Dee Estuary Birding

"Movements and records of this species continue to be bewildering in terms of trying to establish a regular pattern." Cheshire Bird Report 1976.

"The erratic occurrence of the Little Gull makes it difficult to judge its true status, abundance and any rate of change" and "The transient and ephemeral nature of the Little Gull makes it difficult to judge its conservation status."  The Birds of Wales (2021).

Little Gull - an intriguing species and I picked out the two quotes above, 45 years apart, to demonstrate that there is an awful lot we don't know about them. They spend the winter mostly out of sight from land so we have little idea exactly where they are or how many, and they breed around remote lakes in Scandinavia and east to Siberia where they are difficult to monitor. As you will read below, when they are on migration they are much easier to see but even then they are subject to abrupt changes of routes and numbers. We are  lucky here on the edge of Liverpool Bay where for the past forty years they are routinely seen on spring migration. Although numbers have dropped from what they were in the first decade of this century Liverpool Bay remains one of the the best places in the UK to see Little Gulls on spring passage and there were 86 off North Wirral this last spring on the early date of March 5th 2024, which is the highest number we've had here since 2016.

History of Little Gulls

In the Birds of Cheshire (Ref 1) T. Hedley Bell says that they were known as winter rarities going back to the 19th century, and far less than annual, but by the time he wrote his Supplement (Ref 2), in 1965, they were more often seen in summer and autumn although still mostly just single birds. But there was a hint of an increase in numbers with a report of the largest party so far recorded in Cheshire/Wirral with nine off New Brighton in September 1965.

"The status of the Little Gull Larus minutus in Liverpool Bay has changed dramatically since 1965" (Ref 3). So wrote Ray Eades, who some of you will remember, in 1982. From 1963 to 1976 Ray counted Little Gulls almost on a daily basis whilst working as a Pilot and I can do no better than to illustrate the dramatic change he saw by reproducing the table in the article he wrote for the 1977-1981 Seabird Report.

From none at all in 1964 and 1965 numbers increased just eleven years later to 661 in 1976. Two things I noted in the article was that, (1 ) all but 5% of records were in summer and autumn, and (2) nearly all the Little Gulls were in the Crosby/Formby Channel (i.e. in the Channel between Formby Point and Seaforth), with very few in the area between the Bar Lightship and Point Lynas on the north-east coast of Anglesey.

J.D. Craggs writes in the Hilbre book (Ref 4) summarising records gathered by the Hilbre bird Observatory between 1957 and 1977: Records have increased in frequency from 1970 before which we had only 2. Numbers are extremely variable and the peak was reached in December 1975 when 135 were seen on the 7th and 128 on the 21st - no doubt the same flock. At that time numbers in spring were very low, something which was soon about to change.

It wasn't just Liverpool Bay where numbers of Little Gulls increased dramatically, similar increases were being seen right across the country as detailed by Hutchinson and Neath in their British Birds article (Ref 5). I reproduce their bar chart for Lancashire, Cheshire and Flintshire which is a summary of land based records going all the way back to 1934, and it shows a similar pattern to Ray Eades' ship based records. Hutchinson and Neath published very similar bar charts for the rest of the UK, with the exception of the west coat of Scotland where they have always been rare.

What caused this massive increase in the late 1960s and early 1970s and beyond isn't clear. There is evidence for a western expansion of the breeding range into Finland with BWP (Ref 6) stating that they had increased from 200 pairs in 1958 to over 1,000 pairs by 1980 - although the numbers all seem a bit vague. Since then expansion has continued with a north western movement of their breeding range with less breeding in the countries bordering the south-east shore of the Baltic and more in Sweden and Norway, as shown when comparing the first European Breeding Bird Atlas (1980s) with the second (2013-17) (Ref 7). Finland, and further east into Russia, still remains the most important breeding areas. With the current European population estimated at 23,700-45,200 pairs, which equates to 47,400-90,500 mature individuals (BirdLife International 2015 Ref 8), that estimate of 'over 1,000 pairs' in Finland is surely a big underestimation, even if it's technically true. But all this doesn't explain the sudden increase in the UK in just 10 years, so it seems likely that there must have been changes in migration routes and wintering areas to go along with the range expansion, probably they found good sources of food in the Irish and North seas, and further south.

