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Predators are supposed to exert strong selection pressures on their prey, especially when phenotypic traits such as secondary sexual characters promote mating success at the expense of costs in terms of natural selection. Signaling theory predicts that individuals of superior phenotypic quality will enjoy an advantage in term of mating success, but also in term of natural selection, if such individuals are in prime condition both before and after development of exaggerated secondary sexual characters. We tested this prediction in the Barn Swallow Hirundo rustica being preyed upon by the Eurasian Sparrowhawk Accipiter nisus, using extensive samples of feathers from prey and non-prey. We measured tail length and coloration of outermost tail feathers in the black area of the proximal and distal part of tail feathers, but also the white spot of the tail feathers. Prey had significantly less dark distal, but not proximal parts of their tails, while there was no difference in coloration of the white spot between prey and non-prey. Prey had significantly paler tail feathers than non-prey, especially among long-tailed individuals. These results suggest that Barn Swallows with long tails that fail to deposit large amounts of melanin in their tail feathers run an elevated risk of predation.
During a four-year study of the breeding biology and ecology of an atypical population of Barn Swallows nesting in 13 abandoned post-war bomb shelters, the unexpected presence of foreign juveniles in active nests with nestlings was recorded on eight occasions. In five cases, single birds were noted, and in the other three, two foreign individuals were observed. The average age of the nestlings joined by foreign juveniles was 11.6 days (SE = 1.08, range 8-16), while the average age of the latter birds recorded with the nestlings was 23.2 ± 1.02 days (range 20-25). The mean distance between the hatching and parasitised nests was 0.9 ± 0.11 m (range 0.5-1.2). This unusual behaviour in swallows seems to be deliberate and is aimed at choosing a nest with nestlings in order to obtain extra food from experienced adult birds rather than an error caused by the darkness in the shelter.
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.
Ninety-nine road-killed Barn Swallows were found during three years of studies on a 48.8 km road network in an intensively farmed landscape in SW Poland. Nearly 88% of all road-kills were recorded in built-up areas and on road sections in their vicinity. The average number of road-kills per 1 km of roads was over twenty times higher in built-up areas than in open agricultural landscape (6.74 vs 0.33 road-kills/1 km). This paper investigates the influence of environmental factors (lines of trees along roads, number of livestock, volume of traffic, number of inhabitants) on the level of Barn Swallow mortality on the roads in question. During the breeding season the number of birds killed in built-up areas was related positively to the number of cattle reared, the overall number of livestock (including pigs) and the number of inhabitants. In the multiple regression model following stepwise forward selection, the number of cattle explained 41% of the variance in the size of the whole-year road mortality of swallows in the built-up area. During the autumn migration period the length of tree-lined road sections in the built-up area had an significant influence on road-kill frequency, explaining 36% of the variance in mortality. Mortality was high on tree-lined sections of road in adverse weather conditions.
A new geographical record of Stromitrema koschewnikowi (Skryabin et Massino, 1925) is reported from swallow Hirundo rustica (Aves, Passeriformes) in the Czech Republic. Morphological variability of the species is described.
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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