Lesser Kestrel Falco naumanni / Common Kestrel Falco tinnunculus
The figure, Figure 1, to the left shows an adult male Lesser Kestrel (left) and an adult male Common Kestrel (right). Simple enough to see the difference, but in the field it can be hard to separate them. The females and juveniles can sometimes be nigh impossible, even for the most experienced observer.
As well as giving comparative detail, I have also given species accounts and descriptions, see the appendixes, hoping that the combination of information will help those who find these particular birds hard to separate.
Peter Jones
Flight identification. Lesser Kestrel when soaring shows more rounded wings than Common Kestrel, also whilst soaring or hovering it appears to be bulkier in the body, both sexes appear paler on the underwing, the male very markedly white compared to dark breast and with more distinct black wing tips. In flight and more especially when hovering, Lesser Kestrel show wide and triangular tail-band, Common Kestrel nearly always shows fan-shaped tail-band. In silhouette the bulkier and shorter body is useful to distinguish both sexes and juvenile Lesser Kestrel from Common Kestrel. When hanging in a headwind Lesser Kestrels give the appearance of a small Peregrine with their shorter tail, plump body and pointed wings swept back in scimitar shape. Of course the male Lesser Kestrel has very distinctive features such as grey head, little or no moustache stripe, grey upperwing coverts (remarkably difficult to see at a distance) and with spotless upperparts.
Author’s note: Whilst watching flying birds always stay focused and wait for the bird to spread its tail, either when it pauses to hover or using it to manoeuvre, it is then possible to view the shape of the black subterminal bar to tail, a very useful aid to successful id. Plumage differences are discussed below.
Identification of perched birds. See Figure 1 for comparison of both species of male. A good guide is Lesser Kestrel can be distinguished by longer wings, either reaching or nearly reaching the tip of the tail. Caution is necessary though for 2nd year birds in spring that may have replaced their tail with longer feathers! The normal upright posture of both these Kestrels will normally allow the observer to see the wing length in relation to tail tip. Claw colour is another very positive, although sometimes difficult to see, identification feature; very pale or grey with Lesser Kestrel and black with Common Kestrel. Adult male Lesser Kestrel have spotless upperparts with part grey upperwing coverts and tertials; head is uniform grey, but can occasionally show a faint moustache, never with pale cheeks as with Common Kestrel. Both females and juveniles can be separated from Common Kestrel by head pattern and feather pattern to upperparts; head is plain except for dark moustache below the eye and pale cheek patch reaching the crown, no dark eye-line as in Common Kestrel; upperparts finely barred i.e. much narrower than rufous interspaces.
Illustrated Guide
Left: Lesser Kestrel. Right: Common Kestrel
Left: Lesser Kestrel. Right: Common Kestrel
Figure 3. Upper/underwing LK-CK
Left: Lesser Kestrel. Right: C- Kestrel
Left: Lesser Kestrel, note how much shorter the 7th primary is in comparison to the 10th (outermost primary).
Left Common Kestrel, the 7th primary is equal to the 10th.
Figure 5. Illustration of the different head pattern and colours.
Male Lesser Kestrel
Male Common Kestrel.
Figure 6. Upperparts of Lesser and Common Kestrel
Left male Lesser Kestrel. Adult male Lesser Kestrel have spotless upperparts with part grey upperwing coverts and tertials; head is uniform grey, but can occasionally show faint moustache. Note broad subterminal band on tail. Smaller bill.
Right male Common Kestrel. Adult male Common Kestrel have spotted upperparts; head has pale cheek patch and moustache. Bare parts always pale/bright yellow compared to rich ochre in Lesser Kestrel.
Left female Lesser Kestrel. Adult female has no eye line and less defined moustache below the eye. The mantle and wing coverts are finely barred, much finer than rufous interspaces. Also has broader subterminal band on tail. Smaller bill.
