Folia Historico-Naturalia Musei Matraensis - A Mátra Múzeum Természetrajzi Közleményei 21. (1996)
The pons supratendineus directed laterally at the cranial side of the distal end of the bone is the widest in the Kestrel and the narrowest in the Red-footed Falcon and Lesser Kestrel. At the distal end of the bone the most prominent difference among the species is found in the shape and size of the condyli. In the Hobby and Merlin the diameter of the condylus medialis is considerably larger (cranio-caudal direction, DH size) than the condylus lateralis, where the cranial part of the condylus is smaller. In the Hobby this difference is 0.4 mm (0.3-0.5 mm) in the Merlin 0.3 mm (0.1-0.5 mm). In the Kestrel and Lesser Kestrel - where the cranial part of the condylus lateralis is larger than in the other species - the difference between the diameters of the condyli is only 0.1 mm (0.0-0.3 mm), but sometimes the diameter of the condylus lateralis is larger than that of the condylus medialis. In the Red-footed Falcon this difference is larger than in the Kestrel and Lesser Kestrel. In average 0.1-0.2 mm but might be as much as 0.3-0.4 mm (Plate XLIII, Figures 1-5). In the separation of the species the ratio calculated from the diameter of the proximal end of the bone (PT) and the cranio-caudal size of the condylus lateralis (CL) is very useful. The PT/CL value is given for the following species with the average in parenthesis: Falco subbuteo: 1.70 - 1.87 ( 1.80) Falco columbarius: 1.62 - 1.86 (1.73) Falco tinnunculus: 1.48 - 1.68 (1.59) Falco vespertinus: 1.53 - 1.77 (1.64) The shape of the trochlea is also different in the examined species. In the Hobby and the Merlin the arch of the lateral crista sulci is less rounded, and hence connected to the corpus tibiotarsi more gradually than in the Kestrels (lateral view). On the contrary in the case of the Kestrel the arch of the lateral crista sulci is strongly rounded and the trochlea is round shaped in lateral view (Plate XLII, Figures 11-12). In the case of the Merlin the distal end of the bone is diverging into medial direction compared to the longitudinal axis of the corpus tibiotarsi, and the cranial part of the condylus medialis also bends more into the medial direction than in the rest of the species (caudal view). In the case of the Hobby there is a similar phenomenon, but emphasised to a lesser degree. Summary Falco subbuteo. - the bone ends of the tibiotarsus are quite big, - the crista patellaris is low in proximal direction, at the same time the crista interna is high, - the area interarticularis and the facies articularis lateralis in proximal direction is high, - the cranial part of the condylus the diameter of condylus me dialis lateralis is small, _ is sign jfj cant i y larger man that of - the arch of lateral crista sulci is fte condylus lateralis (distal view) flattened, - the cranial part of condylus medialis is diverging outwards into medial direction (distal view). Falco columbarius. - the corpus tibiotarsi is relatively narrow, but at the distal part (after the connection of the fibula) it becomes wide and flattened, - the crista patellaris is low in proximal direction, at the same time the crista interna is high, 46
