The effect of morphology and physiology on butterfly territoriality

Males of many butterfly species compete for territories via aerial interactions. How butterflies settle a contest is rather a mystery because it is obscure what kind of costs they can inflict on their opponents. A study by Davies (1978) on the speckled wood butterfly, Pararge aegeria provided empirical support for the idea that residency is used as an arbitrary means of contest settlement. On the contrary, recent research on the green hairstreak, Chrysozephyrus smaragdinus indicated that contest outcome could not be explained by the bourgeois strategy, at least in its original form. In the present Study, I compared several morphological and physiological traits of territorial residents to those of intruders to investigate whether resource-holding potential (RHP) is correlated with these traits in C. smaragdinus. The differences in body size, flight-muscle ratio, and age between residents and intruders were not significant. Residents had less lipid reserves than intruders suggesting that residents consume more energy during territorial defense. This result indicates that the tested parameters are not correlated with RHP, and does not support the idea that superiority of territorial residents in C. smaragdinus is attributable to morphological or physiological traits.