A paper from the British Ornithologists’ Union Records Committee
Records of Hawk Owls
in Britain
Ben Green
Andrew H. J. Harrop
Abstract As a consequence of a recent review by BOURC, there are now just
four accepted British records of the Hawk Owl Surnia ulula. A bird of the North
American race S. u. caparoch, found in an exhausted state on board a ship off the
coast of Cornwall in March 1830, remains the first acceptable British record. The
other three records, two of which date from the late nineteenth century, involve
the nominate race, which breeds in Scandinavia. The only recent record refers to a
bird in Shetland in September 1983, and this Hawk Owl remains on Category A of
the British List. A summary of racial identification and ageing is presented, and
taxonomy, distribution and irruptions are discussed briefly.
s part of its ongoing work on the
British List, BOURC aims to determine the first acceptable record of
each taxon. In the case of the Hawk Owl
Surnia ulula this required a review of all the
previously accepted records. Following two
circulations, many of these records were
A
276
found unacceptable, for reasons which are
explained here. There are now just four
accepted British records, one of the North
American race S. u. caparoch (hereafter
caparoch) and three probably or certainly of
the Eurasian breeding form S. u. ulula (hereafter ulula).
© British Birds 103 • May 2010 • 276–283
Records of Hawk Owls in Britain
Historical status in Britain
fraudulent, collector of rare and unusual
birds and, unsurprisingly, they were not
recorded at the time, so subsequent authors
suspected fraud. One of these Hawk Owls
is now at the Booth Museum, Brighton
(accession number BC207259), and is
identifiable as ulula on the basis of the
pattern of the underparts (see below)
(www.virtualmuseum.info/collections/object.
asp?searchText=hawk+owl&ckid=377867&
row=5&view=1). Another caparoch, said to
have been obtained on the north coast of
Ireland in 1910, found its way into Harpur
Crewe’s collection in 1914 and has never
been formally accepted.
There are also references to
very small numbers of this
species in captivity (e.g.
Alexander & Fitter 1955,
Cage & Aviary Birds 12th
June 2008), but birds of
captive origin were not
considered likely to be
involved in any of the
records reviewed here.
Despite this species’ distinctive appearance, the
identification of two sight
records formerly accepted
by BBRC is no longer con143. Upperside of five specimens of Hawk Owl Surnia ulula. From
sidered acceptable: on the
left to right: S. u. caparoch from Canada; dark immature S. u. ulula from Bleasdale Fells above ChipSweden; typical S. u. ulula from Sweden; S. u. ‘pallasi’ from Kultuk,
ping, Lancashire, on 13th
Russia; and S. u. tianschanica from Aksu, Turkestan.
September 1959 (Brit.
Birds 92: 585), and at
Gurnard’s Head, Cornwall,
on 14th August 1966 (Brit.
Birds 101: 551).
Taxonomy and
distribution
Andrew Harrop © NHM, Tring
Andrew Harrop © NHM, Tring
The Hawk Owl has been judged a rare
vagrant by all authors who have discussed its
status in Britain. Some (e.g. Saunders &
Clarke 1927) have considered records of
caparoch likely to involve ship-assisted birds,
but until now there has not been a full systematic review of all records. Several older
records of this species have been associated
with fraud. Wood (2007) listed three
allegedly taken in Essex in February 1913,
which found their way into Sir Vauncey
Harpur Crewe’s collection. Harpur Crewe
was a notoriously uncritical, and perhaps
144. Underside of five specimens of Hawk Owl Surnia ulula. From
left to right: S. u. caparoch from Canada; dark immature S. u. ulula from
Sweden; typical S. u. ulula from Sweden; S. u. ‘pallasi’ from Kultuk,
Russia; and S. u. tianschanica from Aksu, Turkestan.
