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Abstract Studies of model animals like mice and rats have led to great advances in our understanding of the process of tumorigenesis, but this line of study has less to offer for understanding the mechanisms of cancer resistance. Increasing the diversity of nonmodel species from the perspective of molecular mechanisms of natural cancer resistance can lead to new insights into the evolution of protective mechanisms against neoplastic processes and to a wider understanding of natural cancer defense mechanisms. Such knowledge could then eventually be harnessed for the development of human cancer therapies. We suggest here that seabirds are promising, albeit currently completely ignored candidates for studying cancer defense mechanisms, as they have a longer maximum life span than expected from their body size and rates of energy metabolism and may have thus evolved mechanisms to limit neoplasia progression, especially at older ages. We here apply a novel, intraspecific approach of comparing old and young seabirds for improving our understanding of aging and neoplastic processes in natural settings. We used the long‐lived common gulls (Larus canus) for studying the age‐related pattern of expression of cancer‐related genes, based on transcriptome analysis and databases of orthologues of human cancer genes. The analysis of differently expressed cancer‐related genes between young and old gulls indicated that similarly to humans, age is potentially affecting cancer risk in this species. Out of eleven differentially expressed cancer‐related genes between the groups, three were likely artifactually linked to cancer. The remaining eight were downregulated in old gulls compared to young ones. The downregulation of five of them could be interpreted as a mechanism suppressing neoplasia risk and three as increasing the risk. Based on these results, we suggest that old gulls differ from young ones both from the aspect of cancer susceptibility and tumor suppression at the genetic level.

Aim. The purpose of this research was to find out what local weather factors influence the nesting timing of the common gull (Larus canus). Material and Methods. The time of egg laying by the common gull was determined using data obtained during regular surveys over 8 years (1996‐1998, 2002‐2003, 2006‐2008) on the islands of Lake Bolshie Chany. Weather and climatic factors were assessed using open‐access databases. Results. It was been established that the start of egg‐laying in the colony of the common gull is determined by wind strength, the number of rainy days, the associated atmospheric pressure during the second decade of April, and the air temperature – the transition date at which the average daily air temperature rose above 0°C. In years with unstable spring temperatures, a relationship was revealed between the air temperature and the intensity of egg laying by the common gulls by day. In years when temperatures rise evenly, precipitation and wind speed become the main factors.Conclusion. We conclude that the egg‐laying dates of the common gull is influenced by weather variables during the whole nesting season and not predominantly by early season variables. We also show the importance of large‐scale climatic phenomena such as the EAWR in explaining variability in timing of the nesting of the common gull in Siberia. We suggest that future studies should focus on the effects of extremes in weather variables and global climatic phenomena.

Studies of model animals like mice and rats have led to great advances in our understanding of the process of tumorigenesis, but this line of study has less to offer for understanding the mechanisms of cancer resistance. Increasing the diversity of nonmodel species from the perspective of molecular mechanisms of natural cancer resistance can lead to new insights into the evolution of protective mechanisms against neoplastic processes and to a wider understanding of natural cancer defense mechanisms. Such knowledge could then eventually be harnessed for the development of human cancer therapies. We suggest here that seabirds are promising, albeit currently completely ignored candidates for studying cancer defense mechanisms, as they have a longer maximum life span than expected from their body size and rates of energy metabolism and may have thus evolved mechanisms to limit neoplasia progression, especially at older ages. We here apply a novel, intraspecific approach of comparing old and young seabirds for improving our understanding of aging and neoplastic processes in natural settings. We used the long‐lived common gulls (Larus canus) for studying the age‐related pattern of expression of cancer‐related genes, based on transcriptome analysis and databases of orthologues of human cancer genes. The analysis of differently expressed cancer‐related genes between young and old gulls indicated that similarly to humans, age is potentially affecting cancer risk in this species. Out of eleven differentially expressed cancer‐related genes between the groups, three were likely artifactually linked to cancer. The remaining eight were downregulated in old gulls compared to young ones. The downregulation of five of them could be interpreted as a mechanism suppressing neoplasia risk and three as increasing the risk. Based on these results, we suggest that old gulls differ from young ones both from the aspect of cancer susceptibility and tumor suppression at the genetic level. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine whether offspring sex ratios in Mew Gulls (Larus canus) change non-randomly according to the current condition of females, empirically evaluating the predictions of the cost of reproduction hypothesis in colonies on the islands of the middle reaches of the Vistula River in Poland. It was assumed that Mew Gull females in poor condition would produce more daughters (10-15% smaller than males). The condition of females was reduced by removing first clutches shortly after completion, inducing a second clutch. Non-manipulated pairs that laid first clutches at the same time constituted controls. In first clutches (control, 3 eggs), the mean proportion of daughters at hatching was 51.0 ± 15.4% (n = 50), and on the fifth day after hatching was 51.2 ± 12.0% (n = 48). The share of broods with a predominance of daughters in both periods was similar (range = 47.9-48.0%). In experimentally induced replacement clutches (3-egg), the mean proportion of daughters was higher than in first clutches both at hatching (69.3 ± 14.9%; n = 45) and 5 daysays after hatching (62.1 ± 16.2 %; n = 42). Offspring sex ratio at hatching reflected the current condition of females, corresponding with predictions of the cost of reproduction hypothesis. Frequency of replacement broods with a predominance of daughters declined between hatching (77.8%) and the fifth day after hatching (59.5%), reducing broods in favor of males; and more frequent losses were observed at 5 daysays after hatching in replacement broods (of which only ∼13% of broods were without losses) compared to first broods (46.0% without losses). [ABSTRACT FROM AUTHOR]

