| Description |
Birds and mammals engage in regular grooming behaviors to combat ectoparasites. While grooming to control parasites is well-studied in mammals, little is known about some of the most common grooming behaviors of birds. For birds, self-preening is the primary defense against ectoparasites. Yet there are regions, such as the head and neck, which are inaccessible to self-preening. Birds must rely on other defenses to control ectoparasites in these regions. Two behaviors that may be important for controlling parasites in these regions are allopreening - whereby one bird preens another - and scratching. To my knowledge, no experimental test of either behavior's effectiveness at controlling ectoparasites has been conducted. In this dissertation, I examine the roles of allopreening and scratching for controlling avian ectoparasites. In Chapter 1, I introduce this area of research in more detail. In Chapters 2 and 3, I investigate the role of allopreening for controlling lice on Feral pigeons (Columba livia). By infesting birds with equal numbers of lice and tracking their behavior over time, I demonstrate that allopreening rates are negatively correlated with louse abundance. These results also have important implications for the evolution of social behavior. I next tested whether allopreening is inducible. I compared the allopreening rates of pigeons before and after infesting them with feather lice. I found that pigeons did not alter allopreening rates after experimental infestations. These results indicate that allopreening is not a direct response to ectoparasites, at least in the short term. In Chapter 4, I investigate the role of scratching for controlling avian ectoparasites. I first conducted a series of experiments where I manipulated the ability of pigeons to scratch and experimentally infested them with lice. I demonstrate that 1) scratching is an effective antiparasite behavior, 2) the effectiveness of scratching is contingent on having claws, 3) the flange on middle claw is not necessary for controlling lice, and 4) for scratching to be effective, birds must also be able to preen. The connection between preening and scratching suggests that scratching may work by forcing lice into regions where they can then be self-preened. |
