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

than the size of the Hobby. Among the Kestrels the Kestrel has especially short sternum. This is demonstrated by the fact that its length measures largely overlap with that of the Red-footed Falcon, only the maximum values are different. Even the maximum values of the Lesser Kestrel sternum is reaching the minimum values of the Kestrel (Plate XIX, Figure 1). The sternum of the true Falcons morphologically considerably differs from that of the Kestrels. Their sternum is longer, the carina sterni is higher and longer, and hence the margo cranialis bends more forward (the apex carinae extends more forward) than in the Kestrels. The sternum of the Hobby and Merlin is very similar, often impossible to distinguish. Some minute differences can be still found: the sternum of the Hobby is a bit wider at the same length (GL/GW value is higher, Plate XIX, Figure 2), and the crista sterni is higher (CH/GW value is higher (Plate XX, Figure 1), than in the Merlin. In the Hobby the margo cranialis and margo ventralis is more curved (the latter especially on the caudal section), than in the Merlin (Plate XXXIX, Figures 1-2). The spina externa of rostrum sterni in the Hobby is thicker, and at the middle sharply breaking upwards (in dorsal direction). In the Merlin the spina externa is thinner, straight and cylindrical. The processus craniolateralis compared to the tip of spina externa in the Hobby is positioned caudally more backwards than in the Merlin. This demonstrated by the fact that the angle formed by the lines connecting the tips of the processus craniolaterales on the two sides with the apex of spina externa is more acute in the Hobby than in the Merlin (Plate XXXIX, Figures 6-7). The last (caudally positioned) processus costalis in the Merlin is positioned caudally more backwards than in the Hobby. And hence in the Merlin the last processus costalis is positioned at the half of the distance between the apex of processus craniolateralis and the caudo-lateral edge of the sternum. This is positioned in the Hobby cranially more forward, and hence the costal section is shorter. Morphologically the sternum of the Eleonora's Falcon is similar to that of the Hobby, but due to its larger absolute size it is easily distinguished from that. On one of the examined specimens the shape of the margo ventralis carinae and margo cranialis carinae is more similar to that of the Merlin, as they were less curved than in the Hobby. The ratio of the length and width of the sternum (GL/GW) differs among the Kestrels. The shortest and widest sternum is found in the Kestrel, then comes the Lesser Kestrel. In the Red-footed Falcon this ratio equals with that of the Merlin, that is the sternum is more elongated (Plate XIX, Figure 2). The carina sterni is shortest in the Kestrel (CL). In the Red-footed Falcon and Lesser Kestrel it is a bit longer, but still much shorter than in the true Falcons (Plate XXXIX, Figures 3-5). The relative height of the carina sterni (CH/GW) does not differ significantly among the Kestrels, but the average value is still higher in the Red-footed Falcon (0.72) than in the Kestrel (0.70). Plate XX, Figure 1 shows the height of the carina sterni proportional to its length, in a way that through the ratio of the length and width of the sternum eliminates the absolute size differences of these species. In the Red-footed Falcon the margo cranialis carinae bends more forward, and hence the carina sterni is longer, and consequently the apex carinae is more pointed than in the Kestrel and Lesser Kestrel. In some specimens the margo cranialis is more curved, in these the carina sterni is very similar to that of the Hobby (Plate XXXIX, Figure 5). In the Red-footed Falcon the margo ventralis carinae is more curved than in the rest of the species. In the Kestrels the shape of spina externa is variable, both the forms similar to the Hobby and Merlin can be found. The spina interna is shorter than in the true Falcons, the shortest in the Kestrel, in cranial direction often it does not extend further then the labra dorsalia. The angle formed by the tip of the spina externa and the two processus craniolaterales in 37