Portland Bird Observatory and Field Centre

18th July

Another searingly hot day made bearable by the light south-easterly wind. Hirundine passage carried on today with 37 Sand Martin and 17 Swift. On the land highlights were 2 Great Spotted Woodpecker and a Yellow Wagtail. Slightly more interest in the sea with 4 Yellow-legged Gull, 20 Common Scoter, 3 Shelduck, 2 "Commic" Terns, a Redshank and a Curlew. Elsewhere 2 Yellow-legged Gull at Blacknor and 15 Mediterranean Gulls, a Sanderling and 4 Little Egrets at Ferrybridge.

Moth interest came in the form of numbers rather than quality, with fresh immigrants still poorly represented. What are likely now to be home-bred Diamond-back Moths continued to increase (including 151 at the Obs) but totals at the Obs of just 6 Silver Y and singles of European Corn-borer, Rusty-dot Pearl and Dark Sword Grass were typical of immigrant numbers/variety at all the regular trap sites.

Mediterranean Gull and Yellow-legged Gulls - Ferrybridge and Portland Bill, 18th July 2016 © Pete Saunders (Med Gull), Keith Pritchard (YLGull upper) and Martin Cade (YLGull lower)

...the Yellow-legged Gulls - both of which headed north past the Obs - were two of a minimum of six about the island during the course of the morning.

17th July

Shouldn't really complain but it was a bit too hot for meaningful fieldwork at times today. The bird of the day was a Serin that popped up twice during the morning at Blacknor. Early autumn passage remained at the bitsy level, with 75 Swallows, 20 Sand Martins, 4 Grey Herons and singles of Redshank, Yellow Wagtail and Blackcap through or on the deck at the Bill, where 59 Common Scoter, 16 Manx Shearwaters and a skua sp passed by on the sea. Elsewhere, 13 Mediterranean Gulls, 3 Sanderling, a Whimbrel and a Redshank were at Ferrybridge.

Although a few relatively regular strays featured in the moth-traps, 'proper' immigrants were still thin on the ground: Diamond-back Moths continued to increase, including 77 at the Obs, but none of the other routine species managed double figure totals.

Common Tern, Little Tern, Sparrowhawk, Whitethroat and Grey Seal - Ferrybridge, Southwell and Portland Bill, 16th/17th July 2016 © Pete Sanders (the terns), Debby Saunders (Sparrowhawk) and Ted Pressey (Whitethroat and Grey Seal)

Moth-wise, the pick of the day's sightings was a second Orange-tailed Clearwing in two days; this one, which again came to Robert Payne's pheromone lure, was discovered in the Obs Quarry:

...with two found in quick succession in widely separated parts of the island it's hard to believe the species isn't a well-established resident. As far as we can recollect, previous searches have been concentrated on the Penn's Weare area where Wayfaring Tree is extremely common; perhaps those attempts didn't coincide with the main flight period, or maybe the species prefers its Wayfaring Trees amongst flowery grassland rather than thick scrub (there are only isolated trees at both Inmosthay and the Obs Quarry, whereas they're mainly tightly packed amongst other scrub at Penn's Weare).

Finally, a nice Sulphur Pearl Sitochroa palealis from yesterday. Although most likely just a transient breeder, this species had until recently looked to be getting pretty well established on Portland; however, our trap totals at the Obs have declined sharply in the last couple of years so perhaps it's fizzling out once again?

16th July

The mothing was considerably more interesting than the birding on a lovely warm, sunny day with the chief highlight being the discovery of an Orange-tailed Clearwing - a new species for Portland - at Inmosthay Quarry. Overnight trapping had come up with few immigrants - 17 Diamond-back Moth, 2 Rusty-dot Pearl and a Dark Sword Grass made up the Obs total - but there were signs of some dispersal from the mainland, including 3 Cream-bordered Green, 2 Elephant Hawk-moth, a Wood Carpet and a Barred Red at the Obs. By day, single Clouded Yellows were at the Bill and Ferrybridge.

Bird interest consisted of little more than singles of Little Ringed Plover and Reed Warbler at the Bill and 5 Sanderling at Ferrybridge.

Orange-tailed Clearwing - Inmosthay Quarry, 16th July 2016 © Martin Cade

With the larval foodplant - Wayfaring Tree - so common in places we'd always thought it odd that this species was unrecorded from Portland, but repeated searches had drawn a blank so it seemed like the species really was absent. Thanks to Robert Payne and his pheromone lures there is now this fully confirmed record and it'll be interesting to see if some other off the beaten track spots like Inmosthay also harbour populations.