THE MEW GULL Larus canus is both a coastal and inland breeder and can be found on many different substrates, including man-made structures. It is known since long to nest in urban areas of Sweden, but neither the number of urban breeding pairs nor their behaviour have been well documented. We made some observations of breeding Mew Gulls in the city of Malmö in south Sweden and asked the chair of the tenant owners' association that comprised one of the buildings with Mew Gull nest about the tenants' experience of the species. Some perceive Mew Gulls as harmful because they dirty the roofs, leave a bad smell, are noisy, and defend their young with aggressive behaviours. Given the often-conflicting interests of gulls and humans, a better documentation of the nesting population in urban areas of Sweden, as well as their behaviour and interaction with people, is called for. [ABSTRACT FROM AUTHOR]

The costs and benefits of interactions among species can vary spatially or temporally, making them context-dependent. For example, benefits associated with nesting near species that deter predators may give way to costs if the association increases the risk of predation during other stages of reproduction. We examined the extent to which the costs and benefits of heterospecific aggregations between a declining shorebird, the Hudsonian Godwit (Limosa haemastica), and a potential protector and predator, the Mew Gull (Larus canus), varied with breeding stage. Specifically, we assessed the spatial distribution and fate of 43 godwit and 262 gull nests in Beluga, Alaska, from 2014 to 2016. We then evaluated the effect of habitat and proximity to gulls on daily survival rates of 120 godwit nests from 2009 to 2016. We also examined the relationship between the proximity to gulls and survival of godwit chicks to 5 days old, the period when they are vulnerable to gull predation. Nests of godwits and gulls were significantly clustered across the landscape, a pattern that habitat heterogeneity failed to explain. Hatching success of godwit nests improved with proximity to the gull colony and increasing numbers of gull nests within 200 m. In contrast, survival of godwit chicks to 5 days improved with increasing distance to the gull colony. The costs and benefits that godwits derived from associating with Mew Gulls were thus context-dependent, with benefits pre-hatch and costs post-hatch. Our results show how spatiotemporal variation in species interactions precludes simple generalizations about the nature of their outcomes. [ABSTRACT FROM AUTHOR]

The article provides an overview of "mew" as the deepest historical roots for sea gull (Larus canus) in England and Scotland. The "Oxford English Dictionary" cites Latin-Old English glossary as first attestation of "mew," while an early application in specific context is found in the poem "The Seafarer." The vocalism of the forms "mew," "meav" and "meaw" invites the queries whether there is another factor at work, even though Middle English orthography is variable notoriously.

