Comments on Letter: Breeding Honey-Buzzards in Britain, published May 2003
References:
Collins Bird Guide, Mullarney, K, Svensson, L, Zetterström, D, & Grant, Peter J, (2001), Collins Field Guides, HarperCollins, London.
Combridge, P, Christie, D A, & Ferguson-Lees, J, (2003), Breeding Honey-Buzzards in Britain, British Birds 96(5) p.258-260.
Ferguson-Lees, James, and Christie, David A, Raptors of the World, Christopher Helm (2001).
Roberts, S J, & Lewis, J M S, (2003), Observation of Honey-buzzard Breeding Density in Britain, British Birds 96(1) p.37-39.
Introduction:
The letter cited above by Combridge, Christie & Ferguson-Lees is essentially a reply to recent publications by Roberts, the most recent of which is also cited above. The letter stresses that:
Earlier published totals for populations of Honey Buzzards Pernis apivorus are certainly too low because of observers withholding information.
We therefore cannot compare current more open breeding figures with those from the past.
Breeding was widespread in the past in the New Forest, Scotland, north east England, midland England and Wales.
Data previously withheld should now be deposited with the Rare Breeding Birds Panel.
The current population trends for Honey Buzzards in Britain are uncertain.
All the above, other than the last statement, seem eminently reasonable. However, it is possible that in some respects the authors of the letter are missing the big picture:
The Honey Buzzard in the last two to three decades has extended its range in north west Europe to colonise more maritime areas: Holland, Belgium and the Atlantic coast of France. There must be pressure on birds from these areas to move further north west still into Britain.
Persecution of most raptor species by game estates has substantially declined since 1990 enabling such species as the Common Buzzard Buteo buteo to undergo a dramatic range expansion in eastern Britain. Before 1990 prospecting Honey Buzzards in eastern Britain would have been shot.
The amount of forest in northern and western Britain has increased enormously since 1926 when the Forestry Commission was established. The considerable contribution of Roberts and his team in Wales is to show that this very large volume of woodland can be utilised successfully by Honey Buzzards.
Identification is regarded as a simple matter by the authors of the letter. So all sites are evidently known. Yet to survey the large areas of woodland in areas sparsely occupied by birders requires expertise in separating Honey Buzzards from Common Buzzards at long distances of two to five kilometres. Furthermore periods of activity can be very brief. Field guides until recently concentrated on plumage features which are more variable than is generally conceded and illustrated birds on migration in classical, sometimes almost caraciture, poses photographed under ideal lighting conditions. Experience at western Mediterranean migration points does not develop skills in separating Honey Buzzard from Common Buzzard as the latter is an infrequent crosser this far south. Recent publications are better such as the Collins Guide (2001) and Ferguson-Lees & Christie (2001). Both of these document the calls as well as stressing structural and jizz features more. However, many observers still seem to regard the 'three tail bands' as crucial for Honey Buzzard identification and this will have led to a significant under-recording of the species in Britain.
The number of birds recorded on passage in Britain has greatly increased. Obviously the 2000 movement was exceptionally visible because of the weather conditions and the successful breeding season but numbers are on a general upward trend. Some birders think that the increase in passage birds is due to more Scandinavian birds passing through Britain. This though seems very fanciful as the Swedish population has been declining steadily over recent years.
None of these 'big picture' points on their own might be that significant but taken together, they provide the context for a steady rise in the Honey Buzzard population in Britain since around 1990. The view of the current status of the Honey Buzzard in Britain seems to be linked very much to the relationship assigned between the number of pairs found (69 in the 2000 survey) and the actual number of breeding pairs. On the one hand a conservative ratio of 1:1 can be assigned (assuming all nests known) and on the other a ratio of 1:5 as found for the Hobby Falco subbuteo. Observers in southern England tend to go for a ratio of 1:1, those in the north and west, with vast amounts of habitat to search, to a higher figure. Strategically the idea that all nests can be found for a difficult to identify, highly secretive, short-stay summer migrant occupying a broad range of habitats with brief periods of visibility seems to be very fanciful.
© Copyright Nick Rossiter 2004
