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The Common Buzzard in Britain: A new population estimate
Abstract
During recent years, the Common Buzzard Buteo buteo has spread eastwards from its former strongholds in western and northern Britain. At the same time, there is evidence that the species is now breeding at a much higher density than previously recorded, largely as a result of consolidation and in-filling in areas of prey-rich farmland habitat. An increase in the Rabbit Oryctolagus cuniculus population, and a reduction in persecution are both likely to be important contributing factors. This paper summarises recent data on Common Buzzard population densities from survey work in many parts of Britain. A new national population estimate, based on an analysis of the habitats found in its range, suggests that there were between 44,000 and 61,000 territorial pairs in 2001. Consequently, the Common Buzzard is probably now the most abundant diurnal raptor in Britain.
... Across Europe, the common buzzard Buteo buteo is considered to have one of the greatest impacts on game hunting, second only to goshawks Accipiter gentilis (Kenward 2002). In the UK, the population has shown substantial increases, including an eastward range expansion, and has become the most abundant diurnal raptor in Britain (Clements 2000(Clements , 2002. The British Trust for Ornithology's Breeding Bird Survey reports regional 'short-term' trends in populations of buzzard between 1995 and 2011: UK +80 %*, England + 167 %*, Scotland +31 %*, Wales +4 % (*statistically significant; Risely et al. 2013; BTO/JNCC/RSPB). ...
... It is important to note that the most recent empirical studies on levels of impact were completed around 20 years ago (Kenward et al. 2001), and in some cases over 35 years ago (Lloyd 1976a). Over the ensuing period, the populations of common birds of prey have undergone various changes in numbers and range; for buzzard, significant population growth and range expansion has occurred (Clements 2000(Clements , 2002. Investigations of the extent and magnitude of the impacts of buzzards and other birds of prey at release pens have not been undertaken widely in the context of the current status of raptor populations. ...
... A number of factors potentially mitigate an effective outcome of buzzard translocation in the UK. The increase in their numbers and range (Clements 2000(Clements , 2002, together with the density and distribution of pheasant shoots, will limit opportunities for suitable release sites. A key decision when considering translocation to reduce conflict is whether there is any real benefit in moving individuals of a species that is at carrying capacity in all areas in which there is suitable habitat (Kenward 1999(Kenward , 2002. ...
In the UK, alongside an expanding common buzzard population, there is increasing concern of raptor predation at pheasant release pens. Historically, losses of poults to raptor predation has been low, commonly (90 % of shoots) ≤1 % of birds released into pens, representing a small percentage of losses relative to all causes of mortality. A small number of shoots did suffer higher losses, estimated at >5 % at one in 30 estates and >10 % at some estates. Predation was lower (i) with increased poult age at release, (ii) in later releases, (iii) in pens with good vegetative cover, (iv) in pens within woods
... This can be easily interpreted considering that during breeding sessions, individuals were less detectable because of restricted activity and high development of vegetation. Moreover, as already pointed in method section and following assumptions of Clements (2003), we may also obviously suppose that sessions performed outside breeding season included both wintering sedentary and semi-migratory or nomadic individuals. Such seasonal fluctuations were neglected and only between-year fluctuations make sense and were considered in our study. ...
There are serious concerns about the ecological degradation caused by modern agriculture and its impact on top-chains predators. But, scientists still disagree on how to assess which are the winners and losers of Anthropocene biodiversity changes.
In this field of research, many studies have been carried out on passerine birds but long-term ones, and especially on raptors, are still missing. Our study reports a twelve-year survey on two diurnal common raptors (the Buzzard, Buteo buteo and the Eurasian kestrel, Falco tinnunculus) facing recent land use changes in Western France farmland landscapes. Precise remote sensing data were analyzed each year, allowing us to precisely describe land use changes and stability along this time series.
Buzzards showed reduced abundances in intensified landscapes and responded negatively to wood habitat instability while kestrels were more abundant and stable when areas of meadows increased. According to life history traits of these two-raptor species, we may suppose that buzzards, as generalist predators, mainly suffer of nesting site decrease while kestrels suffer of food depletion and namely voles living in meadows.
