Introduction by Ian Newton
Many people enjoy the fun and excitement of Atlas work. It has also given some observers their rewarding first taste of systematic bird recording. The collective efforts of large numbers of observers, each working to a consistent methodology in a different area, gives Atlas projects their special value. After the fieldwork is done, and the results are analysed, they provide an accurate snapshot of bird distributions at the time, and provide a firm basis for assessing future distributional changes. Not surprisingly, Atlas results now play a vital role in setting national conservation policy. For example, they feed invaluably into Biodiversity Action Plans (BAPs) and into the Red and Amber listing system for species of conservation concern. For all these reasons, it is a pleasure to welcome this new Atlas, which maps the distributions of bird species across Cheshire and Wirral in the period 2004–06 (and early 2007 for wintering birds).
This is not the first Atlas to be produced for this region. Its predecessor covered the period 1978–84, but dealt only with summer breeding birds. This new Atlas updates the findings for breeding birds, showing the main distributional changes that have occurred in the intervening twenty years, and also provides information at the same scale for wintering birds. In addition, for the recording of breeding status, three categories are used (confirmed, probable or possible, with supporting details), rather than the two categories (breeding and seen) widely adopted in previous Atlases.
The publication of this new county Atlas coincides with the start of a new national Atlas project, run by the British Trust for Ornithology (BTO), which is scheduled to cover the period 2007–11. Like previous national Atlases, it will map bird distributions in 10 km squares. Set against these national projects, local Atlases generally operate at finer scales. This new Atlas for Cheshire and Wirral shows birds in every tetrad (2 × 2 km square) rather than in every 10 × 10 km square, giving 25 times more resolution. This extra detail can give early warning of distributional changes not visible at a national level. For instance, widespread species such as Skylark and Linnet have shown large population declines over the past twenty years, but their distributions have not noticeably contracted at the scale of the 10 km square. In Cheshire and Wirral, both species still breed in every 10 km square but, since the previous Atlas, the Skylark has gone from 150 tetrads (almost one-quarter of the county’s 670) and the Linnet from 161. Such fine-scale information helps to alert us to ongoing distributional declines not yet obvious at the larger scale, and helps to set the context for Local BAPs and county-level conservation targets.
Two other novel aspects of this new Cheshire and Wirral Atlas warrant comment, as they could also be employed in other counties. In collaboration with the BTO, the county’s population of more than sixty breeding species was estimated from the Breeding Bird Survey transects and, for many species, maps show relative abundance across the county. The difference between distribution and abundance can sometimes be striking: the House Sparrow, for instance, is no longer amongst the top ten most widespread species in Cheshire and Wirral, but remains the most numerous.
The other new feature of this Atlas is the recording of habitat alongside every bird record. Using an easy but effective coding system, already familiar to participants in BTO surveys, the habitat data provide insights into the factors underlying species’ distributions. They have additional value when linked with land-use statistics from the Centre for Ecology and Hydrology at Monks Wood, Cambridgeshire. Simply recording the size and type of waterbody, for instance, confirms that several species of waterfowl, including Canada Goose, Greylag Goose and Coot, now readily breed on ponds and small waters, but in winter almost all move to lakes and reservoirs, especially Cheshire’s meres.
The organizers of this Atlas were intent on completing the work in as short a period as possible to avoid the distorting effect of population changes during the survey period: the county’s First Atlas took seven years of fieldwork (1978–84), during which the populations of several farmland species halved as agricultural changes took effect. On the other hand, the benefits of shortening the survey period had to be balanced against the numbers of dedicated fieldworkers available, and the desire to record as high a level of proof of breeding as possible. A three-year project was an acceptable compromise, and the organizers have followed this up with rapid progress towards publication.
As the years pass, some may remember this Atlas project for particular events, such as the discovery of a wintering Pallas’s Warbler, the first breeding in the county of Mediterranean Gull, the largest recorded winter numbers of Leach’s Petrels, or the unprecedented invasion of Waxwings in the winter of 2004–05. However, the major value of the Atlas is in quantifying recent distributional changes, as shown, for example, in the welcome spread of some raptors. During 1978–84 the Buzzard was present in just 10 tetrads and was proved to breed in only two, yet in 2004–06 it was found in no less than 560 tetrads, breeding throughout the county except for treeless areas and conurbations. Twenty years ago, no Hobbies were found breeding in the county but, during the current Atlas period, around 50 pairs were found. Peregrines and Ravens showed similarly impressive range expansions. It was also good to learn of the ample distribution and high population of breeding Swallows; and that Grey Herons may be more numerous here than in any other part of England, benefiting from what gave Cheshire its reputation as the pond capital of Britain. On the other hand, this book documents the rapid demise of the Turtle Dove, present in more than one-fifth of the county twenty years ago, but now apparently no longer breeding here. Likewise, the Yellow Wagtail, for which Cheshire was once renowned, was found in 385 tetrads in 1978–84, shrinking to 126 tetrads in 2004–06. Similar statistics are given for some other declining species.
Turning to wintering birds, Cheshire and Wirral cover one of the most important regions in Britain for waterbirds,
as confirmed by recent Wetland Bird Surveys. This is not surprising, for in addition to abundant fresh waters, the area contains two internationally important estuaries, the Dee and the Mersey, which still support large numbers of wintering wildfowl and waders. Some other wintering species have become more numerous over the past twenty years, probably benefiting from the warming climate. In the recent survey, wintering Blackcaps were present in almost one-quarter of the county, and wintering Stonechats were also more numerous than ever before. Some other resident species show intriguing differences between their distributions at the two seasons. For example, the maps show a winter withdrawal of Dippers from high to low ground within the county, not previously quantified.
Wherever one dips into this publication, there are gems to be found, and many of the findings provoke suggestions for further work. This Atlas results from more than 50,000 hours of fieldwork from hundreds of ‘citizen scientists’. It gives unprecedented understanding of the region’s birds. I congratulate Cheshire and Wirral Ornithological Society and their members and other fieldworkers in delivering this Atlas, all operating under the inspirational leadership of David Norman. Whether you live locally or further afield, you will find much of interest in the pages of this volume.
OBE FRS FRSE