KLAVER A (1964) On the biology of the Wryneck).. LIMOSA 37 (3): 221-231.

Eurasian Wryneck Jynx torquilla The author studied from blind the family life of Wrynecks (lynx torquilla L.) housing in a nestbox provided with a glass wall. Observations started when nestlings were 12 days old and rather well feathered. At this age parents no longer warm their young continuously. The latter keep close together with their heads in the centre. As in woodpeckers (Sielmann 1958) they form in this way a pyramidal cluster, a situation which is even preserved during feedings (fig. 1). Both male and female feed the young and remove faecal sacs. Table 1 records frequency of feedings. Parents provoke the begging activity of a nestling by chucking with their bill the swollen corner of the latter's bill. Sielmann observed the same in woodpeckers. Nestling wrynecks beg in a definite direction and search for the parent's bill, this in contrast to nestling Passeres which beg in an undetermined direction. The parent puts its bill in the nestling's bill in an angle of 90° (fig. 1). Nestlings defecate in between feedings, contrary to nestling Passeres, which defecate immediately after being fed. By means of the collar method we collected 13 food lumps. Food consisted exclusively of pupae and imagines of Lasius niger L. (table 2). Nearly all the imagines have bitten themselves in a pupa, which suggests that the former were not collected separately but only because they adhered to the latter. The Wryneck carries many sharp objects to its nest, such as bone splinters and small stones (table 3, fig. 4). Several times we observed a parent feeding these objects to a nestling. They were also found in food lumps (table 2), and remnants of them were excreted in the faeces. In 13 faecal lumps we found 12 small stones (2 x 2 mm), many grains of sand, 7 bone splinters (average measurements 4 x 2.5 mm), chitinous remnants of ants, vegetable material, and one imago of Formica fusca L. The stones are most probably required for grinding food in the stomach of the nestling and the bone splinters as a source of Ca and P for its skeleton. Larger pieces are regurgitated by the nestlings, and are to be found in the box (fig. 4).

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