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© British Birds 94:409-418, September 2001 409
In recent decades, the Lesser Kestrel Falco
naumanni has suffered a rapid and dra-
matic decline in its numbers in Europe
and, perhaps to a lesser extent, throughout
its world range, which extends from Spain
and northernmost Africa eastwards to China
and Mongolia. The city of Matera, in Basili-
cata, southern Italy, holds one of Europe’s
largest breeding colonies of Lesser Kestrels
(Palumbo 1997).The population is concen-
trated in the centre of the city, within the
confines of which the falcons also roost. As
many as 2,000 individuals can be observed
arriving at the roost, where they then spend
the night in a single large pine tree Pinus
(Corso & Palumbo in prep.).
In May and June 2000, during a study of
the age and sex ratios of Lesser Kestrels at
the Matera roost, and the timing of their
arrival at it, I gathered extensive data on the
moult and plumages of this species. The
results obtained are presented here.
Methods
Observations were carried out from 20th
May to 15th June. During this period, at least
three days in each week were devoted to
gathering data. Lesser Kestrels were
observed not only at the roost, but also in
the foraging areas and at the breeding
colony. The observations at the main roost
were made from 18.00 to 19.30 hours local
time (scientific study of other aspects at the
roost continued until 21.00 hours: Corso &
Palumbo in prep.). Field observation at the
colony and in the foraging areas was under-
taken throughout the day.
Individuals were watched at close range,
and many were photographed. I also
obtained extensive video-film footage of the
Notes on the moult
and plumages of
Lesser Kestrel
Andrea Corso
ABSTRACT During a study of Lesser Kestrels Falco naumanni at Matera, in
Basilicata, southern Italy, in May-June 2000, special attention was paid to the
state of moult of individuals, and details of plumage were recorded. On
average, second-calendar-year females showed five or six newly moulted
primaries, and second-calendar males three; adult females usually exhibited
three new primaries, while adult males typically showed none (rarely, one to
three).A degree of plumage variability was observed, mostly in facial pattern
(all ages) and tail pattern (second-calendar-year males), but also in the
underwing-covert and underpart patterns.The dark moustache varied in
thickness, length and contrast, and the cheek patch was also somewhat
variable.The tail varied in number/shape of bars and in the colour of the
central feathers and other rectrices.The underwing-coverts of males varied
from uniformly pale and unmarked to diffusely dark-spotted,as did the
underparts, while females exhibited some variation in the length and thick-
ness of the dark streaking below. Claw colour was typically pale, rarely darkish.
Corso: Notes on the moult and plumages of Lesser Kestrel
410 British Birds 94:409-418, September 2001
falcons. Details of plumage pattern and state
of moult were observed by using 10 ×32
binoculars and a 20-60 ×77 telescope (used
mostly at 30×). Data were gathered and
written down on prepared recording sheets;
each of these contained separate sections for
plumage areas (head, mantle, upperwing/
underwing, underparts, legs, and so on), and
a sketch of an open wing with numbered
primaries and secondaries.
For the purposes of assessing moult, I was
able to make very close study of a total of
270 individual Lesser Kestrels. Of these, 175
were males (including 80 adults) and 95
were females (52 adults). Details of the state
of moult of each were carefully recorded.
Plumage variability was recorded by close
examination of 369 individual Lesser
Kestrels.These comprised 230 males, of
which 107 were adults, and 139 females,
including 79 adults. Particular attention was
paid to the facial pattern, the tail pattern and
shape, and the patterns of the underwing-
and upperwing-coverts and the underparts.
Moult
Among adults, the moult is always more
advanced in females compared with males.
For individuals in their second calendar-year,
partial moult of body and tail feathers is
more advanced in males, although wing
moult is more advanced in females; overall,
the moult of second-calendar-year kestrels is
more advanced than that of adults. Details
are summarised in table 1.
In 76.9% of adult females in June, some
moulting/growing primaries were evident. In
most cases, P2-4 were new, sometimes also
with P1 or P5 growing, or P3-4 new and P2
growing; very rarely, P1-4 or P2-5 were new.