Liverpool Bay - A big increase in spring

Whilst the majority of Little Gull records for the country in the 1970s were, and still are, in late summer and autumn - that was about to change in Liverpool Bay. There were signs of increasing numbers in spring with 30 off Red Rocks on March 27th 1977, 53 off Hilbre on March 9th 1979 and 205 off Meols on April 4th 1982. On the Sefton coast the Little Gulls were being monitored by Philip H. Smith with frequent visits between January 1975 and December 1984. Using these, and earlier observations, Smith wrote in Ref 9 that between the years of 1969 and 1974 1.1% of the Little Gulls recorded were present in April and 58.7% in August/September. In contrast, between 1975 and 1984 51.7% were seen in April and 25.4% in August/September. A remarkable turnaround.

For the next 30 years Liverpool Bay became the Little Gull capital of Britain! Here's a couple of bar charts to illustrate numbers.

The first counts of over 100 off Hilbre came in 1975 when a flock of up to 135 was seen several times over November and December that year. Most peak counts prior to 1980 were in summer or autumn, but after 1980 they were all in March or April.

At Seaforth/Formby all peak counts between 1980 to 2024 came in April. However, numbers have plummeted at Seaforth over the past ten years and reached a low point in 2022 with a max count of just three. Indeed, that was the highest count anywhere in Lancashire and North Merseyside for the whole of that year! Thankfully there have been higher counts since with a maximum at Seaforth of 10 in April 2023 and 11 in April 2024, and good numbers elsewhere including 187 past Heysham on April 20th 2023.

The bar chart above shows the weekly distribution for Little Gulls off the Dee Estuary and North Wirral for the past 10 years (2015 to 2024). You can clearly see how the large majority of records are between the first week of March and the third week of April, whereas the return passage, in September and early October, is virtually non-existent in comparison.

The usual pattern of spring arrival is that Little Gulls are first seen off Hilbre and North Wirral in late February or during March. Here they are often recorded dip feeding and occasionally roosting on sand banks with West Hoyle Bank a favourite spot.  Most years they will only be recorded on a few days with, typically, numbers varying from around 10 up to 60 or more. They appear to use Liverpool Bay as a staging post in March and they are also often seen off Formby at this time, with probably larger numbers further out. Sadly, the gathering in April and early May of hundreds of Little Gulls at Crosby Marine Lake and Seaforth, where they fed on non-biting midges (Chironomid), no longer takes place with the last big count being on May 2nd 2012 with 183. The high count of 172 in April 2015, was off Formby.

There have been two very big counts at Hilbre this century - one in 2006 and the other in 2011. The bar chart above, for 2006, shows nicely the transient nature of this species as recorded from Hilbre with just two days of three-figure counts, compared to Crosby Marine Lake and Seaforth where they were present in good numbers throughout April.

Chris Felton was the lucky observer on Hilbre on March 20th 2006 and he wrote an article about his experience which was published in both the Hilbre and the Cheshire & Wirral Bird Reports for 2006. I loved his description of the Little Gull flocks and here is a short extract (there was a brisk easterly wind blowing which the birds were flying into):

"I caught sight of a flock of Little Gulls Larus minutus, making it's way towards me from across the mouth of the Dee. Eventually, 111 came along, strung out low over the water, rising and dipping, butterfly-like, as they passed, the black underwings clearly noticeable. As Some birds landed briefly on the water, those behind leap-frogged over them causing them to take flight and hastily catch up."

In all Chris saw around eight distinct groups mostly of around 60 birds, and with clear gaps in between each flock. The total was 628, and, at the time, the highest ever March count for Liverpool Bay.

An even higher count came on March 31st 2011, as described in the Hilbre Bird Observatory Blog for that day:

"After overnight rain a west south westerly blew up to force 6/7 and then gale force 8 by 08:00hrs. With obviously not much action to be expected on the migration front, sea watching was the main attraction this morning. Right from the off flocks of Little Gulls were seen moving west in a narrow band in the medium distance (above, the sort of view one might see through binoculars!), in large groups at first and then thinning out later in the morning. The end of the session total came to 651 birds, a record count for Hilbre."

Where do they spend the winter?

We don't know for sure where these Little Gulls spend the winter but both Smith, writing in 1987, (Ref 9) and Messenger, writing in 1993 (Ref 10), concluded that it was very likely that many of the Little Gulls we see in Liverpool Bay in spring had spent the winter in the Irish Sea. An examination of recent records up to the present time suggests they still do.

