blinded study. Overall, anti-T. gondii antibodies were detected in 2.8% (3/106) of black vultures and 60.9% (14/23) of ring-billed gulls by the POC test. One false-positive POC test occurred in a black vulture that was negative by MAT. False-negative results were obtained in 2 black vultures and 4 ring-billed gulls that had MAT titers of 1:25 or 1:50. The sensitivity and specificity of the POC for both black vultures and ring-billed gulls combined were 95.7% and 95.5%, respectively. This is the first study using human POC tests to detect antibodies to T. gondii in birds. Further study of the rapid test as a screening tool for serological surveillance of T. gondii in birds is warranted., (© American Society of Parasitologists 2024.)

The life cycles of many species of Diplostomum (Digenea) have been elucidated; however, few studies include the details of egg development and hatching success. Here the eggs of 2 molecularly delineated sympatric species of Diplostomum were observed for differences in developmental parameters. These parameters included prepatent period, time required for first visible eyespot formation, hatching time, and hatching success. There was no significant difference in the mean prepatent period, total number of miracidia that developed eyespots, or number of days to hatch between the 2 species. There was a significant difference in the average time for first visible eyespots to appear and hatching success. These data highlight the need for further studies investigating sympatric species of Diplostomum to document and understand differences in life history traits during the various phases of their life cycles and their role in transmission success. [ABSTRACT FROM AUTHOR]

West Nile virus (WNV) emerged in the Americas with its introduction in 1999 and now is considered endemic across the continent. In 2002, WNV was detected in Mexico, where its occurrence and mortality are considerably lower compared with the US. However, continuous national surveillance programs in Mexico are nonexistent. Birds are considered the primary hosts and primary geographic dispersers of this pathogen. A total of 200 cloacal and tracheal samples from wild migratory or resident birds were retrospectively analyzed using reverse transcription PCR to detect WNV from birds collected in Mexico from 2008 to 2009. The overall prevalence was 8% (16/200), and positive samples were from Oaxaca, Chiapas, and Tamaulipas in Ruby-throated Hummingbird (Archilochus colubris), Double-crested Cormorant (Phalacrocorax auritus), Ring-billed Gull (Larus delawarensis), and Mourning Dove (Zenaida macroura). Analysis of the partial sequence of the envelope gene from one of the samples from Oaxaca provided evidence that the virus belonged to the WN99 genotype. Taken together, these results demonstrated that WNV circulated in wild birds from northern and southern Mexico during the 2008–09 season, providing further information about the presence of WNV in Mexico. [ABSTRACT FROM AUTHOR]

Oiling eggs is a potential management method for controlling nuisance or depredating populations of ring-billed gulls, Canada geese, and other bird species. However, no registration for an oiling compound currently exists with the Environmental Protection Agency. Efficacy data were collected for white mineral oil and corn oil to reduce the hatchability of ring-billed gull eggs. Egg failure was 99% in corn oil, 96% in white mineral oil, and 35% in control eggs. Most treated eggs that hatched were treated early in the incubation period, 1 to 8 days after clutch completion. A Wildlife Service Technical Note on the use of com oil as an oiling agent is now available.

Gulls are commonly attracted to landfills, and managers are often required to implement cost-effective and socially accepted deterrence programs. Our objective was to evaluate the effectiveness of an intensive program that integrated the use of trained birds of prey, pyrotechnics, and playback of gull distress calls at a landfill located close to a large ring-billed gull (Larus delawarensis) colony near Montreal, Quebec, Canada. We used long-term survey data on bird use of the landfill, conducted behavioral observations of gulls during one season and tracked birds fitted with GPS data loggers. We also carried out observations at another landfill located farther from the colony, where less refuse was brought and where a limited culling program was conducted. The integrated program based on falconry resulted in a 98% decrease in the annual total number of gulls counted each day between 1995 and 2014. A separate study indicated that the local breeding population of ring-billed gulls increased and then declined during this period but remained relatively large. In 2010, there was an average (±SE) of 59 ± 15 gulls/day using the site with falconry and only 0.4% ± 0.2% of these birds were feeding. At the other site, there was an average of 347 ± 55 gulls/day and 13% ± 3% were feeding. Twenty-two gulls tracked from the colony made 41 trips towards the landfills: twenty-five percent of the trips that passed by the site with falconry resulted in a stopover that lasted 22 ± 7 min compared to 85% at the other landfill lasting 63 ± 15 min. We concluded that the integrated program using falconry, which we consider more socially acceptable than selective culling, was effective in reducing the number of gulls at the landfill.

