Visible migration at
Sunderland Point:
For most birders the autumn migration period means one of
two things: sea-watching or rarities (depending on the weather). The movements
of commoner birds - pipits, wagtails, thrushes, starlings, finches and buntings
- hardly seem to merit a second glance. These species tend to move in a south or
south-westerly direction on a broad front, often in small or dispersed flocks
and such movements can be witnessed almost anywhere. However in the right
weather conditions (clear or overcast skies and light headwinds), visible
migration over certain locations can be particularly impressive.
When I first began birding in the late seventies, my
local patch was a rather bleak reservoir on the edge of the Pennines just west
of Sheffield. Although the peat-stained water and boulder-strewn shorelines of
Redmires Reservoir attracted relatively few birds (an Oystercatcher would have
constituted a good record), the site did offer one major ornithological
attraction. Almost daily watches by a small number of local enthusiasts, made
during the first few hours of daylight, revealed that each autumn Redmires
played host to the visible migration of in excess of 100,000 birds. Although the
scale of this migration fluctuated from year to year, total autumn counts have
included 40,000 Woodpigeon, 20,000 Meadow Pipit, 30,000 Redwing, 40,000
Fieldfare and 25,000 Starling. To witness the spectacle of a 'big day' in
mid-October when thousands of Woodpigeons, thrushes and finches are moving
overhead is, to my mind at least, one of the most exciting aspects of birding.
Unfortunately my opportunities for studying 'vis'
experienced something of a ten year hiatus after I left Sheffield in the
mid-eighties for the somewhat different charms of Liverpool. Autumn birding on
Merseyside most definitely revolves around Leach's Petrels, gulls and, er, more
gulls. However since moving to Lancaster in 1993 increasingly regular visits to
Sunderland Point have reawakened my interest in visible migration and during the
last three autumns much of my birding time has been devoted to learning more
about bird movements over this rather neglected stretch of coastline.
It is perhaps worth stating at this point that visible
migration over Sunderland in no way matches the sheer scale of the movement that
occurs over the southern Pennines, though this is partially a reflection of
coverage. Only one other birder (John Girdley) covers Sunderland on a regular
basis and most of our visits are limited to Saturday and Sunday mornings. 'Vis'
counts are normally made from close to the end of the Point during the first 2-3
hours of daylight between early September and late October. The majority of
birds pass relatively close overhead, seemingly following the inner edge of the
salt-marsh on a line from Heysham Power Station and Potts Corner south-east over
the River Lune towards Cockersand Abbey. Counting involves a fair degree of
concentration, patience and an ability to identify birds by call and 'jizz' in
flight.
Despite only limited coverage (12 'vis' counts between
30th Aug. and 31st Oct.), the settled conditions which prevailed for much of the
autumn meant that 1997 proved to be a good year for 'vis' over Sunderland. The
counts produced a total of 11,746 birds (of 34 species) moving in a southerly
direction, compared with 3,412 birds (from 16 counts) in 1996 and 2,739 birds
(from 3 visits) in 1995. Although these figures in themselves may not seem
wildly exciting, the mean number of visible migrants per visit in 1997 was
almost 1,000. If coverage had been possible on a daily basis for the whole of
September and October and if the above mean figure was reasonably representative
(a big 'if') then it would suggest that the total number of birds moving over
Sunderland Point this autumn may have been somewhere in the region of 60,000.
The main species moving over Sunderland seem to be Meadow
Pipit (4,032 in 1997, including 1,559 on 28th Sept.), Starling (3,536 in 1997,
with 1,032 on 18th Oct.) and Swallow (1,296 in 1997 with 1,168 on 21st Sept.).
Smaller annual totals (200-700 birds) of Skylark, 'Alba' Wagtail, Redwing,
Chaffinch, Greenfinch and Linnet were also recorded. One interesting aspect of
'vis' at Sunderland is that while the timing of some species' movements
correlate with visible migration over the southern Pennines (eg. a
distinct peak in Meadow Pipit passage in the last few days of September), the
huge movements of certain of the characteristic trans-Pennine migrants (eg.
Woodpigeon, Redwing and Fieldfare) do not appear to reach Sunderland. One
possible explanation is that the birds moving over west coast sites such as
Sunderland and Heysham are largely derived from populations breeding in Cumbria
and Scotland. The huge movements of continental migrants passing over the
southern Pennines begin to appear about two hours after dawn, generally on calm,
sunny days. Such movements probably involve birds which have crossed the east
coast at high altitude and continued inland. Having crossed the Pennines these
flocks of Fieldfare and Redwing may disperse before reaching the west coast. In
addition, such birds probably do not reach the west coast until after midday -
long after the main period of west coast 'vis' has usually ceased.
Interesting observations from Sunderland include the fact
that both Sparrowhawk and Tree Sparrow appear to be annual migrants in small
numbers. A total of 9 Sparrowhawks (5 in 1996, 4 in 1997) have been observed
flying over high to the south (and are usually only noticed whilst scanning for
other birds), while Tree Sparrow counts have totaled 28 in 1995 (flocks of 15,
10 and 3) and 19 in 1997 (flocks of 13 and 6). In addition, the antics of Blue
Tits and Long-tailed Tits dithering over whether to cross the River Lune can
become quite comical. For example, on 12th October this year one party of 9
Long-tailed Tits appeared in the southernmost bushes at 7.20am before
disappearing back north towards Sunderland village. They reappeared at 7.30am
and again at 8.15am before finally flying east across the Lune at 8.25am.
Despite lacking the sheer spectacle of trans-Pennine
migration (where, for example, on 2nd November 1986 observers at just six sites
in the Sheffield area recorded over 65,000 birds), one incentive for persisting
at Sunderland (apart from being able to witness some impressive sunrises) is
that sooner or later a decent rarity ought to appear. If the evidence from 'vis'
counts at Heysham is anything to go by then Richard's, Tawny and Red-throated
Pipits are all possibilities - assuming they call!
Pete Crooks