British Birds 103 • May 2010 • 276–283
The Hawk Owl is conventionally placed in a monotypic genus, with three
subspecies recognised by
Cramp (1985). Siberian
populations, formerly separated as a fourth taxon,
pallasi, are now included
within nominate ulula by
this treatment. The nominate form is found from
northern Europe east
277
Harrop
through Russia to Kamchatka and Sakhalin
and in central Siberia south to Tarbagatay; S.
u. tianschanica occurs in central Asia and
northwest and northeast China; and caparoch
from Alaska through Canada to Newfoundland, and south to extreme north USA.
Among several other bird taxa, what were
formerly regarded as different subspecies in
the Old World and New World have recently
been reclassified as separate species on the
basis of significant genetic differences
(Koopman et al. 2005) – for example, American Picoides dorsalis and Eurasian Threetoed Woodpeckers P. tridactylus, Black-billed
Pica hudsonia and Eurasian Magpies P. pica.
The Hawk Owl is relatively poorly studied
and it is likely that comparable genetic differences exist between Nearctic and Palearctic
populations, although this remains to be
confirmed.
Movements and irruptions
All populations of the Hawk Owl are
nomadic, moving in response to food availability and climatic conditions, with a cycle
that follows that of rodent prey. Irruptions
may occur when vole populations crash, at
3–5-year intervals. The earliest date for significant autumn movement by caparoch is
15th September; most move between mid
October and late November. Movements of
ulula begin in early September and peak
during October–November. Periodic irruptions have been recorded during the twentieth century for both ulula and caparoch. It
is known that those in Europe have involved
large numbers of juveniles (85% in one
Swedish study; Edberg 1955), that distances
of up to 1,860 km have been covered, and
that the Baltic forms a significant barrier to
dispersal. It is notable that there were only
two records from the Netherlands during 1800–1999 (van
den Berg & Bosman 2001). In
North America, females and
juveniles are known to move
earlier and farther than adult
males. All states of the USA with
accepted records are in the
north, and the few ringing recoveries there involve distances of
up to just 259 km from the
ringing site. There is, however, a
recorded movement of 3,187 km
by a bird ringed in Canada in
February 2000 and recovered
dead in Alaska during October of
the same year (per Bird Banding
Office, Canadian Wildlife
Service).
Raymond Barlow
Racial identification and
ageing
145. Hawk Owl Surnia ulula of the North American race
S. u. caparoch. Separated from ulula by the darker and greyer
colour to the facial disc, darker ground colour of the
upperparts and upperwing-coverts, which show smaller white
feather tips, and broader black barring on the flanks and across
the upper breast. Note how snowy conditions make the ground
colour of the underparts appear paler than normal.
The identification of Hawk Owl
taxa has been discussed elsewhere, notably in Cramp (1985).
The following discussion is
based on a study of skins at the
Natural History Museum, Tring
(27 ulula including 9 ‘pallasi’, 8
tianschanica and 41 caparoch),
photographs and the literature.
It was established that tianschanica is doubtfully distinguishable
278
British Birds 103 • May 2010 • 276–283
Raymond Barlow
Records of Hawk Owls in Britain
146. Hawk Owl Surnia ulula of the North American race S. u. caparoch showing the underparts and
underwings. Note the relatively heavy dark barring on the underparts of caparoch, which is of more
consistent width than on ulula. In addition, the underwing of caparoch appears darker than that of
ulula, in part because the barring on the underwing-coverts is darker and broader, but also because
the white ovals on the outer primaries are smaller and narrower, often completely encircled by the
darker colour of the feather, giving a more spotted appearance than ulula. See main text for further
details on the differences in the pattern of the barring on the flight feathers between the two races.
identifiable to taxon.
Of the differences described in Cramp
(1985), the most useful are that caparoch
shows a blacker ground colour to the upperparts and upperwing-coverts, with smaller
white marks; a distinctly broader, blackbarred band across the upper chest; and
David Tipling
from ulula except by measurements; since it
is a highly unlikely vagrant to Europe, it is
not discussed further. The main findings are
that caparoch is rather consistent in appearance; that ulula is more variable, with darker
individuals close to caparoch in appearance;
and that typical individuals are readily
147. Hawk Owl Surnia ulula of the Eurasian race S. u. ulula. In comparison with caparoch, the facial
disc and underparts are whiter, and the dark barring on the breast is narrower. In addition, the white
barring in the primaries is of similar width to the adjacent dark barring, and is not encircled by it as is
the case with caparoch, thus giving a more barred appearance. Compare the underparts and
underwings with those of the North American caparoch in plate 146, above.