15th July

The last couple of day's migration momentum dissipated today, with Sand Martins not even getting into double figures and nothing much more than singles of Redshank and Reed Warbler on the land and 10 Common Scoter through on the sea to provide further interest at the Bill. Elsewhere there were 7 Sanderling and 3 Whimbrel at Ferrybridge.

Odds and ends by way of immigrants/wanderers making it into the moth-traps included a Barred Red at Sweethil and 21 Diamond-back Moth, 3 Rusty-dot Pearl, 3 Silver Y and singles of Rush Veneer, Dark Sword Grass and Slender Brindle at the Obs

Last night's petrel-luring session at the Bill was entertaining even if it was no more productive than others have been this summer. Although only four birds were trapped it was sufficiently clear and moonlit that these and several others were easily visible as they whizzed around after being attracted in - if you're only used to seeing Storm Petrels fluttering slowly through the waves on a seawatch then the sight of them zipping around erratically in the half-light way above net height comes as quite a revelation! We've probably remarked before on how as the season advances so the birds tend to get a good deal more vocal, and that proved to be the case last night. One individual was especially noisy, giving a host of churrs and other peculiar calls as it flew about before blundering into the net; once in the hand it still wouldn't shut up so we switched off the lure for a while and recorded it with the phone whilst it was being ringed:

14th July

A nice warm, sunny day afforded more opportunity for migrants to get going. At the Bill, 65 Sand Martins were logged but there was no coverage of West Cliffs so - like yesterday - the feeling was that this total was a considerable underestimate; small numbers of Swallows were also again mingled in. Three Whimbrel and singles of Dunlin, Yellow Wagtail, Chiffchaff and Reed Warbler also cropped up there, whilst 13 Sanderling, a Great Crested Grebe and a Redshank were at Ferrybridge. Seawatching at the Bill came up with 35 Common Scoter, 3 Manx Shearwaters, 3 Black-headed Gulls and an Oystercatcher.

Obs immigrant moth totals: 24 Diamond-back Moth and 3 Silver Y.

Great Crested Grebe, Emperor Dragonfly and Marbled White - Ferrybridge, Portland Bill and Verne LNR, 14th July 2016 © Debby Saunders (GCGrebe) and Ken Dolbear (Emperor & Marbled White)

Also, many thanks to John Dadds for an update on the latest situation with the Ferrybridge Little Terns: This year looks like yet again being a fantastic year for the little terns of Chesil Beach. Breeding pairs continue to rise with 38 this year up from 33 last year. Almost all the eggs hatched with the help of the continued use of sand patches. Food supply appears to be good with several pairs laying 3 eggs and plenty of food available to the chicks. Well over 20 pairs laid their eggs in the first week of nesting at the end of May and the vast majority of chicks have now fledged with, unlike the last two years, no predation from the West Weares kestrels. It must be a good vole year! There should now be over 50 fledglings (photo of one of them below) and there could well be over 60 by the end of the season. Darvic ringing has been very successful with 13 adults and over 30 chicks ringed. One of the photos on the PBO website a couple of days ago showed a bird which was ringed as a chick last year. If this bird bred then it is most unusual as it is believed that little terns normally don’t breed until 3 or 4 years old.

13th July

On a day when it looked like Portland had a series of near misses from hefty rain showers it was nice to see sure signs of passerine passage/dispersal getting going. Sand Martins (with a few Swallows mingled in) featured most conspicuously with 130 through at the Bill and 30 over Ferrybridge, whilst singles of Grey Heron, Great Spotted Woodpecker, Yellow Wagtail, Sedge Warbler, Blackcap and Willow Warbler were also new in at the Bill; elsewhere a Green Sandpiper headed over Blacknor and 23 Dunlin, 6 Sanderling, a Little Ringed Plover and a Curlew were at Ferrybridge. The sea came up with 33 Manx Shearwaters, 18 Common Scoter, 2 Sandwich Terns and an Arctic Skua through off the Bill.

Obs immigrant moth totals: 11 Diamond-back Moth, 2 Silver Y and singles of Rusty-dot Pearl, Dark Sword Grass and Delicate.

Gannets, Great Spotted Woodpecker, Little Ringed Plover and Grayling - Portland Bill, Ferrybridge and Tout Quarry, 12th July 2016 © Martin Cade (Gannets & GSWoodpecker), Pete Saunders (LRP) and Ken Dolbear (Grayling)

And also from Ken Dolbear, a nice little series of photos from recent days of grasshopper variation; a couple of Field Grasshoppers:

...and three Mottled Grasshoppers:

12th July

Although Sand Martins trickled through at the Bill - 23 made the log but there was feel that this was a poor reflection on true numbers - most of the day's interest again concerned seabirds and waders. Seawatches at the Bill came up with 35 Manx Shearwaters, 2 each of Common Scoter and Arctic Skua, and singles of Dunlin, Curlew, Pomarine Skua, Mediterranean Gull and Sandwich Tern, whilst wader variety at Ferrybridge included 29 Dunlin, 4 Sanderling, 3 Whimbrel, a Little Ringed Plover and a Common Sandpipier; a Yellow-legged Gull also loitered at Ferrybridge for a good part of the day.