Right female Common Kestrel. Adult female has dark eye line and heavier moustache starting from in front of the eye. The mantle and wing coverts are more like spotting from a distance and not barred. Head also looks patterned from a distance compared to plain head of Lesser Kestrel.
Figure 7. Claw colour, a definitive identification between Lesser and Common Kestrel
Left Lesser Kestrel – Claw pale to light grey
Left Common Kestrel – Claw always black
KESTREL (Falco tinnunculus)
SIZE 31-38 cm. Tail 12-15 cm. Wing-span 71-80 cm
IDENTIFICATION Pointed wings and long tail, with black terminal band; dark claws; brown upper-parts, mottled in both sexes; pale buff under-parts; grey head and tail in male, buffer and streaked in female and juvenile; outermost primary with the same length than 7th.
SIMILAR SPECIES The only small raptor with brown upperparts is Lesser Kestrel, with pale claws and the outermost primary longer than 7th; male Lesser Kestrel has unspotted upperparts and a blue band on wings.
STATUS IN ANDALUCIA
Resident. Widely distributed throughout the Region.
SEXING
Adult male with grey head, unstreaked; uni-form grey, without barred, on uppertail coverts and rump; sparse mottled on upperparts and upperwing coverts.
Adult female with streaked head; tail, uppertail coverts and rump barred and with greyish tinge; upperparts and upperwing coverts mottled.
Juveniles cannot be sexed using plumage characters till moult of rump and upperparts.
CAUTION: plumage in adult females is very variable and can be similar to a male with grey rump, tail and head.
AGEING
3 types of age can be recognised:
Juvenile with flight feathers, greater coverts and primary coverts with broad pale tips; streaked breast; fresh plumage without moult limits on the wing.
1st year winter/2nd year spring with moult limit between body feathers with adult pattern and worn juvenile wing feathers.
Adult without juvenile feathers on body and wings.
MOULT
Complete post-breeding moult, starting in May and finished in November. Partial post-juvenile moult confined to body, scapulars and, sometimes, lesser and median coverts; starts late August and finished in January.
LESSER KESTREL (Falco naumanni)
SIZE 27-33 cm. Tail 11-12 cm. Wing-span 58-72cm
IDENTIFICATION Pointed wings and long tail with black terminal band; pale claws; brown upperparts, mottled only in female; pale buff underparts; grey head and tail in male, buffer and streaked in female and juvenile; outermost primary longer than 7th.
SIMILAR SPECIES The only other small raptor with brown upperparts is Common Kestrel, with dark claws and the outermost primary the same length as 7th; male Kestrel have spotted upperparts and have no blue band on the wing.
STATUS IN ANDALUCIA
Resident and summer visitor. Most common in summer; breeds in buildings, old ruins and also cliffs. Widely distributed throughout the region.
SEXING
Adult male with unstreaked grey head; uniform grey and without barring on tail, upper tail coverts and rump, buff underparts without mottling; broad bluish band on wings.
Adult female with streaked head; barred tail with greyish tinge, upperparts and upperwing coverts mottled.
Juvenile can be sexed in extreme cases. Male with upper tail coverts and tail feathers tinged grey, lesser coverts scarcely spotted. Female with upper tail coverts and tail feathers without or with only a little grey tinge; lesser coverts strongly spotted. After post-juvenile moult both sexes are similar to adults.
AGEING
3 types of age can be recognised:
Juvenile with flight feathers, greater coverts and primary coverts with broad pale tips; streaked breast; fresh plumage without moult limits on wing.
2nd year with moult limit between body feathers, with adult pattern, and worn juvenile wing feathers. Caution: in females it is not always easy to separate both generations of feathers.
Adult without juvenile feathers on body and wing.
MOULT
Complete post-breeding moult starting in May/June. Migrant birds suspend moult and finish in their wintering quarters. Partial post-juvenile moult which starts in October, which is suspended in migrant birds and completed in their wintering quarters, confined to scapulars, lesser and median coverts; some birds can moult most if not all wing coverts.