The common gull is a widespread species, occurring in almost the whole of Europe that shows no sexual dimorphism in plumage and some dimorphism in size. To propose a method for sexing birds from this species by linear measurements, a discriminant function analysis was applied to a set of morphometric traits in birds captured in northern Poland during the non-breeding season. In total, 138 males and 76 females were measured and sexed molecularly. The averages of measurements of males were larger than the average measurements of females. All individuals with a total head length shorter than 90.6 mm were females. However, the occurrence of larger individuals of the subspecies heinei among common gulls of the nominate subspecies canus wintering in Europe makes separating males according to a single border value of this measurement less efficient. The proposed discriminant function containing the total head length allowed for correct sexing of 95.7 % of males and 90.9 % of females. This discriminant equation may be used for sexing common gulls when DNA sampling is not possible, and could be applied to data collected in the past, providing the opportunity to re-examine the results of previous analyses. However the higher misclassification rate than in other gull species should be taken into account. [ABSTRACT FROM AUTHOR]

According to handicap principle, exaggerated ornamental traits are supposed to exert costs on their bearers. However, there is much less theoretical and practical consensus about whether and under which conditions ornament expression should positively correlate with survival. We measured age-related variation and survival selection on the size of white wing patches and black wing tips in a long-lived monogamous seabird, the common gull Larus canus. Males had larger white patches than females but patch size showed concave relationship with age irrespective of sex, suggesting that white patch size was prone to senescence in both sexes. Extent of wing tip abrasion correlated negatively with the size of white patch, suggesting, in agreement with the Zahavian handicap hypothesis that only individuals with largest ornaments are able of maintaining them and not paying cost of displaying them. Areas of white wing patches and black wing tips correlated negatively. Irrespective of sex, survival selection favored birds with larger white wing patches and smaller black wing tips, which suggests that white and black wing markings may have coevolved as reverse components of a single ornament. Altogether, our results provide an evidence for the case where survival selection on ornamental traits in females is not weaker than in males. Absence of sex differences with respect to most of observed patterns is consistent with a prediction that among monogamous long-lived species with biparental care, mutual mate choice leads to evolution of elaborate ornamental traits in both sexes. [ABSTRACT FROM AUTHOR]

The questions about why and how senescence occurs in the wild are among the most pertinent ones in evolutionary ecology. Telomere length is a commonly used marker for aging, while other biomarkers of aging have received considerably less attention. Here we studied how another potent indicator of aging-skin pentosidine concentration-relates to age and blood telomere length in a long-lived seabird with well-documented reproductive senescence. We found no associations between telomere length, skin pentosidine and chronological age in male common gulls ( Larus canus), aging from 2 to 30 years. However, the variance in telomere length was 4.6 times higher among the birds older than 13 years, which hints at relaxed selection on telomere length among the birds that have passed their prime age of reproduction. These results suggest that physiological and chronological ages may be largely uncoupled in our study system. Furthermore, our findings do not support a hypothesis about the presence of a common physiological factor (e.g., such as oxidative stress) that would cause covariation between two independent markers of aging. [ABSTRACT FROM AUTHOR]

A nematode species belonging to the genus Cosmocephalus was collected from the stomach of 2 common gulls, Larus canus. The common gulls were found dead on the seaside of Gangneung City, the Republic of Korea. The worms were identified and classified by light (LM) and scanning electron microscopy (SEM) on the basis of important tax-onomic characters. The nematodes were characterized by a body length 9.1-9.3 mm (males) and 15.5-15.9 mm (females) and cordons recurrent in anterior direction and anastomosing laterally at about the level of anterior quarter of the buccal cavity. The salient bicuspid deirids were located on the posterior to the cordons. Lateral alae were well-developed, extending from the level just posterior of deirids to the level about middle of the body. LM and SEM observations identified the worms as C. obvelatus. This is the first reported case of C. obvelatus infection in common gulls in Korea. [ABSTRACT FROM AUTHOR]

