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

two species, and that of the Red-footed Falcon and Lesser Kestrel is more similar to that of the Merlin. The phalanx is the narrowest in the Merlin (GW), and its height (GH) is small, and these features separates it from the Hobby quite well. The width measures even separates it more or less from the Kestrel. From the ratio values the GW/PW is most adept for the separation of the Hobby and Merlin. The GW/GH ratio is approximately equal, as the phalanx of the Hobby is wide and high, and that of the Merlin is narrow and flat, and hence the two proportions are similar. In the Kestrels the phalanx is relatively wide and flat, and hence the GW/GH values are higher than in the former species. They are the highest in the Lesser Kestrel. In the male specimens of the Kestrels compared to its length the phalanx is narrower (GL/PW and GL/GW values are higher) than in the females. Morphologically in all the species the individual variability is great, but usually the distal part of the phalanx of the Hobby is narrower and its apex is more pointed than in the Merlin. The cranial edge is straighter, in the Merlin this is in the middle of the corpus in the line of prominentia caudalis is broken in cranial direction (Plate XXXVIII, Figure 9). In the Kestrels the distal part of the phalanx is even narrower than in the Hobby (Plate XXXVIII, Figures 10-11 ). In the Kestrel in cranial view the corpus phalangis abruptly narrows distally from the proximal end of the bone. In the Red-footed Falcon the phalanx in average narrower than in the other species, the prominentia caudalis is placed longitudinally towards the middle (Plate XXXVIII, Figure 11). Summary Falco subbuteo: - the phalanx is long, wide and thick, the GW/PW value is high, - the distal part of the phalanx is narrow, the apex is pointed, - the cranial edge is approximately straight. Falco columbarius: - the phalanx is short, narrow and flat, the GW/PW value is low, - the cranial edge is curved, sharply breaking in the line of prominentia caudalis. Falco tinnunculus: - the phalanx is wide and relatively flat, - in cranial view the phalanx abruptly narrows distally from the proximal end of the bone. Falco vespertinus: - the phalanx is relatively narrow, - the prominentia caudalis in longitudinal direction runs almost at the middle of the phalanx. Falco naumanni; - the phalanx is wide and flat, the GW/GH value is the highest. Sternum The sternum of the true Falcons is considerably larger than that of the Kestrels. Between the two group the length measures are well separated, considerable overlap is only found between the male of Merlin and Kestrel. But the length measures of the sternum of the Merlin and Hobby overlap considerably. The size range of the Hobby males is coincides with hat of the females of the Merlin. The sternum size of the Eleonora's Falcon is considerably larger even 36