Study species

Tawny owl (Strix aluco)

The tawny owl is a common terrestrial bird of prey in Europe, typically inhabiting the interface between urban areas and natural habitats. It is territorial throughout the year, and pairs usually show life-long site fidelity (Millon et al., 2010). Central Norway is inhabited by the northernmost extension of its European population (Solonen, 2005; Sunde et al., 2001), and it has experienced a strong increase since the early 1980s(Sunde et al., 2001). Since 1986, consistent annual sampling of female tail feathers and addled eggs have been conducted including taking records of reproductive (brood and clutch size, egg size, and fledgling success), female fitness (morphometric measurements) and survival data. In addition, some dietary, i.e. prey abundance, and toxicological data (POPs, PFAS and metal concentrations) have been analyzed for a subset of the sampled individuals.

Common goldeneye (Bucephala clangula)

The common goldeneye is a medium-sized diving duck that breeds all over Eurasia and North-America, mainly in association with coniferous forests and freshwater habitats. In Norway, large numbers of breeding pairs can be found from Vest-Agder in south through all the eastern counties up to Trøndelag, and sporadically further north. Similar sampling efforts as described for the tawny owl have been conducted on the common goldeneye since 1999.

References
Millon, A., Petty, S.J., Lambin, X., 2010. Pulsed resources affect the timing of first breeding and lifetime reproductive success of tawny owls. J Anim Ecol 79:426-435
Solonen, T., 2005. Breeding of the Tawny Owl Strix aluco in Finland: responses of a southern colonist to the highly variable environment of the North. Ornis Fennica, 82:97-106
Sunde, P., Overskaug, K., Bolstad, J.P., Oien, I.J., 2001. Living at the limit: Ecology and behaviour of Tawny Owls Strix aluco in a northern edge population in central Norway. Ardea, 89:495-508