Nest Site Preparation and Reproductive Output of the European Starling ( Sturnus Vulgaris )

Abstract

Hole-nesting birds are faced with the problem of dealing with the presence of nests from previous seasons. In a few species, specific nest site preparation behaviour has evolved, whereby birds remove part or all of old nest and only later build a new one. Such behaviour has not been studied in any great detail. European Starlings (Sturnus vulgaris) were allowed to breed in nestboxes that were empty or contained old nests from a previous year. The material of old nests was marked so it was possible to evaluate the amount of material that was removed by the bird itself. Additional observations were carried out to study the temporal aspect of such nest site preparation. Birds started old nest removal soon after arrival at the breeding location, around one month before egg laying. Birds with the highest cleaning effort, i.e. removed a larger part of the old nest, began laying eggs later, laid fewer eggs and brought food to nestlings less frequently. Besides wing length, there was no relationship between cleaning efforts and fledgling body mass nor tarsus length. Nest site preparation did not decrease the load of fleas in nests. Time and energy invested in the removal of an old nest may negatively affect the entire reproductive cycle. Other hypotheses connected with nest site preparation and low reproductive output are discussed.