Differential resilience to extreme climate events of tree phenology and cavity resources in tropical dry forest: Cascading effects on a threatened species

Abstract

The influence of climate extremes on tree phenology or cavity resources, and the consequences for threatened species, are poorly understood. We determined flowering and fruiting phenology, and availability of tree-cavities and snags in deciduous and semi-deciduous tropical dry forest from 2009 to 2016, prior-to and following landfall by hurricanes Jova (category 2) in 2011 and Patricia (category 4) in 2015. We also evaluated reproduction of the threatened Lilac-crowned Amazon (Amazona finschi) throughout this period. Flowering and fruiting phenology was reduced during the first year post-hurricanes, but the major Hurricane Patricia had a significantly greater impact on fruit and flower abundance than the minor Hurricane Jova. ARIMA time series modelling indicated that deciduous forest recovered phenological cycles by the second-year post-Hurricane Jova, but semi-deciduous forest demonstrated a level shift in fruiting phenology after landfall by this minor hurricane. Subsequent landfall by the major Hurricane Patricia then also led to a level shift in fruiting phenology of deciduous forest. Tree-cavity and snag resources were reduced by half post-Hurricane Jova, and remaining tree-cavities had significantly wider entrances, while snags were of larger diameters. Hurricane Jova caused the loss of 35.6% of Lilac-crowned Amazon nest-sites, whereas a significantly greater 61.5% of parrot nest-sites were lost after Hurricane Patricia. New nest-cavities used by parrots after Hurricane Jova had significantly wider entrances compared to nest-cavities used prior to hurricane impacts. In the first breeding season post-hurricanes, Lilac-crowned Amazons delayed nest initiation, few pairs nested, and reproductive output was low. Parrot reproduction recovered in subsequent years post-Hurricane Jova, but parrot reproductive output remained among the lowest recorded for the species in the second year post-Hurricane Patricia. Our results suggest that deciduous forest may be resilient to low-level hurricane impacts, such as Hurricane Jova, but semi-deciduous forest did not recover over the five years after hurricane landfall, and is a priority for restoration management. By comparison, the major Hurricane Patricia may be characterized as an extreme climatic event as this was coupled with extreme ecological responses of level-shifts in fruiting phenology, and had severe cascading effects on nest-site availability and reproduction for large-bodied cavity-nesting species, such as the Lilac-crowned Amazon.