In recent years both the popular press and some scientific journals have done much to highlight the climatic changes that are being brought about as a result of man-induced climatic processes, particularly through the burning of fossil fuels. Most of these accounts have placed the emphasis on temperature change, the so-called ‘global-warming’ effect, with the popular press in particular stoking the myth that the North of England will soon be basking in temperatures akin to those of the Channel Isles, if not the Mediterranean!

The reality is that the effects of climate change are likely to take place in a fairly gradual fashion, with the latest report of the UK Climate Impacts Programme [Hulme and Jenkins (1998): UKCIP Technical Report No. 1, Climatic Research Unit, Norwich] suggesting that the most likely climate scenario for Northwest England and South Scotland over the next 30 years could see:

• a rise in temperature of between 0.5 and 1.2 degrees Celsius relative to the 1961/1990 mean (with every degree increase moving us the equivalent of some 250 km/155 miles southwards, or approximately as far as South Wales);

• a similar magnitude of temperature increase between both summer and winter;

• a rise in the annual level of precipitation by between 3% and 6% compared to the 1961/1990 mean;

• this increase in precipitation being mainly concentrated in the period December to May, with a rise of between 5% and 12%, compared to between 1% and 2% for the period June to November.

This picture of a more oceanic climate, in which the increased incidence of westerlies and cyclonic conditions produce warmer and wetter weather throughout all seasons and especially during Winter and Spring, rings particularly true in the light of our experience over the last several months. It is likely to be associated with increased cloud cover, a reduced incidence of frost, a decrease in the diurnal temperature range and less winter temperature variability. Still a far cry from the sizzling temperatures eschewed by the popular press!

So what of Cumbria’s birds?

The extent to which anticipated changes in climate will impact positively on existing bird populations within Cumbria is very much a matter for debate, for although milder winters may assist the winter survival rates of birds such as the Little Grebe, Grey Wagtail, Kingfisher, Blackcap and Goldfinch, the increased incidence of precipitation, particularly in Spring, could have a counterbalancing effect through the flooding of nest sites and a reduction in food sources, with ground-nesting and insectivorous birds being particularly hard hit. Only through the continued and systematic monitoring of the population of some of Cumbria’s commoner bird species, using output from schemes such as the BTO’s Breeding Bird Survey, the Nest Record Scheme and Constant Effort Ringing Sites, will it be possible to reach an informed judgement regarding such issues.

There is a strong likelihood that some birds which currently have a southerly bias to their breeding range within Great Britain will see an increase in status within Northern England in response to climatic changes. Recent work at the University of Leeds [Thomas and Lennon (1999) Nature 399, p. 213] has shown that in the 20 years between the two national breeding Atlases, for example, bird species such as the Nuthatch, Reed Warbler, Lesser Whitethroat and Jay which have a predominantly southern distribution in the UK shifted their range margin northwards by approximately 19 km (12 miles) on average. It is anticipated that the Bird Club’s own Atlas of Breeding Birds will provide further evidence of the gradual northwards advance of birds such as these. It will also provide an important yardstick against which to assess future changes in the population of birds such as the Water Rail, Yellow Wagtail, Lapwing and Rook, which may be displaced from parts of Southern and Eastern England by the warmer and drier conditions that are likely to prevail within that area over the next 30 years and the consequent land use changes that these drier conditions are likely to bring about.

There is already evidence that global warming is resulting in a gradual increase in sea level as a result of the melting of the world’s ice-caps. As this trend continues it is likely to impact adversely on wintering wader populations, through a reduction in the intertidal areas around parts of our coast on which these birds rely for their food resources and also in the duration that such areas are uncovered during the tidal cycle. This, too, calls for increased attention to population monitoring so that corrective action can be taken wherever feasible, with the Wetland Bird Survey (WeBS) High and Low Tide Counts both having a crucial role to play in this respect.

Incorporation of the results of these and other systematic monitoring schemes into future County Bird Reports, thereby ensuring that these Reports provide maximum benefit in terms of nature conservation, is an issue that is currently under examination by a small Sub-Committee that has been set up under the Chairmanship of Dave Shackleton by the newly-elected Council of Cumbria Bird Club.