Breeding biology of Barn Swallows Hirundo rustica in Algeria, North Africa

Breeding biology of the Barn Swallow Hirundo rustica was compared between the first and second clutches in Annaba, Algeria, in 2001-2003. Swallows nested in different buildings used by humans, including factories, garages, staircases and balconies in blocks of apartments. 55%-69% of breeding pairs produced two clutches. The average dates of the onset of first clutches were between 21 April (2003) and 21 May (2002). Average clutch size was 4.60-4.85 eggs for the first brood and 3.18-4.06 for the second brood. There was a clear negative relation between clutch size and laying date. Nest height, nest diameter, nest depth, cup diameter and cup depth did not differ between first and second clutches. Clutch size, number of hatchlings and fledglings differed between the first and second broods, being greater in first clutches. Egg length, breadth and volume did not differ between the first and second clutches. High repeatabilities (0.63-0.92) in these egg traits were detected. This indicates that there exists high variation in the egg traits between clutches laid by different females. The heights at which nests were constructed and nest shape were shown to influence hatchability; nests with deeper cups, located at lower height were more successful. Comparison with other populations shows that the proportion of pairs that produced second clutches decreased with increasing latitude. Our results indicate that extreme southern breeding populations of Barn Swallows show some specific features which need further study.