Sea and skuas but not much sun

In spring 2011 I was involved in a research expedition on board RRS James Cook off the northwest UK, investigating the impacts of commercial fishing on deep-water coral communities and associated fauna. This expedition was in partnership with JNCC and formed part of a research programme that I co-ordinate at the National Oceanography Centre in Southampton. Most of our work was undertaken in the Rockall Trough, Rockall Basin and Hatton Basin regions, between 150 and 550 km offshore. We were able to use cutting-edge Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs) to image the ocean floor hundreds of metres beneath us, providing fantastic images of these vulnerable ecosystems and the impacts of man's activities upon them. Background information and a blog of the cruise can be viewed here.

In between our primary scientific activities I had plenty of opportunities to record and photograph the marine wildlife around us, and this article summarises some of the most notable sightings.

Week One: 9th–15th May

The initial passage north through Sea of the Hebrides and The Minch on 10th May produced most of the commoner seabirds, including 140 Puffins, a few Great and Arctic Skuas, a pod of at least 10 Common Dolphins, and single Collared Dove and Willow Warbler on deck dodging the blustery showers. A brief port call in Ullapool produced a distant Great Northern Diver and a scatter of smart Black Guillemots in Loch Broom.

Common Dolphins accompanying the ship through The Minch (Russell Wynn).

On 11th May we were on transit to our work area over the Darwin Mounds, about 150 km NNW of Lewis. Timed hourly counts consistently produced 100–250 birds per hour, mostly Fulmars, Gannets and Kittiwakes with smaller numbers of Manx Shearwaters, Great Skuas, Black-headed Gulls, Lesser Black-backed Gulls, Arctic Terns and Puffins.

Adult Gannet (Russell Wynn).

Great Skua (Russell Wynn).

The first few days of work (12th–15th May) in the Darwin Mounds area at ~1,000m water depth produced a northwards passage of 24 Pomarine Skuas and smaller numbers of Great and Arctic Skuas. Most of the Pomarine Skuas were in ones and twos, with no sign of the large flocks seen passing the Outer Hebrides at the same time (presumably because of the lack of a topographic focussing effect). Smaller numbers of large gulls and Kittiwakes were also attracted to the vessel at this time, which in turn attracted regular close fly-bys from the photogenic Pomarine Skuas.

Pomarine Skua (Russell Wynn).

Pomarine Skua (Russell Wynn).

There was also a steady northwards passage of Arctic Terns and Puffins, with occasional Manx Shearwaters and a single migrant Shag. Hundreds of Fulmars aggregated around the ship each day, including occasional intermediate- and dark-morph birds.

Curious Fulmars investigating Autosub6000, our Autonomous Underwater Vehicle (Russell Wynn).

Intermediate-morph Fulmar and Autosub6000 (Russell Wynn).

Migrant land birds on deck included Swallow, Wheatear, Meadow Pipit, White Wagtail and Blackcap, while a Turnstone circled the ship for a couple of minutes one morning. The two Wheatears, a male and a female, arrived independently on deck on 12th May, and both looked exhausted and in poor condition. Later that day they were seen huddled close together on top of a container, but the next morning the female was picked up dead. The wing length of 101 mm confirmed that this was a Greenland-race bird, and the lack of body fat indicated she had probably been over the water for some time.

Close-up of male Greenland Wheatear on deck (Russell Wynn).

Later in the day the male and female were seen huddled together for warmth (Russell Wynn).

Sadly the next morning the female was found dead (Russell Wynn).

The first offshore sighting of cetaceans came on 15th May, with a mixed group of about 100 Long-finned Pilot Whales and White-sided Dolphins around the ship for most of the day.

Part of a large pod of Pilot Whales (Russell Wynn).

Spy-hopping juvenile Pilot Whale checking out the ship (Russell Wynn).

White-sided Dolphins and Fulmar (Russell Wynn).

Week Two: 16th–22nd May

Work continued in the Darwin Mounds area from the 16th–17th May. The highlight was two Iceland Gulls (a first-summer and a third-summer), mixed in with a large flock of Fulmars and gulls around the ship on 17th May. Two adult Long-tailed Skuas passed northwards overhead while the Iceland Gulls were being photographed, and a blue Fulmar was picked out from the flock.

First-summer Iceland Gull (Russell Wynn).

Third-summer Iceland Gull with Fulmar (Russell Wynn).

Adult Long-tailed Skua (Russell Wynn).

Blue Fulmar (Russell Wynn).

Pomarine Skuas also continued moving north, with ten seen including one dark-phase bird. Also of note were three Leach's Storm Petrels, one European Storm Petrel, at least 40 Puffins, and small numbers of Manx Shearwater, Great Skua, Arctic Skua and Arctic Tern. The only land bird migrants were Purple Sandpiper (which was later found dead) and White Wagtail, while a distant view of at least five Pilot Whales on 16th May could have related to some of the animals seen the previous day.

Purple Sandpiper: this exhausted bird drowned when flushed off deck and was later seen being pecked at in the water by hungry Fulmars (Russell Wynn).