In May, when numerous adult females did
not show any signs of moult, 98% of second-
calendar-year females did. Moreover, the
moult of the latter was more advanced, with,
in most cases, new P1-5 and old, worn P6-10;
a few individuals had P1-6 or P2-6 new with
the remaining primaries retained and worn,
or had P1-4 new, P5 missing and P6-10
retained (plate 238). In June, newly moulted
secondaries (S4-5 or S3-5) were evident on
only a few individuals. In 86.5% of adult
females, all rectrices were of the same gener-
ation (old), while only seven individuals had
moulted the central pair; by contrast, 67.4%
of second-calendar-year females had replaced
the central tail feathers, which projected
well beyond the rest.
In both May and June,adult males were in
a much less advanced state of moult. In
92.5% of these there was no apparent moult
in the flight feathers, which appeared to be
all of the same generation. In June, two indi-
viduals had P3 and P4 newly moulted and
one had P3-5 new, while on three others P4
was newly moulted and P3 was growing.
Almost all adult males (97.5%) had all rec-
trices of the same generation; the central
pair was newly moulted on the male which
had replaced P3-5 and on one of the three
birds with a new P4 and growing P3.
Age and sex Sample % in primary Remarks
moult
Adult male 80 7.5% Two with new P3-4,one with new P3-5, three with
new P4 and growing new P3
2nd-cal-year male 95 70% Usually new P2-4, sometimes P3-5 or P4-5; rarely,
P3-5 new, P1-2 and P7-10 retained and P6 missing;
very rarely, P2-4 new and P1 growing; or P2-5 new
(two individuals)
Adult female 52 76.9% Mostly new P2-4, sometimes P2-4 plus growing P1
or P5, or new P3-4 with P2 growing, and very
rarely new P1-4 or P2-5.
2nd-cal-year female 43 98% (in May) Usually new P1-5 and old and worn P6-10;in a few
cases, P1-6 or P2-6 new and remaining primaries
retained and worn, or P1-4 new with P5 missing
and P6-10 retained
Table 1. Wing moult of Lesser Kestrels Falco naumanni,Basilicata, south Italy, June 2000.
Primaries numbered from innermost (P1) outwards. Note that second-year females moult earlier,in May.
See text.
Corso: Notes on the moult and plumages of Lesser Kestrel
British Birds 94:409-418, September 2001 411
230. Adult female Lesser Kestrel Falco
naumanni, Basilicata, Italy,May 2000.This
individual shows no visible signs of moult.
Note wing formula like that of Common Kestrel
F. tinnunculus, with P10 same length as P7 or
only very slightly longer; here, the tail shape is
also like that of Common Kestrel (i.e.not wedge-
shaped). Note typical and distinctive contrast
between strikingly dark-spotted underwing-
coverts and paler,minimally marked remiges; also
paler cheek patch. Underpart streaking is often
concentrated on breast, being very thin or absent
on vent and trousers, producing visible contrast
between darker breast and paler lower
underparts (on Common Kestrel, streaking is
normally more extensive,bolder and more even).
232. Second-calendar-year male Lesser Kestrel
Falco naumanni,Basilicata, Italy,May 2000.No
wing moult evident, all remiges old; tail feathers
all retained but for a single central feather;body
feathers almost all replaced after partial post-
juvenile moult, new adult-type feathers densely
dark-spotted, much more so than in typical full
adult plumage; also underwing-coverts possibly
renewed, but densely spotted, appearing juvenile-
like.Very interestingly,the pattern of retained
juvenile tail differs from that of typical juvenile
in being pale grey, not rufous or brownish, with
narrow black barring.
231. Adult female Lesser Kestrel Falco
naumanni, Basilicata, Italy,May 2001. No wing
moult. On this individual, the wing formula is
more typical of the species, with P10 longer than
P7.
