Official journal of the Netherlands Ornithologists' Union
|Walters J. (1957) Gedrag in de legperiode en arbeidsverdeling in de voortplantingstijd bij de Strandpluvier, Charadrius alexandrinus L. ARDEA 45 (1-2): 24-62|
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Behaviour during the egg-laying period in the Kentish Plover (Charadrius alexandrinus L.), and the division of labour during the nesting-cycle. I. Behaviour during the egg-laying period. The origin of three clutches on Texel in June 1955 is described in detail. The following call-notes are discriminated: 1. alarm-notes-'prrr' and 'weet'; 2. threat-note-'rooh'; 3. song-note-'song-rattle'; 4. hostility-cry-perhaps the sharp 'tjekke-tjekke' during the song flight; 5. tenderness-call ('Zartlichkeit')-'peechurrr'; 6. distraction-display note-'Schnarren und Kreisen' as in Ringed Plover (Ch. hiaticula); (Laven 1940); 7. fear-note-'kjuk', uttered with closed bill; 8. parents' call-up note for the young-'pu-pu-pu'; 9. flying-call-toneless 'pt'; (no special note during scraping). On p. 36, a comparison is made with the corresponding notes 6f the Ringed and Little Ringed Plover (Ch. dubius). A description of 'appeasement' behaviour is given for both dubius and alexandrinus. Kentish Plovers often nest in existing colonies of Avocets (Recurvirostra avosetta) or Common Terns (Sterna hirundo) and find protection there. The eggs are laid with the pointed end downwards. Incubation generally starts after the completion of the clutch. Some males are more interested in the growing clutches before incubation than their partners, which often only visit the nests for egg-laying. II. The division of labour during incubation. The starting point is the earlier publication (Walters 1954a). The regular division of the daily task is confirmed once more. Brooding by the males at night is certainly the rule; they were also found on the nests early in the morning on a few occasions. There may be a tendency for the afternoon relief to become earlier during the course of the incubation-period and very early relief may cause double relief. Little is known about the morning-relief. One male proved indistinguishable from females in the field. Therefore, one should know both male and female of each pair individually when judging the division of labour of the sexes. III. The division of labour in the care of the young. On the basis of diary-protocols a large number of data is mentioned, from which it appears that: 1. Strictly speaking, exclusive female tending of the young only occurs with newly hatched chicks, still in the nest-scrape or in its immediate surroundings (one may expect that, in such cases, the males do not know of the hatching of the young) ; 2. Care of the young by the male alone occurs much more frequently, especially with older young, but in some cases already with newly hatched chicks too; 3. Simultaneous participation of both sexes can be observed the most often, especially when the chicks are rather young (e.g. not older than two weeks). In the third case, a certain division of labour between the parents does occur. Out of 19 clear cases, the male arrived first to brood the chicks on 14 occasions, the female staying in the neighbourhood of the observer. The opposite was the case in the five remaining examples, though some disturbing influence i may have caused the exceptions. Eight further cases concerned variable or less clear behaviour. Many of these observations are compared with behaviour in Ringed and Little Ringed Plovers and also in some less closely related species of waders.