British Birds 103 • May 2010 • 276–283
279
broader dark bars on the breast, belly and
flanks (2.5–3.0 mm in caparoch compared
with 1.5–2.5 mm in ulula) that are tinged
rufous. In addition, the ground colour of the
facial disc and underparts of caparoch has a
greyer cast than the typically much cleaner
white of ulula.
When the underwings of specimens or
good digital images are compared, caparoch
consistently shows heavier, broader brown
barring on the underwing-coverts combined
with a distinctive pattern on the outer primaries. The white ovals on the outer primaries are often completely enclosed, giving
a more spotted appearance than ulula, in
which the white typically reaches the shaft
and/or the edge of the feather, giving a more
barred appearance. The dark areas appear
blackish-brown on caparoch compared with
paler greyish-brown on ulula. Measurements
of the relative depths of the pale and dark
areas on the outer primaries confirm that the
pale areas are consistently shallower on
caparoch (pale areas c. 6 mm compared with
8–9 mm for the dark areas). There is more
variation in ulula, but typically the pale areas
are deeper than or equal in depth to the dark
(9–10 mm compared with 8 mm or, in some
cases, as little as 5 mm for the dark areas).
Nominate ulula is rather variable. Paler
examples are distinctive but darker birds may
resemble caparoch. Among the study skins
examined, the darkest specimens were immaTable I. Measurements (mm) and weights
(g) of Hawk Owls Surnia ulula (from Cramp
1985 and Duncan & Duncan 1998).
Comparative measurements from British
specimens are as follows: Somerset in 1847,
unsexed, caparoch, wing 241 mm, tail 190 mm;
Shetland in 1860, unsexed, ulula, wing 235 mm,
tarsus 28–29 mm; Grampian in 1898, unsexed,
ulula, weight 326 g. Note that some
measurements from British specimens are
from the literature; the 1860 Shetland and
1898 Grampian specimens are no longer
extant.
S. u. ulula
male
female
S. u. caparoch
male
female
wing
224–239 230–249
213–245 210–242
tail
164–187 166–191
138–190 156–191
tarsus 23.9–27.0 24.4–27.2
weight 215–375 285–380
280
242–375 250–454
Paolo Viscardi © National Museum of Ireland
Harrop
148. Hawk Owl Surnia ulula of the North
American race S. u. caparoch, Cornwall,
March 1830.
ture birds. In such cases it is important to
check all the characters carefully before
making an identification. However, caparoch
is sufficiently consistent in appearance for it
to be unlikely to be confused with nominate
ulula, though it is more variable in size.
Ageing
Ageing birds in the field is extremely difficult,
though immatures in their first autumn show
irregular grey-and-white V-shaped fringes
along the tips of the outer primaries compared with the relatively even white arcs of
adults (Cramp 1985).
Measurements
Measurements of specimens show much
overlap between caparoch and ulula, and
those of the British specimens are not in
themselves sufficient to determine the taxon
involved.
Results of the BOURC review
Acceptable records
Following the review, only the four records
listed below were considered acceptable.
1830, Cornwall
The first British record of Hawk Owl
British Birds 103 • May 2010 • 276–283
Records of Hawk Owls in Britain
1860, Shetland
mentioned; remainder of front of neck and
its sides mottled with white and brownish
black. Upper surface Back, scapulars, and
uppertail-coverts, nearly black, spotted with
white, the scapulars being darkest, and those
nearest the wing having numerous bar-like
white marks. Wings Lesser coverts faded
brownish black; greater coverts and all the
quills the same, but spotted with white; the
spots upon the outer webs somewhat square
in form. Under surface White, barred with
brownish black, the bars paler on the breast
and near the tail; on each side of the breast,
near the bend of the wing, a large dark patch.
