Honey Buzzards in Lincolnshire 2000000
Reference: Catley, G, Honey-buzzards in Lincolnshire with special reference to the 2000 invasion, in Lincolnshire Bird Club Articles, click here (2001).
A very useful analysis and historical context is given for the movement through Lincolnshire in 2000. Some interesting observations in the article:
Its true status as a breeding bird in Lincolnshire may still be one of the surprises of the new millennium. The increasing number of mid-summer records suggests that the species may just be breeding at some localities within the county or at least be seriously looking for suitable nesting woodlands.
There has been an obvious increase in the number of birds occurring during the 1990s. Records have increased during all periods but not necessarily in the same years. Thus a year with a good spring influx may have few autumn birds and vice versa.
The proportion of spring records relative to autumn ones has increased from 1967-1982 to 1983-1998 even taking into account the notable autumn arrival in 1993 when 10 juveniles were recorded between September 14th and October 3rd.
The movement in autumn 2000 was on an unprecedented scale: the autumn total of 97 birds exceeded the total for the previous 150 years. Such was the scale of the movement through the county that on the peak day, September 20th, a minimum of 44 Honey-buzzards were seen in the county, that is over half the county total to 1999.
After the initial movement on 20th there appeared to be a further arrival of birds in the clear anticyclonic weather from 25th-27th.
Few other raptors seem to have been involved in the movement, the exception being Ospreys of which about 11 birds were seen over the ensuing ten days following the main arrival on the 22nd.
Data for satellite tracked birds from 2000 (Dr Mikael Hake, Grimsö forskningsstation Institutionen för naturvårdsbiologi, Sweden personal page, consulted 2002, no longer available October 2002) showed that two adult females had already crossed into Africa via Gibraltar by September 2nd. Two juveniles took different routes one going south via Italy reached Africa on October 4th but the second bird may give a clue to the origin of the British birds. Having moved south from Sweden it stayed in Denmark from September 8th-13th but was then drifted west and recorded from the Netherlands on September 19th the date of the easterly gales in Lincolnshire. The individual in question presumably managed to avoid the drift across the North Sea moving south through central France to cross the Pyrenees between 28th and October 1st before crossing the Straits of Gibraltar on 2nd and reaching Nigeria by 14th.
Comments:
The data from the satellite-tracked birds shows on a very small sample that 0 out of 2 juveniles from Sweden crossed the North Sea. Although one bird apparently came close to the North Sea in Holland, it is worth noting that a similar route was taken by two other tracked birds in 1997 and 1998 which passed though Luxembourg before turning decisively south through France. See Swedish Breeding Populations of Honey Buzzards. The failure of either bird in 2000 to cross the North Sea is yet further evidence that a continental origin is unlikely. The declining population and poor productivity requires some half of all the Swedish juveniles fledged in 2000 to have crossed the North Sea to account for the numbers involved in Britain.
The actual movements and behaviour of the birds at Gibraltar Point on 20th September is apparently the subject of some confusion in various quarters. The following (from Lincolnshire Bird Club Website Newsline article on Honey Buzzard Influx, September 2000; only the current issue is available; the cited issue, perhaps for December 2000, was found in Google's cache) provides a useful record of the original observations:
Kevin Wilson, warden at Gib. Point witnessed the unprecedented HB (Honey Buzzard) influx. The following is an extract from an e-mail dated 22nd September: 'Hot news from the east coast raptor flyway....another 3-4 HB's through today.....not seen by me though. The last one mobbed by two short-eared owls over the Old Saltmarsh. Fortunately I was on the end of the 25 the other day. This included a flock of 6 and two flocks of 4 with the others ones and two's. The flock of 6 was going south over adjacent farmland whilst another dark morph juv was going overhead at the tern hut. A further unidentified raptor was almost certainly a honey and there was a single common buzzard. Many were going so low that it would have been possible to miss them behind the dunes or seabanks. Although a few were going down the east dunes, they seemed reluctant to go out over the sea and into the headwind and they generally moved off south or south-west. They were obviously moving down in a broad front, a few were well inland (the one that we couldn't confirm was probably about 4kms away). Can't imagine I'll ever witness that again in blighty.'
Unfortunately other secondary accounts have re-interpreted the evidence perhaps to reinforce their own views as to the origin of the movement. For example Brian Unwin apparently wrote on UKBN on 31st October 2000 in reply to my question:
> Why were no birds seen moving
west?
Many were The highest single location count on the
20th was 26 at Gibraltar Point, Lincs, and Kev Wilson, the warden
to with I spoke on the day, said all of them flew inland (ie
westwards).
The statement in the final report for the 20th (Catley, 2001) that "juvenile Honey-buzzards appeared to be coming in off the sea and turning south-west as they headed inland low over the fields" is also apparently not consistent with the email from the warden given above. In the detailed table of records in the final report, none are actually recorded on 20th anywhere in Lincolnshire coming in off the sea. Maybe it is difficult for observers to commit themselves as 'in off the sea' is a very subjective term ( Birds in off the Sea).
The primary unfettered account above from the warden must take precedence. This confirms that the birds were moving S/SW on a broad front at Gibraltar Point. Coastal passage S on a broad front is entirely consistent with a British origin for the Honey Buzzards.
