23rd August

With a very humid Atlantic airflow firmly established low cloud blanketed the island overnight and persisted on and off throughout the day; inevitably, migrant interest diminished and, apart from the likes of a very belated first Redstart of the season, included little of note. In one of the brief clearances the first Sooty Shearwater of the autumn also passed by on the sea. The humidity and gentle southwesterly breeze combined to offer better prospects on the moth front and the rewards included two first records for the island - a Dusky Hook-tip and a Hawthorn Moth.  

Portland Bill
Migrants Wheatear 25, Willow Warbler 25, Tree Pipit 6, Yellow Wagtail 5, Pied Flycatcher 3, Blackcap 2, Ringed Plover 1, Dunlin 1, Whimbrel 1, Redstart 1, Spotted Flycatcher 1.
Sea passage Balearic Shearwater 8w 1e, Sooty Shearwater 1w, Great Skua 1e, Arctic Skua 1w, Common Gull 1w; also Bluefin Tuna 1.

Pied Flycatcher 1.

Knot 1.

Selected immigrants Obs: Rush Veneer 91, Rusty-dot Pearl 43, Dark Sword Grass 3, Diamond-back 2, Marbled Piercer Cydia splendana 2, Hawthorn Moth  Scythropia crataegella 1, Dusky Hook-tip 1, Convolvulus Hawkmoth 2, Hummingbird Hawkmoth 1, Pearly Underwing 1, Delicate 1, Bordered Straw 1, Scarce Bordered Straw 1, Silver Y 1.

A nice little Tree Pipit vs Meadow Pipit comparison - hopefully more on this in the next few days © Nick Bond (Tree Pipit) and Martin Cade (Meadow Pipit):

Once a quality rare immigrant, Dusky Hook-tip has increased in numbers in southeast England to the extent that it's now a breeding resident in places. In this context it's long been expected at Portland and the first duly put in an appearance at the Obs overnight; maybe surprisingly, this is seemingly also the first record for traditional 'old' - vc9 - Dorset (there's a record from Boscombe which is in administrative 'modern' Dorset but that's in vc11!).

Dusky Hook-tip's a pretty numerous moth just across the Channel in northern France where we've trapped plenty of them on several recent family holiday/mothing trips. These are four random examples photographed back at the end of July in Normandy; today's Portland specimen fell more or less in the middle of their variation - it lacked the lovely violet wash of some of the best specimens but wasn't as pale as the ones that most resembled Pebble Hook-tips...

...these two Pebble Hook-tips (also from Normandy) clearly show the much larger main discal spot on the forewing but also hint at there being a fair bit of variation in the prominence of the dark bar across the centre of the hindwing - although usually much more prominent on Dusky it was far weaker on some and, conversely, noticeably stronger than expected on some of the Pebbles © Martin Cade:

Having already had a 'two Portland moth ticks' night a few weeks back (Plumed Fan-foot and Small Scallop on 19th/20th July), astonishingly it happened again last night with this Hawthorn Moth also trapped at the Obs. Hawthorn Moth is one of those apparently fairly common and widespread species that's oddly rarely encountered in the Weymouth area and had hitherto never been recorded at all at Portland. However, it's fortunes might be changing locally since Paul Harris tells us that Phil Sterling's recently discovered it breeding at Radipole - perhaps the larval webs are something to look out for at Portland? © Martin Cade: