cogenershb2000

Cogeners of the Honey Buzzards in autumn 2000

Reference: Nightingale, B, & Elkins, N, The Birdwatching Year 2000, British Birds 94(12) 590-600 (2001).

Notes from reference:

In northern Britain and northern Europe, September was characterised by periods of east to south east winds, mainly during 19th-27th.
Shetland had a memorial September.
In general numbers of common passerine migrants were again low and Spurn reported its lowest September ringing total ever.
Notwithstanding the dearth of many small migrants, a large movement of hirundines and pipits was observed throughout the country in September, a virtual repeat of events in 1999.

From 7th-27th September over 35,000 Meadow Pipits Anthus pratensis moved S at Spurn

Large counts of hirundines were made elsewhere up to 17th.

Then a gap with poor weather from 18th-20th: see Weather .

But very large totals emerged again when the Honey Buzzards were moving:

21/9 1,700 House Martins Delichon urbica were at Rod Moor (South Yorkshire).

22/9 20,000 Swallow Hirundo rustica at Frampton (Avon)

23/9 12,000 Swallow at Dungeness

23/9 3,000 Swallow + 10,000 House Martin through Portland

25/9 4,800 Swallow + 1,100 House Martin through Sandwich Bay

26/9 8,000 Swallow at Dungeness

29/9 5,500 Meadow Pipit at Walney

29/9 1,954 Meadow Pipit at Landguard

30/9 6,250 Meadow Pipit at Walney

2/10 10,000 Swallow + 7,000 House Martin through Sandwich Bay in late surge.

Very significant passerine passage was noted in the Northern Isles from 20th September but passage was unexceptional further south.
Some interesting falls of Blackcaps were noted: 250 on Fair Isle on 21st September and 2,000 in Sandwich Bay on 1st October but the latter may well have meant to come here for the winter so they were presumably not drift migrants.
Also note in Devon: 75,000 Swallow and 10,000 House Martin passing in Start area on 1st October at local peak of Honey Buzzard passage (Devon Bird Report 2000, p. 11, 47, 104).

Comments:

The movement of Honey Buzzards was accompanied by hirundines, Meadow Pipits and birds of prey such as Marsh Harrier Circus aeroginosus, Common Buzzard Buteo buteo and Hobby Falco subbuteo Confirmed Honey Buzzard totals .

There is no evidence that these accompanying birds were anything but British in origin.

Only the Northern Isles of Scotland experienced heavy falls of passerines.

However, very few Honey Buzzards were recorded this far north.

It is very surprising that such an unprecedented Honey Buzzard movement is attributed to an influx from the continent when other more usual drift migrants seem to have been unaffected by the weather.

The second phase of the movement of the largely insectivorous cogeners appears to have been triggered by the sudden dip in temperatures around 18th-20th: see Weather.

The conspicuous movement of these birds in 2000 is likely to have been caused by the adverse (southerly) winds which forced the birds to fly at low altitude and to cover relatively short distances each day.