2022
Legbegin, broedseloverlap en polygamie bij Nederlandse Draaihalzen Jynx torquilla
Publication
Publication
Onset of laying, brood overlap and polygamy in Wrynecks Jynx torquilla in The Netherlands
Over the past century, Wrynecks have been the focus of study in three episodes, i.e. in 1911-18 (G. Wolda, Veluwe, nest boxes), in 1958-71 (H. Stel, Veluwe, nest boxes) and off-on in 1974-2022 (RGB, Veluwe + Drenthe, natural cavities). Stel’s study included the ringing of 225 nestlings and 21 adults, whereas some ringing commenced in Drenthe in 2015-19 (S. Waasdorp, 8 adults and 29 nestlings). Including anecdotal information gleaned from the literature and from other sources, start of laying could be calculated for 150 first layings, with a mean of 22 May (SD=7.1, range 9 May-12 June) and peak of laying in the second half of May. Second layings (i.e. layings commenced when first brood successful) were produced between 20 June and 10 July (man 30 June, SD=0.6, n=15), whereas the start of repeat layings (after failure of first breeding attempt) averaged 12 June (SD=7.0, n=15, range 2-29 June). Clutch size for first layings was 2x 5, 12x 6, 15x 7, 26x 8, 14x 9 and 2x 10 eggs, of second layings 2x 5 and 1x 6 eggs, and for repeat layings 2x 5, 2x 6, 1x 7 and 1x 8 eggs. Brood overlap was recorded twice in the Drenthe study, and involved one bird of a pair with active brood and a third Wryneck of unknown origin and sex. Both cases were preceded by a resurgence of calling during the late brood stage of active nests, but it remained a mystery whether the initiative was taken by a ‘strange’ bird or one of the birds of the breeding pair attending young, nor was the sex known of either strange bird or breeding bird. In 2020 a copulation was recorded 7 days before the first brood fledged, and again on the day prior to fledging (between 7.18-10.23 h on respectively 8.08 h and 9.18 h, copulations lasting 5 and 4 sec). When the young fledged on 24 June, the nest already contained 4 eggs, the clutch eventually increasing to 6 eggs; this laying failed in the early chick stage. A second case of brood overlap, in 2021, was also preceded by a resurgence of calling prior to fledging of the first brood, which fledged on 1 and 2 July. On the latter date, the nest contained 2 eggs and developed into a nest with young that failed later on 30 July. As with the brood overlap in 2020, apart from the certainty that one of the adults of the first brood paired up with a ‘strange’ bird, its sex was not known.
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Drentse vogels | |
CC BY 3.0 NL ("Naamsvermelding") | |
Organisation | Werkgroep Avifauna Drenthe |
R.G. Bijlsma. (2022). Legbegin, broedseloverlap en polygamie bij Nederlandse Draaihalzen Jynx torquilla. Drentse vogels. |