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271
[Dutch Birding 38: 271-292, 2016]
Lesser Kestrel Falco naumanni has a chequered
taxonomic history. The species has generally
been considered polytypic from the 19th century
up to a few decades ago. Opinions began to
change in the late 1970s, leading to the present
general consensus to treat the species as mono-
typic. However, the reasons why it should be
monotypic have not been clearly explained (cf
Vaurie 1965, Cramp & Simmons 1980, Clark
1999, Corso 2000, 2001, Ferguson-Lees & Christie
2001, Forsman 2016). The geographical variation
has been ignored in some recent publications
(Rasmussen & Anderton 2005, 2012, Naoroji
2006, Dickinson & Remsen 2013, Forsman 2016,
Gill & Donsker 2016). Corso et al (2015) re-instat-
ed the subspecies F n pekinensis (‘Chinese Lesser
Kestrel’; hereafter pekinensis), therefore (re)consid-
ering Lesser Kestrel a polytypic species with two
subspecies, nominate naumanni and pekinensis.
The nominate (‘Western Lesser Kestrel’; hereafter
naumanni) had been described by Johann Gottlieb
Fleischer from a bird collected in either southern
Germany or Switzerland (the whereabouts of the
type specimen(s) are unknown) (Fleischer 1818),
while pekinensis had been described on the basis
of two males (one adult and one juvenile) collect-
ed by Robert Swinhoe near Beijing, China (Swinhoe
1870); both syntypes are stored at the Natural
History Museum, Tring, England. A large area with
intermediate birds showing clinal variation con-
nects the breeding ranges of naumanni in the west
and pekinensis in the east. These intermediate
birds led previous authors to synonymise pekinen-
sis with naumanni but without any quantitative
and/or qualitative analysis. Populations of inter-
mediate birds showing features of different sub-
species occur regularly, usually clinally, in species
with wide distributional ranges (Mayr & Ashlock
1991, Huggett 2004, McCarthy 2006, Corso et al
2015). For instance, many widespread falcon spe-
cies, such as Merlin F columbarius and Lanner
F biarmicus, Saker F cherrug and Peregrine Falcon
F peregrinus show intermediates or clines in bio-
metrics or morphology within the boundaries of
various accepted subspecies, often across a vast
area, making it impossible to objectively delimi-
tate subspecies borders (Vaurie 1965, Cramp &
Simmons 1980, Forsman 1999, 2016, Zuberogoita
et al 2009, White et al 2013, Corso et al 2015).
Even among raptor taxa often considered separate
species, wide areas of intermediate populations
exist, such as between Black Kite Milvus migrans
and Black-eared Kite M lineatus and Peregrine Fal-
con and Barbary Falcon F pelegrinoides (Forsman
2016). Therefore, we regard a large clinal zone of
birds showing features of both naumanni and pe-
kinensis as insufcient reason to synonymise them
and to regard the species as monotypic.
The aim of this paper is to document the plum-
age variability of Lesser Kestrel over its wide distri-
bution range in Eurasia and to document the mor-
phological differences between western and east-
ern populations, with special focus on pekinensis
in China. For the validity of pekinensis and details
about its distribution range, see Corso et al (2015).
This paper focuses on the plumage variation and
elaborates further on Corso et al (2015); several of
the photographs and illustrations already pub-
lished in Corso et al (2015) are repeated here and
new ones are included to further document the
geographical plumage variation.
Material and methods
For the research used to prepare Corso et al (2015)
and this paper, we studied Lesser Kestrels in the
eld in 2003-15 (Andrea Corso studied the species
in general since 1987), visiting Egypt, France,
Georgia, Greece, Israel, Italy, Kazakhstan, Kyrgyz-
stan, Morocco, Portugal, Spain, Tunisia and Turkey.
In addition to eld observations and study of
photo graphs from these countries, we also studied
photographs from Armenia, Azerbaijan, China,
Eri trea, India, Kenya, Laos, Mongolia, Myanmar,
Oman, Somalia, Sudan, Tanzania, Turk menistan
and Yemen. To better understand the plumage vari-
ation across the whole distribution area, we stud-
ied specimens in the following museums: Institute
of Zoology, Almaty, Kazakhstan (IZA); Naturalis
Biodiversity Center, Leiden, the Nether lands
(NBC); Natural History Museum, Tring, England
(NHMUK); National Museums Scotland, Edin-
burgh, Scotland (NMS); Naturhistorisches Museum
Wien, Vienna, Austria (NMW); Natur historiska
Riksmuseet, Stockholm, Sweden (NRS); Museo
Geographical plumage variation in
Lesser Kestrel
Andrea Corso, Michele Viganò, Justin J F J Jansen & Lorenzo Starnini
272
FIGURE 1 Western Lesser Kestrel / Kleine Torenvalk Falco naumanni naumanni (upper two birds), Lesser Kestrel /
Kleine Torenvalk F naumanni of intermediate population and Chinese Lesser Kestrel / Chinese Kleine Torenvalk F n
pekinensis (lower two birds) (Lorenzo Starnini). In upper two birds, note least grey extension on upperwing-coverts
and tertials in left bird, with typical plumage for naumanni shown in right bird; note also plumage colour saturation
of both birds compared with typical pekinensis. Lower two birds (pekinensis) show typical darker grey tones and
more saturated plumage overall than nominate naumanni, upperwing-coverts are almost entirely grey (but in most
birds with sparse rusty tinge on inner lesser and median wing-coverts and along leading edge on marginal wing-
coverts). Central bird shows intermediate plumage, typical for birds from western Asia to Central Asia.