I've shown the map, above, which was published in Ref 10 in 1993 because the exact same map could be drawn today. The shaded areas show 'The only area with regular counts over 25' - and that applies to the whole of the Irish Sea, not just the portion shown. It took Messenger a lot of work to find and collate all the data but these days we have BirdGuides and I was able to look at all records from around the Irish Sea for December and January since the turn of the century and, for those two months, I found 14 counts of over 25 in the area just south of Dublin and along the Wicklow coastline (max 155 in 2013), and 21 counts of over 25 between the south coast of Morecambe Bay to Seaforth (max 195 in 2005). Messenger said "Little Gulls usually begin to arrive on these coasts immediately the winds exceed force 3 and, as they increase in severity, so more gulls arrive", the fact that the flocks appear so soon after the onset of fresh on-shore winds must mean the birds are not far from the coastline. I've not found any other records of flocks of over 25 elsewhere in the Irish Sea for December and January this century.

As well as the BirdGuides data, aerial surveys were carried out over Liverpool Bay during the winters of 2004/05, 2005/06 and 2010/11 which specifically looked for Little Gulls. They came up with a figure of 333 based on the mean peak over those three winters (Ref 11). Most of the Little Gulls were around 12 miles out off Blackpool, and the figure of 333 was thought to be an underestimate.

How much Little Gulls move between these two main areas in the Irish Sea is a complete unkown. If they are moving across the Irish Sea in winter they are doing so out of sight of land as records from North Wales including Anglesey and Bardsey Island, and the Isle of Man are just of a handful of of one or two birds. It's strange that westerly gales don't result in flocks of Little Gulls from the east coast of Ireland ending up on the Welsh coast, but it doesn't appear to be the case.

A lot of Little Gulls winter further south around the European coastline and, as suggested in the next section, it seems likely that some of these make their way up the Irish Sea in spring on their way to the breeding grounds.

The Spring Passage

Little Gulls arrive in Liverpool Bay in spring with the first ones recorded in March, they appear to spend a few weeks here before heading across the country in April on their way to Finland and nearby countries to breed. In some years there is also an obvious movement further south with birds making their way up the Severn Estuary in April and then heading north-east across the country. But until they hit the coast their movements into, and in the Irish Sea are unknown as they always stay out of sight of land. A lot of Little Gulls over-winter off the south-east coast of Ireland and must cross the Irish Sea by going round to the north of Anglesey yet records from there are almost non-existent. The same applies to any Little Gulls coming into the Irish Sea from further south, these must end up either going into the Bristol Channel or further north to Liverpool Bay - but again, records from the west coast of Cornwall, the Scilly Isles, Pembrokeshire, Bardsey Island and Anglesey are very sparse indeed. I find it fascinating that this species will, at times, quite happily roost and feed, sometimes in their hundreds, on the coast and inland waters, yet on passage they stay resolutely at least 10 miles out to sea!

The spring passage in 2023 and 2024 were very different from each other, so I thought it would be interesting to go into some detail.

In 2023 the peak of the Little Gull passage took place over three days, from April 19th to 21st. The map below tells the story with several hundred moving up the Severn Estuary and heading north-east whereas others reached Liverpool Bay and Morecambe Bay before flying east, all within this three day period. To give an idea of numbers a few sites are marked with the max daily count, and many sites posted record numbers, for example 67 were at Woolston Eyes, the previous highest count was just nine. The 187 which flew past Heysham in three flocks was the highest count this century and both the 217 at Severn Beach, Gloucestershire, and the 59 over Chasewater Reservoir in Staffordshire were record high counts.

There were several sightings of Little Gulls off Leasowe in late February and early March 2024 peaking at 86 on March 5th, the highest count for the British Isles for that month. There was another flurry of records at the end of March including 16 seen from Hilbre on the 30th, indicating that Little Gulls were still out there in Liverpool Bay. 10, at Seaforth on April 5th, may well have been the same birds.

There was one other site in the country which had good numbers in early April - that was at Monikie CP, just a few miles north-east of Dundee, with a remarkable 220 Little Gulls on April 1st. There were none reported from here in April 2023 but the Firth of Tay area has long been associated with Little Gulls going right back to the 1950s when they were a rarity eleswhere  in the country (Ref 5).

