Introduction

The growing understanding of the energetic cost of reproduction in birds derives from studies on the costs of egg production, incubation and chick rearing, but there are, as yet, few such studies on nest building. This may in part be due to the difficulties in making the necessary measurements, but also to the undeclared assumption that nest building costs are likely to be low. This chapter pieces together such evidence as there is to test that assumption. For species that re-use nests or nest cavities, there appears frequently to be a cost to be borne of the accumulation of blood-sucking arthropods retarding chick development. This cost is borne as an alternative to building a new nest or, for cavity nesters, as an alternative to finding and competing for a new nest site. The second part of this chapter is an assessment of these costs and the behavioural responses of birds to minimise them.

The determination of construction costs and consideration of their implications have been best illustrated by research on silkspinning arthropods. In such species, the energetic costs are those of the energetic value of the silk, the cost of silk synthesis, and of the construction behaviour. The cost of sheet-funnel web construction by the wolf spider (Sosippus janus) was determined from the oxygen consumption of spinning and non-spinning spiders in a respirometry chamber, plus the energetic value of the silk, determined by bomb colorimetry.