Official journal of the Netherlands Ornithologists' Union
|Eygenraam J.A. (1947) Het gedrag van de Zwarte Specht, Dryocopus m. martius (L.). ARDEA 35 (1-2): 1-44|
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The observations for this study of the Black Woodpecker were made in a wooded area near Ede, Netherlands ('Edese Bos') between 1932 and 1943. The area occupied by one pair here has ,an average surface of 925 ha of mixed forest. From August till March the birds wander through a still larger area. The territorial instinct is only poorly developed. The males, are drumming 30 times a day, at the utmost; drumming by females is even less frequent; intruding Black Woodpeckers are not chased and often a half-finished nesting-hole is abandoned at the slightest disturbance or even without obvious cause. The drumming period begins at the end of January and lasts until the young are fledged. There is a culmination point in March. The following calls are described: (1) In March the 'quee-quee-quee'-call is more frequently heard, than any other call. This note bears a slight resemblance to, the 'laughter' of the Green Woodpecker. It is the call for the sex partner. Other notes, which can be heard throughout the year, are (2) the 'cliSh'-call, (3) 'the flight call, which is only used in flight and, like the 'cliSh'-call, is generally uttered at slight disturbances and (4) the 'Jackdaw'-Call. This call is only uttered when the members of a pair are close together. Further I heard a low note ('tuuk-tuuk') which .is exclusively heard in some stage of courtship. The Black Woodpecker has three different 'instrumental' sounds, viz: 1) drumming, 2) knocking, 3) 'tokkelen.'. I have little doubt that these movements are derived from the hammering movements which form an essential part of the foraging activities of daily life. They are ritualised forms of hammering. Drumming and knocking serve as social signals, whether 'tokkelen' has a social function is yet uncertain. The forms of display are, like the instrumental sounds derived from other movements. 'Maatslaan', which is part of the courtship, is the ritualised derivate of the characteristic movements of smashing an ant-hill. The nest-hole is indicated to the partner by an incipient forward-movement of the head, demonstrating of the intention to enter the hole; it is a ritualised 'Intentionsbewegung' (Heinroth). Another movement, the 'mirror display', serves to show off the red cranial cap. Both male and female show this remarkable display, in which a bird turns its back to the partner and stretches its neck so as to demonstrate the red cap. Unlike the foregoing ceremonies, this movement does not show any relationship to activities of daily life, but it is admirably adapted to display a conspicuous structure, viz. the red cap. Contrary to what is known from most other birds, in the Black Woodpecker most of the incubating and of caring for the offspring is done by the male. The female takes the leading part in courtship; she often takes the initiative in premating ceremonies and also in actual copulation. Copulations begin at the beginning of March and last for six weeks or longer. The nesting-hole is excavated in a straight beech without branches below the hole. Nest-building lasts for almost a month. At first male and female take equal parts in the work; in the last week the male builds alone. The entrance of the hole is always an oval measuring about 12 x 8 cm, and the nest lies closer to the outer surface of the tree than holes of the Great Spotted Woodpecker. The young therefore are not so well protected; at the same time they are less noisy than. young Great Spotted Woodpeckers, which may be more than sheer coincidence. Of the 53 holes examined, the majority open to the northeast, which I consider to be connected with the predominance of south-westerly winds. The nest-building birds prefer to do their work on the 'lee-side of the tree. The incubation lasts 12 days. The male incubates during the night and during .the greater part of the day; the female takes her turn during three short spells daily of one and a half to three hours each. The fledging period is 27 days; Till almost the last day the male sleeps with the young in the nest. After fledging it leads them for a long time, probably two months. A pair of Black Woodpeckers holds together during at least four months, generally from January till May. Black Woodpeckers sleep in old nesting-holes. They go earlier asleep and awake later in the morning than any other bird in the wood. The Jackdaw is a serious rival, often intruding in nesting-holes and driving the Black Woodpecker out. For the rest the Goshawk is its only enemy.