Background: Wild aquatic birds constitute the natural reservoir for avian influenza viruses (AIVs). Separate Eurasian and American AIV gene pools exist. Here, the prevalence and diversity of AIVs in gulls and dabbling ducks in Norway were described. The influence of host species and temporal changes on AIV prevalence was examined. Five AIVs from Norway, including three from common gull (Larus canus), were analyzed along with 10 available AIV genomes from gulls in Eurasia to search for evidence of intracontinental and intercontinental reassortment of gene segments encoding the internal viral proteins. Methods: Swabs collected from 2417 dabbling ducks and gulls in the south-west of Norway during five ordinary hunting seasons (August-December) in the period 2005-2010 were analyzed for presence of AIV. Multivariate linear regression was used to identify associations between AIV prevalence, host species and sampling time. Five AIVs from mallard (Anas platyrhynchos) (H3N8, H9N2) and common gull (H6N8, H13N2, H16N3) were full-length characterized and phylogenetically analyzed together with GenBank reference sequences. Results: Low pathogenic AIVs were detected in 15.5% (CI: 14.1-17.0) of the samples. The overall AIV prevalence was lower in December compared to that found in August to November (p = 0.003). AIV was detected in 18.7% (CI: 16.8-20.6) of the dabbling ducks. A high AIV prevalence of 7.8% (CI; 5.9-10.0) was found in gulls. A similar temporal pattern in AIV prevalence was found in both bird groups. Thirteen hemagglutinin and eight neuraminidase subtypes were detected. No evidence of intercontinental reassortment was found. Eurasian avian (non H13 and H16) PB2 or PA genes were identified in five reference Eurasian gull (H13 and H16) AIV genomes from GenBank. The NA gene from the Norwegian H13N2 gull isolate was of Eurasian avian origin. Conclusions: The similar temporal pattern in AIV prevalence found in dabbling ducks and gulls, the relatively high virus prevalence detected in gulls and the evidence of intracontinental reassortment in AIVs from gulls indicate that gulls that interact with dabbling ducks are likely to be mixing vessels for AIVs from waterfowl and gulls. Our results support that intercontinental reassortment is rare in AIVs from gulls in Eurasia. [ABSTRACT FROM AUTHOR]

Blood parasites often incur a substantial fitness cost to the infected individuals, sometimes resulting in death of the host. Some bird species, however, are apparently free of blood parasites, presumably due to the lack of exposure to blood parasite vectors. Protective immunity may be also responsible for the absence of infections by haematozoa. In this study, we tested the presence of blood parasites in Common Gulls ( Larus canus) and Black-headed Gulls ( Chroicocephalus ridibundus) nesting in environments with varying vector exposure. We failed to find blood parasites in Common Gulls irrespective of vector exposure, whereas infection rates of Black-headed Gulls were generally very low. We propose that the absence of haematozoa and low prevalence of blood parasites in these species of gulls is probably not a function of vector exposure and suggest alternative explanations such as enhanced immunity. [ABSTRACT FROM AUTHOR]

In this study, the mercury concentrations of liver, breast feathers and tail feathers in three species of Gull; Black-headed Gull ( Larus ridibundus), Common Gull ( Larus canus) and Little Gull ( Larus minutus) from the South coast of the Caspian Sea in Iran were assayed. Mercury accumulation in liver, breast feathers and tail feathers of species were 1.69–3.16, 2.88–7.18 and 2.09–5.66 mg/kg, respectively. Mercury concentration hierarchy in tissues we tested was as follows: breast feather > tail feather > and liver. We found that despite its small size, Little Gull had highest (3.85–8.05 mg/kg) and Common Gull lowest (1.69–2.88 mg/kg) level of Hg in their bodies. An inverse relationship between body size and Hg levels in these Gulls was detected. Mercury in Little Gull and Black-headed Gull exceeded the 5 ppm threshold for adverse effect. [ABSTRACT FROM AUTHOR]

A personal narrative is presented which explores the author's experience of taking a picture of brachyrhyncus Mew Gull bird at Hammonasset Beach State Park in Madison, Connecticut in April 2016.

