Thomas Holm Carlsen

Research Scientist

(+47) 934 99 413
thomas.holm.carlsen@nibio.no

Place
Tjøtta

Visiting address
Parkveien, 8861 Tjøtta

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Abstract

I 2014 ble 22 øyer i Breiðaförður, Vest-Island, vegetasjonskartlagt. Hensikten med kartlegginga var å registrere vegetasjonstyper, artssammensetning og gjengroingsstatus på øyer som har ulik størrelse, topografi, geologisk sammensetning, brukshistorie, samt ulikt fugleliv. De fleste øyer i denne undersøkelsen har ikke blitt kartlagt før, slik at prosjektet har bidratt til ny kunnskap om deler av dette unike øyriket i Breiðafjörður. In 2014, 22 islands in Breiðafjörður, West-Iceland were mapped for vegetation. The purpose to this study was to map vegetation types, distribution of plant species and overgrowing status in islands which differs in size, topography, bedrock composition, land use and birdlife activity. Most of the islands in this study have not been mapped before. This project provides new knowledge to part of the unique archipelago of Breiðafjörður.

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Abstract

Insulation is an essential component of nest structure that helps provide incubation requirements for birds. Many species of waterfowl breed in high latitudes where rapid heat loss can necessitate a high energetic input from parents and use down feathers to line their nests. Common eider Somateria mollissima nest down has exceptional insulating properties but the microstructural mechanisms behind the feather properties have not been thoroughly examined. Here, we hypothesized that insulating properties of nest down are correlated to down feather (plumule) microstructure. We tested the thermal efficiency (fill power) and cohesion of plumules from nests of two Icelandic colonies of wild common eiders and compared them to properties of plumules of wild greylag goose Anser anser. We then used electron microscopy to examine the morphological basis of feather insulating properties. We found that greylag goose down has higher fill power (i.e. traps more air) but much lower cohesion (i.e. less prone to stick together) compared to common eider down. ese differences were related to interspecific variation in feather microstructure. Down cohesion increased with the number of barbule microstructures (prongs) that create strong points of contact among feathers. Eider down feathers also had longer barbules than greylag goose down feathers, likely increasing their air-trapping capacity. Feather properties of these two species might reflect the demands of their contrasting evolutionary history. In greylag goose, a temperate, terrestrial species, plumule microstructure may optimize heat trapping. In common eiders, a diving duck that nests in arctic and subarctic waters, plumule structure may have evolved to maximize cohesion over thermal insulation, which would both reduce buoyancy during their foraging dives and enable nest down to withstand strong arctic winds.

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Abstract

Denne rapporten oppsummerer resultatene fra er treårig forskningsprosjekt vedrørende den unike ærfuglduna. Dunprøver fra 19 kolonier i fire ulike land ble renset på en standardisert måte og ulike parametere ble målt og testet som fill power, sammenhengskraft og resiliens. Det ble dokumentert variasjon i ulike parametere både mellom kolonier og mellom individer. Dette er den største og mest dyptgående studien av ærfugldun som har blitt utført. This report sums up the result from a three-year lasting study regarding the unique eider down. Eider down from 19 colonies was collected and we measured various parameters such as fill power,cohesion and resilience. Overall, this is the largest and most in-depth study of eider down ever performed.