233. Second-calendar-year male Lesser Kestrel
Falco naumanni,Basilicata, Italy,May 2000.
Plumage similar to that of individual in plate 232,
but four tail feathers moulted.The central pair of
rectrices (the first to be moulted) already have
the white tips abraded, while fresher adjacent
pair still shows a wide white tip. Primaries look
very worn; on left wing, moult seems to be
starting at P5. Note rufous-washed tail, with black
subterminal band on adult-type feathers much
broader than on juvenile feathers.
Andrea CorsoAndrea Corso
W. S. ClarkAndrea Corso
Corso: Notes on the moult and plumages of Lesser Kestrel
412 British Birds 94:409-418, September 2001
Approximately 70% of second-calendar-
year males showed signs of primary moult,
generally with two to four new or growing
primaries: P2-4 (often), P3-5 or P4-5 new; or
P3-5 new, P7-10 and P1-2 retained and P6
missing (rarely) (plate 239); or P2-4 new and
P1 growing (very rarely); or P2-5 new (two
individuals). Those males which were
breeding appeared to have a smaller number
of moulted primaries compared with non-
breeding individuals. Evidence of secondary
moult could be confirmed only for two
second-calendar-year males (one with new
S4-5, and one with S5 new and S4 growing).
The central tail feathers were moulted in
62% of second-calendar-year males, and in
June 21% of them had moulted at least four
rectrices; only 16 second-calendar-year males
(11 in May and five in June) had not moulted
any tail feathers.
Moult of the upperwing-coverts can be
easily observed only on second-calendar-year
males, this being due to the obvious differ-
ences between juvenile and adult feathers.
Many males of this age had moulted a large
part of the median and lesser coverts, while
others (c. 36%) retained almost all their juve-
nile wing-coverts. Only a few individuals (c.
14%), in late June, had moulted almost all of
the coverts, retaining only some barred inner
greater coverts (and tertials).
All second-calendar-year males had
moulted almost all feathers of the head,
mantle, rump, uppertail-coverts and under-
parts. It appeared, however, that males which
were breeding had a more advanced partial
moult, and therefore a higher percentage of
new, adult-like feathers all over the body.The
same moult is certainly undertaken by
females, albeit later, but in their case the dif-
ferences between juvenile and adult feathers
are much more difficult to see in the field
(Clark 1999; Forsman 1999; Corso in prep.).
The only noticeable difference relates to the
greater coverts and tertials, and even then
only with perched birds at close range: the
barring on the greater coverts and tertials is
thicker, more obvious, coarser and more
irregular on second-calendar-year females
than on adults; in addition, the colour of the
coverts is rustier and brighter on adult
females, being yellower and duller on
second-calendar-years (owing to feather
wear).
Plumage and bare parts
Close examination of 369 individual Lesser
Kestrels, comprising 139 females (79 adults)
and 230 males (107 adults), revealed a
certain amount of variability in plumage and
in claw colour. In particular, the facial
pattern, the tail pattern and shape, and the
markings on the underwing- and upperwing-
coverts and the underparts were studied.
Variability in facial pattern
Compared with female Common Kestrel F.
tinnunculus, female Lesser Kestrel typically
has a less well-marked and less conspicuous
dark ‘moustache’, the dark eye-line is lacking,
the head streaking is thinner and more
diffuse, and the cheeks appear paler, almost
whitish, showing at most only very faint grey
streaking, whereas Common Kestrels have
dirtier cheeks with dark streaking, often
looking the same colour as the neck and
nape (Corso 2000). Lesser Kestrel’s pale
cheeks are bordered by dark streaking on
the neck sides, nape and crown, this contrast
giving it a face pattern that, in the field, is
reminiscent of that of a female harrier Circus
(Corso 2000).
Male Lesser Kestrels typically have a paler,
more bluish head than male Common. More-
over, the head is completely uniform, lacking
the dark streaking and the dark moustache
shown by Common Kestrel.
