Date of Award
Individuals in many group-living species form dominance hierarchies, and higher ranked individuals have more access to resources or mates. Rank often depends on size. Dominance rank is settled quickly between different -sized individuals, but animals that are similar in size exchange behaviors that escalate until one individual withdraws. Dominance displays in male fiddler crabs include waving the large claw and arm wrestling. My objective was to determine if dominance behavior between male fiddler crabs varies between pairs that are similar or different in size. Because size can indicate dominance for fiddler crabs, I predicted that pairs of different-sized crabs would spend more time waving and less fighting compared to similar-sized crabs. I obtained 10 male fiddler crabs and paired each individual with a similar-sized partner and a different sized partner I observed each crab with its partners for 10 min in a neutral arena and observed each crab with its partners for 10 min in a neutral arena and observed each crab with its partners for 10 min in a neutral arena and observed each crab with its partners for 10 min in a neutral arena and recorded display behavior. Different -sized partners tended to spend more time waving than similar-sized partners. However, time spent waving, fighting, or performing other behaviors did not differ. These results did not support my predictions, probably due to the small sample size. I can conclude that behaviors between similar-sized males did not escalate any more than behaviors between different-sized male behaviors.
Bondeson, Heather T., "Effects of size on dominance behavior in male fiddler crabs, Uca pugnax" (2017). Thinking Matters. 84.