Male quality influences male provisioning in house wrens independent of attractiveness

Female reproductive investment can vary according to their mate's attractiveness, and males may differentially invest according to their own attractiveness. Thus, when studying female parental investment, male investment must also be considered. We tested the hypothesis that the attractiveness of male house wrens (Troglodytes aedon) influences their investment independent of their own intrinsic quality by manipulating the number of nest sites (one control; 4 attractive) in each male's territory. Treatments (attractive or control) were applied prior to (natural state) or after (imposed state) male settlement, and male investment was determined twice during the nestling stage by the number of trips males made to the nest to provision their nestlings. Males that settled in the attractive territories were significantly older than those that settled in control territories in the natural state. There was a significant interaction effect between state and treatment on male provisioning. Provisioning rates of attractive and control males in the imposed state did not differ, but attractive males in the natural state provisioned at a lower rate than control males late in the nestling stage. Thus, provisioning by males is influenced more by their intrinsic quality than their attractiveness.