Survival selection against individuals of inferior quality (measured as breeding success) has been proposed to account for the increase in average reproductive success with advancing age in presenescent birds. This so-called selection hypothesis relies on quality-dependent survival. In the present breeding performance study of common gulls, Larus canus, this assumption was not verified. In particular, omitting the last breeding year from the analysis resulted in the disappearance of the correlation between breeding success and survival. A positive correlation in the full dataset was thus solely based on the poor breeding success of ultimate breeders. Indeed, presenescent individuals were shown to have a specifically low breeding success in their terminal breeding event. The poor success of ultimate breeders thus reflects an abruptly declined condition rather than the birds' overall quality. A comparison of the survival of poor and good performers, involving last-time breeders, thus needs not to be a proper test of the selection hypothesis. Longitudinal analysis revealed a steady increase of individual breeding success until the tenth breeding year. The results suggest that an increase of breeding success with age often found in cross-sectional analyses is primarily a result of age-related improvements of competence and/or increased reproductive effort. [ABSTRACT FROM AUTHOR]

Common gulls drop cockles onto hard sand to open them. Gulls dropped cockles 2.9 ± 0.36 times to open them, from a mean height of 24.68 ± 1.74 m. Drop heights decreased significantly during a dropping sequence. Opened cockles had a mean shell-length of 32.22 ± 0.59 mm, which was similar to the size of available cockles. An economic model showed that gulls should drop cockles of average size twice from a mean height of 31.22 m to maximise their net rate of energy gain. The model showed that intake rates were similar for two-drop strategies with a mean drop height of 31.22 m, irrespective of the distribution of drop heights within the sequence, provided the first drop was less than the height at which cockles reached terminal velocity. The combination of number of drops and drop heights varied between cockle sizes, but model results were general - the optimum economic dropping strategy for a given size consisted of a number of drops from a constant height. Model predictions were, therefore, significantly different from observed behaviour. A risk of kleptoparasitism was added to the economic model by assuming gulls lost their cockle to a parasite if it was dropped above a threshold height immediately prior to opening. This showed that the number of drops in a sequence increased and mean drop height decreased compared with the average economic optimum. Drop heights within a sequence were also predicted to decrease in the presence of kleptoparasitism because the final drop was constrained to be lower than the height at which kleptoparasitism occurs. Previous drops in the sequence have to be increased in height as a result to ensure the cockle experiences sufficient impact energy to open. The inclusion of a risk of kleptoparasitism, therefore, increased the correspondence between model predictions and observed behaviour. The role of kleptoparasitism in decision making by gulls in the wild is discussed. [ABSTRACT FROM AUTHOR]

Studies the adoption of chicks and level of relatedness in common gulls. Kin selection as cause of adoption behavior in gulls; Occurrence of kin groups; Band-sharing coefficients for adopted chicks and adopting neighbors.

The aim of the present paper was to estimate the survival rates of breeding common gulls, using mark-recapture data, gathered in 1968-1983 (16 sampling periods) in Estonia. We analyzed effects of age (breeding experience), year and sex on survival. Every year we observed more than 90% of the breeders and ringed about 95% of the nestlings. Two samples of gulls were used in the analyses. The first sample (347 individuals) consisted of birds thought to be first-time breeders when first observed in colony. The second sample (1269 individuals) may contain birds which have nested earlier. In the first sample, we did not detect any influence of age and sex on survival, but time dependence was significant and can be explained by winter severity. In cold winters the survival was lower (0.865) than in normal (0.896) and warm (0.929) winters. We suspect that the age effect on survival rate remained undetected owing to sparse data. In the second sample, we detected age- and time-dependent survival for both sexes. We also found differences between the sexes in recapture probability (in both samples). This was probably caused by lower site tenacity of females. [ABSTRACT FROM AUTHOR]

We studied the heritability of head length in a common gull (Larus canus) population breeding in western Estonia. Heritability estimates obtained from offspring-parent regressions were moderate to high and significantly different from zero. Head size might hence respond evolutionarily to phenotypic selection. Offspring-mother and offspring-father regressions yielded similar heritability estimates. This indicated that size-related maternal or paternal effects were absent or weak. Heritability and additive genetic variance estimates obtained from offspringparent regressions and full-sib analyses were higher when offspring had grown up under good environmental conditions than under poor environmental conditions. Such a pattern has previously been found in some other studies of birds. This suggests that genotype-environment interactions might be frequent within the range of conditions experienced by natural bird populations. [ABSTRACT FROM AUTHOR]

This article offers information on gull. The term gull means gorge or swallow voraciously. Most species of gulls are omnivorous. Gull species include Larus canus, Larus argentatus and Larus marinus. Overview of the books about gull, written by Milton is provided, including "An Apology Against a Pamplet" and "Colasterion."