Geographical plumage variation in Lesser Kestrel
273
Civico di Scienze Naturali ‘Angelo Priolo’, Ran-
dazzo, Italy (MCR); Museo Civico di Storia
Naturale di Milano, Milano, Italy (MCSM); Museo
Civico dell’Università di Scienze Naturali di
Catania, Cantania, Sicily, Italy (MCUCT); Museo
Civico di Terrasini, Palermo, Sicily, Italy (MCT);
Museo Civico di Zoologia di Roma, Rome, Italy
(MCZR); Muséum National d’Histoire Naturelle,
Paris, France (MNHN); Museo Regionale di Scienze
Naturali di Torino, Torino, Italy (MRSN); Museo di
Storia Naturale ‘La Specola’, Firenze, Italy (MSNF);
Museo di Storia Naturale ‘Giacomo Doria’,
Genova, Italy (MSNGD); Museo Civico di Storia
Naturale di Carmagnola, Torino, Italy (SNCa); and
Museum für Naturkunde, Berlin, Germany (ZMB);
in addition, specimens were studied in 13 private
collections. We received additional information
from: American Museum of Natural History, New
York, USA (AMNH); World Museum, National
Museums Liverpool, Liverpool, England (LIV);
Museum of China, Beijing, China (NZMC); Man-
chester Museum, University, Man chester, England
(MMUE); and Peabody Yale Museum of Natural
History, New Haven, USA (PMNH).
The studied specimens, identied according to
Corso et al (2015), are listed in table 1. To dene
the main plumage variation of Lesser Kestrel (sensu
latu), we deal here chiey with birds from group A
and D as dened by Corso et al (2015). Figure 3
shows typical nominate naumanni and pekinensis,
as well as the main intermediate plumage. For
plumage descriptions and for the preparation of
gure 1-3, we only considered fully developed
fresh adult plumage, in order to avoid the inu-
ence on plumage colour of sun bleaching and
abrasion. However, while the plumage may be in-
uenced by these causes, the extent of grey on the
wing-coverts does not change. Juveniles are not
discussed here as we failed to nd any obvious
differences between naumanni and pekinensis. No
immature males (second calendar-year) were con-
sidered because, although the post-juvenile partial
Geographical plumage variation in Lesser Kestrel
TABLE 1 Skins of Lesser Kestrel Falco naumanni studied for this research, divided to subspecies, sex, age and geo-
graphical area
Taxon Number of skins studied Geographical area Note
F n pekinensis 20 adult males, 8 females from terra typica in China including one of two
syntypes by Swinhoe
F n ‘pekinensis’ 28 adult males, 25 females India, Myanmar (Burma) and Laos age of females combined;
birds showing all
characters referred to
typical pekinensis; we
report them as ‘pekinensis’
being not directly from
terra typica of breeding
grounds
F naumanni 87 adult males, 60 females Asia/Middle East: Arabian Peninsula, age of females combined;
Afghanistan, Armenia, Azerbaijan, intermediate birds in
Georgia, Iran, Iraq, Israel, Jordan, various characters and
Kazakhstan, Kyrgyzstan, Mongolia, therefore not assigned to
Pakistan, Russia, eastern Turkey, subspecies
Turkmenistan
Africa: Eritrea, Kenya, Somalia,
Tanzania
F n naumanni 349 adult males, 172 females Europe: Albania, Czechia, France, age of females combined
Greece, Italy, Macedonia, Portugal,
Slovenia, Spain
Asia/Middle East: Lebanon, Palestine,
Syria, western central Turkey
Africa: Algeria, Angola, Botswana,
Egypt, Ethiopia, Libya, Mauritania,
Morocco, Niger, Senegal, South Africa,
Tanzania, Tunisia
Total number 749 (484 adult males, only full adult males;
of skins studied 265 females) age of females combined
274
FIGURE 2 Western Lesser Kestrel / Kleine Torenvalk Falco naumanni naumanni (upper two birds), Lesser Kestrel /
Kleine Torenvalk F naumanni of intermediate population and Chinese Lesser Kestrel / Chinese Kleine Torenvalk F n
pekinensis (lower two birds) (Lorenzo Starnini). Same birds as in gure 1. Upperwing-coverts differ in naumanni and
pekinensis, with central right bird showing intermediate features.
Geographical plumage variation in Lesser Kestrel
275
moult starts as early as prior to the rst pre-breed-
ing migration north (Corso 2000, 2001), the com-
plete adult plumage is not yet fully developed be-
fore the late second autumn/winter, after the end
of the rst complete moult (when in rst adult
plumage) (Corso 2000, 2001, Dernjatin & Vat tu-
lainen 2004, Forsman 2016). For further details on
materials and methods, see Corso et al (2015).
Breeding distribution and wintering areas
Lesser Kestrel breeds in a broad zone stretching
from the Iberian peninsula eastward via the
Mediterranean region (southern Italy, the Balkan
and patchily in northernmost Africa), and north
and south of the Black Sea and Caspian Sea, and
through Central Asia and Mongolia to a relatively
small area in northern China (gure 4). The species
mainly winters in sub-Saharan Africa, although
some birds winter around the Medi terranean (Cor-
so et al 2015). Corso et al (2015) divided the
breed ing range into four groups (A-D), with A
representing pekinensis and D nominate nau-
manni. Group B and C included intermediate
popu lations more closely resembling pekinensis
and nominate naumanni, respectively. The divid-
ing lines between B and C, and C and D are arbi-
trary (the limits of A are easier to dene because of
its geographical separation from B) and should be
subject of further studies to establish whether this
division is helpful to approach the variability of
Lesser Kestrel across its wide range.
Due to the confusion surrounding Lesser Kestrel
taxonomy, little is known about the distribution in
winter, and much remains to be researched in this
regard. According to older literature, the wintering
grounds and migration areas of pekinensis include
Laos and Myanmar and possibly Eritrea, Ethiopia,
Somalia, Kenya and Tanzania (Hartert 1912-1921,
Baker 1923, 1928, Hartert & Stein bacher 1932-38,
Stanford 1937, Archer & Good man 1937, Brown
& Amadon 1968, Brown et al 1982). According to
our specimens study, at least the birds collected in
Laos and Myanmar show all characters associated
with pekinensis. In addition, this subspecies ap-
parently used to winter in small numbers in the
Indian subcontinent and nearby countries (Hartert
1912-21, Baker 1923, 1928, Corso et al 2015).
However, reliable data of wintering birds for those
regions from recent years are limited or lacking
(BirdLife International 2001). Possibly, pekinensis
also winters in the Horn of Africa, where birds
showing characters associated with this taxon (but
also birds with intermediate characters) have been
observed (Archer & Goodman 1937, Brown et al
1982, Corso et al 2015). Countries in Central Asia
(Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan
and Uzbeki stan) and the Altai region may also be
part of the migration or breeding range but the
presence of intermediate birds makes the situation
in these areas complex (cf Corso et al 2015).
Main characters and plumage
variability
Adult male
General
Overall, pekinensis is a darker, more colourful bird
compared with naumanni (gure 1-2). Both the
upperparts and underparts are warmer, more richly
coloured. Caution should be taken in comparing a
fresh plumaged naumanni with a faded pekinensis.
FIGURE 3 Chinese Lesser Kestrel / Chinese Kleine
Torenvalk Falco naumanni pekinensis, female (left), and
Western Lesser Kestrel / Kleine Torenvalk F n naumanni,
female (Lorenzo Starnini). Note differences mainly in
colour of bare parts. Often, dark markings of eye-line
and moustache mark of pekinensis are more dened
and marked. However, variability in plumage traits of
females and juveniles still needs study and may be larger
than found here.
Geographical plumage variation in Lesser Kestrel
276
Indeed, fresh adult birds show richer colours than
faded ones.
Head
The forehead, crown, nape, hind-neck, ear-coverts
and neck-side are tinged sooty-bluish or bluish-
lead in pekinensis. For 13 fresh adult males col-
lected in the breeding area in northern China
(group A in Corso et al 2015, including the adult
male syntype by Swinhoe; plate 415-416), we
found an average grey colour of 11.46 (range 10-
12) on the Kodak Grey Scale (Kodak 2007). For 56
fresh adult male western birds (group D in Corso et
al 2015), we found an average of 8.07 (range 6-10;
plate 414). As shown in plate 414 and 433-435,
this feature is obvious but as the shades of grey are
often hard to establish in the eld, it has to be used
in combination with other features. Intermediate
birds can be closer to naumanni in eastern Europe
and the western part of the Asian range, or closer
to pekinensis (though apparently never as dark) in
the eastern part of the Asian range outside the terra
typica of pekinensis in China.
Upperparts
Most notably, the orange-red mantle is more chest-
nut in pekinensis compared with naumanni (where
often a pinkish hue can be perceivable). Inter-
mediate birds show a variable richness and inten-
sity of the upperparts, ranging from chestnut in
pekinensis to a paler, less intense and more orange-
brick red in naumanni. This variation occurs within
the same breeding site. Corso et al (2015) gave
more details about this character. Only fresh plum-
aged birds or birds at the same time of the year
should be compared.
