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

GENERAL PART The examined species are very similar morphologically to each-other. In many cases it is very difficult or even impossible to find distinguishing markers, the existing markers are very weak, they are not exclusively valid for the given species, and they can be only statistically evaluated. The size differences between the species are small, in most of the cases the measurements of the females of the smaller species are overlapping or equal with the measurements of the males of the larger species. Therefore in the process of identification the measurements and the morphological characters must be evaluated together. The size rank of these species according to the body mass from the literature (PÁTKAI, 1958, WEICK, 1980) is the following: F. eleonorae > F. subbuteo = F. tinmmculus > F. columbarius > F. vespertinus = F. naumanni The species can be divided into two groups from several point of view. The sternum of the Eleonora's Falcon, Hobby and Merlin are longer, these species form the group called "true Falcons", their humerus and the bones of the shoulder are also stronger than in the Kestrels. In the true Falcons sexual dimorphism is also more pronounced than in the Kestrels, where the dimorphism is negligible. Usually in average the females of the Kestrels are a bit larger than the males, but it is not always true for every individuals. The Falco genus - as opposed to other European genera of birds of prey - can be characterised by the following features in general: Cranium: the cranium is relatively short, especially at the orbital part, the neurocranium is more or less rounded. The beak (rostrum) is thick and short, on the crista tomialis at the os premaxillare there is a protrusion, it is the so-called "Falcon tooth". On the palatal part of the os premaxillare there is a longitudinal rib set out from the tip of the beak. The nostril (apertúra nasi externa) is rounded, in the middle there is a bony part. The os prefrontale (lacrimale) in the true Falcons, and on older specimens of the Kestrels becomes fused by a bony tissue to the cranium at the faciès articularis frontonasalis. The processus supraorbitalis is long, relatively narrow, its distal part (supraorbitale, PYCRAFT, 1902) does not separate. Mandibula: the ramus mandibulae at the symphysial part is curved downward very strongly, on the palatal edge (corresponding to the Falcon tooth) there is an incision. The fenestra mandibulae rostralis and the fen. mand. caudalis are both present, although the latter is very small. The tip of the processus mandibulae lateralis is strongly curved into caudal direction (lateral view), and hence stronger connected to the quadratum than in another birds of prey. The processus retroarticularis is very small, or completely missing. The dorso-medial edge of fossa caudalis is strongly protruding (later I will refer to this point as prominentia caudalis). This anatomical marker is missing in other birds of prey, only in the case of owls can we find a similar part. Clavicula (furcula): the size of processus acromialis (tuberculum scapulare, LAMBRECHT, 1933) is equal with the size of processus acrocoracoideus (tuberculum coracoidale, LAMBRECHT, 1933). In the European members of the Accipitridae and Pandionidae families the processus acromialis is hardly visible or completely missing. Coracoideum: the processus procoracoideus (proc. scapularis, OTTO, 1981) is large and long, the processus lateralis is usually missing at the sternal end of the bone, or very small in size. Scapula: the lateral part of the acromion is considerably smaller, while the medial (costal) part is considerably larger than in the members of the Accipitridae and Pandionidae families. Humerus: the crista pectoralis is large, only the Accipiter, Pernis and Pandion species have similarly sized or larger cristas. In the members of the Accipitridae and Pandionidae 15