But once we got past the first week of April numbers in the UK were very low. 15 spotted at Staines Reservoir, London, on the 27th hinted at a passage across the south-east but elsewhere nearly all records were of just one or two birds. The map shows the records for the whole of the second half of April 2024 when we would normally expect Spring passage to peak, quite a contrast with 2023!

Ringing

Thanks to ringing the evidence that the Little Gulls we see on spring passage end up breeding in Finland and nearby countries is strong. A total of 16 Little Gulls ringed at Seaforth have been found elsewhere including several in Finland and one well into Russia, in the Arkhangelsk Oblast 2,759Km from Seaforth (Refs 12 and 13).

Huge numbers at Hornsea Mere and the East Yorkshire Coast

Although on the other side of the country from the Dee Estuary, I can't finish this article without mentioning Hornsea Mere and the adjacent Yorkshire coast as it's a classic example of very big numbers of Little Gulls appearing in an area where they were virtually unknown before. I start with an article in British Birds 'Little Gulls at sea off Yorkshire in autumn 2003' by Clive Hartley (Ref 14). During a ship-based survey on 11th-12th September 2003 off the Yorkshire coast, between Flamborough Head and Spurn Point, he came across large numbers of Little Gulls and Kittiwakes feeding about 12 miles out from the coast - the number of Little Gulls far surpassed all previous records. They were seen "feeding... often in a frenzy of activity with other seabird species" and he noted "these flocks took the form of dense clusters, containing up to 120 Little Gulls". The number of Little Gulls counted during that survey was estimated to be at least 9,500, this number was confirmed on the evening of September 12th 2003 when an unprecedented 10,000+ were recorded offshore from Spurn Bird Observatory.

Hornsea Mere is just one mile from the East Yorkshire coast, almost exactly halfway between Flamborough Head and Spurn Point where these big feeding flocks of Little Gulls were being seen. The first mention of large numbers of Little Gulls on the mere I can find was by Hartley when he wrote that 3,000 were there in September 1997. Numbers continued to increase with 7,000 in 2004 and 16,000 in 2006, both in September, then a truly massive 21,500 in August 2007 - what a spectacular sight that must have been! Numbers have never been quite as high since but there have still been some big counts including 8,200 in August 2021. The birds use Hornsea Mere as a roost site and fly in in the evening, presumably after feeding off-shore during the day.

References and sources of information:

I have used records from Cheshire & Wirral Bird Reports, Lancashire Bird Reports, Wetland Bird survey (BTO) and BirdGuides throughout the article - for which many thanks to all.

Here is the list of References mentioned in the text:

1. T. Hedley Bell, The Birds of Cheshire, 1962.

2. T. Hedley Bell, Supplement to The Birds of Cheshire, 1967.

3. R.A. Eades, Notes on the distribution and feeding of Little Gulls at sea in Liverpool Bay. Seabird Rep. 6: 115-121, 1982.

4. J.D. Craggs (Editor), Hilbre - the Cheshire Island, 1982.

5. C.D. Hutchison and Brian Neath, Little Gulls in Britian and Ireland, British Birds 71, December 1978.

6. Birds of the Western Palearctic (BWP), App edition, 2023 (NatureGuides Ltd).

7. The European Breeding Bird Atlas 2, https://ebba2.info/ (last updated 2024).

8. Birds in the European Union: a status assessment (BirdLife International, 2004).

9. Philip H. Smith, The changing status of Little Gulls Larus minitus in north Merseyside, England, SEABIRD 10, 1987.

10. Doug Messenger, Spring passage of Little Gulls across Northern England, British Birds 86, September 1993.

11. J. Lawson et al., An assessment of the numbers and distributions of wintering waterbirds and seabirds in Liverpool Bay area of search, JNCC, 2016.

12. Robinson, R.A., Leech, D.I. & Clark, J.A. (2023) The Online Demography Report: Bird ringing and nest recording in Britain & Ireland in 2022. BTO, Thetford (http://www.bto.org/ringing-report, created on 21-September-2023).

13. The Eurasian African Bird Migration Atlas, https://migrationatlas.org/ , 2022.

14. Clive Hartley, Little Gulls at sea off Yorkshire in autumn 2003, British birds 97, September 2004.

Richard Smith