BREEDING BIOLOGY OF THE BARN SWALLOW (HIRUNDO RUSTICA) IN NORTHEAST TEXAS WITH TEMPORAL AND GEOGRAPHIC COMPARISONS TO OTHER NORTH AMERICAN STUDIES

摘要

The reproductive output of American barn swallows (Hirundo Fustica ervthrogaster) was studied over a five year period at a colony in northeast Texas. Clutch size, hatching success, nestling success, and nesting success were all found to vary significantly among years suggesting that the swallows were influenced by annual changes in environmental conditions. However, the observed annual variations in clutch size, hatching success, and nesting success were well within the range observed among 14 other studies in North America. The greatest sources of mortality were hatch failure, followed by infanticide and ectoparasites. These sources of mortality were also common in other studies. Despite the wide geographic range of barn swallows in North America, there were no latitudinal trends in clutch size, hatching success, or nesting success. Lastly, in the 44 years spanned by the analysis, there was no evidence of changes in reproductive output, suggesting that American barn swallows have not yet been obviously impacted by global climate change.