Folia Historico-Naturalia Musei Matraensis - A Mátra Múzeum Természetrajzi Közleményei 21. (1996)

The phalanx of the Red-footed Falcon compared to the Kestrel is considerably narrower, the phalanx dismal from the proximal end (the neck of the phalanx) abruptly narrows down. The rib on the dorsal side of the corpus phalangis is well developed, but apex is almost not detectable, and towards the caudal edge the depression is shallow. On the ventral side, the depression distally from the proximal end of the bone is smaller than in the Kestrel. The cranial edge in the Red-footed Falcon is concave, in the Kestrel on the distal part straight or undulating (Plate XXXVIII, Figures 14-16). Summary Falco subbuteo: - the phalanx is long and wide, - the proximal end of the bone is very large, - the phalanx only on its distal half narrows strongly (dorsal view), - the apex at the dorso-caudal edge of the corpus phalangis is located nearer to the distal end of the bone than in the other species. Falco columbarius: - the phalanx is short, - the proximal end of the bone is relatively large, - the phalanx narrows in distal direction evenly on its whole length (dorsal view), - the apex at the dorso-caudal edge of the corpus phalangis is located more far away from the distal end of the bone than in the Hobby, - the depression on the dorso-caudal edge of the proximal half of the phalanx is the largest in this species. Falco tinnunculus: - the phalanx is wide as compared to other Kestrels, - the proximal end of the bone is the largest among the Kestrels, - the apex and depression on the dorso-caudal edge of the corpus phalangis are hardly visible. Falco vespertinus: - the phalanx is very narrow and relatively long, - the proximal end of the bone is relatively small and narrow, - the phalanx distally from the proximal end abruptly narrows (dorsal view), - all the cranial edge of the phalanx is concave. Falco naumanni: - the phalanx is relatively long, - the proximal end of the bone is wide and flat. Phalanx proximalis digiti majoris (phalanx 1 digiti 2 anterior) The phalanx proximalis digiti majoris similarly to the phalanx discussed before is the largest in the Hobby. Then follows the Kestrel, then the Merlin and the Red-footed Falcon, in which the phalanx is approximately equal. The Lesser Kestrel has got the smaller phalanx here (Plate XVIII, Figure 1). In the Hobby the sizes are so large that this species is safely separated from the Merlin and Red-footed Falcon, only the PH and DH values overlap. The Kestrel overlaps with its absolute values with all of the species, while the Lesser Kestrel only reaches the minimal value of the Red-footed Falcon. This phalanx of the Merlin can be easily separated from that of the Kestrels, since the size 33