Great
Northern Diver - Islom
- Gavia
immer Svartnäbbad
Islom - Islom - Amerikanjääkuikka -
Plongeon imbrin
Adult Great Northern Diver heading north at Skogsøy, May 2016
Great
Northern Diver is a regular migrant in both spring and autumn
at
Skogsøy, and is one of the main "target" species for
seawatches at all times of year with the exception of the summer
months. It is the second commonest of the diver species on an annual
basis. Birds can be seen passing or on the sea during the winter
months; during the spring the vast majority are seen heading north with
only occasional individuals on the sea. Great Northern Diver
are at their most numerous during October and November when the
majority logged heading south. Usually only one or two are seen and
double figure day counts have yet to be experienced.
There
are some indications
that this species, in common with
White-billed Diver, is on the increase.
The
diagram below shows the
maximum counts per 3-day period using my
own sporadic and non-systematic counts. The blue line shows the number
of visits and the orange the number of days Great Northern Diver have
occured. The green line shows the maximum count per three
day
period.
Occurrence of Great Northern Diver at Skogsøy by week number
Note that this histogram also includes stationary birds, not just those
migrating
Numbers
of Great Northern
Diver at Skogsøy far exceed those
at
Utsira with day counts at Skogsøy exceeding seasonal counts
at Utsira (8 in an autumn is the best Utsira total).
For directly migrating birds Skogsøy would appear to be one
of the better localities in Europe.
Maximum:
9, 05 November 2005
Great Northern Diver with three Red-throated Diver, Skogsøy,
May 2018
Great
Northern Diver in flight, Skogsøy, October 2017
Great
Northern Diver in flight, Skogsøy, October 2017
Great
Northern Diver in flight, Skogsøy, October 2017
References Tveit,
B.O., Mobakken, G. og Bryne, O. 2004 Fugler
og fuglafolk
på
Utsira. Utsira Fuglestasjon
Ellis,P., Harvey, P.,Heubeck,M.,Okill, D., Osborn,
K.,Pennington,M.,Riddington, R. Birds
of Shetland. 2004.