During my study, some slight variability
was noted in the moustache, cheek col-
oration, and eye-stripe. Some females showed
dirtier cheeks with some dark streaking and
a more pronounced moustache; on 5% of the
Matera females, the moustache was well
marked and very similar to that of Common
Kestrel. Only four females showed a slight
blackish eye-stripe, and in every case it was
narrower, shorter and less conspicuous than
on typical Common Kestrels.The presence
of an eye-stripe or a well-marked moustache
did not seem to be age-related.
Of all male Lesser Kestrels studied, 42.5%
showed some evidence of a dark moustache,
and well over half of those (61%) were
second-calendar-year individuals. In 76.5% of
cases, the moustache was barely evident,
while in the remainder the moustache was
more obvious,but never so striking as that of
Common Kestrel.
In addition, the throat colour of males
Corso: Notes on the moult and plumages of Lesser Kestrel
British Birds 94:409-418, September 2001 413
was variable. Normally it is buff-white, but at
Matera I found that it could be tinged ochre,
or be uniformly yellowish, uniformly white,
deep buff-cream, or even washed pale
rufous.
Tail pattern
Although the tail pattern of female and adult
Lesser Kestrels does, of course, exhibit a few
subtle variations, these are not observable
under field conditions.
On the other hand, the tail pattern of
second-calendar-year males can vary visibly,
and this feature was recorded for young
males. The newly moulted central tail
feathers are generally similar to those of
adult males. Of all young males examined,
57.7% showed an adult-like pattern, while
42.2% had a different pattern. Of the latter,
71.2% showed grey central rectrices but, in
addition to the typical black subterminal
band, had two or three narrower black distal
234. Adult male Lesser Kestrel Falco naumanni,
Basilicata, Italy,June 2001.Note wing-tips almost
reaching the tail-tip (unlike Common Kestrel F.
tinnunculus).
235. Adult male Lesser Kestrel Falco naumanni,
Basilicata, Italy,June 2000.Note wedge-shaped
tail, although all feathers of same generation.
Almost unmarked pale underwing-coverts typical
of adult male.
236. Adult male Lesser Kestrel Falco naumanni,
Basilicata, Italy,June 2001.Underwing-coverts
slightly more spotted than on many adults,but
still not so much as on first-adult-type birds. Note
typical Lesser Kestrel wing formula.
237. Adult male Lesser Kestrel Falco naumanni,
Basilicata, Italy,June 2000.No signs of moult.The
tail does not appear wedge-shaped, but this is
due to varying degrees of abrasion of the white
tips of the feathers; if all were equally worn, the
tail would look wedge-shaped as the central
feathers are effectively longer.
W. S. Clark
Andrea Corso
W. S. Clark
Andrea Corso
Corso: Notes on the moult and plumages of Lesser Kestrel
414 British Birds 94:409-418, September 2001
bars, while 28.8% showed instead six or
seven additional bars of variable thickness
along the entire length of the central
feathers. In many cases, these extra bars
were limited to oval or irregularly shaped
markings alongside the shaft. In 69% of those
having a different pattern from that of adults,
the grey central tail feathers showed a faint
rusty or ochre wash.
On the majority of second-calendar-year
males, the outer tail feathers were of the
typical juvenile pattern, since they are
retained from juvenile plumage. On some,
however, the outer feathers were light grey
(plate 232) with a wide black subterminal
band and three to six very narrow black
bars; the tail then appeared similar to that of
adult males. Normally, only the central rec-
trices are moulted during the winter, and all
other tail feathers are identical to those of
juveniles. Juveniles of both sexes have a tail
very similar to that of adult females, and
therefore quite different from that of certain
individuals observed at Matera. According to
Forsman (1999), juvenile males occasionally
have a grey tail, and it is not unknown for all
tail feathers to be moulted in the first
autumn, but no further details are given.The
state of growth and wear of the rectrices of
these ‘odd’ individuals at Matera suggested
that their tail feathers were all of the same
generation. My observations would appear,
therefore, to confirm Forsman’s statements.
