Clicking Warrior Butterflies!

Today I visited a new Sector of the ACG - Munde Nuevo. After driving some severely eroded roads and crossing though a stream we arrived at the La Perla Station. I was able to get measurements from 22 individual caterpillars, so a good haul. At lunch though I took a walk around and watched some of the adult butterflies. After being briefly distracted by a few White-throated Magpie-Jays I heard an odd clicking sound. Looking around I eventually realized that it was coming from pairs of butterflies.
Many butterflies are territorial. Males defend these territories by chasing out intruding males. They are sometimes seen engaging in a spiralling flight where eventually one male gives up and leaves (usually the intruder). Many species here in Costa Rica are territorial and I enjoy watching them defend their areas and trying to mentally figure out where one territory ends and the another begins.

I only saw the clicking expressed during these spiral flights, so I suspected that it had something to do with territoriality. I was told today that the clicking butterfly I observed was from the Hamadryas genus- the so-called Cracker butterflies. They primarily eat fermenting fruit. The Wikipedia article details the behavioural ecology pretty well so you can read more about that really interesting work there:

Hamadryas sp. (Nymphalidae)
Apparently these guys are becoming less common around Santa Rosa. This is partly attributed to the progressive loss of host plants resulting from natural succession of the forest here (much of the ACG forest is secondary growth). La Perla is in an earlier successional stage, and it is at a higher elevation, so it is thought that this is an example of a mobile species sliding up mountain sides with climate change.


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