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Rock Pipits in
Christchurch Harbour - February 2008
Between 15th and
18th February 2008, visits were made to Stanpit Marsh and Hengistbury
Head with the specific intention of photographing Rock Pipits. The main
purpose of the exercise was to try and draw exact comparisons between
birds believed to be of the Scandinavian race littoralis and
those of the resident British race petrosus.
A degree of supposition,
based on habitat, was applied to determine the likely race of individual
birds prior to them being scrutinised in detail. For example, petrosus
birds are resident on the Hengistbury Head shoreline and cliffs, where
they breed. Other than the appearance of juveniles, there is no significant
fluctuation in numbers throughout the year, suggesting the population
is largely resident. Conversely, the mainly freshwater marshes of Stanpit
only harbour Rock Pipits during the winter months and, historically,
it is these areas where classic spring individuals appear from March
onwards. Taking these factors into consideration, the current thinking
is that many, if not all, the birds on Stanpit are littoralis
type, whereas the Hengistbury individuals are likely to be exclusively
petrosus.
The photographs
below were taken within four days of each other using the same camera
with identical settings. Further, any subsequent digital processing
was consistent across all images and the actual light conditions in
the field were extremely similar.
Plate 1: 15th February, Central Marsh, Stanpit - presumed littoralis
Mark Andrews
When compared to
Plate 2 (presumed petrosus), note:
- the paler, greyer upperpart colouration.
- stronger and broader supercilium, particularly behind
the eye.
- apparently paler outer tail feathers.
Plate 2: 18th February, Hengistbury Head - presumed petrosus
Mark Andrews
When compared to
Plate 1 (presumed littoralis), note:
- the darker, olivey upperpart colouration.
- weaker supercilium.
- apparently darker outer tail feathers.
The following plates
provide additional images of birds from both sites. Further points of
interest may be:
-
there is a suggestion that the dark upperpart streaking on a littoralis
appears to contrast more with the
background colour. In particular, see Plate 6. This is presumably a
function of the overall paler colour
of such birds.
- the shape and extent of the breast streaking
does not seem to vary noticeably across the birds.
- the bare part colouration seems consistent
in all these photographs. However, observations of
birds not photograhed here suggest that the lower mandible in particular
can vary from black to pale yellow/pink,
but this seems to be the case on both races.
Plate 3:
15th February, Central Marsh, Stanpit - presumed littoralis
Mark Andrews
Plate 4: 15th February, Central Marsh, Stanpit - presumed littoralis
Mark Andrews
Plate 5: 15th February, Central Marsh, Stanpit - presumed littoralis
Mark Andrews
Plate 6: 15th February, Central Marsh, Stanpit - presumed littoralis,
but different
individual
to Plates 3 to 5. Mark
Andrews
Plate 7: 18th February, Hengistbury Head - presumed petrosus
Mark Andrews
Plate 8: 18th February, Hengistbury Head - presumed petrosus
Mark Andrews
The
points raised in this article are merely those observed by the authors,
who would welcome feedback of any kind.
David Taylor
& Mark Andrews
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