Gunnar Thor Hallgrimsson

Wild birds of declining European species are dying from a thiamine deficiency syndrome.

Wild birds of several species are dying in large numbers from an idiopathic paralytic disease in the Baltic Sea area. Here, we demonstrate strong relationships between this disease, breeding failure, and thiamine (vitamin B1) deficiency in eggs, pulli, and full-grown individuals. Thiamine is essential for vertebrates, and its diphosphorylated form functions as a cofactor for several life sustaining enzymes, whereas the triphosphorylated form is necessary for the functioning of neuronal membranes. Paralyzed individuals were remedied by thiamine treatment. Moreover, thiamine deficiency and detrimental effects on thiamine-dependent enzymes were demonstrated in the yolk, liver, and brain. We propose that the mortality and breeding failure are part of a thiamine deficiency syndrome, which may have contributed significantly to declines in many bird populations during the last decades.

North Atlantic Migratory Bird Flyways Provide Routes for Intercontinental Movement of Avian Influenza Viruses

Avian influenza virus (AIV) in wild birds has been of increasing interest over the last decade due to the emergence of AIVs that cause significant disease and mortality in both poultry and humans. While research clearly demonstrates that AIVs can move across the Pacific or Atlantic Ocean, there has been no data to support the mechanism of how this occurs. In spring and autumn of 2010 and autumn of 2011 we obtained cloacal swab samples from 1078 waterfowl, gulls, and shorebirds of various species in southwest and west Iceland and tested them for AIV. From these, we isolated and fully sequenced the genomes of 29 AIVs from wild caught gulls (Charadriiformes) and waterfowl (Anseriformes) in Iceland. We detected viruses that were entirely (8 of 8 genomic segments) of American lineage, viruses that were entirely of Eurasian lineage, and viruses with mixed American-Eurasian lineage. Prior to this work only 2 AIVs had been reported from wild birds in Iceland and only the sequence from one segment was available in GenBank. This is the first report of finding AIVs of entirely American lineage and Eurasian lineage, as well as reassortant viruses, together in the same geographic location. Our study demonstrates the importance of the North Atlantic as a corridor for the movement of AIVs between Europe and North America.

Genotoxicity in herring gulls (Larus argentatus) in Sweden and Iceland.

Adult and young herring gulls (Larus argentatus) in Sweden and Iceland were investigated with respect to DNA adducts, analysed with the nuclease-P1 version of the (32)P-postlabelling method, and micronucleated erythrocytes. Three important aims were: (1) to estimate the degree of exposure to genotoxic environmental pollutants in the Baltic Sea area and Iceland, (2) to evaluate the utility of the investigated biomarkers in birds, and (3) to investigate if there was any relationship between genotoxic effects and thiamine deficiency. The results demonstrate that both Swedish and Icelandic herring gulls are exposed to genotoxic pollution. Urban specimens have higher levels of DNA adducts than rural specimens, but background exposure to genotoxic environmental pollutants, such as PAHs, is also significant. In the herring gull the general level of DNA adducts in the liver seems to be higher than in fish. DNA adducts were most abundant in the liver, followed by the kidney, intestinal mucosa, and whole blood, in decreasing order. The frequency of micronucleated erythrocytes was probably slightly elevated in all the investigated sites, reflecting a significant background exposure. The level of DNA adducts was unrelated to the frequency of micronucleated erythrocytes, and both these variables were unrelated to symptoms of thiamine deficiency. The investigation confirmed the utility of DNA adducts, and probably also micronucleated erythrocytes, as biomarkers of genotoxicity in birds.

Migration pattern of Icelandic Lesser Black-backed Gulls Larus fuscus graellsii: indications of a leap-frog system

