Social Pattern and Behaviour Between Two Falco Species (Aves)

Transcription

1 ANNALES HISTORIOO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 67. Budapest Social Pattern and Behaviour Between Two Falco Species (Aves) by L. HORVÁTH, Budapest Abstract Comparing social pattern and behaviour of two raptors, a colonial breeder Red-footed Falcon and a solitary one Kestrel the author concludes that there are many common and also different aspects of their ethology being founded on their colonial and solitary nature. I have worked on the Kestrel (Falco tinnunculus L.) around the villages Csornád and Vácrátót in the vicinity of Budapest, in My aim was to characterize the basic organization and dispersion-pattern of the species, principally adults but also the social organization of family group and young birds. This was necessary because I wish to compare the social pattern and behaviour of a solitary breeder with a colonial one. The colonial breeder was another raptor, the Red-footed Falcon (Falco vespertinus L.). On this species I have worked in 1953 at the Ohat-Wood in Hortobágy (Great Hungarian Plain). The results concerning the above mentioned two birds I will communicate one after another under same headings to facilitate the comparison between the two. Social Pattern Organization. The Red-footed Falcons are gregarious. Even outside the breeding season they are almost invariably found in flocks of 4 6 two-three males and females right up to about 20 individuals in autumn, that is 3 4 families collectively. These small flocks have a territory, that is before and after the breeding season they catch prey on the same territory near to their breeding place. The Kestrels are non-gregarious although in environments being suitable to their requierements they nest in fairly big numbers close to one another. For instance as I have observed myself many times on a wet meadow with scattered willow and poplar trees it likes to occupy hooded crow- and magpie-nest about metres from one another, rarely within 200 metres. But more than 3 4 occupied nests on a km 2 area is very rare a case. It breeds a little nearer to one another at the edge of a forest bordering some open places, like a meadow or a ploughfield. In any case, it is not a colonial breeder. In all of its breeding localities it is a territorial bird chaseing any birds as big as or bigger than itself, including Kestrels within the neighbourhood of its occupied nest. These territorial combats associate with very fierce pursuits and heavy wingbeats accompanying many loud cries and restless noise. Their offsprings are not exceptions aither, even the yuong ones returning to places where they were reared in the previous year, are frustrated by their parents. Outside the breeding season it is also non-gregarious. It likes to be alone or in pair, rarely in family parties. Seemingly contrasting the above statement it

2 rather likes to breed together with Jackdaws and Martins even i n very populous colonies. B u t always only one Kestrel-pair i n a colony! B o n d s. Red-footed Falcons are monogamous. The duration of the bond is for one breeding season only for the first breed and if that is destroyed for the replacement one, too. The youngs form pairs and breed i n the following spring. Commonly one young bird and an old one form a pair. Both parents tend youngs until fledgeling. Parental care: the task of brooding seems to be shared equally between the two sexes, though on the whole, the male is working harder. I n fine weather on sunny, windless days the female brings more food to the nestlings. I n very bad weather in windy and in rainy days i t is anly the male that brings food to the nest. Kestrels are monogamous. The duration of the bond in for one breeding season only like i n the case of Red-footed Falcons. For a replacement breeding the pair stay together. There in no second breeding i n a year. After the establishment of the breeding place both birds commence very beauti ful evolutions i n the air above their nest. The male is more ardent to perform these spectacle aerial displays, accompanying them with exulting shoutings. The youngs form pairs and breed in the following spring. Concerning the pa rental care i t seems sure that the female undertakes the majority of home duties for the wellfare of the youngs. The male broods only in short periods. After the eggs are hatched the male become more self-sacrificing. B r e e d i n g d i s p e r s i o n. The Red-footed Falcon is a colonial breeder and territorial. The birds of a colony defend their occupied rookery. The breeding and brood territory are the same but the feeding one i t is not, though i t is close by. The latter one is generally a meadow or a fallowland. The number of Falcons sett ling in a rookery (nest colony of the Rook, Corviis frugilegus) does not depend on the height or age of the trees, yet always seems to be i n proportion the number of nests forming the rookery. They occupy 12 13% of the nests. Most of the Fal con-occupied nests were found to be near the edge of the wood, in several cases even in one of the outermost trees. I t should also be noted that solitary trees stand ing well out i n some clearing have never been favoured by Falcons, though they may have held up to 12 Rook's nests! On the whole, i t can be stated that within a nesting colony, Red-footed Falcons will t r y to congregate as much as conditions will permit. When the young birds are one year old, i.e. i n the following spring, the territories of the first breeding are established. The Kestrel is a solitary breeder and territorial. I t is most likely that the breed ing and brood territories are the same because the old birds vigorously defend their breeding territory before and under the nest occupation, and in the time of tending their offsprings too. On the contrary of the two above mentioned cases i t has not a feeding territory. The old birds forage in very different nature of places and from time to time fly far from their nest. The parents are very affectionate to their youngs, and when they are out of nest they lead them away immediately when danger threatens. When the youngs are one year old the first breeding terri tories are established. R o o s t i n g. The members of a colony of Red-footed Falcons spend nights i n each other's company before the beginnig of the breeding. They roost on trees of medium height in single flocks if possible, or on some neighbouring trees if their

