Monitoring and conserving Scotland's birds of prey
The common buzzard is now living up to its name. Formerly widespread throughout Scotland it was subject to much persecution during the 19th and much of the 20th centuries, and as a result was restricted to the more upland areas of north and west Scotland, though often at quite high densities. In the last 20-30 years there has been a considerable range recovery into eastern Scotland and the central belt; so much so that this species is now the commonest raptor in Scotland. The BTO Breeding Bird Survey showed a 33% increase in numbers in Scotland between 1995 and 2010. It is now to be seen soaring over most of the Scottish countryside giving its characteristic loud mewing "piiyay" call or perched on poles and even on street lights at the edge of some of our largest towns and cities.
The common buzzard is a very adaptable species. Although its preferred prey is vole and young rabbit it will take an exceptionally wide range of prey. These include other small mammals such as mice and moles, a wide range of birds from goldcrests to gulls, amphibians such as frogs and toads, reptiles including adders and lizards, invertebrates such as earthworms and large beetles and, particularly in the non-breeding season, carrion. They have a range of hunting strategies such as hovering, low level flight strikes, pouncing on prey from a variety of perches and walking over fields looking for invertebrates. Because of their very catholic choice of diet common buzzards can be found in a very wide range of habitats from upland moorland, through forestry plantations to intensively farmed agricultural land. The species probably reaches its highest densities in areas of mixed countryside where there is a mix of open land for hunting interspersed with small woodlands, which provide nesting sites.
Buzzards are also very adaptable in their choice of nest site. The preferred nest site would be about two-thirds up a fairly mature tree (coniferous or deciduous) situated within a small wood, but fairly close to a clearing, a woodland ride or in larger plantations, the woodland edge. In such situations in ideal countryside nests can be found in a fairly regular pattern with birds distributed up to 1km apart. If suitable nesting habitat is not available that does not necessarily deter them from breeding. In upland areas and at the coast they will nest on crags. In a lowland study area in Easter Ross they have been recorded nesting in isolated bushes, on the roof of disused buildings and on the ground on the edge of drainage ditches.
Buzzards tend to lay 2-4 eggs, but occasionally single egg clutches are produced and in exceptional cases up to 7 eggs have been recorded, though these larger clutches probably involve two females laying in the same nest. Overall breeding success varies from location to location. A study in the north of Scotland showed that in the prey rich coastal plain of west Moray each nesting pair produced an average of 2.2 young per attempt, whereas those in Glen Urquhart 65km to the west produced only 1.1 young. There was also much annual variation in breeding output of the Glen Urquhart birds, probably associated with vole abundance cycles.
In southern Scotland a study showed that lagomorphs, voles and birds formed over 70% of the food items analysed from prey remains and pellets collected at nest sites. Indices of prey abundance differed significantly between habitat types. The percentage of lagomorph in buzzard diet in different localities was significantly correlated with the index of lagomorph abundance; no such correlation was found between the percentage of vole in buzzard diet and an index of vole abundance. The mean nearest-neighbour distance between buzzard nests was 1.9km. There was a significant negative correlation between nearest-neighbour distance and lagomorph abundance. It appears that lagomorphs were the primary prey which influenced the diet and breeding density of buzzards in the study area.
A study comparing buzzard breeding success in Argyll with other areas of Britain also found clutch size to be low in areas where rabbits were scarce and birds were an important component of the diet. The study also showed marked differences in hatching and fledging success between different areas in Britain. Buzzards in Argyll, despite laying comparatively small-sized clutches, had among the highest fledging success of any area. This was largely due to high egg survival. Human predation is unimportant in Argyll, but in some other areas of Britain it contributed to reduced breeding success.
Buzzards are highly territorial and remain on or close to their territories throughout the year. At the end of summer juveniles start to disperse, though according to the Migration Atlas most do not move far with a median mid-winter dispersal distance of only 18km.
At the moment common buzzards are thriving throughout most of Scotland. There are, however, still some gaps in their distribution. This is because they are vulnerable to illegal persecution, which still unfortunately exists in many areas.
Austin, G.E. and Houston, D.C. (1997). The breeding performance of the Buzzard Buteo buteo in Argyll, Scotland and a comparison with other areas in Britain. Bird Study 44:146-154.
Graham, I.M., Redpath, S.M. and Thirgood, S.J. (1995). The diet and breeding density of the Common Buzzard Buteo buteo in relation to indices of prey abundance. Bird Study 42:165-173.
Swann, R.L. and Etheridge, B. (1995). A comparison of breeding success and prey of the Common Buzzard in two areas of northern Scotland. Bird Study 42:37-43.
White Tailed Eagle•
Hen Harrier• Goshawk• Sparrowhawk• Common Buzzard• Golden Eagle
Osprey• Kestrel• Merlin• Hobby• Pergrine Falcon• Barn Owl
Tawny Owl• Long-eared Owl• Short-eared Owl• Raven