The only possible explanations are that some
second-year males moult all of their tail
feathers between winter and spring, thus
acquiring a ‘first-adult’ tail that is only a little
different from that of a full adult; or, alterna-
tively, that some males have a greyish tail
similar to adult even when they are juve-
niles, rather than having a tail pattern like
that of females.
Tail shape
Despite earlier statements in the literature
(e.g. Porter et al. 1981), the ‘wedge-shaped’
tail of Lesser Kestrel is not diagnostic.In fact,
tail shape is subject to age-related, moult-
related and individual variation. It can appear
strongly wedge-shaped on second-calendar-
year individuals as a result of the newly
moulted central tail feathers, which are
longer and project beyond the others, but
this holds true also for second-calendar-year
Common Kestrels, albeit not so strongly. On
many adult Lesser Kestrels of both sexes, the
tail does appear in the field to be more
wedge-shaped, with a more distinct projec-
tion of the central feathers, than on Common
Kestrel. Common Kestrel usually has a more
rounded-looking tail; on those on which it is
more wedge-shaped, the tail shows a more
regular profile, without the obvious projec-
tion of the central feathers. Additionally, the
tail of Lesser Kestrel appears more wedge-
shaped partly as a result of its being shorter
(both in absolute terms and in relation to
wing length) compared with that of
Common Kestrel: when spread, Lesser’s tail
appears more rhomboidal, less rectangular.
While the wedge-shaped tail is not, there-
fore, diagnostic, it can be very useful in
picking out certain individuals for closer
examination. After reviewing many hours of
video film, I have noticed that, for all age
classes, the central tail feathers project more
on Lesser Kestrel than they do on Common
Kestrel.This is due in part to wear, as the
central feathers have a narrower white tip
than the other tail feathers (plate 237) so
that, once all the tips wear off, the other tail
feathers look shorter than the central pair
(Forsman 1999; pers. obs.);and in part to the
fact that the central feathers really are longer
than the other rectrices. Indeed, even though
the white tips of the central pair – because
they are narrower and, especially, because
the central feathers are moulted first – wear
off faster than do the tips of the other tail
feathers, the central feathers, even after
losing the tips, still look longer than the
others which have retained their white tips
(plates 235 & 240).
Wing formula and wing shape
Forsman (1999) mentioned the difference in
wing formula between Common Kestrel and
Lesser Kestrel, stating that Lesser has ‘p10
distinctly longer than p7’while Common has
‘p10 and p7 roughly equal in length’.
Although Forsman is surely correct in this
assertion, the wing formula is, in my experi-
ence, not always useful for field identifica-
tion, being in many cases virtually impossible
to assess with 100% certainty in the field.
Furthermore, several Lesser Kestrels appear
to have P10 of the same length as P7 (plate
230), or even shorter, then showing a wing
Corso: Notes on the moult and plumages of Lesser Kestrel
British Birds 94:409-418, September 2001 415
formula very like that of Common Kestrel.
The apparent primary length may be influ-
enced by differences in the degree of abra-
sion, or in moult stages, by individual
variation or by other, unknown factors, or
simply by posture and wing position and
action. Just compare the wing formula of
Lesser Kestrel in Forsman’s plates 540-541
with the identical-looking Common Kestrel
in his plates 559-569; and look at the
Common Kestrel showing a Lesser-like wing
formula in his plates 569-570. If this char-
acter is not 100% reliable in photographs,
238. Second-calendar-year female Lesser Kestrel
Falco naumanni,Basilicata, Italy,late June 2000.
Note advanced wing moult, with P6-10 retained
(appearing longer), P5 missing and P1-4 new
(appearing shorter). Juvenile-type feathers show
obvious dark tip (reported to be more typical for
Common Kestrel F. tinnunculus).
239. Second-calendar-year male Lesser Kestrel
Falco naumanni,Basilicata, Italy,late June 2000.
This individual has P7-10 retained, P6 missing
and P3-5 new.The new central tail feathers again
show some dark barring, while the body feathers
have a pattern almost as that of definitive full
adult.