3 number so requires. When the youngs leave their nests they also spend the nights in company with other young Falcons, youngsters of various broods roosting close together, within the thick foliage of some rather high tree at the fringe of woods of their breeding territory. At this time the old birds also roost near-by in each other's company though separate from the young ones. The site of the roosting in both cases is well concealed in the foliage, i.e. on boughs near the trunk, not at the top of the tree and nor on very low branches. They arrive to the roost at sunset just before total darkness and depart at down twilight. During the breeding season the male Kestrel roosts near the nest wherein the female is brooding their youngs. Outside the breeding season the roosting takes place in a family party after the youngs leave the nest. When the youngs detached from the old ones the old pair rest together in the roosting sites in autumn as well as in spring before the breeding season. The site of the roosting in both young and olds is well concealed in the foliage. When roosting on buildings they are also very hidden. They arrive to the roost before full darkness and leave it only at twilight. During mild winters they stay in Hungary. In these cases they like to roost in coniferous trees, though generally they do not prefer pines for roosting. I think the pinetree well conceals the bird but it also distenes the sight (visibility) of the bird. This is not the case in a deciduous tree. Behaviour Organization. The old males of Bed-footed Falcons occupy the most inaccessible nest in a colony, that is the control role in the rockery belong to that pair where the male was an old bird. The Kestrel is a peaceful bird to its conspecifics. On the contrary very ferocious against Crows and Magpies near their nests and even outside the breeding season. It seems likely that in spite of these birds are not colonial breeders and are non-gregarious they like to be each other's neighbourhood both in the breeding season and outside of it. Antagonistic behaviour. Inspecting young Red-footed Falcons in order to prove first signs of defensive instinct it was found that during the first ten days they could be touched without showing any such signs, indeed, without giving a sound. Eleven-day-old youngsters, when touched, nipped my hand slighly. On their twelfth day they snapped at me more angrily, uttering feeble chirps when touched. On their thirteenth day, however, as soon as my head appeared bending over their nest, they threw themselves backwards, struggling against my hand with feet and beak, chirping viciously at the same time. The old birds are very tolerant when with them. The numbers of a colony, nevertheless, defend their territory with sound and attack against the birds of another' Red-footed Falcons living in a rookery (colony of Rooks) do not chase the Rooks breeding in the same colony. The old and young Kestrels are very tolerant towards each other. As a territorial bird the Kestrel attacks intruders of its kind males and females equally with fairly low aggressivness and not very loud cries comparing those delivered against Crows and Magpies. In the breeding season the males perch on exposed positions, e.g. on the top of a tree or a side branch strong enough to support the bird. They are no disputes over individual distance and food.