AbstractOn the species level, the non-breeding distribution and the migration patterns of most European birds are well known. In contrast, the knowledge of the contribution of different breeding populations to particular non-breeding sites (migratory connectivity) is far more limited. We studied the non-breeding distribution of individually colour-ringed Lesser Black-backed Gulls (Larus fuscus graellsii) from Iceland and sought information on their migration pattern in respect to other populations (leap-frog, chain migration, random mix). Most winter resightings (94%) were from the southern part of the known winter range (Iberian Peninsula and northwest Africa). No statistical difference was found according to age on the latitudinal winter distribution, although 1st winter birds were on average 2° further south. Both 2nd and 3rd calendar year (cy) birds performed a northward spring migration,but spent the summer at lower latitudes than adults. The autumn migration for adults was earlier compared with 1st cy birds. A comparison of resightings of birds ringed in Iceland and in two projects from the Netherlands showed that these populations are not likely to contribute much to the wintering population in the UK. The proportion of winter resightings from Icelandic and Dutch populations showed that 44–65% were from the Iberian Peninsula. However, Dutch birds were much more likely to be seen in France (18–48 vs. 0.4%), but Icelandic birds were more likely to be seen in Africa (29 vs. 6–16%). These results indicate that Icelandic birds to some extent leap-frog more southerly populations.ZusammenfassungZugmuster der Isländischen Heringsmöwe (Larus fuscus graellsii): Hinweise auf ein Übersprungs-System Auf Art-Niveau sind das Vorkommen und die Zugmuster der meisten europäischen Vögel gut bekannt. Deutlich weniger weiß man hingegen über die Präsenz der unterschiedlichen Brut-Populationen in Gebieten, in denen nicht gebrütet wird (migratory connectivity). Wir untersuchten das Vorkommen einzelner beringter, isländischer Heringsmöwen (Larus fuscus graellsii), um Informationen über ihre Zugmuster in Zusammenhang mit anderen Populationen zu sammeln (Überspringen, Kettenwanderung, Zufalls-Mix). Die meisten (94%) Ringfunde und Sichtungen lagen im südlichen Teil der bekannten Überwinterungsgebiete (Iberische Halbinsel, Nordwest-Afrika), und es gab keine statistischen Unterschiede bezüglich des Alters der geographischen Winter-Verteilung, obwohl erstmals überwinternde Vögel im Schnitt 2 Grad weiter südlich zu finden waren. Vögel, die zum zweiten und dritten Mal überwinterten, zeigten eine mehr nördlich ausgerichtete Frühlingswanderung, verbrachten den Sommer aber auf südlicheren Breiten als die adulten Tiere. Die Herbstwanderung adulter Tiere ist früher schon mit der von Erstziehern verglichen worden. Ein Vergleich von in Island beringten Wiederfunden wie auch zwei Projekte in den Niederlanden zeigten, dass diese Populationen höchstwahrscheinlich nicht viel zu den im U.K. überwinternden Populationen beitragen. Ein Teil der Winter-Wiederfunde isländischer und niederländischer Populationen zeigte, dass 44–65% von diesen von der Iberischen Halbinsel stammten. Aber niederländische Vögel wurden mit größerer Wahrscheinlichkeit in Frankreich gesichtet (14–48 vs. 0.4%) und isländische Vögel eher in Afrika (29 vs. 6–16%). Diese Ergebnisse sind ein Hinweis darauf, dass isländische Vögel in gewissem Ausmaß südlichere Populationen überspringen.

Population structure, biometrics and moult of migrant Purple Sandpipers Calidris maritima in southwest Iceland in spring

Capsule Iceland is a stop‐over site for a population of Purple Sandpipers that winter in Britain. Here, they accumulate fuel loads for onward migration along with birds that have wintered in Iceland. Aims To establish whether Purple Sandpipers from Britain stop‐over in Iceland during spring migration and, if so, to describe their population structure, changes in mass and moult. Methods Purple Sandpipers were cannon‐netted on the coast of the Reykjanes Peninsula in southwest Iceland during May 2003 and 2005. Birds were aged, sexed (some by DNA) and standard biometric measurements made. Active body moult was scored. Results Bill and wing lengths showed that the Purple Sandpipers we caught were similar to one of the populations that winter in Britain rather than Icelandic breeding birds. There were more males than females throughout the migration period (63% males for first‐year‐birds and 67% for adult birds). Accounting for a bias due to a higher percentage of males in a less usual habitat (muddy/sandy bays), the values for rocky sites were 52% males for first‐year birds and 62% for adults. The percentage of first‐year birds was 19% in 2003 and 32% in 2005, though the latter figure was biased by catches in muddy/sandy bays where there was a higher percentage of young birds. The percentage of first‐year birds was 25% on just the rocky shores in 2005. Many birds were in latter stages of body moult, and males were slightly in advance of females. Increasing mass showed that they were preparing for onward migration. The average increase of 0.58 g per day was similar to the rate measured in Orkney at an earlier point on the migration route. However, a high turnover of birds could be the reason for these low values. By late May, and close to the assumed departure date, the Purple Sandpipers of the different age/sex classes had fuel indices of 24–29% (33–42% of the lean mass). This was lower than that for the high Arctic sandpipers (Knots and Sanderlings) leaving southwest Iceland for Greenland and Canada. Conclusions Our study confirmed that Purple Sandpipers do stop‐over in Iceland, and the possible lower rate of fuel accumulation and smaller amount stored, compared with Knots and Sanderlings, suggests a different migration pattern.