Tail Brownish black, the middle feathers with
several narrow white bars.’
Unfortunately the specimen was destroyed
by moths (Evans & Buckley 1899), but
Saxby’s description of the white facial disc
and white underparts with brownish-black
bars that were paler on the breast and near
the tail supports the identification as ulula.
1898, North-east Scotland
An adult female shot at Gight on 21st
November by William Smith, factor on the
Haddo House Estates, was documented by
Sim (1899, 1903). The account includes some
measurements (weight 11.5 ounces [326 g],
expanse of wings 28.5 inches [723.9 mm],
length from beak to end of tail 14.5 inches
[368.3 mm] but unfortunately lacks a
description. The bird’s stomach was filled
with bones and the hair of mice. Sim was a
highly critical assessor of records; in this case,
One procured from Skaw, Unst, in December
1860 by James Hay was mentioned by Crotch
(1861) and described by Saxby (1874) as
follows: ‘Head and neck Facial disc white,
stained and slightly mottled with light dusky
brown, becoming
darker between the
bill and the eye. Top
of head and back
of neck blackish
brown, spotted with
white, but much less
on the back of the
neck, where the
brown lies more in
patches. Outer edge
of facial disc has
each feather tipped
with
blackish
brown; on each side
of the neck, a long,
broad, irregular line
of the colour last 149. Hawk Owl Surnia ulula of the race S. u. ulula, Shetland, September 1983.
British Birds 103 • May 2010 • 276–283
281
Dennis Coutts
involved one taken on board a collier (coal
ship) a few miles off the coast of Cornwall, in
an exhausted state, in March 1830 (e.g. Proc.
Zool. Soc. 1835: 77, Yarrell 1845). According
to the account of the ship’s captain, Captain
Stacey, the bird was so exhausted that it
allowed itself to be captured by hand. The
ship was bound for Co. Waterford and following its arrival the bird was kept alive. It
lived for a few weeks with a friend of Dr
Robert J. Burkitt’s before coming into
Burkitt’s possession. Burkitt subsequently
presented it to the Museum of Trinity
College, Dublin, from which it passed to the
National Museum of Ireland (accession
number NMINH 1959.13.1). The specimen
is clearly of the Nearctic race caparoch,
showing relatively broad, rufous-tinged bars
of consistent width on the underparts.
BOURC members had some reservations
about the probability of caparoch making an
unassisted transatlantic crossing in light of
the absence of records from the southern
USA, Greenland, Iceland and the Azores, but
the record’s credentials (a named finder, firsthand account, plausible date and location,
and extant specimen) were sufficiently strong
for the record to remain acceptable.
Harrop
he evidently considered the possibility both
of ulula and of caparoch (then regarded as
separate species) and positively identified it
as ulula. The specimen is presumed to have
entered a private collection but is no longer
traceable.
1983, Shetland
The only accepted record since the formation
of BBRC involved one first seen by Angus
Nicol in his garden at Frakkafield, near
Lerwick, on 12th–13th September, which
then moved to Bressay, where it remained on
20th–21st September (Brit. Birds 77: 538).
The bird was seen by several observers and
photographed. It occurred during an invasion of ulula, which brought large numbers
to southern Norway and Sweden, 510 to
Denmark and singles to Germany and the
Faeroe Islands (Brit. Birds 77: 238, 589; Brit.
Birds 78: 343). As expected, the photographs
show it to be a typical example of ulula –
note especially the whitish ground colour of
the facial disc and underparts, and the relatively narrow blackish barring of variable
width on the underparts.
Records not accepted
The following records were not considered
acceptable, for the reasons given.
1847, Somerset
This bird was said to have been shot near
Yatton on 25th or 26th August at about 2.00
pm (Higgins 1851 – note that this author’s
initials are E. T., not T. E. as given in error by
Melling 2005). The specimen, which is
mounted in a position which matches that
shown in the drawing accompanying
Higgins’ account, is extant at the Booth
Museum, Brighton (accession number
BC207261; www.virtualmuseum.info/
collections/object.asp?searchText=hawk+owl
&ckid=376680&row=2&view=2). It was
identified as caparoch by Dresser (1871), and
the pattern of barring on the underparts of
the specimen confirms this identification.
