Abstract
Treefrogs represent 22% of amphibian species in Costa Rica, but gaps in the knowledge about this group of amphibians can impede conservation efforts. In this study, we first updated the status of Costa Rican treefrogs and found that a total of 38% of treefrog species are threatened according to the most recent IUCN assessment in 2019. Additionally, 21% of Costa Rican treefrog species have a high vulnerability to extinction according to environmental vulnerability scores. Then, we predicted the historical climatic suitability of eight target species that we expected to have exhibited changes in their ranges in the last 20 years. We assessed the location of new occurrence records since 2000 to identify recovery, range expansion, or previously underestimated ranges due to methodological limitations. We also estimated the area of each species’ suitable habitat with two metrics: extent of suitable habitat (ESH) and area of minimum convex polygon (AMCP). Six declined species exhibited recovery (i.e., new occurrences across historical range after 2000), with the widest recovery found in Agalychnis annae. We also found that Isthmohyla pseudopuma appears to have spread after the decline of sympatric species and that the range of I. sukia was originally underestimated due to inadequate detection. We found that the ESH was 32–49% smaller than the AMCP for species that are slowly recovering; however, the ESH is similar or greater than the AMCP for species that are recovering in most of their ranges, as well as rare species with widespread ranges. Results of this work can be used to evaluate the risk of environmental threats and prioritize regions for conservation purposes.
Highlights
We assessed all 48 known species of treefrogs included in the most recent official list of amphibian species in Costa Rica [43]. We found their updated status in Costa Rica [49] according to the most recent IUCN Red List Assessment conducted in 2019 [50] as follows: NA = “Not Applicable”; DD = “Data Deficient”; LC = “Least Concerned”; NT = “Near Threatened”; VU = “Vulnerable”; EN = “Endangered”; CR = “Critically Endangered”; EX = “Extinct in the wild”
A total of four treefrog species is endemic to Costa Rica
According to the most recent IUCN Red List Assessment in 2019 [47], 18 treefrog species are classified in threatened categories, including one species that is possibly extinct (I. calypsa), and five are categorized as critically endangered (Table 1)
Summary
8400 known species [1]; the tropics are where they have diversified more than many other region [2] Given their nearly pan-global distribution, amphibians can provide relevant insights into the biology of communities and populations in a wide variety of environments, and in some scenarios, may act as useful indicators of ecosystem health [3]. In Costa Rica and throughout Central America, declines were most severe at mid and high elevations (800–2500 m) and along stream corridors [24,25]. This mountain habitat, well-suited for the growth and proliferation of Bd [15], was home to many treefrog species, those in the genera Isthmohyla, Duellmanohyla, and Agalychnis [26].
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