Upperwing
The upperwing-coverts are always more extensive-
ly grey and darker in pekinensis, with most birds
studied showing the greater, median and most
lesser coverts dark lead-grey, as well as the tertials
(gure 1-2, plate 416-423, 435-440). Most adult
males show a variable amount of rusty tinged
(either fringed or with rusty tip) median and inner
lesser coverts and chiey the marginal coverts,
all along the leading edge of the upperwing, best
FIGURE 4 Distribution range of Lesser Kestrel / Kleine Torenvalk Falco naumanni (yellow = summer, blue = winter,
green = year round). Area between approximate ranges (rectangles) of F n naumanni and F n pekinensis is the inter-
mediate zone.
Geographical plumage variation in Lesser Kestrel
277
visible on the open wing (gure 2, plate 423-424
and 429). Indeed, in most birds, the inner ‘arm’
appears strongly rusty tinged, while the most ex-
treme pekinensis may have almost the entire up-
perwing-coverts slaty-grey (gure 1-2, plate 417-
418 and 430). In typical pekinensis, when the bird
is perched, almost the entire wing-coverts appear
dark grey, with only a very limited rusty tinge or
fringing on the ‘shoulder’, hardly visible or visible
only at close range. In ight, the rusty coverts on
the inner wing appear more obvious (gure 2,
plate 423-424 and 429). All naumanni from
European breeding grounds show grey only on the
greater coverts. Among them, the most marked
birds show a grey tinge also on some outermost
median coverts, near the carpal joint or ‘wrist’
area, while the least marked naumanni may have
the grey tinge limited to the outer or inner greater
coverts and only partially on the tertials (mostly on
the proximal part of the feathers; gure 1-2). Note
that birds from eastern Asian populations (and par-
tially from Central Asia too), such as from Afghani-
stan, Kazakhstan, Mongolia and Pakistan, have on
average more extensively grey greater and median
coverts than typical naumanni, with grey-tinged
lesser coverts in a few birds (plate 425-428 and
441-442). Thus, these birds often appear inter-
mediate between typical naumanni and pekinensis
in wing pattern (gure 1-2; intermediate bird in the
middle). The grey coverts are always darker and
deeper coloured in pekinensis, more lead-grey
than sooty grey compared with naumanni. Again,
birds from central-eastern Asia show slightly dark-
er or similar intensity of grey on the upperwing-
coverts.
Underparts
The breast and underparts are richer peach-orange
ochre in pekinensis, almost rusty or russet on the
breast and more orange or apricot on the lower
belly, ank and thigh compared with naumanni.
However, very fresh adult males of the latter may
appear almost as richly coloured, chiey if com-
pared with faded pekinensis.
Underwing
The underwing is bright white with sometimes a
rich orange-buff or chestnut colour on the under-
wing-coverts and axillaries, these showing a vari-
able amount of dark spotting (or being unmarked)
in pekinensis. The wing-tip is extensively black
and the secondaries are also extensively blackish
on the distal part, in many birds giving a more de-
ned dark trailing edge compared with typical
naumanni. The dark wing-tip is said to be more
extensive than in naumanni by several authors, in-
cluding in the original description of the syntypes
(Swinhoe 1870, 1871, Hartert 1912-1921, Brown
et al 1982). However, we found strong variability
in the underwing pattern. Furthermore, the stage of
abrasion and sun bleaching highly inuences the
eld appearance and boldness of the dark wing-tip
and the trailing edge, with abraded birds giving a
less obvious and less contrasting impression.
Adult female
Head
In adult female Lesser Kestrel (sensu latu), the dark
eye-line is almost always absent or weak, unlike in
Common Kestrel F tinnunculus (Cramp & Simmons
1980, Clark 1999, Forsman 2016). On average,
pekinensis has a more marked dark eye-line, some-
times even approaching that of Com mon, as well
as a bolder moustache than naumanni (Corso et al
2015). Corso (2000, 2001) reported a certain
amount of variability in the plumage of naumanni
in Europe, including the head and face pattern of
females, so that a certain overlap between most
marked naumanni and least marked pekinensis is
found. In addition, juveniles (chiey the darker,
414 Chinese Lesser Kestrel / Chinese Kleine Torenvalk
Falco naumanni pekinensis (right) and Western Lesser
Kestrel / Kleine Torenvalk F n naumanni, NHMUK, Tring,
England, 29 January 2009 (Andrea Corso/NHMUK).
Kodak Grey Scale value (Kodak 2007) of hood in adult
males showing range encountered in specimens stud-
ied: range 10-12 in pekinensis (mean 10), range 6-10 in
naumanni (mean 8). Grey hue and intensity on average
deeper and darker in pekinensis compared with nau-
manni. Both birds are in fresh plumage and collected at
same time of year.
Geographical plumage variation in Lesser Kestrel
278
415-416 Chinese Lesser Kestrel / Chinese Kleine Torenvalk Falco naumanni pekinensis, adult male (collected near
Ming Tombs, north of Beijing, China, on 18 September 1868), NHMUK, Tring, England, 11 June 2014 (Hein van
Grouw/NHMUK). Syntype of pekinensis, collected by Robert Swinhoe. In plate 415, note entirely lead-grey wing-
coverts and tertials, much darker and more extensively grey than in any naumanni; note also dark sooty lead-grey hood
and saturated colour of mantle. In plate 416, note richly coloured underparts, much richer than in any naumanni.
more patterned females) of all populations of
Lesser show bolder dark markings than adult fe-
males, including moustache and eye-line (Corso
2000, 2001, Corso et al 2015). Therefore, the dif-
ferences between typical adult female naumanni
and pekinensis are only of use when precisely age-
ing a bird rst.
Upperparts
Generally, the dark markings average bolder, wider
and better marked in pekinensis compared with
typical naumanni. However, the least marked birds
are comparable and therefore overlapping with
the most marked naumanni.
Underwing
On average, the dark wing-tip and trailing edge is
bolder and wider in typical pekinensis compared
with typical naumanni, thus better visible in ight
in the eld. However, juveniles of both taxa have a
darker patterning (Corso 2000, 2001) and inter-
mediate birds are widely overlapping, so this char-
acter should be used only as an additional feature
and not as a relevant one.
Adults of both sexes
Bare parts
Adult pekinensis of both sexes show the cere and,
to a lesser extent, the eye-ring yellow with an obvi-
Geographical plumage variation in Lesser Kestrel
279
417 Chinese Lesser Kestrel / Chinese Kleine Torenvalk
Falco naumanni pekinensis, adult male, Beijing prov-
ince, China, 10 May 2013 (Zhangey Hu). Upperwing-
coverts almost fully lead-grey but some sparse rusty
fringes present to some feathers. Note ochre-orange eye-
ring and cere as well as richly coloured underparts.
418 Chinese Lesser Kestrel / Chinese Kleine Toren valk
Falco naumanni pekinensis, adult male, Beijing prov-
ince, China, 10 May 2013 (Zhangey Hu). Same bird as
plate 417. 419 Chinese Lesser Kestrel / Chinese Kleine
Toren valk Falco naumanni pekinensis, adult male,
Beijing province, China, 10 May 2013 (Zhangey Hu)
420-421 Chinese Lesser Kestrel / Chinese Kleine Toren-
valk Falco naumanni pekinensis, adult male, Beijing
province, China, 25 April 2013 (Yanxq Hei)
417
419
418
420
421
Geographical plumage variation in Lesser Kestrel
280
422 Chinese Lesser Kestrel / Chinese Kleine Torenvalk
Falco naumanni pekinensis, adult male, Beijing prov-
ince, China, 25 April 2013 (Yanxq Hei). Note intensely
orange-tinged bare parts. 423 Chinese Lesser Kestrel /
Chinese Kleine Torenvalk Falco naumanni pekinensis,
adult male, Beijing province, China, 25 April 2013
(Yanxq Hei). Same bird as plate 422. Note that, with
open wing, some rusty lesser coverts are visible.
424 Chinese Lesser Kestrel / Chinese Kleine Torenvalk
Falco naumanni pekinensis, adult male, Beijing prov-
ince, China, 25 April 2013 (Yanxq Hei). Same bird as
plate 422. Note very intensely coloured underparts and
extensive dark trailing edge and tip to underwing.
425 Lesser Kestrel / Kleine Torenvalk Falco naumanni,
advanced second calendar-year male, Chokpak pass,
Kazakhstan, 21 September 2003 (Andrea Corso). Intermediate bird with plumage between pekinensis and nau-
manni but closer to pekinensis, due to amount of grey on upperwing-coverts. Plumage almost like full adult but for
retained juvenile s1-2 and growing p10 (making the wing-formula closer to that of Common Kestrel F tinnunculus).
426 Lesser Kestrel / Kleine Torenvalk Falco naumanni, adult male, Chokpak pass, Kazakhstan, 21 September 2003
(Andrea Corso). Intermediate bird, very similar to pekinensis but considered intermediate based on paler grey
colours than typical pekinensis from breeding grounds in China, paler mantle and underparts and more yellow, less
ochreous-orange bare parts. Bird has old p8-10 and s1-3.
422
424
423
425
426
Geographical plumage variation in Lesser Kestrel
281
427-428 Lesser Kestrel / Kleine Torenvalk Falco nauman-
ni, adult male, Chokpak pass, Kazakhstan, 17 September
2015 (James Kennerley). Intermediate birds, similar to
pekinensis but considered intermediate based on paler
grey colours than typical pekinensis from breeding
grounds in China, less extensive grey on upperwing-
coverts, paler breast and less extensive dark wing-tip.
