Seawatching @ Coliemore: Seawatch

Weather: A very mild morning with light southerly winds. Overcast with moderate visibility decreasing from about 5km to 1km (partial sea fog), but improving again later on. Some light rain around 7am (clearing quickly). Total seawatch time of 3.5 hours.

Count totals:

Fulmar: 21 north & 9 south
Manx Shearwater: 4,010 north & 146 south
Common Scoter: 15 north & 55 south
Arctic Skua: 1 dark-phase flew north
Kittiwake: 97 north & 40 south
Puffin: 1 north & 2 south
Black Guillemot: 2 north & 1 south
Razorbill/Guillemot: 1,250 north & 38 south
Guillemot: 1 south
Razorbill: 3 north & 4 south
Not counted: Common Gull, Sandwich Tern

On the islands:

Maiden Rock: 19 Cormorant, 2 Shag, 3 Kittiwake, 1 Oystercatcher, 38 Common and Arctic Terns
Clare Rock: 8 Cormorant, 2 Shag, 2 Great BB Gull, 3 Common/Arctic Tern
Lamb: 9 Cormorant, 1 Shag, 2 Oystercatcher, Herring Gull: 18 adults and at least 9 chicks, 4 Great BB Gull, 1 Arctic Tern, Hooded Crow
Dalkey Island: 3 Cormorant, 8 Shelduck, 5 Oystercatcher, 32 Herring Gull, Great BB Gull: 8 adults and 2 chicks, 1 Rock Pipit, Jackdaw, Starling
Coliemore: Black Guillemot, House Martin, Swallow, Rock Pipit, Robin, Blackbird, 1 Coal Tit, 3 Raven flying south, Chaffinch, Linnet

A long early morning seawatch with a few interesting sightings, best of which was a dark-phase Arctic Skua heading north as well as a couple of Puffins. Also one new species for the year list in the form of a Coal Tit heard singing from the gardens behind Coliemore during the seawatch.

Of the almost 6,000 birds counted passing by offshore, the majority were Manx Shearwaters (4,156) followed by Razorbill/Guillemots (1,288) and 100+ each of Kittiwake and Gannet. The Manxies reached a peak passage of 868 birds/15 minutes at around 07:30. However, the total numbers alone only tell half the story:

Manx Shearwater passage off Coliemore - north in blue and south in orange

After the peak, the numbers of Manxies dropped off, though it appears that poor visibility between 08:00 and 08:30 may be partly responsible for the trough at that time. The peak about half an hour later correlates with improving visibility, but numbers of Manx Shearwaters passing by dropped off rapidly after that. Southward passage throughout was barely noticeable by comparison.

The nearest main breeding colonies of Manx Shearwater are located on the islands off Pembrokeshire in south-west Wales. As the Manx Shearwater flies, this would be about 170 kilometers:

Assuming the majority of the birds left colony in the hour before sunrise (5am @ Fishguard) and with an average flight speed of 55-60km/hr, this would leave the majority of Manx Shearwaters passing Coliemore between 7 and 8am ending up at the main feeding grounds in Dundalk Bay about an hour later.

Auk passage followed a similar trend initially, but became a bit more confused later on:

Auk passage off Coliemore. North in blue, south in orange

Kittiwake and Gannet was very confused initially, with seemingly random peaks and troughs, but along with Manx Shearwater and the auks, passage dropped off quite sharply after 9am: