OuTrop Masters student, Connie Tremlett, conducted the first-ever studies of carrion-feeding butterflies in a tropical peat-swamp forest and fills us in on what she found…
I was lucky enough to get the chance to spend 12 weeks with OuTrop in Borneo last year, studying the responses of carrion- and fruit- feeding butterflies to disturbance in Sabangau. Few people have studied carrion-feeding butterflies and nobody has studied them in tropical peat-swamp forest, probably due in part to the unpleasantness of using carrion as bait!
Using OuTrop’s standard butterfly canopy trapping methods, I baited traps with shrimp paste for carrion-feeders or a banana, sugar and alcohol mix for fruit-feeders, and erected traps in both relatively heavily and less disturbed forest. These results were compared to data on forest condition collected from trees plots, which formed the topic of my Masters thesis at the University of Leeds (UK).
Connie checking a butterfly trap. Photo by OuTrop.
As expected, forest structure was impacted by disturbance: less disturbed areas showed more tree species richness and density, but trees in disturbed areas were smaller and there was also less variation in tree architecture (and so fewer micro-habitats).
Interestingly, carrion- and fruit-feeding butterflies responded differently to disturbance: abundance and species richness of fruit-feeders did not differ between heavily and less disturbed forest, but was higher for carrion-feeders in heavily disturbed forest, compared to less disturbed.
Despite the label, carrion-feeding butterflies actually feed mostly on floral nectar, tree sap and rotting fruit, with carrion providing supplementary nutrients. Possibly increased light levels in disturbed forest stimulate growth of ground-dwelling plants, providing extra nectar resources for carrion-feeding butterflies in more disturbed areas. Carrion-feeding butterflies may also be better able to colonise disturbed forest than fruit-feeders.
A Eurema nicevillei butterfly inside a trap. Photo by Connie Tremlett/OuTrop.
OuTrop’s long-term fruit-feeding butterfly research is revealing that butterfly species’ abundance fluctuates dramatically throughout the year, so it is possible that studies in different seasons might yield different results.
Nevertheless, my research shows that related species with different ecologies – in this case dietary niche – may respond differently to human disturbance. This is important for conservation managers to consider when using butterflies as an ecological monitoring tool.
This research was facilitated by a grant from the Whitley Wildlife Conservation Trust.