429 Chinese Lesser Kestrel / Chinese Kleine Torenvalk
Falco naumanni pekinensis, adult male, Beijing prov-
ince, China, 25 April 2013 (Yanxq Hei). Same bird as
plate 420-421.
ous ochreous-orange tinge (gure 1 and 3, plate
417-424, 429 and 448). This tinge may become
brighter and more conspicuous in adult birds dur-
ing courtship, almost bright orange (approaching
that of Amur Falcon F amurensis). Adult naumanni
of both sexes always show paler yellow, more lem-
on-tinged bare parts, brighter during mating (Corso
2000, 2001), but according to our observations
not as orangey as in pekinensis. Differences in the
colour of the cere may be the most relevant eld
character to identify adult female pekinensis from
naumanni.
Conclusions
Adult males in fresh plumage from the eastern and
western end of the distribution area are easily
separable. Adult male pekinensis differs from adult
male naumanni in the intensity of grey in the
hood, amount of grey in the upperwing-coverts,
intensity of the colour on the underparts and col-
oration of the upperparts. It is always different
from naumanni and is diagnosable in the eld.
Indeed, all birds studied fall into a well-dened
cluster differing well over 75% from European
naumanni (Corso et al 2015), thus according well
with the so-called 75% rule, wherein at least
three-quarters of all individuals of at least one sex
must differ diagnosable from adjacent subspecies
(eg, Amadon 1949, Mayr & Ashlock 1991, Svens-
son 2013, 2015). The characters noted in Lesser
Kestrels from China are constant and we found no
birds showing all the characters of pekinensis
within western populations. Even those of the
inter mediate populations, although showing some
overlapping features or characters closer to the
one or other taxa, never showed the full set of
characters combined for pekinensis or naumanii.
Adult female pekinensis is almost identical to
adult female naumanni, differing only when show-
ing wider, bolder and well-dened dark markings
on the head, mantle and underwing. However,
due to apparently wide overlap in female plum-
427 428
429
Geographical plumage variation in Lesser Kestrel
282
430 Presumed Chinese Lesser Kestrel / vermoedelijke Chinese Kleine Torenvalk Falco naumanni pekinensis, adult
male (collected at Cachar, Assam, India, in March 1880), NHMUK, Tring, England, 29 January 2009 (Andrea Corso/
NHMUK). All upperwing-coverts entirely dark grey; note also very deep grey hood (Kodak Grey Scale 11).
431 Presumed Chinese Lesser Kestrel / vermoedelijke Chinese Kleine Torenvalk Falco naumanni pekinensis, adult
male (collected at Cachar, Assam, India, in March 1880), NHMUK, Tring, England, 29 January 2009 (Andrea Corso/
NHMUK). Same bird as plate 430. Darker saturated and intense coloration is notable in pekinensis, with naumanni
being paler. Typically, pekinensis shows saturated and intense coloration also on underparts, being richer and darker
coloured than in any naumanni (see plate 454). 432 Western Lesser Kestrel / Kleine Torenvalk Falco naumanni nau-
manni, adult male (collected in Spain in April 1902), NHMUK, Tring, England, 29 January 2009 (Andrea Corso/
NHMUK). Note that in many European birds (c 20%), grey on wing-coverts is very limited and hard to see in the eld
or even in the hand. Note that plumage is paler, less intense and less deep in both grey of hood and wing-coverts and
of rufous on mantle and underparts compared with pekinensis.
Geographical plumage variation in Lesser Kestrel
283
433 Presumed Chinese Lesser Kestrels / vermoedelijke Chinese Kleine Torenvalken Falco naumanni pekinensis, adult
males (left and right; both collected in India, in March 1880) and Western Lesser Kestrel / Kleine Torenvalk F n nau-
manni, male (centre; collected at Famagusta, Cyprus, on 20 March 1938), NHMUK, Tring, England, 29 January 2009
(Andrea Corso/NHMUK). Note much paler and less saturated grey hood and mantle less brick-red of naumanni
compared with pekinensis.
age pattern, we tentatively suggest the best char-
acter to distinguish adult females is the different
bare parts coloration. Further research by the au-
thors, including genetic studies, will hopefully
provide more clarity in the future.
Apart from any taxonomic point of view, the
plumage differences between western and eastern
birds should be acknowledged, eg, 1 to make it
possible to identify the true breeding and winter-
ing areas of the different populations; 2 to estab-
lish the correct number of breeding Chinese birds,
and eventually take conservation measures; 3 to
correctly illustrate birds breeding in China in fu-
ture eld guides and handbooks; 4 to gather data
on genetics of the Chinese population; and 5 to
further study differences among females of the
two taxa. Further targets of future studies should
also be to identify and better dene: 1 to which
taxon the intermediate populations belongs or if
they deserve a name on their own; 2 the extent of
the breeding area of pekinensis; 3 the eastern dis-
tribution of breeding range of naumanni and the
western boundaries of distribution of pekinensis;
and 4 the wintering areas of all populations.
