The North-South divide for Peregrines
?new high for Peregrines breeding in the UK?It is estimated that there was a new high of 1,402 pairs of Peregrines breeding in the UK and the Isle of Man in 2002, a 9% increase since the last survey, in 1991. There is much variation across the UK, with major declines in many areas. The results are published in the latest edition of BTO News.Why all this interest in Peregrines?
The Peregrine is an icon of success for conservation. In 1961, the year of the first survey organised by Derek Ratcliffe on behalf of the BTO, Peregrines were found to have all but disappeared from southern England and were severely reduced throughout Wales, northern England, Northern Ireland and southern Scotland. The organochlorine pesticides DDT and dieldrin were soon implicated in these declines and as a result of concerted conservation efforts over decades, these pesticides were eventually phased out of use and Peregrine and other raptor populations began to recover.
Peregrines are top predators and can act as indicators of the quality of the food chain and of the surrounding environment. The UK also holds an important component of the total European population. Peregrine Surveys took place in 1961, 1971, 1981, 1991 and 2002. The 2002 survey was scheduled for 2001 but rescheduled due to Foot-and-Mouth. The aims of the survey were to visit known and potential sites at least twice in the season, to check for site occupancy by Peregrine pairs or singletons. In the past, the national Peregrine surveys have attempted to cover all known breeding Peregrine territories within the UK and Isle of Man. This is a huge task for volunteer surveyors, especially in the remoter parts of north and west Scotland. So in 2002, for the first time, BTO provided fieldworkers with a randomised selection of eyries to check and, very helpfully, RSPB organised professional fieldworkers to assist in filling some of the gaps in these areas. This randomised approach aimed to ensure a representative and unbiased coverage of those difficult-to-get-to sites.So ? what were the results?
Using the counting method that Derek Ratcliffe has used in past surveys, we can say that there were 1,402 breeding pairs in 2002, compared with 1,283 in 1991 and 874 in the 1930s (before the population crash). Thus the population has increased by 9% since 1991 and is 60% higher than in the 1930s. Since 1991, the number of known potential Peregrine territories in the UK and Isle of Man had risen by 26% to 2,032 sites. Some 1,899 of these were visited in 2002, giving a coverage of 93%. The grand total of occupied territories is now estimated to be 1,492, an increase of 13% above the 1,316 thought to be occupied in 1991. This figure is based on observed occupancy at 1,415 sites, with an additional 77 unvisited sites predicted to be occupied (estimated by multiplying regional occupancy rates by numbers of un-surveyed eyries). We can also estimate how many breeding pairs the UK and Isle of Man actually supports, taking into account that unmated birds occupy some of the territories. Using the counting method that Derek Ratcliffe has used in past surveys, we can say that there were 1,402 breeding pairs in 2002, compared with 1,283 in 1991 and 874 in the 1930s (before the population crash). Thus the population has increased by 9% since 1991 and is 60% higher than in the 1930s.Peregrine numbers have continued to expand in some areas, particularly southern and central England, where they have recolonised the southeast coast and expanded into inland counties where Peregrines have not previously been recorded. They have also increased in south Wales, parts of northern England and southern Scotland. These increases have occurred through the use of new sites, particularly in quarries and on tall buildings. The declines in Scotland have generally been attributed to food shortage, possibly due to the declines in productivity of moorland, associated with over-grazing and regular burning, although research is needed to investigate these possibilities. In coastal areas, marine pollution has been suggested as a reason for declines, as well as the influence of Fulmars that defend their nests from attack by regurgitating foul oil over intruders, such as Peregrines. The decline in breeding pairs in north Wales is a new phenomenon that may also be linked to declines in prey availability. Substantial declines have been recorded among upland and moorland birds in Wales over the last decade. Surveyors indicated that failures and desertions at 95 sites across the UK may have been due to persecution which, for example, appears to explain absences from some traditionally occupied sites in certain parts of Scotland. The declines in north and western Scotland (dating at least from 1971) have continued, with 30% declines recorded in the Highland region between 1991 and 2002. Shetland now has no breeding Peregrines at all. This phenomenon has apparently spread further south, with 30% declines also occurring in Argyll, a decline of 15% in inland north Wales and a decline of 12% in inland Northern Ireland. These declines have been generally attributed to food shortage, marine pollution and in some areas persecution. The UK and Isle of Man holds about 15% of all Peregrines in Europe, so we have a special responsibility to steward these populations. It is important for government and conservation organisations to receive up-to-date population estimates to ensure that these populations are being maintained. Snippets from the Survey
* The most inhospitable site for a nesting peregrine was probably a maintenance platform of a chemical works. It was within 4m of a conveyor belt that carries 1,200 tonnes of limestone per 24 hrs! Very noisy and loud. The pair regularly raises young successfully.
* At one site the male started hunting at night and, although the main prey was Starling, it was also recorded bringing in Sanderling, Dunlin, Knot, Water Rail, Moorhen, Ringed & Golden Plovers, Lapwing, Woodcock, Snipe, Slavonian Grebe, Redwing, Song Thrush, Blackbird, Fieldfare, Kittiwake, Teal and Redshank.
* Well-publicised examples of birds nesting on buildings include those nesting on Battersea Power Station in London and Chichester Cathedral in Sussex. Other man-made sites included bridges, a castle, power stations, a radio mast, a gasometer and a railway station.
* One nest was destroyed by goats!The BTO would like to thank all the volunteer birdwatchers, many of whom are in Raptor Study Groups, for the great efforts that they put into checking and re-checking known and potential Peregrine nesting sites. We are particularly grateful to all the volunteer local area coordinators who liased with the surveyors to ensure such a complete coverage for the survey. Many thanks are also due to Derek Ratcliffe, who has advised on many aspects of the survey and its analysis.They are also pleased to acknowledge the support and funding for the survey by the Esm?e Fairburn Foundation, by the businesses, individuals and trusts supporting the BTO Peregrine Appeal and by the Environment and Heritage Service, Department of the Environment (Northern Ireland) (on behalf of the Statutory Conservation Agencies/RSPB Annual Breeding Bird Scheme (SCARABBS)) and the Scottish Ornithologists` Club. Professional fieldwork in Scotland was organised and managed by RSPB with funding from RSPB and Scottish Natural Heritage.
For further information please contact: Humphrey Crick on 01842 750050 or e-mail: email@example.com during office hours or 01763 838032 evenings/weekends or Graham Appleton on 01842 750050 or e-mail: firstname.lastname@example.org during office hours
4th July 2014