Notes on the changing status of Great Black-backed Gulls in Suffolk: Ed Keeble

Notes on the changing status of Great Black-backed Gull Larus marinus in Suffolk

Ed Keeble

Introduction

Some recent encounters with adult Great Black-backed Gulls in mid-summer on the Stour and Orwell Estuaries prompted me to look into their changing status in Suffolk. I am most definitely not a gull expert, but we are blessed with gull experts in the county and further afield and they have been kind enough to share their knowledge with me.

Background and summary

In Britain, the Great Black-backed Gull breeds along the coasts of Scotland, Wales and southern England, but despite range extensions in the late-20th century as far south as the Farne Islands, it is absent or very scarce as a breeder along the east coast of Englandi .

Consistent with this overall picture, Great Black-backed Gull is mainly a passage migrant and winter visitor to Suffolk, with some oversummering birds, mostly immatures. There has been a substantial increase in numbers reported off the Suffolk coast on passage and in winter.

Great Black-backed Gull has bred in Suffolk in small numbers since at least 1999ii. Since then, it has bred at a number of sites, with a maximum annual total of at least 13 pairs in the county in 2014 (this information not being available to section writers in the 2014 SBR). But it has not been a case of initial colonisation, followed by a steady increase in numbers and occupied sites. In recent years breeding has only been recorded at Felixstowe Docks and it is not known how many pairs are currently breeding there.

For context, colonisation of Suffolk appears to be well ahead of counties adjacent to us. The first breeding record was as recently as 2013 in Norfolk where at Snettisham one pair, but in 2015 two pairs, nested each year between 2013 and 2018 inclusive, raising a maximum of three young in any one yeariii. So far as I can ascertain, Great Black-backed Gull still has not been confirmed as a breeder in coastal Essexiv . The first breeding record from Greater London was in 2008 and, again so far as I can ascertain, there has not been more than one breeding pair reported in any year since thenv .

Passage and wintering in Suffolk

Wintering numbers on the Suffolk coast in the latter part of the 20th Century include many three-figure counts including, for example, an annual peak of roosting birds on the Alde-Ore complex ranging between 150 and 500 during the period 1985-1994vi .

In recent decades higher counts of between 500 and 1000 have been made including one of 600 on Orfordness on November 30th, 2014vii. Very high counts of birds moving offshore off Gorleston were made during this period including 1709 on November 29th 2016 and a record count for Suffolk off there of c2500 on December 8th 2015viii. Off Landguard, recent high counts include 1000 on November 14th 2019 and 1500 on November 20th 2017ix. It is notable that all of these peak counts have come in late autumn or early winter and so they may relate to local or longer-range movements of the population which winters in the southern North Sea or further south into the English Channel and Bay of Biscay. It is also possible that bad weather may force birds which feed and roost at sea to come inshore- as when 1500 roosted on Minsmere Scrape on January 14th 1987x .

It has long been known that a high proportion of Great Black-backed Gulls wintering off the east coast of the British Isles are from Norwayxi and in recent years there have been many readings in Suffolk of colour-ringed birds from Norway. Of 74 colour rings reported by one observer in Suffolk over the period from 2004 to date, 60 were from Norway and 14 from Denmark.xii It has

been suggested that a ban on landfilling biodegradable waste in Norway has caused a higher proportion of birds from that population to winter further southxiii. It is possible that this may be a factor in the increase in numbers recorded off Suffolk.

Breeding in Suffolk

The following is a summary of all of the proven and potential breeding attempts in the county that I have been able to identify.

Orfordness

The first confirmed nesting in Suffolk was in the Orfordness gull colony. Two pairs held territory there in 1998 and breeding was confirmed in 1999, with four pairs in 2000, plus a fifth territorial pair which did not attempt to breedxiv. It is thought that the majority of nests were predated by Red Foxes Vulpes vulpes and the number of confirmed breeding attempts declined to zero in 2006, with one unsuccessful attempt in 2012xv. Only one chick was proven to have fledged from the breeding attempts at the site over the period.

Havergate Island

Breeding has also been confirmed on Havergate Island. The first breeding record was in 2007, with 2 or 3 pairs over the period 2007-2014 and then a decline after that to a single pair in 2015 and 2017, which was the last recorded attemptxvi. There were no breeding records in 2016, 2018 or 2019.

Felixstowe Docks

At Felixstowe Docks, the first breeding record was in 2001xvii with an increase to four pairs by 2006xviii and ten pairs in 2014xix. It seems likely that they have bred there each year since then, but coverage has been incomplete. At least two pairs were reported breeding there in 2018xx and in August 2019 a pair was seen feeding two dependent young at Freston on the Orwell Estuary, which may well have come from therexxi .

Pairs of Great Black-backed Gulls are easily missed at warehouse sites, as some roof areas are likely to be out of view. In 2012 an extensive survey of Lesser Black-backed Gull Larus fuscus and Herring Gull Larus argentatus colonies was carried out in Suffolkxxii and no Great Black-backed Gulls were reported, but a survey at Felixstowe Docks will hopefully be possible in 2021. This should confirm whether numbers of breeding Great Black-backed Gulls have remained at, or above, 2014 levels.

Other sites

Away from the three prime sites, there have been published records from Ipswich (one pair in 2005); from a site in north-east Suffolk (two pairs in 2007); and from an undisclosed location (one pair in 2013)xxiii .

