Graduate Student University of Calgary Calgary, Canada
Background/Question/Methods
In the tropics, hurricanes are an occasional disturbance that can have severe impacts on the structure and composition of biotic communities. As climate change is predicted to increase the frequency and intensity of these storms, it is important to advance our understanding of species' responses to this disturbance to help us predict future impacts. The effects on bats can be direct (i.e., injury, mortality) and indirect via habitat loss and alteration, subsequently affecting food availability and roosting sites. In addition, sensitivity varies among species due to their habitat and food requirements.
In September 2017, Hurricane Maria, a category 5 storm, struck the small island (750 km2) of Dominica, causing substantial damage to the vegetation across the island. This provided a unique opportunity to assess the hurricane’s impact on bat community structure and composition in the Caribbean. I measured changes in diversity, abundance, body condition, and reproductive rate using data I collected during surveys two years prior to Maria and two years after Maria. I then examined the impact of Maria on three foraging guilds (frugivores, nectarivores, insectivores) using generalized linear models for abundance, general linear models for body condition and chi-square tests for reproductive rate.
Results/Conclusions
Hurricane Maria had negative effects on all foraging guilds of the bat community. Plant-reliant species, particularly frugivores, showed stronger negative responses. There was an increase in species diversity after the hurricane due to a lower abundance per species and a decrease in the most dominant species, resulting in a more even distribution. The largest declines in abundance occurred in the frugivore guild. I suggest that some direct mortality occurred from exposure to the hurricane; however, the primary reason for the decrease in abundance was due to loss of food and roost sites. There was no change in body condition for any guild indicating that individuals that survived were able to obtain enough food to maintain a healthy body mass. However, there was a significant decline in female reproductive rate for some species, suggesting a tradeoff between energy for survival and reproduction.
Overall, species-specific differences in diet, roost sites, foraging strategies, and reproductive patterns contributed to the different responses in bats. This emphasizes the importance of increasing knowledge to allow for more comparisons and insights into ecological mechanisms and to help aid in conservation actions and management strategies. A comprehensive understanding will, however, require longer-term monitoring post-hurricane.