Copyright of Avian Diseases is the property of American Association of Avian Pathologists, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT The population of double-crested cormorants ( Phalacorocorax auritus; cormorants) in the North American Great Lakes has increased substantially since the 1970s, sparking economic, social, and biological concerns that have led to widespread management of the species within United States waters. Previous studies have quantified behavioral impacts of cormorants on other waterbird species that share breeding colony sites with cormorants. However, no study has yet examined how these impacts might scale to entire colonies, nor have potential effects of cormorant management on co-nesters been examined. Our objective was to estimate effects of cormorant abundance and management on colony growth indices of 4 species that commonly co-nest with cormorants in the North American Great Lakes; 3 of these species are conservation or stewardship priorities for the region. We estimated colony growth using the Great Lakes Colonial Waterbird Survey and comparable Canadian surveys, conducted between 1976 and 2010. We then applied linear mixed models to determine association of co-nester colony growth indices with cormorant abundance and management presence and intensity while controlling for other factors that likely influenced growth rates. According to the fitted models, black-crowned night-heron ( Nycticorax nycticorax) colony growth was negatively related to cormorant abundance and management, whereas great blue herons ( Ardea herodias) had little response to cormorant abundance, and herring gulls ( Larus argentatus) and ring-billed gulls ( Larus delawarensis) responded positively to cormorant abundance and management. These results suggest that cormorant management may not be as neutral to co-nesters as is often assumed. Responsible management plans for cormorants should take into account the likely effects on co-nesters present so that conservation and management goals for co-nesters can also be met. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]

While it generally has been accepted that evolutionary pressures may drive parasitic worms to produce many small eggs to overcome the challenges of transmission, recent studies suggest wide variability in reproductive strategies among such worms. Although egg morphometrics and numbers have been reported from many species of Diplostomum, the presence of cryptic species has resulted in uncertainty in morphometric measurements for different life history stages. Here we examine differences between egg characteristics of 2 molecularly delineated species of Diplostomum (Digenea). We investigate whether interspecific differences exist in egg morphometrics or egg number and test if there are intraspecific relationships between size of the egg and the hindbody of adult worms or between size of the egg and fecundity. Egg measurements were obtained from both those collected in feces of experimentally infected ring-billed gulls ( Larus delawarensis) and those observed in stained adult specimens of Diplostomum spp. Regardless of the source of measurement, there was a significant difference in the length of the eggs and in egg number between the 2 species, while there was no difference in the widths. Larger worms did not produce significantly larger eggs in either species. Further, egg size was not correlated with the number of eggs present in the stained specimens of either species; smaller eggs were not present in greater numbers. Egg morphometrics can assist in differentiating between these 2 species of Diplostomum. Furthermore, differences in egg sizes and number may reflect other potential differences in life history traits between the 2 species, such as miracidial longevity and infectivity and cercarial output, among others, that still need to be investigated. [ABSTRACT FROM AUTHOR]

Egg oiling is a form of management in which bird eggs are coated with mineral or corn oil, preventing gas exchange through the shell and killing embryos. Unlike other nest disturbance techniques, egg oiling reportedly precludes colony abandonment and, thus, can be advantageous when managers wish to limit dispersal within the breeding season to other locations while stabilizing the population or reducing productivity. However, unintended, indirect effects of egg oiling are not well-characterized. We evaluated the influence of egg oiling on ring-billed gulls (Larus delawarensis) within the Lake Champlain basin, Vermont, during the nesting season to determine whether egg oiling affected colony presence of adults. We radiomarked 58 ring-billed gulls captured on Young Island during 2008 to 2009 and treated all ring-billed gull nests in the colony with egg oiling except for 50% of the nests of radio-marked gulls (control group). Using a radio receiver with automated data logger, we documented the presence of ring-billed gulls at the colony throughout the breeding season. We examined effects of treatment (nests oiled or control), sex, reproductive period (pre- and post-hatch), year, and interactive effects on colony presence (i.e., the proportion of nights ring-billed gulls spent at Young Island). Although we found no effect of treatment, sex, or interactive effects on colony presence, colony presence was 87% greater in the pre-hatch period, presumably due to behavioral mechanisms related to incubation or foraging. Overall colony presence was 118% greater in 2009 than in 2008, potentially a consequence of increased colony disturbance in 2008. We suggest that egg oiling does not influence colony presence of ring-billed gulls within the breeding season