The date was considered too early for natural
occurrence, and the involvement of Higgins,
a wealthy naturalist previously associated
with the discredited taxidermist David
Graham of York (Melling 2005), combined
with a four-year delay between the alleged
282
date of the record and its publication, caused
the Committee to doubt the validity of the
record.
Pre-1857, Wiltshire
This bird was reportedly killed at Amesbury
during severe weather by a Mr Long, though
the date is uncertain, being described as
‘several years ago’ (Proc. Zool. Soc. 1876: 334),
and ‘some thirty or more years since’ (Smith
1887). The specimen was exhibited at a
meeting of the Zoological Society of London
on 4th April 1876, and identified as nominate
ulula by Bowdler Sharpe. Most contemporary
and subsequent authorities either ignored or
overlooked the record, which, combined with
the lack of any detail about the date and circumstances of collection, made the record
unacceptable.
1863 Strathclyde, 1868 Strathclyde and
1871 Strathclyde
These records fall into a cluster so are treated
together. The first was reportedly shot near
Maryhill before 29th December 1863 (Proc.
Nat. Hist. Soc. Glasgow 1: 81; Zoologist 1866:
496); the specimen may formerly have been
in the Kelvingrove Museum and Art Gallery
(GLAMG Z1880.122.az) but is now lost.
Dresser identified it ‘at a glance’ as caparoch
(Dresser 1871). The second, also listed as
caparoch by Gray (1871), was reportedly shot
near Greenock about ten days before 24th
November 1868 (Proc. Nat. Hist. Soc. Glasgow
1: 235–236). Saunders & Clarke (1927) considered that these birds may have arrived on
vessels bound for the Clyde. The last of the
three records involved a specimen in very
poor condition, allegedly taken near
Greenock in December 1871, which had been
owned by a sailor. Dresser (1871) concluded
that it had been caught on board ship, and
the record was considered of very doubtful
authenticity by Witherby et al. (1943). The
Committee was sceptical because the series of
three records were from one area during a
nine-year period; the first record involved a
specimen which was exhibited at the same
meeting as a Purple Swamp-hen Porphyrio
porphyrio, reputedly from Campbeltown,
Argyll; and the second and third records
involved the same Greenock taxidermist. All
this strongly indicated local importation and
British Birds 103 • May 2010 • 276–283
Records of Hawk Owls in Britain
suggested the possibility of fraudulent trade.
In these circumstances, BOURC felt unable
to accept any of the three.
1903, Northamptonshire
This record was reported as shot at Orlingbury on 19th October (Zoologist 1904: 214)
but without any supporting descriptive or
other data. In these circumstances, the Committee was unable to accept the record.
Other records of caparoch
The only other Western Palearctic record of
caparoch involves a bird from the Canary
Islands in 1924. It flew onto a ship off Las
Palmas and was kept alive until reaching Rotterdam harbour, before being delivered to
Rotterdam Zoo on 7th November. The
mounted specimen is held in the Leiden collection (RMNH/Naturalis), catalogue
number 5, and has been confirmed as an
immature male caparoch by Kees Roselaar.
The actual date when it was first seen was not
reported but it is reasonable to assume that it
arrived on the ship in October. No irruptive
movements were recorded in North America
at that time. Although included in Martin &
Lorenzo (2001), this record has not yet been
reviewed by the national records committee
(R. Gutierrez in litt.) and does not form part
of the Spanish List (e.g. de Juana 2006).
Concluding remarks
This review has significantly reduced the
number of accepted records, both of Hawk
Owls sensu lato in Britain, and of North
American caparoch in Europe. From a British
point of view this species should be regarded
as one of the rarest of vagrants, and each
generation of observers will be lucky to get a
chance of seeing one. On the basis of the
accepted records, Shetland and northeast
Scotland are the prime sites. It remains to be
seen whether there will be any further
records of caparoch; if not, the remaining
accepted British record will no doubt attract
further scrutiny.