Acknowledgements
We are grateful to Claudio Carere, Jia Fumin Lei
and He Peng and Zhi-Yun for providing us with
photographs of pekinensis. Sincere thanks go to
all staff in various museums who arranged access
to specimens and sent information. In particular
we thank Mark Adams, Hein van Grouw and
Robert Prŷs-Jones (NHMUK); Fausto Barbagli and
Marta Poggesi (MSNF); Giovanni Boano (SNCa);
Enrico Borgo (MSNGD); Giorgio Chiozzi (MCSM);
Anita Gamauf and Hans-Martin Berg (NMW);
Andrei Gravilov (IZA); Rosario Grasso (MCUCT);
Clemency Fisher and Tony Parker (LIV); Ulf Johans-
son (NRS); Pepijn Kamminga and Steven van der
Mije (NBC); Bob McGowan (NMS); Mary LeCroy,
Matthew Shanley, Paul Sweet, Tomas Trombone
(AMNH); He Peng (NZMC); the late Angelo Priolo
(MCR); the late Vittorio Emanuele Orlando (MCT);
Carla Marangoni (MCZR); Henry McGhie (MMUE);
Anne Previato and Patrick Boussés (MNHN); Clau-
dio Pulcher (MRSN); Kristof Zyskowski (PMNH);
and Sylke Frahnert (ZMB). Others who have
helped are Mark Andrews, Arnoud van den Berg,
Stephen Daly, Stephen Dudley, Wouter Faveyts,
Geographical plumage variation in Lesser Kestrel
284
434-435 Presumed Chinese Lesser Kestrel / vermoedelijke Chinese Kleine Torenvalk Falco naumanni pekinensis,
adult male (left; collected in Laos in spring 1940), and Western Lesser Kestrel / Kleine Torenvalk F n naumanni, adult
male (right; collected in eastern Morocco on 20 April 1954), MNHN, Paris, France, 18 February 2015 (Andrea Corso/
MNHN). 436-437 Chinese Lesser Kestrel / Chinese Kleine Torenvalk Falco naumanni pekinensis, adult male (col-
lected at Hebei, China, on 27 April 1937), NZMC, Beijing, China, 3 December 2014 (He Peng/NZMC). Fresh adult
male showing very intense brick-red mantle and sooty-grey plumage areas typical for pekinensis.
Geographical plumage variation in Lesser Kestrel
285
438-439 Chinese Lesser Kestrel / Chinese Kleine Torenvalk Falco naumanni pekinensis, adult male (collected at
Beijing, China, on 4 April 1961), NZMC, Beijing, 3 December 2014 (He Peng/NZMC). Note typical entirely grey
upperwing-coverts and intensely coloured underparts. 440 Chinese Lesser Kestrel / Chinese Kleine Torenvalk Falco
naumanni pekinensis, adult male (collected at Hebei, China, on 8 October 1965), NZMC, Beijing, 3 December 2014
(He Peng/NZMC). All upperwing-coverts typically solidly dark sooty-grey, never shown by nominate naumanni.
Geographical plumage variation in Lesser Kestrel
286
441-442 Presumed Chinese Lesser Kestrels / vermoedelijke Chinese Kleine Torenvalken Falco naumanni pekinensis,
adult males (collected at Na Bou, Laos, on 18 January 1941), PMNH, New Haven, USA, 19 August 2014 (Kristof
Zyskowski/PMNH). Note very saturated and richly coloured plumage, chiey dark mantle and intense and deep grey
tones of hood and upperwing-coverts, latter being entirely grey in both specimens, never shown by nominate nau-
manni. Also note intense colour on underparts, chiey on breast.
Geographical plumage variation in Lesser Kestrel
287
443-445 Presumed Chinese Lesser Kestrel / vermoedelijke Chinese Kleine Torenvalk Falco naumanni pekinensis,
adult male (collected in Laos in spring 1940), MNHN, Paris, France, 18 February 2015 (Andrea Corso/MNHN). Note
entirely grey upperwing-coverts and saturation of plumage colour.
Geographical plumage variation in Lesser Kestrel
288
446-447 Presumed Chinese Lesser Kestrel / vermoedelijke Chinese Kleine Torenvalk Falco naumanni pekinensis,
adult male (upper; collected in Laos in spring 1940), and Western Lesser Kestrel / Kleine Torenvalk F n naumanni,
adult male (lower; collected in eastern Morocco on 20 April 1954), MNHN, Paris, France, 18 February 2015 (Andrea
Corso/MNHN). Same birds as plate 434-435 and 443-445.
Geographical plumage variation in Lesser Kestrel
289
449 Western Lesser Kestrel / Kleine Torenvalk Falco naumanni naumanni, adult male, Spain, 9 April 2016 (Jyrki
Normaja). Note that in typical adult western males, grey on upperwing-coverts is restricted mostly to greater coverts.
