Honey Buzzards in Nottinghamshire
The 1970s
Source: Irons, Anthony, Breeding of the Honey Buzzard (Pernis apivorus) in Nottinghamshire, Nottinghamshire Ornithological Society 15pp (1980).
Main points
Study area: 50 km2 or 5,000ha, mainly farmland with some heathy patches, comprising estimated 56% agricultural (mainly arable, some sheep), 24% conifers (closely associated with game rearing) and 20% mature deciduous.
Period of Study: 1971-1979.
Plumage/morphology: variation in breeding plumage was quite considerable with differences in spotting on underparts, wing markings and the feathers missing from wings on outer primaries, even in May. Some breeding birds had the plumage of the immature type, bearing out comments in the Handbook that plumage variation is “individual and not connected with sex, age or season” [Witherby et al, 1939, p.99]. In drawings of the birds, the heads are small but the necks are not particularly thin.
Display: observed mostly as wing clapping, presumably associated with competition for mates. Pair display was much less frequent, involving the pair soaring together and climbing higher and higher. Ultimately the male climbed almost out of sight, before diving vertically at the female and passing her by at high speed. This display was repeated.
Feeding in early season: on first arrival feeding communally on dung heaps, excavating grubs, worms, etc.
Visibility: highest in early June in spring, becoming low during July before reaching its highest of the year in the first part of August. Visibility slowly declined through late August and early September, becoming low by late September. In long watches times between 11 and 12 in the morning and 16 to 17 in the late afternoon were favoured for the birds being visible.
Nest building: the earliest date was 1st June, the latest 1st July and the mean 14th June. Sprays were continually brought in to the rim of the nest, building up to a height of 40cm. This was attributed to the need for hygiene.
Pellets: several were recovered with an external appearance, both by feel and look, resembling shellac. Analysis of one revealed fibrous comb substance, wasp stings and carcasses, hard corn and tiny stones. The last two items may have come from Woodpigeon crops but the hard corn may also have been directly eaten when foraging crops.
Nesting success: usually one nest was found each year but two nests were found in 1977 and two to four birds were present each year. Breeding success was mixed with one young fledged in four out of nine years.
Factors behind success/failures: quiet mixed habitat was considered to be ideal for the breeding birds. Heavy public pressure was detrimental to the birds. Bird watchers were also a threat to the species, causing significant disturbance at nest sites.
Comments
The mixed habitat of the study area is clearly favourable for Honey Buzzards and the presence of heathland and game-rearing areas is a further positive feature. The feeding on dung heaps early in the season is an interesting observation. The prominence of wing-clapping in display would suggest the study area is an island of suitable habitat with the surrounding area not able to support the species to the same extent, leading to contention for breeding sites. Visibility and display by breeding pairs is the same as in Northumberland, except that the late summer peak in Northumberland starts from mid-August, not in early August. Nest building times are also similar to those in Northumberland. The covering of the rim of the nest with sprays may have some benefits for hygiene but the large rim must also provide cover for the sitting adult and juvenile. The shellac pellets are similar to those found in Northumberland, which contained chitin from wasp combs.
Nesting success at under 50% compares very unfavourably with that in Scotland and Northumberland, where it is at least 90%. The birds do appear to have been struggling to succeed, perhaps because of excessive disturbance, which if by birdwatchers is clearly unethical.
The plumage observations are very interesting, fitting well those made in Devon where a number of breeding birds were also in what is usually described as immature plumage. Taken in conjunction with the Handbook of Witherby et al (1939) where it would seem that individual variation is thought to over-ride that through age or sex, this would suggest that Honey Buzzard identification is in some need of review after the over-prescriptive views of some recent writers. The missing outer primary feathers on birds in May are presumably due to damage incurred after the moult in the wintering area as in late spring the only moult is by females of much smaller inner primaries.
Observations by NR
No visits have been made to Nottinghamshire searching for Honey Buzzards but opportunistically an adult female Honey Buzzard was seen at 14:20 floating over a wood near the A1 at Clumber Park on 3rd August 2002 and at the same locality an adult was soaring on 16th May 2009.
