Lighthouse Journal: April 2011

Friday, April 29, 2011

The northerly winds have continued and the number of migrants passing through has dropped considerably. But the diversity remains exciting with Spotted Flycatchers, Grasshopper Warblers, Sedge Warblers, Blackcaps, Garden Warblers, Whitethroats, Chiffchaffs and Willow Warblers all passing through along with a few hirundines and plenty of Wheatears. Today's highlight came in the form of the second Subalpine Warbler of the year. The bird was another male, but this time of the western form, cantillans. It appeared in the garden heligoland when trapping a Sedge Warbler and makes us wonder what else must be skulking through the garden unnoticed.

Compared with last weeks Subalp, this nominate male lacks the deep brick-red throat, instead having a peachy cinnamon orange wash which extends right down the flanks. The brown, well-worn flight feathers and coverts suggest this is a first year bird. (c) Richard Brown

An early start is the best way to catch the Grasshopper Warblers feeding out in the open. It seems strange to see them in Gorse but there is little else in the way of vegetation on the South End. Irish Sea coasts have traditionally seen particularly good numbers of spring Grasshopper Warblers and this year seems no exception. (c) Richard Brown

Common Whitethroats and Garden Warblers have also been trickling through. (c) Richard Brown

Monday, April 25, 2011

A change to northerly winds has brought a halt to the large numbers of birds being recorded. But a drake Shoveler heading west at sea was the first since 2006 and a new 30 foot net erected in Carreg Reedbed trapped 11 White Wagtails and a Swallow as they came into roost last night.

Two Lapland Buntings are still hanging on in the Northwest Fields. (c) Richard Brown

Seven Spotted Flycatchers have been recorded so far this spring. (c) Richard Brown

A few Common Redstarts are still trickling through. (c) Richard Brown

High double figure counts of Wheatear are being recorded daily. These two birds nicely illustrate the difference between a full adult bird (which has replaced all the feathers of the wing with nice black feathers during a full moult), and a first year bird (which has only replaced a few inner greater coverts and retains the wing feathers it grew in the nest). (c) Richard Brown

Saturday, April 23, 2011

The last couple of days have seen a continuation of the excellent spring we've had so far. The first Pied Flycatchers, Spotted Flycatchers, Reed Warbler and Turtle Dove of the year have all passed through and good numbers of common migrants have been logged. Whitethroat numbers have reached 16, Blackcap 18, Chiffchaff 8, Willow Warbler 65, Grasshopper Warbler 21 and Sedge Warbler 76. Scarcer migrants have included a few Tree Pipits, Yellow Wagtails (including the first Blue-headed Wagtail of the year), Garden Warblers and Common Redstarts. The second Marsh Harrier of the year, this time a cream-crown, briefly crossed the island.

Scarcer migrants trapped have included two first-year male Pied Flycatchers and a few Garden Warblers (c) Richard Brown

The second Marsh Harrier of the year. The wing could be interpreted as showing six fingers, and at a distance was reminiscent of Black Kite, but the tail and positioning of the wings when gliding, gave the identity away. (c) Richard Brown

Following a beautiful day on Friday, a band of rain and cloud reached the island just as the night set in. An attraction was almost inevitable but the large number of passerines we expected did not arrive. But just over 100 Manx Shearwater circled the tower during the night and we trapped 39. We also trapped small numbers of Sedge Warbler, Whitethroat and Grasshopper Warbler along with a Knot. The Knot was the first to be trapped since 2008 and took the number of species ringed on the island in 2011 to 42.

One of the Manx Shearwater attracted last night and Rich letting it go. Manx Shearwater need a long run up or a strong breeze to get airborne so we have to launch the birds into the air to get them back out to sea where they can feed for the day. (c) Richard Brown and Giselle Eagle.

This Knot dropped down at Giselle's feet as she was reaching to pick up a Sedge Warbler. Despite its encounter with the Lighthouse, the bird flew to the coast when released and began to feed in the saturated ground. (c) Giselle Eagle.