240. Adult male Lesser Kestrel Falco naumanni,
Basilicata, Italy,June 2000.Note closed tail
looking very pointed, and wedge-shaped.
241. Adult female Lesser Kestrel Falco
naumanni, Basilicata, Italy (date unknown). Note
the very obvious and contrasting pale cheek
patch, whitish forecrown, lack of dark eye-stripe,
pale claws, long wings and different pattern of
barring on the upperparts compared with
Common Kestrel F. tinnunculus.
Andrea Corso
Andrea Corso
Andrea Corso
Claudio Galasso
then it should be used with extreme care in
the field.
A difference in wing shape between the
two species may be detected by an experi-
enced eye: Common Kestrel shows a longer,
more pointed and narrower hand, while that
of Lesser Kestrel usually appears shorter and
more rounded.This latter impression is pro-
duced by Lesser’s combination of shorter
primaries and broader hand.The wing shape
of Lesser Kestrel is, in fact, much more like
Corso: Notes on the moult and plumages of Lesser Kestrel
416 British Birds 94:409-418, September 2001
that of Red-footed Falcon F. vespertinus.Of
course, the wing formula as described by
Forsman (1999) and Clark (1999) also influ-
ences the wing shape.
Pattern of upperwing- and underwing-
coverts
Males show some variability in these charac-
ters. The underwing-coverts can show some
dark spotting, although, on most, the under-
wing appears uniformly white, with no or
only very limited dark markings (plates 235
& 237). On a number of males, however,
these dark markings can be more extensive
and conspicuous (plate 236); although this is
not strictly age-related, the most well-marked
individuals are in many cases younger males,
often in their first adult plumage. Males in
transitional first-summer plumage always
have more extensive and noticeable spotting
on the underwing-coverts (plates 232 & 233).
Variability in upperwing-covert pattern is
limited to the extent of grey. Usually only the
greater secondary coverts are grey, but some-
times the tertials are as well, and rarely also
the inner scapulars and outer median
coverts.
Underpart pattern
Males exhibit greater variability in underpart
pattern than do females. Males usually show
a series of round or oval spots, which are
quite sparse and limited to the flanks and
belly, but this spotting can sometimes be
denser and more regular, and can, in extreme
cases, form longitudinal black striping on the
breast and trousers and black arrowhead or
anchor-shaped markings on the lower flanks
and upper trousers, recalling male Common
Kestrel (see photo in Corso 2000). Generally,
the most well-marked individuals are imma-
tures, and they often show underwing spot-
ting as well. On males with little spotting
(plate 242), the underparts can appear quite
immaculate and very pale in the field (older
adults).
On females, underpart streaking is usually
very thin and sparse, more so than on female
Common Kestrels, and, in contrast to the
latter, the markings usually fall short of the
belly and trousers and are even thinner and
sparser in the centre of the lower breast. A
few individuals, however, can be more
heavily streaked,much as Common Kestrel.
Claws
Although these are usually very pale, ranging
from white to pale pinkish or yellowish, I
noted a few individuals, three males and two
females, with brownish or blackish-grey
claws, although never so black as those of
Common Kestrel (Corso 2000). Obviously,
the claws can appear dark in the field if they
are stained or dirty, and this can lead to con-
fusion if claw colour is used as the only iden-
tification character for females. Often, the
claws are not white or pinkish as described
in many field guides, but are in fact a pale
yellowish-grey (plate 242).
Discussion
With regard to moult, the data gathered in
this study reveal several slight differences
from what was reported by Forsman (1999).