Avian influenza virus ecology in Iceland shorebirds: intercontinental reassortment and movement

Shorebirds are a primary reservoir of avian influenza viruses (AIV). We conducted surveillance studies in Iceland shorebird populations for 3 years, documenting high serological evidence of AIV exposure in shorebirds, primarily in Ruddy Turnstones (Arenaria interpres; seroprevalence=75%). However, little evidence of virus infection was found in these shorebird populations and only two turnstone AIVs (H2N7; H5N1) were able to be phylogenetically examined. These analyses showed that viruses from Iceland shorebirds were primarily derived from Eurasian lineage viruses, yet the H2 hemagglutinin gene segment was from a North American lineage previously detected in a gull from Iceland the previous year. The H5N1 virus was determined to be low pathogenic, however the PB2 gene was closely related to the PB2 from highly pathogenic H5N1 isolates from China. Multiple lines of evidence suggest that the turnstones were infected with at least one of these AIV while in Iceland and confirm Iceland as an important location where AIV from different continents interact and reassort, creating new virus genomes. Mounting data warrant continued surveillance for AIV in wild birds in the North Atlantic, including Canada, Greenland, and the northeast USA to determine the risks of new AI viruses and their intercontinental movement in this region.

Evolutionary status of Icelandic Redpolls Carduelis flammea islandica (Aves, Passeriformes, Fringillidae)

AbstractThe Icelandic Redpoll Carduelis flammea islandica is one of three subspecies of Carduelis flammea. The other two are C. f. rostrata, breeding in Greenland, and C. f. flammea, widely distributed at high latitudes in both North America and Eurasia. Recent studies on variation of the mtDNA control region and microsatellites among C. f. r. and C. f. f. and related species (Arctic Redpoll Carduelis hornemanni and Lesser Redpoll Carduelis cabaret) did not reveal clear genetic differentiation among the species. Here we include DNA sequences of mtDNA and nuclear markers of the Icelandic subspecies (C. f.islandica) and from additional samples of the other species and subspecies to evaluate further their taxonomic status within the complex, with special emphasis on C. f.islandica. Mitochondrial and nuclear variation is large within species and does not provide support for the current subspecies and the species classification. Significant differences in haplotype frequencies of the combined genetic data are observed between the C. flammea subspecies, and C. cabaret. The slight genetic differentiation within the redpoll complex could result from introgression and/or incomplete lineage sorting following recent and rapid diversification in morphology, possibly driven by environmental factors.ZusammenfassungEvolutionärer Status des isländischen Birkenzeisigs Carduelis flammea islandica (Aves, Passeriformes, Fringillidae) Der isländische Birkenzeisig Carduelis flammea islandica stellt eine der drei Unterarten des Birkenzeisig (Carduelis flammea) aus der Familie der Finken (Fringillidae) dar. Die anderen beiden Unterarten sind C. f. rostrata, der auf Grönland brütet, sowie C. f. flammea, welcher weit verbreitet ist in den hohen Breitengraden sowohl Nordamerikas als auch Eurasiens. Neuere Studien über Variation innerhalb der Kontrollregion der mitochondrialen DNA (mtDNA) und Mikrosatelliten zwischen C. f. r. und C. f. f. sowie weiterer verwandter Arten (Arktischer Birkenzeisig Carduelis hornemanni und Kleiner Birkenzeisig Carduelis cabaret) konnten keine klare genetische interspezifische Differenzierung zeigen. Um den genauen taxonomischen Status der hier genannten Unterarten des Birkenzeisigs und insbesondere des isländischen Birkenzeisigs C. f. islandica innerhalb des Artenkomplexes bewerten zu können, beziehen wir in dieser Studie mitochondriale DNA Sequenzen und nukleare Marker weiterer Proben von C. f. islandica sowie der anderen Unterarten ein. Sowohl auf mitochondrialer als auch nuklearer Ebene zeigt sich eine große Variation innerhalb der Arten, was der momentanen Klassifizierung der Arten und Unterarten widerspricht. Zwischen den Unterarten von C. flammea und dem Kleinen Birkenzeisig C. cabaret konnten signifikante Unterschiede innerhalb der Haplotypfrequenz für den kombinierten genetischen Datensatz gefunden werden. Die geringe genetische Differenzierung innerhalb des Artenkomplexes der Birkenzeisige könnte auf Introgression und/oder unvollständige Linientrennung zurückzuführen sein, welche ihrerseits aus der schnellen und kurzfristigen morphologischen Diversifizierung resultiert, die möglicherweise durch Umweltfaktoren verursacht ist.

