Breeding biology of the citrine wagtail (Motacilla citreola) in the Gdansk region (N Poland)

In the years 1997-2001, I observed 28 broods of the Citrine Wagtail (Motacilla citreola) in the Gulf of Gdask region. First birds arrived at the study area at the end of April. A successful breeding cycle lasted about 1 month and included: 3-4 days of nest building, 1-2 days of a break, 4-6 days of egg laying, 11-12 days of incubation, and 10-13 days of parental care of chicks in the nest. Females started to lay eggs at the beginning of May. The most common clutch-size was 5 eggs. Hatching success was 55.3%. On average, 2.6 chicks hatched in a nest, the final fledging success reached 38.1% and an average 1.8 chicks left the nest. Nests were always on the ground and were situated in tufts or in thick vegetation. Most entrances faced south-east. The mean external diameter of nests was 10.1 cm, the internal diameter, presented as width and length, averaged 6.3 and 6.8 cm, respectively, and the mean depth of cup was 3.9 cm. Eighty-six measured eggs were similar in shape and colour to the eggs of Yellow Wagtail (M. flava). Their mean width was 14.16 mm, and the length 18.40 mm. The growth and plumage development of nestlings is reported. To estimate the nestlings age a multiple regression equation was established with the measurements of highest correlation coefficients, i.e. wing and tarsus length: D=0.12W+0.23T-0.23 (where: D = day of life, W = wing length, T = tarsus length). In the observed nest, both parents participated similarly in feeding the chicks. The average frequency of feeding increased from about 5 per hour on the day of hatching to more than 20 per hour in the last days in the nest. G-test showed statistically significant differences between the male and the female in the distribution of average duration of visit (G=52.3, df=10, P<0.05). During the first few days the female stayed at the nest longer than the male. After 6 days, average duration of a visit in the nest for both parents shortened to several seconds.

Marta Sciborska, J Ornithol (2004) 145: 41-47