Forsman described Lesser Kestrels in Greece
in late June as having a slightly more delayed
moult than the ones which I observed in
Italy. In Greece, second-calendar-year females
had moulted one to five primaries (usually
two or three), while second-calendar-year
males had moulted none to three (usually
one or two). In my study, despite the earlier
date by 10-15 days, second-calendar-year
females had moulted five or six primaries,
with only a few having moulted four or five,
while second-calendar-year males had
moulted two to four primaries, in most cases
three. Adult females in Greece showed as
many as three moulted primaries (usually
two), and adult males up to two moulted pri-
maries but usually none; among the individ-
uals which I studied, females had moulted or
were moulting two to four primaries (usually
three), and males usually none but occasion-
ally up to three.
Forsman’s (1999) observations go back to
1989. From my own observations, it would
seem that the climatic changes of the last
decade, which have affected the timing of
migration of many species (pers. obs.), may
possibly have led to an earlier moult by
Lesser Kestrels in response to an increase in
temperature. Such a ‘bold’ and highly specu-
lative theory would, of course, need to be
backed up by detailed and thorough studies.
If one considers that more southerly popula-
tions of raptors usually start to moult earlier
than do more northerly ones (Forsman 1999;
Corso in prep.), the differences between
Corso: Notes on the moult and plumages of Lesser Kestrel
British Birds 94:409-418, September 2001 417
Italy and Greece appear to be even more
noticeable.
Possible changes in the timing of
breeding/egg-laying in the last ten years may
also have influenced the start of complete
moult. It would seem that many Lesser
Kestrels have arrived at the Basilicata
colonies earlier in recent years (G. Palumbo,
verbally) and may therefore have begun
breeding earlier, this leading to an earlier
start of the moult. At present, however, I do
not have sufficient definite data to support
this possibility, and the information that is
available is not easy to assess. Since this
species does not concentrate at the migra-
tion watchpoints, such as the Strait of
Messina, and it does not use the typical
migration flyway, it is difficult to judge its
migration pattern. Nevertheless, once the
falcons have arrived at the colony, a warmer
temperature may stimulate them to start
breeding sooner.
As a point of interest, my observations in
Sicily have revealed a general difference
between sedentary and migratory raptors
with regard to recent changes in timing of
breeding. Since about 1990, sedentary
species, such as Bonelli’s Eagle Hieraaetus
fasciatus, Peregrine F. peregrinus and Lanner
Falcons F. biarmicus and Golden Eagle
Aquila chrysaetos, have on average begun to
lay earlier (some pairs from as early as the
end of January), whereas migratory species,
such as Egyptian Vulture Neophron perc-
nopterus, Black Kite Milvus migrans and
others, have laid later. This is due to the fact
that, in southern Italy (and, I believe, in the
southern Mediterranean in general), migra-
tion appears to be delayed in recent years,
becoming progressively later each year, so
that the migrants start to breed later.
By contrast, the Red-footed Falcon, a long-
distance migrant which has a very similar
migration to that of Lesser Kestrel (and
which is, after all, the closest species in
biology, structure, social behaviour and so
on), has shown no significant temporal differ-
ences in recent years at the Strait of Messina,
although first arrivals have been observed
earlier since 1998 (as early as the last ten
days of February, when the spring survey is
still not underway: C. Cardelli in litt.; pers.
obs.).As with Lesser Kestrel, however,the evi-
dence is still difficult to interpret.
In my study in south Italy, there appeared
to be a correlation between the state of
moult of second-calendar-year males and
reproductive activity. A great majority of
those males breeding in their first
spring/summer had a delayed flight-feather
moult compared with the apparently non-
breeding ones. Moreover, many of the
breeding second-calendar-year males had a
more advanced body moult (regardless of
flight-feather moult status). There are two
possible hypotheses to explain this. First,
breeding second-calendar-year males need to
have fewer moult gaps in their wings in
order to fly and hunt more efficiently,
allowing them to bring more prey to the
nest, and, furthermore, they need to allocate
their energy reserves to hunting and to
feeding young rather than to moulting; non-
breeding second-calendar-year males can
instead save their energy for moulting. Sec-
ondly, young males with a more advanced
body moult are more likely to be successful
during courtship, as they have a more attrac-
tive plumage, and additionally, having fin-
ished their body moult (which takes place
earlier than flight-feather moult), they can
devote more energy to breeding and to
feeding young. All these factors also explain
in part why there are differences in the
timing of moult between adults and imma-
tures.
