Flea Toad (Brachycephalus pulex)

Mohamed bin Zayed Species project number 13056093

In this project we want to asses basic data on the natural history of the Flea Toad (reproduction success, reproductive strategy, number of descendants per amplexus, home range, preferred habitat and bioacoustics) and also data that will allow us to asses its potential to be driven to extinction by climate change (thermal tolerance, distribution across the mountain ridge, ecophysiologie). As the mountain range of which Serra Bonita is part is much larger showing several other mountains with similar physiognomies and altitudes we also want to run some rapid amphibian assessments in other mountains. The principal question we want to answer is: Do mountain tops of southern Bahia share their amphibian fauna or does every mountain top have its own characteristic amphibian fauna. Put in other words: Was there evolutionary enough time to allow a divergence between species or was the time space too short. For this we will also collect some tissues of the endemic frogs of southern Bahia. Activity 1: A natural history study of the Flea Toad: In a first phase we will cover a larger area of the mountain ridge in order to detect new Flea toad populations. After this we will select a population which combines two important criteria: It should maintain a large population and should also be of easy access. This population will then be studied: Using the “focal animal” methodology we will gather information on its behavior, including reproductive behavior and thus define its reproductive strategy. In a pilot study we will mark ten individuals with elastomeres and check if this methodology is also valid for so small species. We have applied it successfully for frogs with less than 16 mm by now. The mark – recapture study will allow us to estimate population densities. In already ongoing fieldworks we have detected that the Flea toad shows no continuous distribution along the mountain range. Instead its populations are patchy and we need to assess what makes some habitats attractive and allows the maintenance of populations, while other primary forest areas, that superficially observed look the same, do not harbor Flea Toad populations. We will combine two strategies to solve that question: On one hand we will compile twelve environmental factors such as e. g. presence and number of terrestrial bromeliads, leaf litter depth, canopy coverage. On the other hand we will place datalogger in the leaf litter in order to detect slight daily differences in temperature. With the grants funding we would be able to buy datalogger and elastomeres and also pay for the fieldwork (gasoline, lodging, food). The above listed activities would allow a first assessment of the biology of the target species and maybe explain why the species is not distributed all over the mountain ridge, but only in some specific forest plots. Activity 2: The Flea Toad lives between 700 and 900 m altitude on a single mountain ridge. Despite extensive fieldworks it has not been detected in lower regions. Notheastern Brazil has been found to be one of the areas in the world which will be severely affected by climate change, specifically global warming. Herpetologists suggest that increasing temperatures may lead Atlantic Rainforest species to shift their distribution towards mountain areas. Due to their low dispersal capacity most scientists agree that frogs will be unable to migrate southwards to reach more temperate regions. But what if a frog or toad already lives on the upper third of a mountain range? As a prominent Brazilian Herpetologist (Célio Haddad) always emphasizes emphatically: “Poor Brachycephalus: They can’t fly”. Thus we need to know if these toads are already living on the edge of extinction. This will be assessed using the international protocol suggested by Duarte et al. (2012) using Hutchison’s dynamic method (Lutterschmidt & Hutchison, 1997) in which adult toads are heated until they reached the onset of muscular spasms. The toads survive the procedure and important ecophysiological data as the CTMax (critical thermal limits) is gathered. Prior studies by the group of Miguel Tejedo in Spain, which whom we collaborate, have yielded worrying results: While comparing the CTMax of amphibians living in subtropical (Argentina) and temperate (Spain, USA and Sweden) regions they detected that subtropical amphibians have a higher CTMax than species from temperate regions. This was already expected. They also found that amphibians from subtropical areas show a CTMax much closer to the TMax (maximum habitat temperatures) of the studied regions. Thus an elevation of some degrees could already be catastrophic for subtropical amphibians. We have run some preliminary studies in Bahia and detected that amphibians inhabiting lowland rainforest streams have very low warming tolerance (CTmax–Tmax). Any alteration of their breeding streams, as e.g. selective logging on the margins may result in an elevation of the water temperature and thus preclude tadpole development leading to local extinction of these species. The ecophysiological data, combined with the thermal data registered with the dataloggers from the patches where the Flea toad lives will allow us to assess the extinction risk of this species. The grant would allow us to carry out fieldworks to collect specimen at patches with large populations. Activity 3: The Flea Toad has by now only been found at the mountain of its type locality. The mountain range of which Serra Bonita is only a small part shows several other mountains with similar vegetation and altitudes. In eight expeditions we want to sample some of this other mountains in order to detect if the Flea Toad is more widely distributed or not. References: DUARTE, H.; TEJEDO, M.; KATZENBERGER, M.; MARANGONI, F.; BALDO, D.; BELTRÁN, J.F.; MARTÍ D.A.; RICHTER-BOIX, A.; GONZALEZ-VOYER, A. 2012. Can amphibians take the heat? Vulnerability to climate warming in subtropical and temperate larval amphibian communities. Global Change Biology 18(2): 412-421. LUTTERSCHMIDT, W. I. & HUTCHISON, V. H. 1997. The critical thermal maximum: history and critique. Canadian Journal of Zoology 75: 1561–1574.