Obs immigrant moth totals: singles of Diamond-back Moth, Rush Veneer, Rusty-dot Pearl, Dark Sword Grass and Silver Y.

Yellow-legged Gull and Whimbrels - Ferrybridge, 12th July 2016 © Pete Saunders

11th July

Having already delivered a Sooty Shearwater over the weekend the current spell of windy weather came up with the goods again today when a Long-tailed Skua headed through off Chesil Cove; an Arctic Skua also passed through there, whilst 13 Manx Shearwaters, 10 Common Scoter and a Sandwich Tern were logged at the Bill. The only other reports concerned returning waders, including 27 Dunlin and singles of Sanderling, Whimbrel and Common Sandpiper at Ferrybridge and another Common Sandpiper at the Portland Marina.

Singles of Diamond-back Moth, Rusty-dot Pearl and Silver Y were the only immigrants caught overnight in the Obs garden moth-traps.

Sandwich Tern, Little Tern and Sanderling - Ferrybridge, 11th July 2016 © Pete Saunders (the terns) and Debby Saunders (Sanderling)

10th July

Still very windy with drizzle and fog spoiling the best part of the morning before it eventually brightened up. A fair bit of coverage came up with few rewards at the Bill, where 41 Common Scoter and 13 Manx Shearwaters passed by on the sea and a Yellow Wagtail was again about on the land. The wader selection at Ferrybridge included 25 Dunlin.

Moth interest was also lacking, with 3 Rusty-dot Pearl and 2 Silver Y the only immigrants at the Obs.

9th July

Quite warm and muggy again today but with an at times really brisk south-westerly always a feature. The sea came up with the best of the quality at the Bill with an early Sooty Shearwater doing several laps around the tide race during the morning and the summer's first Yellow-legged Gull lingering offshore during the evening; 7 Manx Shearwaters, 6 Common Scoter and a Sandwich Tern also passed by there. Single figure totals of both Swift and Sand Martin headed south over the Bill, whilst an out-of-season Yellow Wagtail also showed up there. Two Arctic Skuas taking the short cut between Lyme Bay and Portland Harbour were of interest over Ferrybridge, where 12 Dunlin, 11 Mediterranean Gulls and a Redshank also made the list.

A lone Harbour Porpoise passed by off the Bill.

A True Lover's Knot was a wanderer of note in the Obs garden moth-traps but the 'proper' immigrant tally there consisted of just 4 Rusty-dot Pearl, 2 Silver Y and a Diamond-back Moth.

Yellow-legged Gull - Portland Bill, 9th July 2016 © Martin Cade

...juveniles like this are pretty striking, even at vast range off the Bill; how is it that it took us until a dozen or so years ago to notice them? - were we just too inept to identify them before that or did they genuinely not get here in this plumage before that time?

8th July

Despite the brisk wind it felt increasingly muggy today, with one spell when fog rolled in for a while at the Bill. Very little coverage was possible and the day's only reports were of 2 Common Scoter and a Manx Shearwater through off the Bill and 6 Dunlin and a Redshank at Ferrybridge.

Six Rusty-dot Pearl were the only immigrant moths caught overnight at the Obs.

7th July

It's beginning to get to the time when dreary skies and a bit of light rain might do us some favours, but they certainly didn't do the trick this morning when an overflying Grey Heron was the only obvious new arrival at the Bill. The sea was slightly more productive, with 31 Common Scoter, 3 Manx Shearwaters, 2 Sandwich Terns, a Whimbrel and a Great Skua through off the Bill and up to 20 Common Terns feeding offshore.

Another pretty paltry immigrant moth selection at the Obs comprised just 5 Rusty-dot Pearl, 3 Diamond-back Moth, a Rush Veneer and a Silver Y.

6th July

A nice calm, sunny day came up with a few more departing migrants at the Bill, where 50 Swifts and singles of Redshank, Curlew, Sand Martin and Grey Wagtail made up the on/overhead tally on the land and 34 Common Scoter, 4 Sandwich Terns, 3 Manx Shearwaters, 2 Mediterranean Gulls and a Great Skua passed by on the sea.

By day, a lone Clouded Yellow was at the Bill and single Hummingbird Hawk-moths were again at several sites. Overnight, a single Marbled Yellow Pearl Evergestis extimalis at the Grove was easily the best of the thin selection of immigrants attracted to the moth-traps.