Fraser Darling suggested that reproductive synchrony enhances reproductive success of colonial seabirds as a result of predator satiation. However, the cost of yearly reproductive synchrony is high for colonial species for which intraspecific predation is the primary cause of egg and chick loss. A few studies indicate that egg-laying synchrony on a daily time scale within the annual breeding pulse may be an adaptive response to intraspecific predation. Here, we report every-other-day clutch-initiation synchrony in densely nesting cohorts of Ring-billed Gulls ( Larus delawarensis). This is the second known case of clutch-initiation synchrony on a daily time scale in larids, the first being for Glaucous-winged Gulls ( L. glaucescens). In both Ring-billed Gulls and Glaucous-winged Gulls, the degree of clutch-initiation synchrony is inversely related to nearest neighbor distance. Further studies are needed to test whether clutch-initiation synchrony in Ring-billed Gulls is adaptive in the presence of cannibalism, or if it is simply a neutral byproduct of colonial nesting. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Gulls ( Larus spp.) commonly roost in large numbers on inland and coastal waters, yet there is little information on how or where gulls choose sites for roosting. Roost site selection can lead to water quality degradation or aviation hazards when roosts are formed on water supply reservoirs or are close to airports. Harassment programs are frequently initiated to move or relocate roosting gulls but often have mixed results because gulls are reluctant to leave or keep returning. As such, knowledge of gull roost site selection and roosting ecology has applied and ecological importance. We used satellite telemetry and an information-theoretic approach to model seasonal roost selection of ring-billed ( L. delawarensis) and herring gulls ( L. argentatus) in Massachusetts, USA. Our results indicated that ring-billed gulls preferred freshwater roosts and will use a variety of rivers, lakes, and reservoirs. Herring gulls regularly roosted on fresh water but used salt water roosts more often than ring-billed gulls and also roosted on a variety of land habitats. Roost modeling showed that herring and ring-billed gulls selected inland fresh water roosts based on size of the water body and proximity to their last daytime location; they selected the largest roost closest to where they ended the day. Management strategies to reduce or eliminate roosting gulls could identify and try to eliminate other habitat variables (e.g., close-by foraging sites) that are attracting gulls before attempting to relocate or redistribute (e.g., through hazing programs) roosting birds. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Many birds bob their head as they walk or run on the ground. The functional significance of this behaviour is unclear, but there is strong evidence that it plays a significant role in enhancing visual perception. If head-bobbing is advantageous, however, then it is a puzzle that some birds do not head-bob. As a group, gulls (Laridae) are among the birds that reportedly do not head-bob, yet here we report head-bobbing among Ring-billed Gulls (Larus delawarensis), observed and filmed in Ontario, when walking relatively slowly while foraging on the ground. This suggests that head-bobbing plays a key role in the visual detection of food items in this species. We suggest that head-bobbing may be a relatively common behaviour in foraging Ring-billed Gulls and speculate that other gulls (and indeed other birds) previously thought not to head-bob may in fact do so under certain circumstances. [ABSTRACT FROM AUTHOR]

While the breeding ecology of gulls (Laridae) has been well studied, their movements and spatial organization during the non-breeding season is poorly understood. The seasonal movements, winter-site fidelity, and site persistence of Ring-billed (Larus delawarensis) and Herring (L. argentatus) gulls to wintering areas were studied from 2008-2012. Satellite transmitters were deployed on Ring-billed Gulls (n = 21) and Herring Gulls (n = 14). Ten Ring-billed and six Herring gulls were tracked over multiple winters and > 300 wing-tagged Ring-billed Gulls were followed to determine winter-site fidelity and persistence. Home range overlap for individuals between years ranged between 0-1.0 (95% minimum convex polygon) and 0.31-0.79 (kernel utilization distributions). Ring-billed and Herring gulls remained at local wintering sites during the non-breeding season from 20-167 days and 74-161 days, respectively. The probability of a tagged Ring-billed Gull returning to the same site in subsequent winters was high; conversely, there was a low probability of a Ring-billed Gull returning to a different site. Ring-billed and Herring gulls exhibited high winter-site fidelity, but exhibited variable site persistence during the winter season, leading to a high probability of encountering the same individuals in subsequent winters. [ABSTRACT FROM AUTHOR]

Ring-billed Gulls (Larus delawarensis) were rare at the beginning of the 20th century, possibly because of intensive exploitation. Once they became protected in 1916, their numbers increased throughout eastern North America, reaching a maximum of 875,000 breeding pairs around 1990. Since then, an overall decline of 19% has been recorded in the Great Lakes and the St. Lawrence River while their numbers tripled in Atlantic Canada. The largest concentrations are still found on the Great Lakes with 38% and 42% of the birds breeding in Canada and the USA, respectively. The remaining individuals breed along the St. Lawrence River (15%), on Lake Champlain (2%), and in the Gulf of St. Lawrence including the Atlantic Provinces and Saint-Pierre-et-Miquelon (3%). In 2009, a study was undertaken in the largest colony located on Île Deslauriers near Montreal, Québec, to determine the factors that regulate the number of breeding birds. This colony supported 52,000 pairs in 2000 and 44,000 in 2012. Ring-billed Gulls had a lower reproductive output in 2010-2012 compared to the late 1970s attributed to reduced chick survival. The number of gull-days at the nearest landfill declined from 906,000 in 1995 to 40,000 in 2012 following the implementation of a falconry deterrence program. Limited access to an abundant food supply located near the colony may have reduced chick survival. How this affects annual survival and population size remains to be determined. In the long term, policies that aim to reduce input of organic matter at landfills and discourage citizens from feeding gulls could further contribute to the decline of Ring-billed Gulls in eastern North America. [ABSTRACT FROM AUTHOR]

Gulls are commonly attracted to landfills, and managers are often required to implement cost-effective and socially accepted deterrence programs. Our objective was to evaluate the effectiveness of an intensive program that integrated the use of trained birds of prey, pyrotechnics, and playback of gull distress calls at a landfill located close to a large ring-billed gull (Larus delawarensis) colony near Montreal, Quebec, Canada. We used long-term survey data on bird use of the landfill, conducted behavioral observations of gulls during one season and tracked birds fitted with GPS data loggers. We also carried out observations at another landfill located farther from the colony, where less refuse was brought and where a limited culling program was conducted. The integrated program based on falconry resulted in a 98% decrease in the annual total number of gulls counted each day between 1995 and 2014. A separate study indicated that the local breeding population of ring-billed gulls increased and then declined during this period but remained relatively large. In 2010, there was an average (±SE) of 59 ± 15 gulls/day using the site with falconry and only 0.4% ± 0.2% of these birds were feeding. At the other site, there was an average of 347 ± 55 gulls/day and 13% ± 3% were feeding. Twenty-two gulls tracked from the colony made 41 trips towards the landfills: twenty-five percent of the trips that passed by the site with falconry resulted in a stopover that lasted 22 ± 7 min compared to 85% at the other landfill lasting 63 ± 15 min. We concluded that the integrated program using falconry, which we consider more socially acceptable than selective culling, was effective in reducing the number of gulls at the landfill. [ABSTRACT FROM AUTHOR]

Understanding how birds cope with climate change has received much attention in recent years. So far, more emphasis has been given to passerine species than to any other groups of birds, possibly because of the availability of long-term data sets. Our objective was to study the effect of climate change on spring arrival date and breeding chronology of Ring-billed Gulls (Larus delawarensis), a short-distance migrant with a diverse diet. Based on Étude des Populations d'Oiseaux du Québec (EPOQ) checklists, we found that gulls arrived in southern Québec five days earlier in 2012 than in 1971. Sporadic observations in three nearby colonies indicated that Ring-billed gulls laid eggs eight days earlier in 2012 than they did in 1978. Both arrival and laying dates closely fit temperature warming. Because of their diverse diet, Ring-billed Gulls always have access to some food resources during the breeding period making a mismatch between phenology and food abundance unlikely. Continuous warming may enhance the use of agricultural lands by gulls before and during the breeding period. However, this may not be sufficient to compensate for a reduction of refuse accessibility at landfills that have implemented deterrence programs.

The article discusses research which investigated how benthic substrates influence the population of waterbirds at the Great Sale Lake (GSL) region of Utah. Topics explored include the presence of benthic substrates such as mud, sand, and bioherms in the GSL, the results of the benthic core sampling tests and aerial surveys conducted, and the evaluation of salinity parameters for species including Northern Shoveler, Common Goldeneye, and Eared Grebe.

