Effects of nest box size on the nesting and renesting pattern of Aphrastura spinicauda and Troglodytes aedon

Abstract

Using large and small nest boxes I determined the effect of the nest box size upon nesting and renesting probability, as well as the reproductive success of two secondary cavity nesters, the thorn-tailed rayadito (Aphrastura spinicauda) and the house wren (Troglodytes aedon) was determined comparing large and small boxes. In order to assess these effects nest boxes were monitored by two consecutive years. Results indicated that Aphrastura nested mainly in the large instead of the small nest boxes, and nesting Troglodytes used primarily small nest boxes. Nevertheless, the renesting pattern of both species, including renesting attempts after successful fledging and after nest failure, was not affected by nest box size and the probability of renesting was not influenced by the success of previous reproductive events. The size of the nest box did not affect the reproductive success of both species when they nested or re-nested, in spite of the weight of the nest was increased with the size of the nest box. These results apparently are not supported by limitation by space, costs of nest building or the presence and behavior of the nest predator and parasites. Nevertheless, since Troglodytes has the potential to usurp cavities used by other species of birds, I suggest implementing monitoring programs for Aphrastura using both large and small nest boxes in order to avoid the use of large nest boxes by Troglodytes.