Sex ratio and sexual size dimorphism in Purple Sandpiper Calidris maritima chicks

Capsule The uneven sex ratio in favour of males found in flocks of Purple Sandpipers is not evident in chicks; female chicks are lighter than males. Aims To test if there is an uneven sex ratio at hatching and to investigate whether sex ratio changes during chick growth and after fledging. Methods Sex of chicks was determined (by DNA) and each chick given a unique combination of colour‐rings for later re‐sightings. Biometric measurements were made for comparisons between the sexes. Results The sex ratio of 97 chicks did not deviate significantly from parity, 52.6% males (95% CI: 42.2–62.8%), and there was no evidence that the sex ratio changed as chicks grew older. However, sightings of colour‐ringed birds in their first year indicated a change to 61% males. The same sex ratio (61% males) was observed among wintering birds in Iceland. Chicks already showed sexual size dimorphism in skeletal measurements as is also found in full‐grown birds. Female chicks were relatively lighter than males, suggesting poorer condition. Conclusions The uneven sex ratios seen in non‐breeding flocks of Purple Sandpipers are not determined at hatching but might arise owing to higher juvenile mortality among females soon after fledging. This may result from the relatively lighter mass of female chicks.

Reply to Rocke and Barker: The question is not whether birds are affected by thiamine deficiency or botulism, it is about the order of events

Contrary to the suggestion by Rocke and Barker (1), we do not want to exclude botulism as a part of the investigated wildlife disorder (2), because botulism may be secondary to the thiamine deficiency syndrome. This possibility and the investigations by Neimanis et al. (3) are discussed in Text S5 in our SI Appendix (2).

The Winter Range of Nearctic Purple Sandpipers Calidris maritima on the East Atlantic Flyway

Iceland has a large resident population of Purple Sandpipers Calidris maritima, but is also believed to be a wintering area for other populations and is a stopover site for migrants. To determine the wintering areas of those that prepare for westward migration to the Nearctic in spring, Purple Sandpipers were colour-ringed on the coast of southwest Iceland in May 2003 and 2005. We searched for colour-ringed birds along the coasts of Iceland, the European mainland and Britain, particularly in winter 2005/06. Out of 326 marked birds, 82 were re-sighted during 2003 to 2009, of which 69 were seen during winter (October to March) 2005/06. Most sightings (55) in winter 2005/06 were from southwest Iceland, extending the known winter range of this population to Iceland. Resightings from northern Scotland confirmed the evidence from biometrics that this wintering population originates from the Nearctic. The maximum number of colour-marked Purple Sandpipers in Britain and Ireland in winter 2005/06 was estimated at about 65, which was approximately a quarter of the marked sample estimated to be alive. Therefore, the majority of the colour-ringed birds must have wintered elsewhere, most likely in Iceland. There was no evidence of sexual segregation according to whether they wintered in Iceland or Britain. However, those that were colour-ringed before 15 May were more likely to be seen in Iceland than in Britain, whereas those colour-ringed after 15 May were more likely to be seen in Britain, indicating that the migration from Britain takes place mainly after mid-May. Although there have been no ringing recoveries, biometry data suggest that Purple Sandpipers that prepare for westward migration in Iceland in spring, breed in Canada. This population shows a unique winter range for a wader that includes Greenland, Iceland and northwest Europe along the East Atlantic flyway.