With urbanization, anthropogenic foods have grown in importance for several species. A shift away from natural foods is likely to affect trophically transmitted parasites, although this has received limited attention in urban-adapted avian omnivores. We examined the effect of habitat use and diet on gastrointestinal parasite assemblages of Ring-billed Gulls ( Larus delawarensis Ord, 1815) breeding in an urbanized region (Montréal, Quebec, Canada) using three approaches depicting different temporal scales. Birds were fitted with global positioning system data loggers to determine habitat-use patterns during a 2-3 day period. Stomach contents were examined, providing dietary information during the preceding hours. Liver carbon (δ13C) and nitrogen (δ15N) stable isotope signatures served as proxy of nutrient assimilation during the preceding 10 days. Endoparasite community variations were best explained by δ13C and δ15N ratios. Individuals with lower δ15N had lower parasite abundance, while δ13C was enriched in birds with less diverse parasites (fewer helminth genera). Tissue depletion in 15N in Ring-billed Gulls from this colony has previously been associated with predominant consumption of human-related foods. The present study supports the hypothesis that Ring-billed Gulls exhibiting preference for anthropogenic food sources encounter fewer trophically transmitted parasites, which may have contributed, in part, to their population expansion during the last century. [ABSTRACT FROM AUTHOR]

Egg oiling is a form of management in which bird eggs are coated with mineral or corn oil, preventing gas exchange through the shell and killing embryos. Unlike other nestdisturbance techniques, egg oiling reportedly precludes colony abandonment and, thus, can be advantageous when managers wish to limit dispersal within the breeding season to other locations while stabilizing the population or reducing productivity. However, unintended, indirect effects of egg oiling are not well-characterized. We evaluated the influence of egg oiling on ring-billed gulls (Larus delawarensis) within the Lake Champlain basin, Vermont, during the nesting season to determine whether egg oiling affected colony presence of adults. We radiomarked 58 ring-billed gulls captured on Young Island during 2008 to 2009 and treated all ring-billed gull nests in the colony with egg oiling except for 50% of the nests of radio-marked gulls (control group). Using a radio receiver with automated data logger, we documented the presence of ring-billed gulls at the colony throughout the breeding season. We examined effects of treatment (nests oiled or control), sex, reproductive period (pre- and post-hatch), year, and interactive effects on colony presence (i.e., the proportion of nights ring-billed gulls spent at Young Island). Although we found no effect of treatment, sex, or interactive effects on colony presence, colony presence was 87% greater in the pre-hatch period, presumably due to behavioral mechanisms related to incubation or foraging. Overall colony presence was 118% greater in 2009 than in 2008, potentially a consequence of increased colony disturbance in 2008. We suggest that egg oiling does not influence colony presence of ring-billed gulls within the breeding season. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the feeding ecology of an omnivorous bird, the Ring-billed Gull ( Larus delawarensis Ord, 1815), breeding in a highly urbanized and heterogeneous landscape (Montréal area, Quebec, Canada). We used gastrointestinal (G.I.) tract content analysis, GPS-based tracking information, and stable isotope profiles of carbon (δ13C) and nitrogen (δ15N) in selected tissues and major food items. Based on GPS tracking data (1-3 days), Ring-billed Gulls were categorized according to their use of three main foraging habitats: agricultural, St. Lawrence River, and anthropogenic (comprising urban areas, landfills, and wastewater treatment plant basins). Ring-billed Gulls that foraged predominantly in anthropogenic habitats exhibited significantly lower δ15N in blood cells and higher total C to N ratios (C:N) in liver. These lower δ15N and higher C:N ratios were characteristic of profiles determined in food items consumed by Ring-billed Gulls at these urbanized sites (e.g., processed foods). The strong positive correlations between δ13C and δ15N in Ring-billed Gull tissues (plasma, blood cells, and liver) that differed in isotopic turnover times, as well as the strong positive correlations in both δ13C and δ15N between tissue pairs, indicated that Ring-billed Gulls exhibited conserved dietary habits throughout the nesting period. This study demonstrates that combining conventional dietary examination, tissue stable isotope analysis, and fine-scale GPS tracking information may improve our understanding of the large intrapopulation variations in foraging behaviour (and isotopic profiles) commonly observed in omnivorous birds. [ABSTRACT FROM AUTHOR]

The article presents a study which described the waterbird adoption across taxonomic families as shown by the fledging of Caspian Terns Hydroprogne caspian of a Ring-billed gull Larus delawarensis chick. It observed that there are rare instances of interspecific adoptions that occur naturally among waterbirds. It also suggested that the adopted Ring-billed Gull chicks during linear growth had almost the same mass with the Ring-billed Gull chicks that grew up with their natural parents.