No decreasing or increasing regional or local trends was observed for buzzards during these 12-years confirming that populations seem adjust their numbers to fit to local resources. Inversely, kestrels exhibit significant population collapses at both regional and local scales.
If limiting wood habitats fragmentation or disturbance would optimize buzzard densities, drastic management measures improving surfaces and quality of grassland habitats will be necessary to reverse the decline of the Eurasian kestrel, highlighted by this study.
... The British population of the Common Buzzard Buteo buteo increased substantially during the late 20th and early 21st centuries (Clements 2002;Balmer et al. 2013), largely due to a reduction in persecution (Forrester et al. 2007). The increase saw the species become one of the commonest, most widespread midtrophic-level avian predators in Britain. ...
A long-term study of the Common Buzzard Buteo buteo population on the islands of Colonsay and Oronsay, Argyll, was carried out during 1988-2019. Until 2010, the islands held between 18 and 28 occupied territories. Subsequently, numbers dropped to 8-9 pairs while, at the same time, there was an increase in the numbers of Golden Eagles Aquila chrysaetos and White-tailed Eagles Haliaeetus albicilla present on the islands. Competition for food and nest sites and direct predation are believed to be factors in the decline of Buzzard numbers on the islands. Buzzards switched their prey away from European Rabbits Oryctolagus cuniculus in response to declining prey availability during the study period. An increase in the diversity of diurnal raptors was noted with the increasing density of eagles and the decline in Buzzards.
... banning of organochlorine pesticides and comprehensive legal protection) and increasing public awareness have led to a significant increase in the species' population size and range. Most recent assessments indicate that the species has now recolonized many of the areas of the UK from which it had been lost (Clements 2002. ...
Capsule: Distance sampling identified an increase in estimated population size of Common Buzzards Buteo buteo in central southern England between 2011 and 2016 of more than 50%. The rate of population growth slowed in later years.
Aims: To assess the utility of a targeted distance sampling protocol to derive seasonal and annual population estimates for Common Buzzards across an area of southern England.
Methods: We used a line transect survey methodology and multiple covariate distance sampling to assess population density and abundance of Common Buzzards in spring and autumn between 2011 and 2016 across a 2600 km² area of central southern England.
Results: Estimated population size increased by more than 50%, from approximately 2900 to 4500 individuals, across the period in a trend similar to that shown by Breeding Bird Survey data.
Discussion: A slowing of the growth in population size of Common Buzzards in central southern England suggests that the species may be approaching carrying capacity in this area. These results also suggest that currently employed broad scale survey methodologies adequately reflect the general population trends for this species. Our data provide the first published estimates of the Common Buzzard population in central southern England derived from direct empirical assessment.
... In most areas this represents a recolonization of previously occupied range, following decades of persecution and indirect organo-chlorine poisoning (Newton 1979, Dare 2015. Buzzards are now the most abundant diurnal raptor in Britain (Clements 2002), with a recent population estimate of 56 000-77 000 breeding pairs (Musgrove et al. 2013). This population increase and range expansion has reignited conflict between stakeholders concerned with raptor conservation and those involved in gamebird management (Lees et al. 2013, Parrott 2015. ...
Capsule: The winter diet of Common Buzzards Buteo buteo on a Red Grouse Lagopus lagopus scotica moor was dominated by small mammals, whilst grouse were a minor prey item.
Aims: To assess winter diet of Common Buzzards from pellets collected at roost sites on and around a managed Red Grouse moor, and to explore temporal, spatial and age-related variation in diet composition.
Methods: Forty-four winter roost sites were located during two winters using a combination of observations from vantage points and individual Common Buzzards equipped with either radio or satellite transmitters. Pellets were collected between October and March each winter and analysed to assess dietary composition.
Results: Small mammals were the main prey in both years, comprising 60–67% of items and occurring in 88–92% of pellets. Diet varied between years, with more lagomorphs and birds (passerines, corvids and pigeons) but fewer Red Grouse eaten when grouse abundance declined. Grouse formed 1.1% and 0.6% of prey items, and occurred in 3% and 2% of pellets from each winter, respectively.
