Impacts of a drought and hurricane on tropical bird and frog distributions

Abstract

During the last few decades, much attention has focused on how global change is affecting the environment and species distributions. Land-use change is still the major cause of species declines worldwide, but changes in species distributions have been documented even in pristine and protected areas. Here, we document the distribution dynamics of 26 species of frogs and birds within a Caribbean protected area between 2015 and 2019. Specifically, we document species occupancy and detectability in 59 sites along three elevational transects within the El Yunque National Forest in Puerto Rico. Species were sampled using acoustic recorders, species identification algorithms, and post-classification validation. The study period included a severe drought (2015-2016) and a category 4 hurricane (2017). The distribution of most frog species did not change significantly during the study period. In contrast, the distributions of the bird species contracted between the 2015 and 2016 pre-hurricane surveys. This contraction coincides with a severe drought that peaked after the 2015 survey. The response of bird species after H. Maria was heterogeneous. Our results suggest that for many species, particularly birds, the 2015-2016 drought in Puerto Rico had a greater negative effect than H. Maria. The difference in the response of the bird and frog communities is likely related to their abundance at the site level, their ability to disperse, and temporal patterns of reproduction. If a site is occupied by a frog species, it could easily include 100s of individuals, and even if condition worsens, over a relatively short period the species will continue to occupy the site. In contrast, a site may only be occupied by one or a few individuals of birds. Birds have also higher dispersal abilities than frogs. Furthermore, Puerto Rican frogs reproduce year-round, whereas birds concentrate their reproduction during a few months in the wet season. Future climate scenarios predict a decrease in total precipitation and an increase in droughts for the region, which emphasizes the need to consider the diversity of changes that will be associated with future climate change.

The effect of Hurricane María on the richness and calling activity of the Eleutherodactylus assemblages of the Carite State Forest, Puerto Rico

“…The findings of our study are similar to those from the passive acoustic monitoring study of Campos‐Cerqueira and Aide (2021). The location of their study is at El Yunque National Forest, and they utilize occupancy differences between certain years (2015–2019) to assess distributional changes in populations of birds and frogs.…”

“…The findings of our study are similar to those from the passive acoustic monitoring study of Campos-Cerqueira and Aide (2021).…”

“…Eleutherodactylus frogs play an important role in the ecosystem dynamics of the Puerto Rican forests (Herrera‐Montes & Brokaw, 2010; Waide, 1991), being the dominant consumers (Waide, 1991), helping regulate the transmission of mosquito borne diseases (Hocking & Babbitt, 2014), while at the same time serving as food for vertebrate and invertebrate predators (Stewart, 1995). Unfortunately, their sensitivity to environmental stressors makes them vulnerable to disturbances (Burrowes et al, 2004; Ríos‐López & Aide, 2007; Stewart, 1995), and changes in their populations have the potential to reshape the fauna and flora of communities in the forests of the Island (Campos‐Cerqueira & Aide, 2021).…”

The future of Caribbean endemic bird conservation in the Anthropocene

“…Initial surveys found only eight birds a couple of weeks after the hurricane (BirdsCaribbean 2017a), but a year and a half later, the species was reportedly recovering reasonably well (BirdsCaribbean 2019a). While such range-restricted species will have naturally small populations (Graham et al 2017) and many island species are resilient to hurricanes since they have evolved with these natural events (Lloyd et al 2019, Campos-Cerqueira andAide 2021), this example illustrates their vulnerability to extreme weather events. Hurricanes are predicted to become more intense, wetter, and slower due to climate change (Knutson et al 2019), which could negatively impact this resiliency.…”

Editorial: The Impact of Weather on the Behavior and Ecology of Birds

“…This Research Topic highlights that rainfall impacts birds in diverse ways, and Rosamond et al show that Dickcissel (Spiza americana) populations decline with increasing amounts of summer rainfall. However, drought also influences the distribution of breeding birds (Barbaree et al, 2020;Campos-Cerqueira and Aide, 2021) and particularly so in arid regions (Herremans, 2004). Bourne et al advance our understanding of adaptive responses to drought by showing that Southern Pied Babblers (Turdoides bicolor) in the Kalahari Desert in South Africa significantly reduce their reproductive effort during breeding seasons characterised by drought but subsequently increase their reproductive effort during the breeding seasons immediately following droughts.…”