Bad weather on 18th May saw the ship retreating back to The Minch, where another Pomarine Skua, two Red-throated Divers, a Swallow and a pod of 5–10 Common Dolphins were seen. On 21st May the wind eased and the ship headed back out to the Darwin Mounds, with the passage north producing four Long-tailed Skuas and one Pomarine Skua heading north, as well as a European Storm Petrel and a total of 11 Whimbrel over.

On the shelf the density of birds was reasonably consistent (130–250 birds per hour) but it rapidly increased in deep water on the continental slope, with many hundreds of Fulmars, Gannets, Kittiwakes and other common seabirds. A lone Swallow visited the main lab for a few hours and later left of its own accord, but was sadly found dead on deck the following day.

Exhausted Swallow roosting in the main lab; sadly this bird was found dead on the outer deck the following day (Russell Wynn).

Week Three: 23rd–29th May

Bad weather saw us heading westwards to the next work area, and on 25th May we started work in Hatton–Rockall Basin about 550 km west of Lewis. Seabird sightings on that day included a 2nd-summer Iceland Gull, two Pomarine Skuas (including one dark-phase bird) and four Arctic Terns. More surprising was a flock of three Great Northern Divers flying west, presumably heading for Greenland.

Second-summer Iceland Gull (Russel Wynn).

Pomarine Skua (Russell Wynn).

Pomarine Skua harassing Lesser Black-backed Gull (Russel Wynn).

The following day saw two first-summer Glaucous Gulls and a first-summer Iceland Gull accompanying the Lesser Black-backed Gulls around the ship. A pale adult Pomarine Skua and a Blue Fulmar were also seen amongst the commoner seabirds.

First-summer Glaucous Gull (Russell Wynn).

First-summer Glaucous Gull; a paler individual (Russell Wynn).

First-summer Iceland Gull (Russell Wynn).

The only land bird migrants were two Common Redpolls on board on 27th May. Their size and plumage indicated that they were of one of the northwest races, presumably en route to Iceland or Greenland.

Common Redpoll, presumably heading for Iceland or Greenland (Russell Wynn).

Further stormy weather on 28th May saw us relocating to the eastern part of Rockall Bank, about 330 km west of Barra. The following day an adult Sabine's Gull was attracted to food discards behind the ship.

Adult Sabine's Gull (Russell Wynn).

Week Four: 30th May–5th June

The ship continued to operate in the East Rockall Bank area on 30th–31st May, despite the ongoing bad weather. Another one or two adult Sabine's were seen, together with an unseasonable moulting Sooty Shearwater and a Leach's Storm Petrel. A brief visit from a Common Redpoll on 30th presumably related to a new bird, as it is unlikely that the birds from 27th could have survived on board without food for three days.

Sooty Shearwater; note the obvious wing moult (Russell Wynn).

Sightings made on North Rockall Bank between 1st and 5th June included a pale adult Pomarine Skua (2nd), an adult Long-tailed Skua moving north (5th), and small numbers of European Storm Petrels, Manx Shearwaters, Great Skuas, Arctic Skuas, Arctic Terns, Guillemots and Puffins. A Wheatear briefly visited the ship (5th), on which date two pods of Pilot Whales totalling 25+ animals and an associated pod of at least 20 unidentified dolphins were seen.

Week Five: 6th–12th June

A pale adult Pomarine Skua was seen on 6th June on North Rockall Bank, and a small arrival of late migrant land birds included Wheatear, Meadow Pipit and two Swallows. A further spell of bad weather on 7th–8th June saw the ship relocate back to the Darwin Mounds work area. On 9th June two Fin Whales spent an hour in the vicinity of the ship, and a Dunlin flew over.

Fin Whale blowing (Russell Wynn).

Fin Whale on a pre-dive roll, showing the falcate dorsal fin (Russell Wynn).

The following day (10th June) the ship was again visited by an inquisitive pod of Pilot Whales, this time numbering at least 20 and including several calves. An intrepid Collared Dove on deck in the morning remained on board as we began the passage back to port, and in the evening it was joined by another bird with both preening on the after deck as the ship rounded the Butt of Lewis.

Pilot Whales; note the small calf (Russell Wynn).

Pilot Whales; close enough to hear the blow! (Russell Wynn).

Collared Dove (Russell Wynn).

The final day of passage (11th June) through the North Channel in calm seas produced good numbers of commoner seabirds and a fly-over Whimbrel and Curlew.

Overall, the expedition was a great success despite the frequent periods of inclement weather; we barely encountered conditions below a sea state four during the entire cruise and we had a couple of uncomfortable days with Force 10 winds! The most notable marine wildlife sightings were probably the photogenic Pomarine Skuas, supported by unseasonable Sooty Shearwater and Sabine's Gull and a range of immature white-winged gulls; the excellent close views of Long-finned Pilot Whales were also memorable. However, the most enduring image was seeing the two Greenland Wheatears huddled together as they slowly faded away on the deck, representatives of what must be a very large number of these birds that fail to negotiate the perilous Atlantic crossing to their breeding grounds.