Ross's Gulls
in the Arctic
pack-ice
Hans Meltofte, Carl Edelstam,
Gunnar Granstrom, Johan Hammar
and Christian Hjort
Little studied since the journeys of the 19th-century polar
explorers, Ross's Gulls were seen in unprecedented
numbers during the Swedish 'Ymer-80' expedition
through the Arctic Ocean
D
uring the Arctic research cruise with the Swedish ice-breaker HMS
Ymer (figs. 1 & 2), continuous watch for birds and mammals was
carried out from the top deck, 24m above sea level. Numbers observed, as
well as such data as age, behaviour, aggregation and direction and height of
flight, were recorded in 10-minute periods on data sheets. All the observations made during the expedition will be analysed later in relation to food,
ice conditions and so on. This paper is a preliminary report on the observations of Ross's Gulls Rhodostethia rosea.
The first leg, from 3rd July to 6th August, traversed the sea between and
north of Svalbard and Franz Josef Land. There, a t,otal of 1,356 Ross's Gulls
was recorded in the pack-ice (fig. 2). Since some were recorded in several
consecutive 10-minute periods, these sightings represented a minimum of
670 individuals. The largest concentrations were found north of Nordaustlandet and at the farthest north of Franz Josef Land, and there were also
two flocks, of 50 and 20 respectively, south of Victoria Island.
The first Ross's Gulls were observed on 7th July, east of Nordaustlandet,
and during 9th to 11 th July a total of at least 276 individuals was seen north
of this island. Of these, 189 migrated in westerly directions in rather loose
groups mainly of two to 16 individuals flying a few metres above the sea ice.
Some of the flocks flew around the ship a few times or alighted on the ice,
but most just passed by. In this period, many of the birds, especially those
in migrating flocks, appeared to be paired.
316
[Brit. Buds 74: 316-320, August 198! ]
Ross's Gulls in the Arctic pack-ice
317
Fig. 1. The route of HMS Ymer (dashed line) and observations of Ross's Gulls Rhodoskthia rosea
during second leg, 9th August to 23rd September 1980. Zigzag line shows edge of dense pack-ice.
Fringes and isolated fields of pack-ice were found outside compact edge. Area covered by fig. 2 is
framed. In spite of several passages of east Greenland ice south of 77°N, no Ross's Gulls
have been observed there
Of 492 aged individuals, 12% were 2nd-calendar-year birds, readily
distinguished by the remaining juvenile wing pattern and single darkedged tail feathers. All but a few of these one-year-old birds had a dark neck
collar, bright red legs, and more or less rosy underparts. The rosy tinge
varied greatly among the adults too, but we were surprised by the intensity
of this colour. Throughout the period, several individuals were in full
primary moult. Only a few were seen near Nordaustlandet, when we passed
again during the last days of July, when more open water occurred, although
much heavy pack-ice was still present.
318
Ross's Gulls in the Arctic pack-ice
During the second leg, from 9th August to 23rd September, 31 records of
at least 20 individual Ross's Gulls were recorded between 15th and 19th
August, north of Nordaustlandet, most of them close to 82°N (fig. 1). A total
of 165 records involving at least 116 individuals was observed in the period
from 23rd August to 10th September in the east Greenland ice between
Svalbard and north Greenland. Ross's Gulls were encountered scattered
nearly all over the pack-ice, but most were seen in the outermost parts of the
ice, in which, however, most time also was spent watching during this time
of the cruise.
During the last part of the expedition, again working in the pack-ice
north of Svalbard and Franz Josef Land, Ross's Gulls still occurred in
numbers north of Nordaustlandet, whereas fewer were seen farther east
(fig. 1). A total of 482 records of a minimum of 116 individuals was seen
there during 10th-19th September, most of them between 81° and 82°N. Of
these, 97 migrated in easterly or southeasterly directions in groups of up to
13 individuals.
Due to advanced moult, only few Ross's Gulls seen on the second leg
could be recognised as immatures, and none after 25th August. At this time,
most were in winter plumage, with less of a rosy tinge and no or only a slight
collar. Heavy primary moult was recorded until 15th August. No juveniles
were seen.
Ross's Gulls were apparently less attracted to the ship than were the
other gull species. They were often seen flying over the ice, occasionally
taking food from the water surface of channels (leads) in the ice, either by
swooping and snatching in flight, or by alighting on the ice or water.
Sometimes they plunge-dived like Kittiwakes Rissa tridactyla. When following the boat, they usually searched the broken ice farther behind the
ship than the other gulls. When the ship stopped, they caught up with it
after some time and gathered on the ice together with Kittiwakes and Ivory
Gulls Pagophila eburnea, or simply moved on and left our company. The
larger flocks encountered south of Victoria Island on 3rd August were
flushed by the ship from ice-floes.
