The Lesser Kestrel (Falco naumanni) is a small falcon. This species breeds from the Mediterranean across southern central Asia to China and Mongolia. It is a summer migrant, wintering in Africa and Pakistan and sometimes even to India and Iraq. It is rare north of its breeding range, and declining in its European range.
It is a small bird of prey, 27–33 cm in length with a 63–72 cm wingspan. It looks very much like the larger Common Kestrel but has proportionally shorter wings and tail. It shares a brown back and barred grey underparts with the larger species. The male has a grey head and tail like male Common Kestrels, but lacks the dark spotting on the back, the black malar stripe, and has grey patches in the wings.
The female and young birds are slightly paler than their relative, but are so similar that call and structure are better guides than plumage. The call is a diagnostic harsh chay-chay-chay, unlike the Common Kestrel's kee-kee-kee. Both sexes do not have dark talons as usual in falcons; those of this species are a peculiar whitish-horn color. This, however, is only conspicuous when seen birds at very close range, e.g. in captivity.
The Lesser Kestrel is, as the name implies, a smaller and more delicate bird than the Common Kestrel, and it is entirely sympatric in its breeding range with it; they compete to a limited extent. Thus, the possibility that there is some form of adaptive advantage to the similar coloration deserves study. Considering that the Lesser Kestrel would in fact have an advantage if some would-be predators confuse it with the larger species and consequently avoid it, it might be a case of Müllerian mimicry.
It is widespread and plentiful on a global scale, but in many areas of its range, it seems to be undergoing a marked and possibly accelerating decline. The IUCN has thus classed it as a vulnerable species (VU A2bce+3bce). This means that the global population and range have declined by some 30% in the last 10 years, and is expected to continue to do so for at least another decade. Apart from possible habitat destruction, it appears that indiscriminate use of pesticides has a strong effect on this species due to its insectivorous habits.