Scilly Sightings - highlights from 2021

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This report covers sightings made from short-range pelagic trips aboard MV Sapphire. The first trip was on 10 June and the last trip on 23 October. Scheduled Birder Special Pelagics ran Friday to Monday inclusive from late July through to early September, including the annual Oriole Birding weekend charter, and almost all were fully booked. Highlights of the year included a record year for Wilson’s Storm-petrel numbers and truly spectacular sightings of Fin Whales and Humpback Whales. Notable were feeding frenzies toward the end of the season involving thousands of Manx Shearwater, along with Great and Sooty Shearwaters, skuas, many hundreds of Short-beaked Common Dolphins, and the great whales. Great Shearwater and Cory’s Shearwater passage was rather light, a fair few Balearic Shearwaters were logged, and several Long-tailed Skuas and Sabine’s Gulls featured. Representation of other seabirds was fairly typical and once again close and prolonged views offered photographers unrivalled photographic opportunities. Please see the Isles of Scilly Bird Group Bird & Natural History Review 2021 for further details. (All photos taken 2021 by Joe Pender, unless otherwise stated.)


Wilson’s Storm-petrel Oceanites oceanicus

Birds were observed on the great majority of trips throughout the core season, July–August. The first record was on 19 June, the last record on 9 September, seen on 20 consecutive trips in August, and the total number seen from pelagic trips was a record 129+ birds. In June, singles were seen on 19 June, 24 June, and 28 June. In July, there was a long break until six birds were sighted on 30 July and 12+ birds on 31 July, marking the start of a superb run of records. In August, Wilson’s was logged on an impressive 20 days, spread evenly throughout the month, involving 106+ birds. Sightings of more than five birds was achieved on nine days as follows: six on 6 August, 10+ on 7 August, six on 8 August, nine on 9 August, a massive 20+ on 10 August, eight on 12 August, seven on 14 August, six on 15 August, and eight on 19 August. Thereafter, passage began to tail off. In September, singles were seen on 2 September and 9 September. (One was seen from the Scillonian ferry on 12 September.)





European Storm-petrel Hydrobates pelagicus

Recorded on all pelagic trips from 31 May to late September. At least six were at sea on 31 May. Less than 15 were reported on four pelagic trips in June, except for 35 on 10 June. Less than 15 were reported on seven pelagic trips in July, except for 100+ on 30 July. Pelagic season was in full swing in August and produced sightings on all 22 trips with higher numbers partly explained by windy conditions and young birds visiting the colony mid season. Counts of 50 or more were reported as follows: 50+ on 5 August, 6 August, and 9 August; 250+ on 10 August (highest count of the year), 80+ on 12 August, 50+ on 13 August, 140+ on 15 August (second highest count of the year), 60+ on 20 August, and 50+ on 24 August. Fewer pelagic trips in September were reflected in sightings on just seven days, including 50 on 2 September and a good count of 20 for the relatively late date 20 September. Birds were unusually hard to find in Scilly in October and pelagic trips found none.


Leach’s Storm-petrel Hydrobates leucorhoa

None seen from the pelagic trips, though one was logged from the Scillonian ferry on 28 September. Cory’s Shearwater Calonectris borealis 2021 was a year to forget for this largest of all shearwaters. A small passage of 19 birds from a pelagic trip on 5 August was the only double figure count. Four were observed from a pelagic trip on 7 August. Three were seen from a pelagic trip on 9 August and this was the last report of the year from Scilly.


Great Shearwater Ardenna gravis

Uncommon this year, involving 114 or so birds from pelagic trips, with at least 50 of these on one day, and recorded from 30 July to 13 October. Singles were noted on 30 and 31 July. Found on 15 days spread evenly across August, with most days involving from one to three birds, with just one double-figure count of ten on 9 August. One was seen on 12 September and from one to five birds on four days from 20–28 September, with the highest count of the year of over 50 on 22 September. Next month registered just a single bird on 13 October.





Sooty Shearwater Ardenna grisea

Sooty Shearwater is a familiar migrant in Scillonian waters June–October at least, generally in small numbers. In 2021, recorded from 28 June to 1 November. The pattern of sightings and numbers involved was quite typical of past years. Many of the following sightings were from pelagic trips. A single was seen on 28 June. Small numbers were reported next month with one on 12 July, two on 15 July, and singles on 19 July and 30 July. Recorded on 17 days in August, with a total of 126 birds, but just one to seven birds per day up to 22 August. Strong passage was noted 23–29 August with 30 on 23 August, and 25 on 28 and 29 August. Again, reported quite frequently throughout September, on ten days, involving 43 birds in total, with from one to five per day, except for 11 on 28 September. In October, small numbers were seen on 15 days totalling 55 birds, about half of which were from pelagic trips. There were no double figure counts. Two birds were observed from one of the last Scillonian crossings of the year on 1 November.