Conclusion: Common Buzzards rely on small mammal prey during winter. When available, Red Grouse are a minor dietary component, the amount of which reflects their abundance in the environment. The opportunism of Common Buzzards can result in temporal variation in winter diet.
... The Kestrel Falco tinnunculus was the most abundant raptor until the last couple of decades, when it was overtaken by the Buzzard Buteo buteo (Clements 2002). The Honey Buzzard Pernis apivorus and Montagu's Harrier C. pygargus are the least abundant breeding species . ...
This paper summarises monitoring of raptors (diurnal birds of prey and owls) in Great Britain. There is a long tradition of raptor monitoring in Great Britain, and all regularly breeding species receive at least a degree of survey coverage. Common raptors such as Buzzard Buteo buteo and Kestrel Falco tinnunculus are included in national all-species surveys coordinated by the British Trust for Ornithology (BTO), while rarer species are typically monitored in less extensive, more intensive studies conducted by specialist raptor fieldworkers. This work is supported (and often funded) by a large number of Non-Governmental Organisations (NGOs) and national government agencies. There is a need for greater coordination of local/regional study groups, which would facilitate the compilation of national-level population and productivity statistics, and also identify areas and/or species that require better survey coverage. There is potential for the better use of data collected by fieldworkers to provide evidence of human interference in breeding attempts.
... However, there is also widespread concern about the potential impact of raptor predation on a broad range of passerine and wader species. This is partly because the size and range of many raptor populations have increased in Europe following recovery from the widespread use of organochloride pesticides and a decrease in human persecution (Elliott and Avery 1991, Newton and Wyllie 1992, Crick and Ratcliffe 1995, Newton et al. 1999, Clements 2002. It is also partly because the increase in raptors has coincided with widespread declines in the range and abundance of many species of passerines and waders across Europe (Tucker andHeath 1994, BirdLife International 2004). ...
The issue of predator limitation of vertebrate prey populations is contentious, particularly when it involves species of economic or conservation value. In this paper, we examine the case of raptor predation on upland passerines and waders in Scotland. We analysed the abundance of five wader and passerine species on an upland sporting estate in southern Scotland during an eight-year period when hen harrier, peregrine and merlin numbers increased due to strict law enforcement. The abundance of meadow pipit and skylark declined significantly during this time. Golden plover also showed a declining trend, whereas curlew increased significantly and there was a near significant increase in lapwings. Contrasting the local population trends of these species with trends on nearby areas revealed higher rates of decline for meadow pipit and skylark at the site where raptors increased, but no differences in trends for any of the three wader species. There was a negative relationship between the number of breeding harriers and meadow pipit abundance the same year and between total annual raptor numbers and meadow pipit abundance. Predation rates of meadow pipit and skylark determined from observations at harrier nests suggested that predation in June was sufficient to remove up to 40% of the June meadow pipit population and up to 34% of the June skylark population. This ‘quasi-natural’ experiment suggests that harrier predation limited the abundance of their main prey, meadow pipit, and possibly the abundance of skylark. Thus, high densities of harriers may in theory reduce the abundance of the prey species which determine their breeding densities, potentially leading to lower harrier breeding densities in subsequent years. We found no evidence to suggest that raptor predation limited the populations of any of the three wader species. We infer that concerns over the impact of natural densities of hen harriers on vulnerable upland waders are unjustified.
... There are two main reasons for this; first, the majority of declines have been identified and quantified through the long-term data sets of the Common Birds Census (Fuller et al. 1995, Siriwardena et al. 1998, which operates at a spatial scale that is generally too small to provide good information for species with large home ranges that are relatively scarce, such as raptors (Marchant et al. 1990). Secondly, during the major period of agricultural change, many of the raptor species using lowland farm habitatssuch as Eurasian Sparrowhawks and Common Buzzards Buteo buteo -were in the process of a population recovery following the end of widespread organochloride pesticide use and persecution (Newton 1986, Elliott & Avery 1991, Clements 2002. As a result, the effects of agricultural intensification on some of these species or populations may have been concealed. ...