4 Heterosexual behaviour C o u r t s h i p d i s p l a y a n d m a t i n g. I was able to observe a pair of Red-footed Falcon on May 13, 3 p.m. to perform this. The female bird perched on the top of an old oak, on the edge of the wood, sitting at a bight of some 18 metres on a horizontal branch, it kept looking up at a male, which fluttered to and fro above i t. The male then glided off and went circling over a nearby clearing at a hight of approximately 40 metres, its rapid wing-beats alternating w i t h spec tacular dives. This showy performance went on for about five minutes, then the courting bird made a sudden headlong dive and settled on the female's back. Spreading its tail fan-like, wings quivering and the act of mating was completed within a few seconds, immediately after the female bows a bit forward while turning its closed tail sideways. Having mated, the male flew off leaving the female sitting on the branch. During the performance none of them uttered a sound. I suppose their matting flight must have started quite some time before I arrived there, so I was able to watch the last few minutes only. This, by the way, was the only matingdisplay and actual mating of these birds I could so far observe. The male Kestrel flutters to and fro above the female sitting on an exposed branch of the nesting tree or some another one near by. I n the meantime he glides off and circling higher and higher i n the air above her. From here he descends with beautiful evolutions and this performance is repeated many times before landing on her back and mating is accomplished. During the performance none of them uttered a sound. The observation of the mating is not rare a case. I n courting time several males may be seen circling above their breeding territory where the localities are suitable for their requirements. Relations within a family group Concerning parental care, I found that the female Red-footed Falcon is much more anxious about her brood than the male. She returns more frequently to the nest then the male does, fanning her tailfeathers lovingly when fluttering about her youngs, the female certainly seemed to be the better partner of the two. The emotional relations between the parents and their youngs are very affectionate. I did not see any parental hostility to own youngs. The youngsters have also showed very kindly nature towards each other. A t the roost they settle side by side quietly and tranquilly. Comparing Kestrel to Red-footed Falcon we may say that the female is also much more anxious about her brood than the male but the male is noisier when an intruder animal or human approaches its territory. The emotional relations between the parents and their youngs are also very affectionate. There is no paren tal hostility to own youngs. A t the roost the youngsters do not settled side by side so near as i n the case of Red-footed Falcons. I think this is so because the Kestrel is not a social bird than its relatives. I t is very interesting from a psycho-biological viewpoint that placing their eggs i n an artificial nest (e.g. i n a paper box) i t is always the male which approaches and settles on the eggs first. The female was very shy and at least one hour has passed before she went to the artificial nest. Connected with the brooding I may assert that i n natural circumstances the case is reversed: only the female is brood ing the eggs, and the male does not relieve her at all.

5 References CSÖRGEY, T. (1911): Der praktische Vogelschutz in Ungarn in den Jahren Aquila, 18: HORVÁTH, L. (1945): A pellérdi halastavak madárfaunája (Birds of Fish-ponds of Pellérd, Hungary). MTA Dunántúli Tud. Int. Kiad v. (Pécs), 6: HORVÁTH, L. (1954): Red-footed Falcons in Ohat-Woods, near Hortobágy. Acta Zool. Hung., 1: HORVÁTH, L. (1954): Madártani vizsgálatok a tüskés-pusztai halastavakon (Ornithological Investigations on the Fish-ponds of Tüskéspuszta, Hungary). Állatt. Közlem., 44: HORVÁTH, L. (1955): Ornithológiai megfigyelések a bellyei Réten (Ornithological Observations on the Rét, near Bellye, Hungary). Aquila, 59 62: HORVÁTH, L. (1956): Communities of Breeding Birds in Hungary. Acta Zool. Hung., 2: HORVÁTH, L. (1958): Avifaunistic and Ecological Conditions of the Peatbog Region between the Danube and the Tisza. Acta Zool. Hung., 3: HORVÁTH, L. (1963): Vergleichende Untersuchungen der Lebensgeschichte des Rotfussfalken (Falco vespertinus L.) und des Grauwürgers (Lanius minor Gm.). I. Von Frühjahrskunft bis zum Ausschlüpfen der Jungen. Vertebr. Hung., 5: HORVÁTH, L. (1964): Vergleichende Untersuchungen der Lebensgeschichte des Rotfussfalken (Falco vespertinus L.) und des Grauwürgers (Lanius minor Gm.). II. Von Ausschlüpfen der Jungen bis zum Herbstzug. Vertebr. Hung., 6: SÁTORI, J. (1941): Das Brüten des Turmfalken in Künstlichen nest. Zool. Ins. Univ. Debrecen, 48 (5): 7 8. Author's address: Dr. L. HORVÁTH Zoological Department Hungarian Natural History Museum H-1088 Budapest, Baross utca 13. Hungary

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