Every lighthouse attraction is documented. We record measures of weather and visibility along with the numbers of birds attracted, trapped and killed. (c) Richard Brown

Drinker moths have only been recorded on the island in the last few years. This caterpillar, found by Giselle, is probably the first evidence that they are now breeding here. (c) Giselle Eagle

Wednesday, April 20, 2011

Fine weather and really good numbers of birds have meant that we have been flat out censusing the island and ringing. By far the best bird of today was a smart male Subalpine Warbler found above the farm. Quite why Bardsey is such a fantastic place for catching up with this species is something of a mystery, but this is about the sixth Subalp I've seen in just over three years here. Yesterday a Twite, rare on the island, joined the Linnet flock in the Northwest Fields. But it's the number of birds passing through that has made the last few days so exciting.

The deep red colouration to the throat which extends downwards only slightly beyond the breast shows this to be an albistriata of Southeast Europe. (c) Richard Brown

Hundreds of Wheatear, a high percentage looking like leucorhoa birds from Greenland and Iceland, have been passing across the island and up the mountain. Over twenty Grasshopper Warbler and Blackcap are being recorded each day and we have already ringed more Blackcap than we do in an average year. Today over 70 Sedge Warbler have passed through and Willow Warbler numbers are again in the high seventies. Scarcer migrants include three Whinchat, three Ring Ouzel, a late Redwing, three Tree Pipit, three Lapland Bunting, a Yellow Wagtail and a ringtail Hen Harrier.

Three Whinchat were logged during the morning census. (c) Richard Brown

The number of Whitethroat passing through has also crept into double figures. (c) Richard Brown

Sadly not all iberian chiffchaffs are Iberian Chiffchaffs! This Spanish ringed Chiffchaff was controlled at Nant. (c) Giselle Eagle

On Solfach the number of White Wagtails has been consistently around 50, but the turnover of birds is quite high with double figure flocks departing northwards. We have been using the portable Heligoland Trap I made a few years ago and managed to catch nine new White Wagtails and a control yesterday.

White Wagtails on Solfach. The top bird, a first year male, has an orange ring above its British BTO ring on its right leg, and yellow over pink over red on its left leg. (c) Richard Brown

The portable Heligoland Trap on Solfach and Giselle ringing a White Wagtail. (c) Richard Brown

Wader numbers continue to increase with ten Dunlin, nine Ringed Plover, five Turnstone, four Common Sandpiper and eight Whimbrel also in and around Solfach. A Sanderling this morning was the first of the year.

Sanderling, Dunlin, Ringed Plover and Turnstone were busy feeding at the waters edge. (c) Richard Brown

Monday, April 18, 2011

Whilst news from the mainland seems to involve sunbathing and barbecues, the weather here has been rather variable with long periods of dense fog interspersed with sun. But the birds have kept arriving with Whinchat and Lesser Whitethroat making their first appearances. The full moon has meant that there have been no birds attracted to the light but the morning survey is still busy with good numbers of Wheatears, Willow Warblers, Chiffchaffs, Blackcaps and Grasshopper Warblers. Finches continue to pass overhead and it was no surprise when the first Common Redpoll of the year turned up in a catch of Lesser Redpoll at the Obs. Scarcer migrants include daily sightings of Tree Pipit, Ring Ouzel and Lapland Bunting.

Tree Pipit sightings on Bardsey are typically of birds giving their buzzing flight call as they pass overhead. So a singing bird in the top of the Plantation was nice to hear. (c) Richard Brown

Redpoll continue to pass noisily overhead. Of those that come down all but one have proven to be Lesser Redpoll, including this smart male. (c) Richard Brown

Large numbers of Herring Gull have been following the plough. (c) Richard Brown

Two Bar-tailed Godwit toured the South End. Whimbrel numbers had increased to eight yesterday and the first Common Sandpipers of the year arrived today. (c) Richard Brown

Friday, April 15, 2011

This morning we awoke to the sound of a Grasshopper Warbler singing in the Lighthouse Garden. Opening the garden net caught a few Willow Warblers and the Gropper. At the Obs the first Garden Warbler of the year skulked through the Damsons and over 25 Phylloscs were trapped. Elsewhere on the island over 100 Willow Warblers were logged and Hirundine passage has increased, with over 60 Swallows and 6 House Martins passing through. Blackcaps, Sedge Warblers and Grasshopper Warblers are present in smaller numbers and two Lapland Bunting remain at the North End. The Hooded Crow we first found in March is now an almost daily visitor.