The use of habitats by hunting Hen Harriers Circus cyaneus just prior to the settlement period was investigated on Orkney, where numbers have declined by 70% over the last 20 years. Both males and females hunted over areas that were closer to subsequent breeding territories. Neither sex differed in the amount of time they hunted over areas dominated by either intensive pasture, moorland or rough grazing. However, male hunting was significantly related to the amount of unmanaged grass habitat with a litter layer. Female hunting was related negatively to vegetation height, and to the prevalence of both Heather Calluna vulgaris and managed grass; after controlling for these habitat features, female hunting also tended to be associated negatively with Common Starling Sturnus vulgaris abundance. Dramatic changes in land use on Orkney have occurred over the last 40 years, with increases in the amount of intensive pasture and decreases in the amount of rough grazing. These changes, coupled with a doubling in sheep Ovis aries densities over the last 20 years, are likely to have reduced the amount of unmanaged grass. These changes will have been detrimental to hunting male Harriers by reducing the amount of food they can supply to the females prior to egg laying and during the incubation period.
Population estimates of birds have a wide range of practical conservation uses, as well as being of enduring interest to many birdwatchers. Following previous reports by the Avian Population Estimates Panel, in 1997 and 2006, we present the third collation of population estimates of birds in Great Britain and the United Kingdom. There are now thought to be about 84 million breeding pairs of birds in the UK. The ten commonest species contribute 57% of this total, with Wren Troglodytes troglodytes alone providing one in ten of our breeding birds. In all, 23 species exceed one million breeding pairs. The individual population estimates come from a wide variety of sources, many from extrapolation of previous estimates by recognised trend measures, others from new surveys and novel analytical approaches developed since the last report. Despite the exceptional level of detail available for some species, many gaps in our knowledge remain. Recommendations are made to allow a continuing improvement in our understanding of the numbers of birds in GB and the UK. There are many opportunities for volunteer and amateur birdwatchers to make a significant contribution.
The history of game shooting since the Second World War might be seen as an enigma. In spite of unprecedented changes to the countryside resulting from the intensification of farming which contributed to a rapid decline in the partridge population, the size of the national game bag increased due to the enhanced popularity of the pheasant as a sporting quarry. This article evaluates the reasons for the expansion of the sport in this period, focusing on the management of the countryside, the evolution of game keeping, the growth of artificial game rearing, and the increasing popularity of game shooting.
The diet and breeding density of 19 pairs of Common Buzzard Buteo buteo¸ were studied in relation to indices of lagomorph and vole abundance during June July 1993 in a range of habitats in southern Scotland. 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 1.9 km. 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.
The failure of the Common Buzzard Buteo buteo to re-establish itself as a breeding species in much of eastern Britain has been the subject of much speculation over the past 30 years. Recently, however, there is evidence that Common Buzzards are finally colonising areas of eastern England and Scotland from which they have been absent for over a century. They can now be observed within 30 km of the centre of London, and seem likely to colonise the remaining areas of suitable habitat within Britain in the near future.
The British breeding range of Buzzards contracted in the nineteenth century, due mainly to persecution by gamekeepers. A partial recovery occurred after the First World War, but the species remained more or less restricted to western Britain. A survey was conducted in 1983 to see whether the Buzzard had re-colonized any more of its former range since the 1968–72 Breeding Atlas. The survey showed that there had been some improvement, especially in Northern Ireland, but that east and northeast Scotland was an obvious exception to this trend, due (apparently) to continued persecution there. Elsewhere, recolonization has occurred mainly along the edges of the Buzzard's range, but largely through infilling, with little sign of eastwards expansion since 1968–72. Within the Buzzard's main range along the western side of Britain, mean densities of soaring birds were higher in England and Wales than in Scotland. The population may now be in the order of 12 000–15 000 territorial pairs. Factors which currently influence the range and abundance of Buzzards are discussed; these include upland afforestation and human persecution.