Central and southern Manitoba contain some of the largest breeding populations of several colonial waterbird species in North America. Despite the value of this region for waterbirds, very little monitoring has been conducted on Lake Winnipeg, Lake Winnipegosis, or Lake Manitoba in the past three decades and little is known about the smaller boreal lakes in adjacent areas to the north. In June 2011, boat surveys were conducted on 11 boreal lakes in west-central Manitoba and east-central Saskatchewan to examine current abundance and distribution of colonial waterbirds in that region. Data from this survey were compared with abundance of colonial waterbirds on Lake Winnipegosis and Lake Manitoba from an aerial survey of these lakes in 2012. Water-bird colonies were located on 7 of the 11 lakes in 2011 and included Double-crested Cormorants {Phalacrocorax auritus) (2373 adults, 1134 pairs in 7 colonies), Common Terns (Sterna hirundo) (1367 adults, 772 pairs in 29 colonies), Forster's Terns (Sterna forsteri) (20 adults, 11 pairs in 1 colony), Herring Gulls (Larus argentatus) (876 adults, 568 pairs in 23 colonies), and Ring-billed Gulls (Larus delawarensis) (3752 adults, 16 colonies). Common Terns and Herring Gulls appeared to be predominantly breeders and pair abundance for both species increased in a sigmoidal fashion; lakes <100 km² in area had few breeding pairs. Numbers of Double-crested Cormorants and especially, Ring-billed Gulls, may have included a sizeable non-breeding component. Densities (pairs/lake area) of Common Terns and Herring Gulls were about 2 and 4 times higher, respectively, on these lakes than on Lake Winnipegosis and Lake Manitoba, while Double-crested Cormorant and Ring-billed Gull densities were higher on lakes Win-nipegosis and Manitoba. Additional studies of productivity in relation to lake characteristics and connectivity among colonies throughout the region would further our understanding of the importance and sustainability of waterbird populations in this region of the boreal forest. [ABSTRACT FROM AUTHOR]

Abstract: Landfill managers often need to implement scaring programmes to deter gulls from feeding at their sites because the birds can be a significant nuisance for both site employees and residents of the surrounding area. Our objective was to assess the efficiency of firing rubber shots, a method assumed to be non-lethal but never tested in a bird deterrence context. This method was compared to selective culling, a well-known lethal technique that some people find ethically unacceptable. Both methods were employed in combination with the use of pyrotechnics. Our study was conducted at the Ste-Sophie landfill site near Montreal (Canada) located 37km from a Ring-billed gull (Larus delawarensis) colony supporting 48,000 pairs. Daily counts and behavioural observations were conducted throughout the breeding and post-breeding periods. Firing rubber shots was ineffective in deterring gulls as we observed the same number of birds at the landfill during periods with and without deterrence (P =0.949). However, we counted 38% less birds during the culling periods than during the rubber shot treatment (P =0.014). We detected no sign of habituation during the 7-day culling trials. Culling was also more effective in getting the gulls to leave the site than was rubber shots (47 vs. 11%; P <0.001) and the birds took longer before returning to the site (16 vs. 2min; P <0.001). Finally, the non-lethal method required an increased use of pyrotechnics to reduce the number of gulls to an acceptable level when compared to culling (P <0.001). The difference between culling and rubber shots may be related to the louder noise produced when firing steel shots and the view of dead or injured birds falling on the ground, which may be a deterrent factor for gulls. We also noted that the number of gulls was greater during the rearing stage when the birds have to feed their juveniles (P =0.005) and after 15:00h when the deterrence activities were adjourned (P =0.003). Our results clearly suggest that the deterrence efforts have to be adapted to seasonal variations in bird numbers as dietary needs are higher during the chicks’ rearing period. Any scaring programme should also be performed from dawn to dusk. In conclusion, the use of non-lethal rubber shots as applied in this study to deter gulls from feeding at landfill sites cannot be used as an effective alternative technique to culling. [Copyright &y& Elsevier]