Forester and Silver-studded Blue - Admiralty Quarry, 6th July 2016 © Ken Dolbear

And on the subject of day-flying lepidoptera, we happened to be passing Ferrybridge in the late afternoon just as Andrew Duff caught this Six-belted Clearwing whilst sweeping thrift for beetles - although they're common enough in places on 'Tophill' we couldn't immediately recollect any previous records of this clearwing from Chesil (...in fact we were quite disappointed that it wasn't a Thrift Clearwing which, since it occurs within sight of the island in east Devon, remains something of a Holy Grail for Portland clearwing-seekers!):

5th July

In the absence of any meaningful coverage of the land the only reports from the Bill were of seawatching that came up with 8 Common Scoter, 4 Manx Shearwaters, singles of Curlew, Mediterranean Gull, Black-headed Gull and Sandwich Tern and a trickle of departing Swifts. Elsewhere, the Mediterranean Gull total at Ferrybridge increased to 30.

On a night when 2 Rusty-dot Pearl provided the only immigrant interest in the Obs garden moth-traps it was a surprise to also catch a likely first for the island in the form of a Brown-barred Twist Epagoge grotiana.

It seems as though grotiana is mainly a moth of deciduous woodland and is relatively uncommon in Dorset as a whole so we probably haven't been overlooking it. Also thanks to Debby Saunders for a photo of a very unseasonable Feathered Brindle caught overnight in her trap at Sweethill:

...this brought to mind an equally out of season Feathered Ranunculus that we caught last week (27th June) at the Grove:

...for reasons that remain obscure, Feathered Ranunculus has become an almost expected mid-summer moth of late - there's never more than the odd one or two each year but we now have records in all but one of the last seven years.

Finally, thanks as usual to Ken Dolbear for some more lovely butterfly photos, this time from this afternoon at Broadcroft BC reserve - Lulworth Skipper and some Silver-studded Blues:

4th July

Quiet but at times quite murky/foggy conditions saw a couple of new arrivals drop in at the Obs: a Serin lingered longer than usual and a Garden Warbler was giving occasional bursts of half-hearted song; a Grey Wagtail was also of note at the Bill. Overnight, another Storm Petrel was sound-lured and ringed at the Bill but a routine selection on the sea during the day included 20 Common Scoter and 7 Mediterranean Gulls.

Evidence of some renewed lepidoptera immigration came in the form of a Clouded Yellow at the Bill and overnight captures of 2 Vestals at Blacknor and a European Corn-borer at the Obs; routine immigrants hardly increased at all, with just 8 Rusty-dot Pearl and a Rush Veneer making up the tally at the Obs.

...apart from giving plenty of typical calls and a bit of brief song the Serin also indulged in periods of giving much less frequently heard calls:

3rd July

Still very uneventful even though there was marked improvement in the weather, with early drizzle giving way to a lovely warm, sunny afternoon and evening. The only worthwhile reports from the Bill were of 64 Common Scoter, 10 Manx Shearwaters, a Mediterranean Gull, a Sandwich Tern and a Puffin through on the sea. The Ferrybridge Mediterranean Gull tally increased to 16.

Immigrant moths in the Obs garden traps consisted of just 5 Rusty-dot Pearl and a Diamond-back Moth.

2nd July

Nothing much changing with either the weather or the birding. The sea provided all the news from the Bill where 50 Manx Shearwaters, 15 Common Terns, 10 Common Scoter, 2 each of Black-headed Gull and Sandwich Tern, and singles of Mediterranean Gull and Arctic Skua made the list. Elsewhere there were 11 Mediterranean Gulls and 3 Dunlin at Ferrybridge.

A Silver-stripe Grass-veneer Catoptria margaritella - the third Portland record - was a surprise overnight capture in the Obs moth-traps; 3 Rusty-dot Pearl were the only routine immigrants caught.

...presumably a wind-blown stray from the high moors of the West Country, but appreciably earlier in the season than the previous two island records that were at the Obs on 26th July 1997 and at Sweethill on 30th July 2014 (is the species on the wing in early July in Devon/Cornwall?).

1st July

Blustery westerlies were again the order of the day and ensured that the only reports were from the Bill where 60 Manx Shearwaters, 30 commic terns, 3 Common Scoter and 3 Arctic Skuas passed though or were lingering on the sea.

Five Diamond-back Moths were the only immigrants caught overnight in the Obs garden moth-traps.

Peregrine, Gatekeeper, Scarlet Tiger and Mullein Moth caterpillar - Southwell, Portland Bill and Easton, 1st July 2016 © Pete Saunders (Peregrine) and Ken Dolbear (the insects)