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The study was carried out in Central Poland (52°15'N, 19°25'E) by all-day visual observation of five nests of Barn Swallows feeding their nestlings. Feeding frequency of older (age of 14-20 days) nestlings changed significantly with time of the day and was highest (46 visits/h) before noon, declining in the afternoon (21 visits/h) and after a slight increase during the early evening (25 visits/h) declining again in late evening. Feeding frequency of younger (age of 6 days) nestlings did not showed significant changes in the day cycle (average 20 visits/h). The proportion of midday feedings increased with nestling age while the proportion of evening feedings decreased.
In the years 1976-1989 392 nests of D. urbica and 584 nests of H. rustica were collectcd from 54 localitics in 6 Provinces in the north of Poland. The highest mean number of specimens per nest was observed in the nest of D. urbica (28.4) and the lowest in nest of H. Rustica (4.2). The highest percentage of nests of the swallows with Oe. hirundinis was recorded in December and lowest in March. The highest mean number of Oe. hirundinis per nest was in the nest of D. urbica in August and lowest in February, and in the nest of H. rustica - in September and in March respectively.
Egg dimensions in 551 complete clutches (2469 eggs) of the Barn Swallow Hirundo rustica in the central part of Poland in 1979-1981 and 1994 were studied. Mean length ranged 19.4-19.7 mm, breadth 13.5-13.8 mm, and volume 1.8—1.9 cm³. The length was not significantly different among years, but both the breadth and volume were. These mean egg dimensions were similar to those reported in a few other European studies, suggesting low geographic variation. Clutch mean egg lengths were weakly correlated with egg breadths. In some breeding seasons or parts of seasons egg size was significantly negatively correlated with the date of laying, hatching success and fledging success. Directions of some of these correlations were opposite to what was expected. No significant correlation was found between egg dimensions and clutch size or female/male wing lengths.
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