Bird colonies are potentially rich sources of social information that can be used to compensate for the numerous disadvantages of communal life. This information can reduce uncertainty about nest locations, mates or food sources. However, there is little empirical evidence that colonies can actually serve as an information exchange point. We asked whether a large nesting colony of ring-billed gulls, Larus delawarensis, could provide its members with social information about the quality and location of food resources during the chick-rearing period. We first determined whether social information was available in the colony, then whether it was signalled by some reliable cue, and finally, whether the birds used it by following knowledgeable individuals. We combined observations of flight departure bearings at the colony with flight tracks obtained from birds fitted with global positioning system (GPS) data loggers. We found that reliable information about feeding site locations could be obtained by observing the vanishing bearings of gulls leaving their nest. Birds nesting in different parts of the colony flew in different directions to reach their feeding grounds, but this did not influence the type of food brought to the chicks. To test whether gulls actually followed departing individuals, we searched for temporal clumping of departures and bearings for different time intervals during a day. We found that departures of gulls nesting in the same neighbourhood were not temporally clustered, nor did the gulls tend to leave in the same direction as their previously departing neighbours. We conclude that ring-billed gulls do not appear to use social information at the nest site to locate foraging opportunities. However, stopovers on nearby water or along the colony edge after a short flight from the nest could allow exchange of information that we could not document. [ABSTRACT FROM AUTHOR]

A burgeoning ring-billed gull population along Chicago's Lake Michigan beaches contributes to degraded water quality through fecal contamination. Egg oiling was conducted at Chicago's gull colonies to reduce production and the influx of hatch-year (HY) gulls using Chicago's beaches, with a second, long-term objective of eventually reducing adult gull numbers through attrition. We also investigated swim season water quality trends through the course of this work. From 2007 to 2009, 52, 80, and 81%, of nests at the two primary nest colonies had their eggs rendered inviable by corn oil application. Counts of HY and after hatch-year (AHY) gulls were analyzed during treatment years for 10 beaches. Water quality data were available from the Chicago Park District during our three treatment years and the prior year (baseline) for 19 beaches. HY counts declined at all 10 surveyed beaches from the initial year (52% nests with oiled eggs) to subsequent years with ~80% of nests oiled. Overall, HY gulls numbers on beaches decreased 86% from 2007 to 2009. Decreases in beach usage by AHY gulls were not detected. Compared to pretreatment, the number of beaches with improved water quality test rates increased each year through the course of the study. The frequency of water quality tests showing bacterial exceedances compared to 2006 declined at 18 of 19 beaches by 2009. Egg oiling resulted in fewer HY gulls using Chicago's beaches and was likely a beneficial factor for reduced frequencies of swim advisories and swim bans. [ABSTRACT FROM AUTHOR]

The article focuses on the association between chewing lice and Ring-billed gull chick immunity. Relationships between lice and immune parameters were evaluated in Ring-billed Gull chicks. Eosinophils made up greater proportions of leukocytes in chicks with more lice suggest louse-induced immunoactivation via either eosinophil production or redistribution to peripheral blood. Results suggests only minor response to lice but experimental manipulations of louse infestations are needed.

This article presents a study on the population trend of Ring-billed Gulls over four decades in the North American Great Lakes and its connecting waterways. The study examined data gathered from four censuses, records colony distribution and occupancy patterns, and evaluated other factors pertinent to variations in nest counts at specific colonies. The four censuses used in this research were conducted by the Canadian Wildlife Service and the U.S. Fish and Wildlife Service from 1976 to 2009.

The possible role of tag color in mediating behaviors that could bias resighting rate has not been examined. In a study that began in 2007, we marked 725 ring-billed gulls (Larus delawarensis) with Bondcote royal blue, green, yellow, or orange patagial tags. Reports we gathered over 2 years indicated approximately a 3.41 bias in resighting rate toward yellow or orange tags. The observed bias is inconsistent with color-associated visibility bias or differential mortality among color-tagged breeding adults. Potential behavioral effects of tag color on individuals and conspecifics should be considered by biologists when planning marking studies. [ABSTRACT FROM AUTHOR]

The article focuses on a study which investigated the epidemiology and significance of avian influenza virus (AIV) in ring-billed gulls (Larus delawarensis) on breeding colonies in southern Ontario. Study authors isolated and characterized AIV and explored the prevalence of avian influenza infection in gulls on Lake Erie in 2000 and Lake Ontario in 200 and 2004. They found that the overall prevalence of AIV from cloaca in embryonated chicken eggs was 32 percent in 2000. The study concluded that the presence of antibody to AIV in chicks is linked with inflammation in heart, kidney, pancreas and liver.

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