[Based on an item from Birdwatch (2002) 118: 12, which appeared under the title "The changing fortunes of white-winged gulls at Midlands roosts"]
Herring Gull Intro text
Wintering Glaucous, Iceland and Herring Gulls in the Midlands
Data from regular observations and counts at gull-roosts in the West Midlands Region indicate that changes are taking place in the status of several species. Much of the enthusiasm among observers at gull-roosts involves the chance of finding the so-called 'white-winged gulls', Glaucous Gull Larus hyperboreus and Iceland Gull L. glaucoides, small numbers of which visit the region from the arctic during the mid-winter months.
The status of these two species appears to be changing but changes are also apparent among relatively common species such as Herring Gull L. argentatus. In summary, Glaucous Gulls are declining but Iceland Gulls are becoming more regular. Prior to the 1990s Glaucous Gull was a considerably more regular visitor than Iceland Gull. At many sites, the numbers of Herring Gulls are declining.
By the mid-1970's the historical counties of Warwickshire, Worcestershire and Staffordshire had accumulated totals of around 65 Glaucous Gulls and 50 Iceland Gulls, with 85 percent of those totals in the decade since 1966 (Dean and Dean, 1976, 'Glaucous and Iceland Gulls in the West Midlands', British Birds 69: 179-180). For some years thereafter Glaucous Gulls remained more numerous than Iceland Gulls (and tended to remain in the region longer). Indeed, in 1980 (an exceptional year admittedly) there were around 40 Glaucous Gulls recorded in the three counties, compared with only five Iceland Gulls.
Since about 1990, however, there has been a shift and Iceland Gull has now become the commoner visitor. Individual gulls clearly move between different feeding and roosting sites during the course of a winter. Thus, published records in the annual West Midland Bird Reports inevitably involve some duplication, while new arrivals early in the 'current' year are not always distinguished from individuals remaining from late in the previous year (such individuals thus appearing in two successive reports). The following figures have attempted to allow for these factors but are inevitably approximations; however, they do illustrate the long-term trend.
Between 1980 and 1999, the West Midland Bird Reports show that in the three counties there were approximately 305 Glaucous Gulls compared with 258 Iceland Gulls, but with five-yearly totals as follows:
Thus, during the 1990s, Glaucous Gulls declined but Iceland Gulls increased.
During the same period in which Glaucous Gulls have declined there has also been a decline in the numbers of Herring Gulls wintering at many sites. The WMBC report for 1995 noted that the species was 'scarcer than a decade ago'. At some roost sites Herring Gulls are now very much in a minority compared with Lesser Black-backed Gulls L. graellsii. This decline probably has a number of contributory factors, as Herring Gull breeding populations are declining in some regions of Europe, but a significant factor at the local level is certainly the changes in methods at many landfill sites. Newer, 'rapid burial' and other techniques mean that open refuse is no longer so readily available to gulls. At such sites and their associated roosts Herring Gull numbers will inevitably decline. The exception which proves the rule is the huge landfill site at Cannock, in Staffordshire. Operations there are such that feeding remains available to gulls. At the associated Chasewater roost, peak numbers of wintering Herring Gulls reported in the WMBC reports have varied quite widely from year to year but the 'running mean' has remained fairly constant, at around 2000, throughout the 1980s and 1990s. This area also remains a regular area for both Glaucous and Iceland Gulls.
[Editorial postscript: Since this was written, the site operators have begun flying raptors to disperse the gulls at Cannock, and numbers have declined in consequence.]
The Herring Gulls at Cannock and some other large sites in the West Midlands have been considered to include a significant percentage of Scandinavian argentatus, based both on plumage characters and timing of arrival and departure (see Hume, British Birds 71: 338-345, and Dean, British Birds 80: 632-633).
Although Glaucous Gulls may originate from both the north-west and the north-east, it may well be that a significant proportion of arrivals of Glaucous Gulls correlate with arrivals of Herring Gulls from the north-east. If wintering Herring Gulls decline, it may then be expected that records of Glaucous Gulls will also decline. Iceland Gulls, conversely, originate only from the northwest and their arrivals will not be associated with those of north-easterly Herring Gulls.
The days of large inland wintering populations of Herring Gulls and their scarcer relatives, from whatever source, may be numbered. Herring Gulls wintering inland appear to be more highly dependent upon landfill sites than are Lesser Black-backed Gulls, for example. If recently drafted EU directives are imposed, restricting the level of organic materials at tips to a very low level (<3% Total Organic Content), then inland wintering populations of Herring Gulls may be severely reduced. In some parts of Germany, for example, where landfill-content directives have already been implemented, the numbers of Herring Gulls wintering at some sites have all but disappeared. At Aachen, Northrhine-Westfalia, waste disposal changed to pre-incinerated materials only between 1996 and 1997, and Herring Gull numbers dropped from 3500 to 10 (per Helmut Sang, 27 February 1998, on EuroBirdNet). If this were repeated in Britain, then not only northern Glaucous Gulls but other tip-frequenting species such Yellow-legged Gulls L. michahellis and Caspian Gulls L. cachinnans from the south and east would seem likely to be affected.
| Laughing |
Ring-billed | Common |
Lesser Black-backed |