Most ice-floes between Svalbard and Franz Josef Land were 1-2 m thick.
Farther north, the ice was heavier, and the east Greenland ice especially
was often several metres thick. Ridges of pack-ice were found everywhere.
New ice regularly formed on pools on the ice-floes throughout the summer,
and, from late August onwards, 10-20 cm of new ice formed on leads and
' many other open-water areas.
Discussion
Little is known about the life of Ross's Gull, especially outside the breeding
season. The only large breeding sites known are in northeastern Siberia,
from the Khatanga river to the Kolyma delta region (Buturlin 1906,
Zhyrnov et al. 1978), but single breeding records are known in Greenland,
on Svalbard and in the Canadian Arctic (L^venskiold 1964, MacDonald
1978, Kampp & Kristensen 1980, Hjor11980); those by MacDonald and by
Hjort were on barren High Arctic coasts.
Ross's Gulls have earlier been found in the pack-ice north of Svalbard
Ross's Gulls in the Arctic pack-ice
319
Fig. 2. Mean numbers of Ross's Gulls Rhodoskthm rosea observed per 10-minute period within
'squares' of 1° lat. X 5° long. (cf. Brown et al. 1975) during 5thJuly to 4th August 1980. Ten to 193
10-minute periods were spent within each square. Navigation route is dashed; squares not
covered are hatched. Pack-ice occurred everywhere inside area, but south of 80°N larger open
water areas often formed.
and Franz Josef Land. Parry & Ross (Parry 1828), Nansen (Collet &
Nansen 1900), and Andree (Lonnberg 1931) recorded several around 82°N
in July and August 1827, 1895 and 1897, respectively; the largest concentrations were seen by Nansen northeast of Franz Josef Land (see map in
L^venskiold 1963). The reason why none has been reported since then may
be that few zoologists have entered the heavy pack-ice since the fight for the
North Pole during the 19th century.
Apparently, most Ross's Gulls in July and August occurred in the heavy
pack-ice in the northern and northeastern areas visited. Very few were seen
over open-water leads or wider spaces (polynias), and only a few just
outside the limit of the pack-ice. The pack-ice areas between Svalbard and
Franz Josef Land especially were extremely productive, the underside of
the ice often being completely covered by algae, whereas the east Greenland
ice was obviously less productive (cf. Divoky 1976).
No extreme weather conditions prevailed in 1980, and the sea-ice conditions showed no extreme patterns. Bad visibility may have biased the
observations in some areas, not so much because of our inability to see the
birds, but more because of their inability to see the ship and thus be
attracted by it. During good conditions, we covered efficiently a range of
500-1,000 m on either side of the ship, but the gulls were probably often
attracted by Ymer, and often followed the ship for some time, especially
when in dense ice. Large numbers of food organisms were exposed from the
underside of the broken ice.
320
Ross's Gulls in the Arctic pack-ice
Other bird species were seen in large numbers, but they were even more
strongly attracted by the ship, and it is likely that Ross's Gull was one of the
most numerous species in the pack-ice. In certain areas, they could be
found simply by searching the horizon with binoculars.
The Ross's Gulls in breeding plumage migrating west at Nordaustlandet
in early and mid July—often in pairs—can not have been breeding birds,
which, irrespective of whether they belong to a Low or High Arctic population, should have been incubating or attending young at this time. They can
either have been 3rd-calendar-year immatures or breeders which had
abstained from breeding (e.g. due to flooding of the Siberian breeding sites,
see Dementiev & Gladkov 1969) or individuals which had failed and left the
breeding areas early. The many paired birds seen in July might support the
two latter assumptions.
The large numbers observed, together with the westerly migration in
July and the easterly migration observed in September, suggest that the
highly productive polar ice bordering the Barents and Greenland Seas
serves as an important feeding and moulting area for non-breeding Ross's
Gulls during the summer.
Acknowledgments
Besides all those who have been involved with the organisation of the 'Ymer-80* expedition, we
should like to thank Jon Fjeldsa and Kaj Kampp, who have critically read the manuscript.
Summary
About 1,000 Ross's Gulls Rhodostethia rosea were seen during the Swedish 'Ymer-80' expedition
north of and between Greenland, Svalbard and Franz Josef Land duringjuly to September
1980.
References
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661-666.
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USSR: mammals and birds. Moscow.
Hans Meltofte, Mfllegade 23,3 tv, DK-2200 Copenhagen N, Denmark;
Carl Edelstam, Gunnar Granstrom,Johan Hammar and Christian Hjort,
Naturhistoriska Riksmuseet, S-104 05 Stockholm 50, Sweden