Also note very pale grey colour of hood, upperwing-coverts and tail, not as dark grey as in pekinensis.
Yanxq Hei, Zhangey Hu, James Kennerley, Peter
Kennerley, Gerald Oreel, René Pop, Rick Roe,
Manuel Schweizer, Brian J Small, Terry Townshend,
Hua-wei Wang, Arend Wassink, Pim Wolf and Xu
Ke Yang. Our thanks go to Paola Di Luzio (MCZR)
for helping us with literature and to Ottavio Janni
for assisting us in museum research and suggest-
ing valuable improvements to our rst manu-
scripts. AC’s visit to MNHN and NHMUK was
made possible by the Dutch Birding Fund. A visit
by JJ to the NMS was made possible via a grant
from the ‘Stichting P.A. Hens Memorial Fund’.
Samenvatting
GEoGRAFIschE kLEEdvARIATIE B I j kLEInE T o R E n v A L k Er is nog
maar weinig bekend over de herkenning van Chinese
Kleine Torenvalk Falco naumanni pekinensis en nomi-
naat Kleine Torenvalk F n naumanni. De hier gepresen-
teerde kenmerken zijn eerder gepubliceerd in Corso et
al (2015) maar worden verder uitgediept en geïllus-
treerd met (nieuwe) foto’s en tekeningen. Hun onder-
zoek is gebaseerd op literatuuronderzoek, bestudering
van balgen (zie tabel 1), verkregen informatie in musea,
van foto’s van internet en van vogels in het veld in
Afrika, Azië en Europa. Bij het bestuderen van grote
aantallen vogels kwamen alleen bruikbare kenmerken
naar voren bij volwassen net geruide mannetjes en
vrouwtjes uit het voorjaar voor de uitersten van het
verspreidings gebied. Deze verspreidingsgebieden be-
448 Chinese Lesser Kestrel / Chinese Kleine Torenvalk
Falco naumanni pekinensis, adult female, Beijing prov-
ince, China, 25 April 2013 (Yanxq Hei). Note intense
orange bare parts and very well marked and wide dark
barring.
Geographical plumage variation in Lesser Kestrel
290
450 Western Lesser Kestrel / Kleine Torenvalk Falco nau-
manni naumanni, adult female, Spain, 9 April 2016
(Jyrki Normaja). Note chiey yellow bare parts, eye-ring
and cere.
451 Lesser Kestrel / Kleine Torenvalk Falco naumanni,
adult male, Spandarian reservoir, Gorayk, Armenia, 25
May 2015 (Peter Adriaens). Intermediate bird; note ex-
tensive grey on upperwing-coverts but not comparable
with pekinensis. Note also very richly coloured mantle.
helzen ‘Europa’ (naumanni) waar vogels een gelijke set
kenmerken vertoonden met een geringe variatie en een
geïsoleerde populatie in China (pekinensis) met even-
eens een gelijke set kenmerken met geringe variatie.
Hiertussen bevindt zich een groot gebied met inter-
mediaire vogels met een grote variatie. Dit laatste feno-
meen is bekend van andere roofvogelsoorten met een
gelijk verspreidingsgebied zoals Zwarte Wouw Milvus
migrans en Oostelijke Zwarte Wouw M lineatus en
Slechtvalk F peregrinus en Barbarijse Valk F pelegri-
noides, en bij ondersoorten van bijvoorbeeld Smelleken
F columbarius, Lan ner valk F biarmicus, Sakervalk
F cherrug en Slechtvalk.
De koptekening van volwassen mannetjes pekinensis
is donkerder grijs dan bij naumanni. De hoeveelheid
grijs in de vleugeldekveren is in pekinensis aanzienlijk
groter (bijna 100% van alle vleugeldekveren is grijs en
100% van alle tertails) tegen ongeveer eenderde van het
totaal bij naumanni. Ook verschillend is de intensiviteit
van de kleur van de onderdelen: pekinensis is donkerder
op de onderdelen dan naumanni. De donkere oogstreep
bij volwassen vrouwtjes naumanni is of afwezig of mi-
niem ontwikkeld, terwijl deze in pekinensis duidelijker
zichtbaar is. Ook zijn de naakte delen meer oranje in
pekinensis dan bij naumanni (meer geel). De bandering
op de mantel en schouder van pekinensis is zwarter en
duidelijker dan in naumanni. Kanttekening is echter dat
voor vrouwtjes en mannetjes pekinensis maar een klein
aantal vogels kon worden onderzocht en met name voor
vrouwtjes kunnen met het beschikbaar komen van meer
foto’s deze kenmerken in de toekomst wellicht meer ge-
wicht krijgen of juist minder.
Veel aspecten van beide ondersoorten zijn nog onbe-
kend, zoals waar de verschillende populaties overwinte-
ren, wat het exacte broedgebied is van pekinensis en of
de intermediaire populaties een eigen taxonomische
status verdienen.
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Geographical plumage variation in Lesser Kestrel
