When having a conversation about the tropics, perhaps the most common image that our brains invoke is that of pouring rain. Although high humidity levels may certainly be a key characteristic of the tropics, this is not always the case. In fact, I was somewhat surprised when my boots collected no mud after hours of walking in the forest… this is the result of a harsher than normal dry season of the current El Niño year.
In a nutshell, during an El Niño event, cloud cover and precipitation are reduced. As a result, trees have an extremely productive season and they put out tons of fruits. This is great for all the animals that like to munch on fruits (a.k.a. frugivores) like agoutis, capuchin monkeys, coatimundis and pecaris. However, an El Niño event is usually followed by the evil twin sister…La Niña.
La Niña is the sobbing toddler who can get away with throwing crazy tantrums. Personification aside, this translates into above average cloud cover and precipitation. Consequently, fruit production is lower than normal during La Niña events. Frugivore mortality is usually extremely high. For example, Dr. Megan Crofoot mentioned a case in Barro Colorado Island where ~60% of the capuchins died. STRI researchers are therefore predicting that next year will be a harsh one for frugivore communities.
Because my research focuses on amphibians, my take on these extreme climatic events is slightly different –well maybe more than slightly. Specifically, I expect El Niño years to be harsher than La Niña years on amphibians. The main reason for this prediction is that amphibians are highly dependent on water.
First, most amphibian species have a fully aquatic larval stage followed by a terrestrial adult. Second, most amphibians have an extremely thin skin prone to dehydration. Thus, I expect the drier El Niño years to have a detrimental impact on amphibian communities. As a matter of fact, I found at least 12 dart frogs huddled in a coffee-cup sized pool of rainwater. In other words, frog density around that particular resource was substantially higher than I would have expected it to be. Having this many individuals in one place may increase competition for resources, as well as disease transmission.
I ended up asking myself more questions than I have answered so far, perhaps I will be able to tackle some of these throughout my research so stay tuned.