Adoption as an offspring strategy to reduce ectoparasite exposure

Area of Science:

• Animal Behavior
• Ecology
• Evolutionary Biology

Background:

• Adoption is common in colonial species due to high costs of parasitism and opportunities for young to find foster families.
• Ectoparasites are often aggregated among colony members, suggesting a potential role in social dynamics.

Purpose of the Study:

• To test the hypothesis that adoption is driven by selection on young to reduce ectoparasite load.
• To investigate if nest-based ectoparasites influence offspring adoption behavior.
• To determine if adoption reduces an individual's parasite load.

Main Methods:

• Experimental infestation of Alpine swift (Apus melba) offspring with ectoparasitic louse-flies.
• Comparison of adoption seeking behavior between infested and uninfested young.
• Measurement of parasite load before and after adoption.

Main Results:

• Experimentally infested Alpine swift young sought adoption significantly more often and at an earlier stage than uninfested young.
• The parasite load of adopted, infested young was reduced.
• Redistribution of ectoparasites among foster family members occurred after adoption.

Conclusions:

• Parasites play a novel role in the evolution of adoption in colonial species.
• Adoption can be an adaptive strategy for young to mitigate ectoparasite burdens.
• Parasite-mediated selection may contribute to the emergence of social interactions.