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Amouret J.,University of Iceland | Barisas D.A.G.,University of Iceland | Hallgrimsson G.T.,University of Iceland | Summers R.W.,Lismore | Palsson S.,University of Iceland
Journal of Avian Biology | Year: 2016

The Icelandic subspecies of Eurasian wren Troglodytes troglodytes islandicus has been described as a large wren which is sedentary on the island. It is one member of a large passerine complex which is widely distributed over the Holarctic except the Arctic. The taxonomic affiliation of the subspecies is mainly based on variation in plumage and on the song complexity. This study investigated the genetic differentiation of T. t. islandicus among the Eurasian wren subspecies in northwestern Europe, and especially in relation to its geographically proximate populations in the Faroe Islands, Scotland, southern Norway, Sweden and Denmark. Troglodytes t. islandicus and the Faroese subspecies (T. t. borealis) were genetically differentiated from the other subspecies (T. t. indigenus and T. t. troglodytes) with an estimated time of divergence from this group during the last glacial maximum; 21 thousand years before present (KYBP) [44-8]. A clear but a more recent split was observed between T. t. islandicus and T. t. borealis 12 KYBP [28-4]. © 2016 Nordic Society Oikos. Source


Hallgrimsson G.T.,University of Iceland | Hallgrimsson G.T.,Reykjanes Environmental Research Institute | Palsson S.,University of Iceland | Summers R.W.,Lismore | Benediktsson G.O.,Duggugeri 1
Bird Study | Year: 2011

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. © 2011 British Trust for Ornithology. Source


Barisas D.A.G.,University of Iceland | Amouret J.,University of Iceland | Hallgrimsson G.T.,University of Iceland | Summers R.W.,Lismore | Palsson S.,University of Iceland
Zoological Journal of the Linnean Society | Year: 2015

The Icelandic Purple Sandpiper Calidris maritima littoralis (C.L. Brehm, 1831) represents one member of a poorly understood subspecies complex. Currently, differences in size define two other subspecies: Calidris maritima belcheriEngelmoer & Roselaar, 1998, which breeds in north-eastern Canada along the Hudson Bay and James Bay, and Calidris maritima maritima (Brunnich, 1764), which breeds along the Arctic coasts elsewhere in northern Canada, Greenland, Svalbard, Scotland, and Fennoscandia, to northern central Siberia. There are large size differences amongst populations of C.m. maritima, however. As an Arctic/Alpine breeding bird, C.m.littoralis could provide an interesting perspective on the evolutionary changes following a northwards expansion of a species after glacial retreat. Considering the extent of the ice sheet in the northern hemisphere during the last glaciation, and the short period of time since it ended, the correct attribution of subspecies status for C.m. maritima may reflect either rapid diversification from a single population or ancestral splits of distinct evolutionary lineages that survived in isolation at southern latitudes. We applied morphometric subspecies criteria, diagnosability by Amadon's rule, and genetic analysis of five nuclear introns, and the mitochondrial DNA markers cytochrome oxidasec subunitI (COI) and NADH dehydrogenase subunit2 (ND2), to geographically separate breeding populations in order to examine the subspecies status of the Icelandic population. The results do not provide support for the subspecies status of the Icelandic population because the nominate and Icelandic subspecies fail to uphold Amadon's rule, and genetic analyses indicate that the study populations derive from a single shared refugium. © 2015 The Linnean Society of London. Source


Summers R.W.,Lismore | Underhill L.G.,University of Cape Town | Waltner M.,5 Montagu Way | Swann R.L.,14 St Vincent Road
Ibis | Year: 2010

We describe the migration, biometrics and moult of Red Knot Calidris canutus canutus in southern Africa and compare them with the biometrics and moult of Calidris canutus islandica in northern Europe to examine possible adaptations to different environments during the non-breeding season. Northward and southward migration of C. c. canutus took place along the coast of Western Europe and there was one recovery in West Africa (Mauritania), suggesting a coastal migration round West Africa rather than migration across the Sahara, as recorded in other waders. Adult Knots in South Africa had no additional fattening in November-January (fat index of 7%), in contrast to C. c. islandica wintering in Britain. This is consistent with the theory that extra fat is required only where food shortages are likely. The bills of canutus were longer than those of islandica but their wings were shorter, confirming the sub-specific assignments and origin of this population. The average duration of primary moult in South Africa was 95 days, shorter than that of other Arctic-breeding waders that moult in South Africa, but longer than of islandica moulting in Scotland (77 days). Mean starting and completion dates were 20 July and 5 October for islandica and 25 October and 28 January for canutus. The timing and duration of primary moult for these two subspecies suggest that waders need to complete moult before the northern winter when food supplies are limited, whilst waders in benign climates face no such pressures. First-year canutus either retained old primaries for much of their first year or had a partial moult of inner or other primaries. Adults departed on northward migration in mid-April, having attained a mean departure mass of c. 190 g (maximum 232 g). The mean fat index at this time was 24% (maximum 29%) and the fat-free flight muscle mass increased. The predicted flight range of 4000 km falls short of the distance to the first likely refuelling site in West Africa, suggesting that birds rely on assistance from favourable winds. © 2009 British Ornithologists' Union. Source


Summers R.W.,Lismore | Foster S.,Scottish Natural Heritage | Swann B.,14 St Vincent Road | Etheridge B.,Beechgrove
Estuarine, Coastal and Shelf Science | Year: 2012

Declines in numbers by several wader species in Britain have been linked to climate change, but the mechanism for the declines has rarely been explored. Britain lies at the northern end of the East Atlantic Flyway, and supports 1.3 million out of the Flyway's 8.5 million coastal waders (Charadrii) in winter and the Purple Sandpiper is one of the species whose numbers have declined. Here, we examine the dynamics of the decline as observed in the Moray Firth, northeast Scotland, investigating whether the decline was due to poorer apparent survival (return rate) or poorer recruitment of young birds. The maximum number in the Moray Firth declined from 860 in 1987/88 to 236 in 2006/07, with some increase during winters 2007/08 and 2008/09. At the three main high-tide roosts (Balintore, Lossiemouth and Buckie) the maximum combined number declined from 574 to 90. Changes in survival and recruitment (percentage of first-year birds) were examined at these roosts from captured samples, which were ringed and recaptured. There were no significant changes between winters in survival rates, nor were there differences between the survival rates of age groups (first-year and adult) or bill size groups, which represented birds of different sex and breeding origin. Annual survival estimates for the three roosts ranged from 72 to 77%. The percentage of first-year birds varied among roosts and years; the lowest values were during the late 1980s/early 1990s and early 2000s. A free-running population model incorporating varying percentages of first-year birds and constant mortality for each roost provided a plausible explanation for the decline. Although modelled numbers followed the observed pattern, a discrepancy in one year was carried forward in subsequent years, so that the fit with the observed numbers was parallel rather than similar. However, it seems that the decline in numbers was largely due to poorer recruitment. We discuss whether breeding success had declined, whether the population had responded to changes in the local sewage treatment systems, which could affect invertebrate food for Purple Sandpipers, or whether fewer birds chose to winter in Scotland. The Moray Firth population is derived from Norway and possibly Canada, and there is evidence that the Norwegian population was disproportionately affected. The reason for poor recruitment requires further study, and other wader species require examination to test if poor recruitment is a common feature of decline in numbers. © 2012 Elsevier Ltd. Source

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