Providing artificial water holes similar to those created naturally by peccaries (skunk pigs) may increase amphibian populations, according to a four-year study. These take the form of special, environmentally calibrated biomes. The work is being undertaken due to concerns with declining frog populations around the world.
The hairy, pig-like peccaries serve as “ecosystem engineers” by stomping and rolling through the forest, creating holes in the ground that fill with rainwater. The “wallows” they leave behind provide an ideal dry season habitat for poisonous frogs like the brilliant-thighed poison frog (Allobates femoralis), which deposits its tadpoles in the small ponds to provide them with an aquatic habitat where they can mature into adults.
To study the impact of these depressions on the reproductive success of the frogs, scientists based at the University of Vienna installed a series of plastic bowls to collect rainwater at regular intervals in a patch of rainforest in French Guiana and monitored frog populations in their test and control plots.
It was found that the frog populations expanded rapidly in both the areas with the bowls and nearby plots, from 148 frogs the season before the bowls were installed to 246 frogs two years later, while no increase was seen in plots far away from the man-made peccary wallows.
While the populations increased, the bowls also appeared to create more territorial competition among male frogs, leading to decreased male survival. Female survival was not affected. Overall, the effect of the bowls appeared to be positive, likely preventing many a tadpole from drying out.
Since peccary populations are declining, and the swine had not been observed in the study area for several years, human supplementation of the rainforest environment could help the frogs to avoid the same fate, the researchers proposed.
The findings have been published in the journal Behavioral Ecology. The research is titled “Populations, pools, and peccaries: simulating the impact of ecosystem engineers on rainforest frogs.”