Finally, plumage variability has scarcely
been mentioned in the literature, yet it is
observable to some extent even in the field.
It can sometimes also lead to difficulties in
the identification of the species.This is true,
in particular, with regard to tail and wing
shapes, wing formula, claw colour (reported
to be occasionally darkish),and the degree of
streaking/spotting on the underparts.
Indeed, some male Lesser Kestrels show
underbody markings resembling those of
Common Kestrel, something which is never
illustrated or mentioned in field guides.Vari-
ability of some plumage areas, such as the
underwing-coverts and the underbody,
appears to be to a certain extent age-related,
with second-calendar-year male and first-
adult male being more patterned and
showing more extensive dark markings,
while adult males are paler, neater and with
fewer/no dark markings.A dark eye-stripe, a
feature considered always to distinguish
Corso: Notes on the moult and plumages of Lesser Kestrel
418 British Birds 94:409-418, September 2001
female/juvenile Common Kestrel from Lesser
Kestrel, may also be subject to some varia-
tion. Lesser can, very rarely, show a hint of a
dark eye-line, but this, apart from being
exceptional in occurrence, is always short
and not conspicuous, never being so marked
as on Common Kestrel. It appears to be,
therefore, a very good character for distin-
guishing perched females/juveniles of these
two very similar species.
Acknowledgments
First and foremost, I should like to thank the Palumbo
family for accommodating me during this and all my
other studies in Basilicata, and in particular Giovanni
Palumbo, who made it possible for me to visit the
Lesser Kestrel colony in Matera and to discover
Basilicata’s incredible avifauna.I also thank my family,
without whose support none of my studies would be
logistically possible. For useful discussions, I am
grateful to M. Bux, V. Cappello, C. Cardelli,A. Ciaccio,
W. S. Clark, C. Iapichino and others.Warm thanks also
to my friend Ottavio Janni (member of the Italian
rarities committee) for his help with editing and with
translating of the original Italian text. A debt of
gratitude is owed to W. S. Clark and Dick Forsman for
their works, which are sources of reference,study and
inspiration for all raptor-watchers.
References
Clark, W. S. 1999. A Field Guide to the Raptors of
Europe, The Middle East and North Africa. Oxford.
Corso, A. 2000. Less is More: British vagrants, Lesser
Kestrel. Birdwatch 91:29-33.
— In prep. A Guide to Sexing and Ageing European
Raptors.
— & Palumbo, G. In prep. Sex/age ratio, counts and
arrival dynamics at a roost of Lesser Kestrel Falco
naumanni in the town of Matera, Basilicata,
Southern Italy.[To be submitted to Ardeola.]
Forsman, D. 1999. The Raptors of Europe and The
Middle East. A Handbook of Field Identification.
London.
Palumbo, G. 1997. Il Grillaio Falco naumanni. Ed.
Altrimedia.
Porter, R. F., Willis, I., Christensen, S., & Nielsen, B. P.
1981. Flight Identification of European Raptors.
3rd edn. Calton.
242. Adult male Lesser Kestrel Falco naumanni,
Greece, late July (year unknown). Note the very
sparse and inconspicuous spotting on
underparts, and claws appearing dark grey.
243. Second-calendar-year male Lesser Kestrel
Falco naumanni,Greece, late July (year
unknown). Note retained tertials and inner
greater coverts showing dark barring.All mantle
feathers have been moulted, as also have outer
greater coverts (grey) and scapulars.Wing moult
very advanced, with P10 retained, P9 growing,
P5-8 new.Wing-tips reach dark tail band. Central
tail feathers are longer than outers and, being
new (fresher), show white tip.
Andrea Corso, C.I.R.(Comitato Italiano Rarità), Via Camastra, 10-96100 Siracusa, Italy
Roberto Garavaglia
Roberto Garavaglia
