Gavia arctica (Linné 1758), Black-throated diver (Gaviidae)

Compiled by: Christof Herrmann, Henrik Skov & Wlodzimierz Meissner

1. Description of the Habitat/Autecology of the species

The Baltic Sea is mainly important during the non-breeding season, when birds from Fennoscandia and Russia visit the region during winter (October – January) and wing-feather moult (February-March). Most birds use sub-littoral sandy areas between 10 and 30 m water depth, where they feed chiefly on fish (Madsen, 1957).

2. Distribution, past and present

Non-breeding distribution in the Baltic Sea only surveyed once; in February-March 1992-93 (Durinck et al., 1994). The species range includes most of the the Baltic Sea, but with the main range beween Fehmarn and Gdansk. Main area of concentration is the Pommeranian Bay, yet total numbers not safely estimated due to difficulties with separation from G. stellata in the field.

3. Importance (Sub-regional, Baltic-wide, Global)

Estimated 5-10 % of the European winter population occur in the Baltic Sea, Pomeranian Bay probably holds more than 1% of the European winter population (Durinck et al., 1994)

4. Status of threat/decline

Large decline in European and Russian breeding populations since 1970’es (Ilicev, 1985; BirdLife International, 2004). Trends in the wintering and moulting populations in the Baltic Sea are generally not known, however numbers in Polish waters have been in decline since 1993 (HELCOM HABITAT, 2004; University of Gdansk, Pers. Comm.).

5. Threat/decline factors

By-catch in gill nets is believed to play a role for the current trend in Polish waters (University of Gdansk, Pers. Comm).

6. Options for improvements

Studies on the extent of by-catch in main non-breeding range. These should possibly be followed by implementation of regulations of gill net fisheries in key areas, especially within SPAs to meet requirements for a favourable conservation status of the species.

7. References

BirdLife International 2004. Birds in Europe. Population estimates, trends and conservation status. BirdLife Conservation series 12, Cambridge, UK. 374 pp.

Durinck, J., Skov, H. Jensen, F.P. & S. Pihl 1994. Important Marine Areas for Wintering Birds in the Baltic Sea. Report to the European Commission.

HELCOM HABITAT 2004. Development of Baltic Waterbird Monitoring Strategy, - Pilot Phase: evaluation of available data and conclusion on necessary follow-up activities. Report to HELCOM HABITAT 6/2004. 

Ilicev, V.B. 1985. Handbuch der Vögel der Sowjetunion, Vol. 1. Wittenberg Lutherstadt, Ziemsen.

Madsen, F.J. 1957. On the Food Habits of some fish-eating birds in Denmark. Dan. Rev. Game Biol. Vol. 3 part 2: 19-83.