Manx Shearwater Puffinus puffinus

The status of Manx Shearwater in Scillonian waters seems to have changed quite dramatically from 2015 / 2016, with relatively very large numbers in recent times. Up until about 2015, a typical pelagic trip would log just a few birds on the outward steam and somewhat more on the inward stream if approaching the island at dusk. Will Wagstaff’s evening Shearwater Special trips for visitors did well to find 200 birds rafting offshore of Annet, where most of the Scilly population breeds. Compare these figures, then, to the ones for 2021 below, which are quite typical of recent years. The obvious explanation is that the massive population increase on Welsh breeding islands is spilling over to Scillonian waters, at least in the number of foraging birds. At the same time, the amount of bait fish like anchovies appears to have increased hugely, at least in autumn, evidenced by large numbers of Short-beaked Common Dolphin and more regular sightings of great whales. Observations to the south of St Mary’s found 200+ on 4 July, 100 on 5 July, and 100s on 10 July. Immature birds visit colonies mid breeding season, and we strongly suspect that this accounts for some of the very large counts in August. Regular three-figure counts were the norm. There were several four-figure counts, impressing pelagic trip goers, with about 2,500 on 7 August, 1,200 on 22 August, over 2,000 on 23 August, around 2,500 on 28 August, about 5,000 on 29 August, and about 10,000 on 30 August. The last two counts could easily have been double the number, but mobile rafts in every direction made counting exceedingly difficult. There were substantially fewer birds in Scillonian waters throughout September, though, with counts from 20 to 80 birds. Small numbers seen on October pelagic trips.


Balearic Shearwater Puffinus mauretanicus

A typical showing of this Critically Endangered shearwater. The regular autumn occurrence off southwest England masks the continuing worrying decline of the population due to a variety of issues in the Mediterranean. Nevertheless, birds were seen off Scilly from 12 July to 6 October. One was logged on 12 July with two on 19 July. Singles were seen on 7 August and 16 August, with six on 22 August and five on 23 August, marking a light passage through Scillonian waters. One was logged on 11 September with one on 2 October. The last record was on 6 October.


Atlantic Fulmar Fulmarus glacialis

A familiar sight during pelagic trips, often involving small groups of squabbling birds.


Great Skua Stercorarius skua

Summer was quiet, with singles on 24 June and 15 July, consistent with recent years, though the species has been regular in summer months in past years. Autumn records, however, involved regular sightings in low numbers from 2 August to the end of the season. Logged on 18 days in August, spread evenly across the month, involving ones and twos, with three on 14 August and 28 August, and four on 29 August. With the main pelagic season over, sightings were limited in September, again in ones and twos, with three on 6 September and four on 9 September. A few were seen from October pelagic trips.


Pomarine Skua Stercorarius pomarinus

Very surprisingly, not a single bird was logged at any location off Scilly in 2021.


Arctic Skua Stercorarius parasiticus

A typical showing this year. All records were in autumn, except one second-summer bird on 7 June. Passage commenced with singles on 15 August, 20 August, and 22 August. One was logged on 29 August. Somewhat surprising, just one bird was seen in September on 6 September. About eight were recorded in October with just a few after 9 October.


Long-tailed Skua Stercorarius longicaudus

Considered a rarity prior to the operation of short-range pelagic trips, but now considered uncommon to scarce, comprising mainly immature birds. Just two first-year birds seen in 2021, one on 13 July and one on 11 August.


Sabine’s Gull Xema sabini

A modest showing of eight birds from 10 June to 8 October. Summer records are scarce and this year just one first-summer individual was logged on 10 June. No further reports until autumn passage, with two birds on 9 August. A small run of records later in the month involved individuals on 22 August, 23 August, 24 August, and 28 August. Surprisingly, thereafter only one more bird was observed, on 8 October.





Little Gull Hydrocoloeus minutus

Extremely scarce off Scilly. Just two juveniles in 2021 on 2 September.


Grey Phalarope Phalaropus fulicarius

A quiet year with records of one on Aug 13, two on Aug 19, and one on Aug 27.


Humpback Whale Megaptera novaeangliae

One breaching on 9 August. Then, two astonishing encounters with at least two animals on 29 August and one animal on 30 August. Observed feeding for around an hour both days.





Fin Whale Balaenoptera physalus

As with Humpback, astonishing views with at least two 29 August and two on 30 August.





Common Minke Whale Balaenoptera acutorostrata

A fair run during the main pelagic season started with two on 15 July. Subsequently, singles were seen on 1 August, 19 August, and 23 August. Two were logged on 28 and 29 August.


Bottlenose Dolphin Tursiops truncatus

One frequented the harbour on and off in August and featured on numerous pelagic departures and returns.


Short-beaked Common Dolphin Delphinus delphis

Seen on just about every pelagic trip. High counts were 200+ on 15 July, 150+ on 19 July, 100+ on 7 August, about 250 on 28 August, and mega pods of 600+ on 29 and 30 August.


Harbour Porpoise Phocena phocena

Regularly seen between and around the islands, especially on departure and return of pelagic trips. Generally, exceptional to find them offshore.


Walrus Odobenus rosmarus

Frustratingly, the young male found on 17 June departed just before the start of the main pelagic season. Early season pelagic goers, though, had superb views as we steamed out of the harbour.





Atlantic Bluefin Tuna Thunnus thynnus

Several decent counts, with 50+ on 22 August, about 40 on 23 August, six on 28 August, and about 20 on 6 September. Very small numbers occasionally noted. Often accompanied by shearwaters.


Shark tagging

Mainly in August and September, many participants witnessed the ‘catch, tag and release’ of many Blue Sharks Prionace glauca and a handful of Porbeagle Sharks Lamna nasus. Data is compiled on board and sent to a university-based research program.


Other

Other fascinating sea creatures were seen, including Ocean Sunfish Mola mola, several fish species, various jellyfish, and bioluminescence on late evening return trips. Numerous common seabirds featured on all trips.