Nowdays, due the increasing human activities we have a lot of habitat and biodiversity loss, which has taken us to understand that species diversity studies are vital to understand biological communities and their conservation. The biota stratification between canopy and understory is an important factor for tropical diversity.
Taking these into account, Tirimbina Biological Reserve is pretending to evaluate how do butterflies species that feed on fruits change on temporary and spatial dimension. That's why since 2003 a vertical and horizontal stratification study with diurnal butterflies has been carry out; Philip J. DeVries and Isidro A. Chacón ,recognized butterfly researchers, are in charge of this project. Our final aim with this project is to reach 10 years of continuos sampling by 2013.
Butterflies that feed on fruits are easy to sample, in vertical and horizontal dimensions, using fruit traps. This method allows us to cover 40 to 55% of the butterflies richness belonging to Nymphalidae family. The objective is to identify most of the species richness of this family, we have 30 stablished stations, every one with a fruit trap on the canopy level and another one at the understory along the Botarrama, Ajillo, Corteza and Cacaotal trail. The canopy traps are hanging between 15 and 30 meters high and they are between trees. The understory traps are located between 1 to 1.5 meters above the ground. Both traps are open during the first seven days of each month.
Until now, we have done 94 sampling weeks, what makes this Project the most important long term study, with butterflies that visit fruits in lowland rainforest of Central America.
As a product of this research we have identified 118 species of butterflies of Nymphalidae family for Tirimbina Biological Reserve. During this year, 2011, while the 5 sampling weeks (from January to may) we have caught 628 butterflies belonging to 66 species. Over half of these species are rare species represented by 5 or less individuals. About the vertical dimensión, species richness is different between layers, 54,5% of the species are only at the canopy level, 30,3% at the understory and 15,2% in both. The abundance is also diferent, species are more abundant at the understory, at the canopy level most of the species are represented just by one individual. Temporal dimensión show difference also on richness and abundance. The month with more individual abundance was march and the mpst richness month was april.
In conclusión, thanks to this study we can understand that some butterflies fly at the canopy and understory level to feed, but most of these species are only in one of those, being the canopy the one with more species richness.