Both juvenile and adult Grasshopper Warblers undergo a full moult in their African wintering grounds and so look identical at this time of year. The lines across the tail, which might be considered growth bars in other species, are a plumage feature present on all birds. (c) Richard Brown

A Clouded Drab was in the Cristin moth trap. Frequent through most of Britain they seem quite scarce here. (c) Richard Brown

Wellies are a must in the Withies at the moment as the morning dew carpets the Horsetails and Marsh Marigolds (c) Giselle Eagle

Thursday, April 14, 2011

Strong winds and rain have dominated for the last few days. The number of migrants has likewise taken a downturn but there are still daily double-figure counts of Willow Warbler, Chiffchaff and Blackcap as they move through the island. Sedge Warblers are singing in the Withies and the odd Grasshopper Warbler is also reeling. Hirundine passage has slowed to a trickle. The bulk of the migrants at the moment are finches with over fifty Goldfinch being recorded most days along with good numbers of Linnet and Lesser Redpoll.

Record numbers of Goldfinch were logged in 2010. This year looks set to follow suit. (c) Richard Brown

Sunday, April 10, 2011

Another gloriously sunny day on Bardsey, and with little wind we mist netted at the Obs and then Nant. At the Obs a number of Lesser Redpoll were caught, along with phylloscs and a stunning male Redstart. There were up to five Ring Ouzels on the hillside just above and Grasshopper Warblers continue to fill the island with their far-carrying song.

This first year male Redstart was one of three at the Obs. (c) Richard Brown

At Nant the catch was predominantly phylloscs.The first White Wagtail and Whitethroat to be ringed this year added some variety. The earliest Whitethroat recorded on Bardsey up until this year was on 9th April (1961 and 2002). The record fell this year by a single day. (c) Richard Brown

Hirundines continue to pile through the island. This morning we were watching Swallows and Sand Martins around the narrows, some of which were enjoying a quick pitstop on the boat trailer. (c) Richard Brown

Saturday, April 9, 2011

We woke up to glorious sunshine! A few migrants were hanging around the south end, including a Tree Pipit and a few finches, mainly Redpoll, Goldfinch and Linnet. Rich also had a brief flyover Yellow Wagtail. Emptying the moth trap was the highlight of the morning because I (Giselle) have paid little attention to moths in the past, so everything is quite new to me (I no longer just think of them as bat food). In the afternoon we saw our first Grasshopper Warbler and Common Redstart of the year and caught a few common migrants as we put the nets up in the Withies.

This Grasshopper Warbler was one of two recorded today. (c) Richard Brown

A female Blackcap caught in the heligoland trap today and bearing a huge pollen horn. The massive deposit was probably collected during migration but the dusting of yellow is from closer to home. The Damson blossom in the obs garden to be exact. (c) Richard Brown

There were two Brindled Ochre in the trap. We know that this is a female as only the ladies overwinter. The adult moths do not feed. (c) Richard Brown

A Herald. This is another species of moth which has hibernated through the winter. The larval foodplants include Willows which are plentiful on Bardsey. (c) Richard Brown

A few things that will make this blog make more sense:

What is a Lighthouse attraction?

It is perhaps surprising how many bird species move nocturnally. Huge numbers of waders, thrushes and warblers are joined by birds such as shearwaters, petrels, rails, terns, larks and starlings. The majority are relying in a large part on the visible night sky to aid navigation and on light, particularly from the moon, illuminating the landscape. If bad weather descends whilst they are on the move they use other features to orientate themselves. The beams of Bardsey Lighthouse, which officially reach up to 43km out to sea, are particularly attractive if other navigational cues are absent. Up to 31,573 birds have descended upon the Lighthouse in a single night. Sadly some of these birds fatally collide with the light, typically Manx Shearwaters and thrushes, but also species such as Thrush Nightingale and Red-eyed Vireo. We are based at the light to monitor these attractions, help to direct birds away from the tower using gantry lights and catch grounded birds to stop them again flying at the light. The lighthouse plays an important role in shipping.