Acknowledgments
Raymond Barlow, Wilson Hum and David Tipling provided
photographs which helped to clarify differences between
ulula and caparoch – some of these are reproduced
above. C. S. (Kees) Roselaar kindly provided information
about the 1924 Canary Islands record; Jeremy Adams
helped with information about specimens in the Booth
Museum, Brighton; Richard Sutcliffe helped with research
into specimens held at Kelvingrove Museum and Art
Galler y, Glasgow; Paolo Viscardi kindly provided
information about, and images of, the 1830 specimen from
Cornwall (now in Ireland). Members of BOURC
commented extensively on the file during two circulations,
and Bob McGowan and Tim Melling commented on and
helped to improve a draft of this paper.
References
Alexander, W. B., & Fitter, R. S. R. 1955. American land
birds in western Europe. Brit. Birds 48: 1–14.
Cramp, S. (ed.). 1985. The Birds of the Western
Palearctic, Vol. 4. OUP, Oxford.
Crotch, W. D. 1861. Birds of Shetland. Zoologist 1861:
7706–7707.
de Juana, E. 2006. Aves raras de Espana. Lynx Edicions,
Barcelona.
Dresser, H. E. 1871. A History of the Birds of Europe.
Zoological Society of London, London.
Duncan, J. R., & Duncan, P. A. 1998. Northern Hawk Owl
(Surnia ulula). In: Poole, A. (ed.). The Birds of North
America Online. Cornell Laboratory of Ornithology,
Ithaca.
Edberg, R. 1955. Invasionen av hokuggla (Surnia ulula) i
Skandinavien 1950–51. Var Fagelvarld 14: 10–21.
Evans, A. H., & Buckley, T. E. 1899. A Vertebrate Fauna of
the Shetland Islands. David Douglas, Edinburgh.
Gray, R. 1871. Birds of the West of Scotland including the
Outer Hebrides. T. Murray & Son, Glasgow.
Higgins, E. T. 1851. Bona fide British-killed Hawk Owl.
Zoologist 1851: 3029–3032.
Koopman, M. E., McDonald, D. B., Hayward, G. D.,
Eldegard, K., Sonerud, G. A., & Sermach, S. G. 2005.
Genetic similarity among Eurasian subspecies of
Boreal Owls. Aegolius funereus. J. Avian Biol. 36:
179–183.
Martin, A., & Lorenzo, J. A. 2001. Aves del Archipielago
Canario. Francisco Lemus Editor, La Laguna.
Melling, T. 2005. The Tadcaster Rarities. Brit. Birds 98:
230–237.
Saunders, H., & Clarke, W. E. 1927. Manual of British
Birds. 3rd edn. Gurney & Jackson, London.
Saxby, H. L. 1874. The Birds of Shetland. Maclachlan &
Stewart, Edinburgh.
Sim, G. 1899. European Hawk-Owl in Aberdeenshire.
Ann. Scot. Nat. Hist. 1899: 49.
— 1903. The Vertebrate Fauna of ‘Dee’. Wyllie,
Aberdeen.
Smith, A. C. 1887. The Birds of Wiltshire. Porter & Bull,
London & Devizes.
van den Berg, A. B., & Bosman, C. A. W. 2001. Rare birds
of the Netherlands. Pica Press, Robertsbridge.
Witherby, H. F., Jourdain, F. C. R., Ticehurst, N. F., &
Tucker, B. W. 1943. The Handbook of British Birds. Vol.
2. H. F. & G. Witherby, London.
Wood, S. 2007. The Birds of Essex. Christopher Helm,
London.
Yarrell, W. 1845. A History of British Birds. Vol. I. 2nd edn.
Van Voorst, London.
Andrew H. J. Harrop, 30 Dean Street, Oakham, Rutland LE15 6AF;
e-mail [email protected]
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