2003 Report

2004 Report

2005 Report

ARCTIC SKUA Stercorarius parasiticus
Rare passage migrant

After only three records up to 1994, there have now been two in just over 24 months. The Group’s fifth record was represented by a pale-phase bird which gave good views as it flew west over Kex Gill on 9th September (AJ).

MEDITERRANEAN GULL Larus melanocephalus
Scarce, but annual winter and passage visitor.

An excellent year for the species, after a rather indifferent one in 2005, with at least nine, and probably ten, different birds being seen.

Most of the records came from the south of the area, and with two from Airedale, where the first one originated on 19th March, when two adults in full summer plumage were at Silsden Ings (MD, AGG, JLT). Four months later, a juvenile bird was found in the fields near Cullingworth on 18th July (KM), and within a week two different adults showed at Thornton Moor Reservoir, on the 22nd and the 25th. The second of these was seen on and off until at least 5th August, another and different bird was at Thornton Moor on the 4th, and possibly a further winter-plumage adult a week later (KM, MD, BV, RHP).

Thornton Moor’s final contribution towards a productive period was the year’s second juvenile which was present on 15th September, and remained in the general area for six days, including a visit to Doe Park Reservoir on the 20th (KM). The Aire Valley came back into the picture on 19th December, when a 1st-winter individual was discovered with Black-headed Gulls on the flooded Bradley Ings (KM), and Cullingworth had its second record on the last day of the year, with an adult in the fields there (MD).

BLACK-HEADED GULL Larus ridibundus
Common resident breeder and abundant passage/winter visitor.

This species was again quite well-recorded, though numbers were down on the previous year, but there were still 51 counts of more than 100 birds from a wide range of locations across the area. As in 2005, no data was forthcoming from Swinsty Reservoir, formerly (and apparently still) a fruitful winter roost for gulls, and the best-watched roost site was Thornton Moor Reservoir, where there were the following four-figure winter counts:

January 2nd 1500, 22nd 1500, 28th 1250 November 7th 1550 December 1st 2700

However, the highest numbers came from Silsden Floods where there were 3000 birds on 17th December, and Embsay Reservoir, with 3400, six days later. Up to 1200 birds were seen in the fields around Cullingworth over the Christmas period, and this area and Thornton Moor hosted the largest post-breeding flock of some 1000 birds at the end of July.

Definite breeding information was limited to Kex Gill Quarry, where a nest was found, and where up to five juveniles were seen at the end of June and in early July. Whilst no count was available for the well-established colony at Upper Barden Reservoir, one observer considered this to be more extensive than in previous years.

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COMMON GULL Larus canus
Common passage/winter visitor, and erratic breeder.

Although reported for every month but May, and from 32 locations, numbers were considerably down on 2005, and generally the lowest for several years.

January produced almost all the highest roost counts, and all from Thornton Moor Reservoir, where numbers fluctuated between 1000 on 1st January to 1500 three weeks later. The only four-figure count for the second winter period came from the same location, and involved 1050 birds on 7th November. Aside from this, even three-figure totals were hard to come by, and the following are the relevant monthly maxima:

LESSER BLACK-BACKED GULL Larus fuscus
Common passage migrant and occasional winter visitor.

The records received indicate that sightings in the area are now fuelled almost entirely by relocating birds, as, though reports came from every month but January, there was little in the winter months and spring.

For the second successive year, numbers were down, despite extensive watching, and the best monthly site counts during the periods of pre- and post-breeding movements were 220 at Cullingworth in April, 360 there in June, and 220 at Thornton Moor Reservoir in August. July, often a productive month for the species, produced a maximum count of only 80, and September’s best tally was 50. In years past, Thornton Moor has been a reliable spot for large numbers of birds, but the total for the months of May to September inclusive was, at best, 1350, which is less than half the corresponding figure for as recently as 2004.

The origins of some of our birds may be indicated by the numbers of Yellow-legged Gulls that regularly appear with them, and by the presence in the same flocks of birds showing characteristics of the race L.f.intermedius. This year around 40 such birds were seen. Another indication is the occasional colour-ringed bird, such as the one seen at Thornton Moor in August, which had been ringed as an adult in Gloucestershire in March, 2005.

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HERRING GULL Larus argentatus
Increasingly uncommon passage migrant and winter visitor.

This species’ continuing decline in the area can be best illustrated by the meagre 32 records submitted, and the fact that the year’s total of around 100 birds is no more than a ninth of the number which could be seen on one day ten years ago!

The south of the recording area predominated, and the only double-figure counts came from there, comprising ten at Thornton Moor Reservoir in November, 12 there in January, and 16 over Bingley in December.

The only Herring Gull present at Thornton Moor on New Year’s Day showed characteristics of the Scandinavian race L.a.argentatus. Another singleton, at Redcar Tarn on 4th October, was notable for a different reason, as it made off with a Mallard-hybrid duckling.

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YELLOW-LEGGED GULL Larus cachinnans
Uncommon but regular passage migrant, and occasional winter visitor.

Despite the closure of the remaining accessible landfill sites in the area, regular sightings of this species continue, and in 2006 there were 39 records of at least 14 birds. This represents the best total for ten years, and, remarkably for a Continental bird, it can be seen there were more records than for the familiar and resident Herring Gull.

As in other recent years, birds were found mainly as they moved through the area in summer with Lesser Black-backed Gulls, and, with one exception, all were located in the fields around Cullingworth and at Thornton Moor Reservoir. Not fitting this pattern was the year’s first, a 2nd-winter individual at Raggalds Sports Field, Queensbury, on 25th March. The first passage bird was found in mid-June, and the sightings at the two locations concerned were:

Cullingworth - A 1st-summer was present on 16th and 18th June, and a different bird of this age on the 24th. As gull numbers built up, three adults were with the flocks on 19th July.

Thornton Moor - A 1st-summer was here on 6th and 8th July, and an adult on the 19th was almost certainly one of the Cullingworth birds. A different adult was present two days later, as was a further 1st-summer individual. There then followed records of different birds in quick succession, comprising a 3rd-summer on the 24th, and different adults on the 25th, 27th and 29th. Further regular observations to 12th August probably involved these same birds. Finally, after a three-week gap, a 2nd-summer bird was present on 2nd September (MD, KM, RHP, BV).

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GREAT BLACK-BACKED GULL Larus marinus
Increasingly uncommon passage migrant and winter visitor.

Remarkably for a formerly common bird, this is now the least-recorded of the regular large gulls, with only 13 reports, and the 17 birds noted is only marginally ahead of Yellow-legged Gull, a species not seen with any regularity in the area until the mid-1990’s.

In January, singles were seen near Eldwick and at Barden Scale (where there were also two on New Year’s Day), and three overflew Soil Hill on the 24th. There was no further activity until August, when individuals were at Thornton Moor Reservoir, in past times the Group’s stronghold for the species, and one was also there on 6th September. Of the remaining four records, a bird passed over Denholme Clough in October, and late in December Otley Wetland had up to two birds, and two were at Barden Scale.

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