A bit about Bardsey’s migrant birds

Bardsey has played host to the first Summer Tanager and Yellow Warbler to be recorded in Britain or Ireland. Additionally American Bittern, Sora, Black-winged Stilt, Killdeer, Spotted Sandpiper, Lesser Yellowlegs, Penduline Tit, Lanceolated Warbler, River Warbler, Booted Warbler, Blyth’s Reed Warbler, Grey-cheeked Thrush, Eyebrowed Thrush, American Robin, Thrush Nightingale, Red-flanked Bluetail, Isabelline Wheatear, Black-eared Wheatear, Collared Flycatcher, Blyth’s Pipit, Olive-backed Pipit, Song Sparrow, Dark-eyed Junco, Pine Bunting, Rock Bunting, Yellow-breasted Bunting and Blackpoll Warbler have all been recorded. Rich has found the second Paddyfield Warbler and White-throated Sparrow for Wales (the first White-throated Sparrow was also on Bardsey), along with good Welsh birds such as Short-toed Lark, Icterine Warbler and Pallas’s Warbler. In recent years we’ve had Glossy Ibis, Black Kite, Woodchat Shrike, Greenish Warbler, Western Bonelli’s Warbler and Ortolan Bunting and species such as Melodious Warbler and Subalpine Warbler are more than annual (the eastern race of Subalp is a particular Bardsey speciality).

A bit about bird ringing

Ringing is a method which has been used for over 100 years to study birds. It has proven very successful because the individually numbered rings make no difference to the behaviour of the birds. Bardsey Bird and Field Observatory has been ringing since 1953. A mass of information has been gathered relating to many aspects of avian biology including movements, physiology and longevity, all of which help us to understand and conserve birds. Some of the multitude of interesting Bardsey records include:

On the 8^th May 2008 we retrapped the Manx Shearwater FB10565. It had first been ringed as an adult on the 17^th May 1957, 50 years 11 months and 9 days previously. This is the oldest known wild bird in Britain.

Bardsey has also hosted the oldest Razorbill, at 41 years 11 months 23 days, the oldest Wren, at 7 years 3 months 10 days and the oldest Chough, at 16 years 8 months 26 days.

We get many records each year of birds ringed elsewhere arriving on Bardsey or of our birds turning up. Recently Manx Shearwaters have been recorded in South America within a few weeks of departing their burrows, our other seabirds have reached various colonies elsewhere in the UK and Europe and our Lesser and Greater Black-backed Gulls have been recorded in Spain, Portugal and Morocco. Waders such as Whimbrel and Sanderling have passed through from the Arctic and Iceland. Migrant passerines include Sedge Warbler and Chiffchaff to Senegal and a Starling from Lithuania.

Movements are often rapid with several hundred kilometres being covered in a few days. Just in the last few years a Reed Warbler arrived from Belgium in 17 days, a Willow Warbler reached Lands End in four days, a Song Thrush reached Spain in 56 days and a Blue Tit reached Cape Clear in 19 days.

We ring birds under licence from the British Trust for Ornithology. Their website gives lots of info about ringing: http://www.bto.org/volunteer-surveys/ringing/about. This is also the place to go if you discover a bird with a ring on its leg.

A bit about birding Bardsey

The Lighthouse As mentioned, this is where we live to monitor birds attracted to the light. Anything is possible and sometimes masses of birds descend on the area. Rarities at the light have included Thrush Nightingale, River Warbler, Grey-cheeked Thrush and Red-eyed Vireo. We’ve seen two hundred Grasshopper Warblers here and a Little Egret hovering above our heads.

The South End Seas of Thrift and not much in the way of cover mean that this is a specialist habitat. We’ve seen Short-toed Lark, Dotterel and Quail on the deck but it’s the overhead vis mig which is best as birds funnel to the tip to cross the Irish Sea. The few patches of Gorse hide grounded migrants, many of which will have been attracted to the light.

The Narrows The narrowest part of Bardsey and home to Solfach and Henllwyn, a small sandy beach and a larger rocky bay. The best place to look for waders and where any storm-blown seabirds rest. Also another vis mig funnel. Recent highlights have included Baird’s Sandpiper, Avocet, Sabine’s, Glaucous and Iceland Gulls and Hoopoe.

