Assessment of fighting ability of opponents prior to escalated territorial conflicts by male damselfly Calopteryx maculata.

Male Calopteryx maculata, known to be involved in aggressive territorial contests, follow a sequence of behaviors that begins with an initial face-off (2-5 seconds), which includes hovering and rapid wing beating, followed either by one male flying away or by an escalated spiraling contest which can last up to an hour in duration. Assuming the spiraling fight is much more energetically costly than the face-off, we hypothesized that the males must assess their opponents' fighting ability by some physical characteristic to avoid costs involved in defending a resource (assessment hypothesis). We found that males that engaged in escalated contests had similar masses that males that did not. The ability to accurately assess opponents in this way is crucial to male reproductive success.http://deepblue.lib.umich.edu/bitstream/2027.42/55024/1/3466.pdfDescription of 3466.pdf : Access restricted to on-site users at the U-M Biological Station