More recently, an adult pair was reported in the mixed-gull colony on a warehouse roof at Lawford (in Essex, but on the Stour Estuary) in 2017xxiv, but they did not breed. A pair then summered on the Stour Estuary favouring a salting on the north shore (in Suffolk) in 2018, 2019 and 2020xxv. These birds were not seen to make a breeding attempt and may have been failed breeders from another locality.

It follows from the above that there was a minimum of 13 pairs in Suffolk in 2014 (ten at Felixstowe Docks and three on Havergate), but it is not clear if the population is decreasing, stable or increasing.

Discussion

Historically, the breeding range of Great Black-backed Gull was discontinuous, with an Atlantic population extending into France and a Scandinavian population extending as far south as

Denmark, but with no breeding birds along the coasts on either side of the southern part of the North Seaxxvi. This situation began to change along the north-west coast of Europe in the latter part of the 20th Century, with the French and Danish populations increasing ahead of the first nesting on the German Wadden Sea in 1985 and in The Netherlands in 1993xxvii. There were estimated to be 60-70 pairs breeding in The Netherlands in 2013 to 2015xxviii .

It may be that our breeding birds in Suffolk derive from the population which has established itself relatively recently on the east coast of the southern part of the North Sea. There is considerable connectivity between populations of large gulls in Suffolk and in The Netherlands, with a number of records of Lesser Black-backed Gulls fledged and ringed in Suffolk subsequently breeding in The Netherlands and vice versaxxix. If this is the origin of our breeding birds, it might explain why colonisation has been concentrated in Suffolk and has not yet occurred to any degree further up the east coast of England, at locations which are further from The Netherlands.

The increase in numbers of Great Black-backed Gulls reported on passage and in winter (see above) should also be considered. It is known that birds from Norway have oversummered here as immaturesxxx and the possibility cannot be ruled out that some of these birds have entered the breeding population here as adults, rather than returning to Norway to breed. In view of the small number of breeding adults in Suffolk, however, we do not yet have any ringing returns to confirm from where any of our breeding birds have originated.

Little seems to be known about the behaviour or ecology of the Great Black-backed Gulls which are breeding in the county, in particular whether they are feeding inland, along the coast or at sea. At Landguard, breeding birds from Felixstowe Docks have been seen to steal Rabbits Oryctolagus cuniculus initially taken by Herring Gullsxxxi and on the Stour Estuary, the summering pair has been seen to catch flatfish at low tide and to hunt Shelduck Tadorna tadorna chicks in late summerxxxii .

Juvenile Great black-backed Gull  

Russell Boland

It is too soon to predict the level at which our breeding population of Great-black Backed Gulls might stabilise. It is notable that the early breeding attempts in the county were within gull colonies at natural sites. It may be that predation by Red Foxes has been, and continues to be, a factor which limits success at such sites and that future breeding attempts may be concentrated on warehouse roofs. The fortunes of the species as a breeder at warehouse sites will depend amongst other factors on how far gull colonies are tolerated or controlled.

Request for observations

It may be that breeding attempts by Great Black-backed Gulls are going unnoticed or unreported in Suffolk. Observers are encouraged to submit observations to the relevant recorder so that we can build up a better picture of the breeding status of this species in the county.

Acknowledgments

Many thanks to Aaron Howe, John Grant, Mike Marsh, Nigel Odin, Steve Piotrowski, Pete Rock, Paul Roper, Adam Rowlands, Andrew Stoddart, David Walsh and Justin Zantboer for patiently responding to my enquiries and for their help with this note.

i Breeding Birds Atlas 2007-11, BTO ii The Birds of Suffolk, ed. Piotrowski S H. Christopher Helm London, 2003 iii Andrew Stoddart, pers. comm. iv The Birds of Essex 2007 v London Bird Reports 2008-2018 vi The Birds of Suffolk, note ii above vii Mike Marsh, pers. comm. viii Suffolk Bird Reports 2014, 2015, 2017 ix Landguard Bird Observatory x The Birds of Suffolk, note ii above xi The Birds of Suffolk, note ii above xii Mike Marsh, pers. comm. xiii Steve Piotrowski, pers. comm xiv The Birds of Suffolk, note ii above xv Mike Marsh, pers. comm. xvi Aaron Howe, pers. comm. xvii The Birds of Suffolk, note ii above. xviii Suffolk Bird Report 2016 xix Pete Rock, pers. comm. xx Mike Marsh, pers. comm. xxi Ed Keeble, pers. obs. xxii Suffolk Bird Report 2012 xxiii Suffolk Bird Reports 2005, 2007, 2013 xxiv Rick Vonk, pers. comm. xxv Ed Keeble, pers. obs. xxvi The Birds of the Western Palearctic, Vol iii Oxford University Press, 1983 xxvii Bird Atlas Netherlands https://www.sovon.nl/en/birdatlas xxviii Great Black-backed Gull Larus marinus. Latest newcomer as breeding bird in the Netherlands Ben J. Koks & Mat G. M. Jongenelen SULA 12(4): 203-208 (1998) xxix Mike Marsh, pers. comm. xxx Mike Marsh, pers. comm. xxxi Nigel Odin, pers. comm. xxxii Ed Keeble, pers. obs.