The Badlands Named by ME and full of possibilities. Wellies are often a must as we tramp for Jack Snipe, Snipe, Woodcock and Short-eared Owls through rushes and bog. Patches of Gorse provide breeding habitat for Linnets and Stonechats.

The Withies and the Green Lane Five main patches of predominantly Willow and Reed linked by hedge-lines, they have a very impressive list. Recent highlights have included Rich’s Paddyfield Warbler along with multiple Icterine and Melodious Warblers. Historical highlights have included American Bittern, Sora, Summer Tanager, Yellow Warbler, Arctic Warbler, Aquatic Warbler and Penduline Tit.

The Gardens Away from the Obs there are 11 mature gardens which all need grilling in search of grounded migrants. Anything could occur, from a Red-flanked Bluetail at Ty Nesaf to a Wryneck at Carreg Bach.

The Observatory A mature garden of Damson and Gorse and our main ringing site. Subalpine Warbler and the commoner Hippos are annual and usually trapped. This is the place in the UK where Subalpine Warblers are known to have progressed furthest in a breeding attempt. Seawatching from the terrace is a real possibility and the kettle is never far away.

The Plantation A belt of older conifers are flanked to the North by a new plantation of scrubby natives. The sheltered side is often the favoured haunt of Flycatchers, including Gis’ R-b Fly in 2011, and the main plantation contains the bulk of our migrants in a good fall when hundreds of Phylloscs and crests can litter the branches and floor. The nearby withy and hillside have harboured some stunning birds, recently including White-throated Sparrow, multiple Barred and Pallas’s Warblers, Western Bonelli’s Warbler, Common Rosefinch, Corncrakes and Greenish Warbler.

The West Coast Perhaps under-covered as the Withies lure birders inland. This is a beautiful stretch of coves and short grass home to Choughs, Wheatears, Rock Pipits and Oystercatchers.

The North West Fields Not just a great area of maritime heath, a lure to scarcer buntings and pipits, but also home to the best seawatching hide on the island. This is where seabirds pass closest and in a good Northwesterly the views and diversity can be belting. The scarcer passage seabirds such as Long-tailed Skua, Sabine’s Gull, Grey Phalarope and Leach’s Petrel are regular at the right times.

The Mountain Often under-covered as it leads the birder away from some other cracking areas, however the mountain is the place to pick up Snow Bunting and is the main fly way for passage raptors which go through rapidly. We’ve recently seen Hobby, Ospreys and several Marsh Harriers as they go through.

Anywhere Else There could be an Ortolan Bunting in the track or a group of Crossbills drinking at a puddle. Anything could pass over with Black Kite, Glossy Ibis and Richard’s Pipits all recorded overhead in the last couple of years.

A bit about Bardsey’s breeding birds

Manx Shearwater There are somewhere between 9000 and 16000 pairs on Bardsey. They usually arrive back in mid March, established pairs returning to the same burrow as in the previous year. After mating the female nips off to form the egg, perhaps to Biscay, whilst the male defends the burrow from other prospecting pairs. They then take turns incubating the single egg for around 52 days and then provision the downy chick for a further 70 days or so. Productivity is usually between 0.70 and 0.88 (2002-2011 average 0.77±s.e.0.02) and was 0.73 in 2011. To avoid predatory birds the Shearwaters only come and go when it’s really dark.

Storm-petrel This is a difficult species to monitor as the colonies are restricted to the treacherous East Side. The birds only return at night meaning that to count apparently occupied crevices during the day is the best way to assess numbers. This is done using a tape-playback of their song to elicit responses from incubating adults. Due to the amount of work involved we don’t count them every year, but in 2002 there were thought to be approximately 35 pairs. Their distinctive smell alerts us to their continued presence each year when we are working in the Razorbill colonies. To see them on Bardsey you need to be present for one of our summer ringing sessions.

Oystercatcher One of our most conspicuous breeders with most of the accessible coastline holding alarming pairs during the breeding season. They are by far the most abundant breeding wader with 85 pairs on territory in 2011, nine fewer than in 2010, but 6.4% more than the 2002-2011 mean (79.90±s.d.12.13). In 2011 52 nests were located. They contained 141 eggs or a mean clutch size of 2.71. Of the 52 monitored nests, 31 failed at the egg/small chick stage, nine failed with chicks and 12 were successful. Predatory gulls and corvids account for many of the failures. A total of 14 chicks fledged from the successful 12, which gives a productivity figure of 0.27 chicks per pair, 25% down on 2010 and 65.4% lower than the 2002-2011 mean (0.78±s.e.0.20).

Ringed Plover In 2011 breeding occurred for the second time since 2003 following two pairs that successfully fledged seven young in 2010. A clutch of three eggs near Solfach on 28 April were covered with a chicken-wire cage to protect them from sheep and predatory birds whilst leaving just enough room for the adults to slip underneath to incubate. This worked well last year and again proved fruitful with all three newly-hatched young ringed in the nest on 22 May. A week after all three young had fledged a further four eggs were discovered in the same covered nest on 28 June. Three newly hatched chicks were ringed on 19 July with the fourth egg failing to hatch. All three had fledged by 20 August. A productivity figure of 6.00 was the highest recorded on Bardsey.

Guillemot This species famously defends the smallest territory of any bird. They have many adaptations for living close together. They recognise their neighbours, which they will tolerate at close proximity, and they have eggs with very diverse patterning so they can recognise which one is theirs. The eggs are extremely conical so they role in a very tight circle. In 2011 981 adults on ledges were recorded, a figure almost identical to 2010, 24.7% more than the 2002-2011 mean (787.00±s.d.156.67) and 116.6% more than the long-term mean (453±s.d.225). Productivity was 0.30 fledging sized chicks per pair.

Razorbill This is the largest auk in the world and one of the commonest seabirds on the East of the Island. The pairs mate for life but will not breed until about five years of age. They’ll mate about 80 times at the start of the breeding period to ensure fertilisation and then incubate the egg for roughly 35 days. The incubating birds are hidden away in crevices and caves which makes counting them difficult. Over 1500 adults were counted around the colonies in 2011. The chick only stays ashore for about 20 days before swimming out to sea with the male. The sea is a safer place to be with so many predatory gulls around.

Little Owl This diminutive owl was introduced to the UK in the 19th century. On Bardsey a minimum of three territories were recorded in 2011. A pair nested in a field boundary to the South of Carreg Bach where two chicks were ringed on 5 June. Both had fledged by 28 June. Additional pairs were to the South of Cristin and near Rhedynog Goch, but neither was proven to breed. Pellet analysis has shown that invertebrates and small birds make up the bulk of the diet although we have not recorded the predation of Storm Petrels seen on other Welsh islands.

Skylark In 2011, three pairs established territories, one in the North West Fields, one East of Nant Valley and one in the West Coast Fields. The West Coast pair produced five eggs, all of which hatched. The five pulli were ringed on 18 May, 18 days earlier than they were ringed in 2010. All fledged in early June. A second brood was suspected but no fledglings were recorded. The Nant Valley pair had fledged at least one chick by 29 May. The North West Fields pair was present throughout the breeding season but no fledglings were observed. This is the best showing since 2005 and the most fledged young recorded since the recolonisation in 2003.

Swallow Nationally this species has undergone a long-term decline in the UK but numbers fluctuate widely. On Bardsey in 2011 the number of breeding pairs was 21, 56.7% more than the 2002-2011 average (13.40±s.d.4.58), and the most ever recorded (equal with 2008). A total of 106 birds fledged from 31 broods, the most fledglings ever observed. Productivity was thus 44.3% up on last year and 6.8% above the 2002-2011 mean (4.73±s.e.0.48). Disappointingly at least nine juveniles were found dead within a short period after fledging. Climatic changes in the African wintering grounds mean that birds are returning to Britain in poorer condition and laying fewer eggs than previously recorded.

Chough This is another species which shows strong mate and site fidelity. A record eight pairs attempted to breed in 2011 with a ninth pair prospecting suitable sites but not attempting. Disappointingly two pairs nesting on Mynydd Enlli failed. Of the remaining pairs, one fledged four, one fledged three, three fledged two and one fledged a singleton. The resulting productivity figure of 1.75 was the second lowest on record, 31.6% up on the record low of 2010 but 34.5% lower than the 2002-2011 mean (2.67±s.e.0.29). Ten young were colour ringed in 2011.