Native to North America, the bullfrog Lithobates catesbeianus (Shaw, 1802) was introduced in several countries, including Brazil, usually by means of commercial breeding. This species represents a threat to native species, causing their population declines and even the apparent local extinction (e.g. Moyle, 1973; Batista, 2002; D’Amore et al., 2009). Negative impact to native communities happens due to adverse effects that bullfrog causes on the fitness of other frogs, which occurs by competition, predation and habitat use alteration (Kupferberg, 1997; Kats and Ferrer, 2003; Pearl et al., 2004; Rocha-Miranda et al., 2006; Boelter and Cechin, 2007; Silva et al., 2011). However, recent works have shown that negative impact on the fitness of other frogs by bullfrog invasion is not expected for all regions or communities (Adams et al., 2011; Both et al., 2014). Thus, further studies are required to investigate the effects of bullfrog introduction over distinct conditions such as habitats, environments and communities.

In a site located at Goiás state, Central Brazil (-15º59’50” S, -48º24’0.5” W; 956 m.a.s.l.), Batista (2002) observed significant changes in a local amphibian community after careless introduction and quick proliferation of bullfrog. In December 1997, Batista

(2002) made a list of the anuran species of the local. In early of 2000 the bullfrog was introduced in the area and already in December 2000 changes were observed in the local community. The author observed that species that were locally abundant, like Leptodactylus labyrinthicus (Spix, 1824) and Leptodactylus latrans (Steffen, 1815) (referred to as Leptodactylus ocellatus in the study) probably had become extinct in the community and the population of Physalaemus cuvieri (Fitzinger, 1826) had decreased. The study was conducted in an area of Cerrado (a Brazilian central savanna), composed by artificial and natural ponds, some dry and wet savannas, gallery forests and disturbed areas (pasture and plantation).

Ten years after Batista’s (2002) inventory, we conducted a new inventory of the amphibian fauna at the same place. Our inventory was conducted at the same water bodies of Batista’s (2002) study, composed mainly by four artificial and two natural ponds nearby pasture and gallery forests (Fig. 1). All ponds are permanent and have not changed significantly, they only suffered natural oscillations of climatic seasonality. The samplings occurred once in each rainy season from October 2008 to February 2010, totaling three visits where all water bodies were inventoried. There were no records of the bullfrog suggesting that bullfrog did not succeed at the site, presenting obvious decline and possible local extinction. Additionally, local residents also confirmed the absence of bullfrog. There were also no records for L. latrans (Butter Frog). On the other hand, we observed few individuals of L. labyrinthicus (Pepper Frog), identified as “absent” in the previous study. We still found Leptodactylus fuscus (Schneider, 1799) in abundance, which had not been previously recorded. It was not possible to make inferences about the size of the population of Physalaemus cuvieri due to the lack of appropriated data about it in Batista’s (2002) study.

Herpetology Notes, volume 8: 263-265 (2015) (published online on 18 May 2015)

Effects of introduction and decline of a Bullfrog population (Lithobates catesbeianus) in a community of amphibians

in the Cerrado from Central Brazil

Mariana Batista1,*, Mara Silva2 and Cristiane Barreto3

1 Programa de Pós-Graduação em Ecologia e Evolução, Departamento de Ecologia, Universidade Federal de Goiás, Goiânia, Brasil. Cx.P. 131, CEP 74.001-970.

2 Programa de Pós-Graduação em Ecologia e Conservação da Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Cuiabá, Brasil, CEP 78060-900.

3 Centro de Desenvolvimento Sustentável, Universidade de Brasília, Brasília, Distrito Federal, Brasil, CEP 70910-900.

* Corresponding author: marianag_bio@hotmail.com

Mariana Batista et al.264

There is a scarcity of studies about the introduction of bullfrog in Brazilian Cerrado. Nevertheless, failed bullfrog colonization was observed in this biome (see review of Giovanelli, Haddad and Alexandrino, 2008). Although the increase in bullfrog records (see Both et al., 2011) and the great suitability predicted for bullfrog in areas of Cerrado (Giovanelli, Haddad and Alexandrino, 2008), most of new records are for other biomes (Both et al., 2011), which might reflect poor ability of bullfrog colonization in Cerrado. As showed by Hecnar and M’Closkey (1997), droughts, that are common in the Cerrado, decrease the number of bullfrog individuals and might lead to population extinction. Thus, the results of this study suggest that bullfrog populations are probably unable to establish in Cerrado environments, in contrast to what has been observed in other Brazilian biomes (see Both et al., 2014).

Despite the impact observed on leptodactylid populations by the invasive bullfrog, after its disappearance, the population of pepper frog seems to be recovering. A population recovering after bullfrog

removal was also observed for the California red-legged frogs, which changed their behavior ensuring their survival (D’Amore et al., 2009). We speculate that the pepper frog may have changed its behavior at the presence of bullfrog and then started to recover their population, however we cannot make a rigorous assessment of this hypothesis as bullfrog was not observed at the area. In addition, there were no records for the butter frog, which appears to have gone extinct at the site after the introduction of bullfrog. This effect is potentially due the higher negative impact by bullfrog on anurans with great similarity in microhabitat use (see Silva et al., 2011). However, we are unable to ensure that bullfrog introduction was the leading cause of local butter frog disappearance. Studies that allow us to better understand bullfrog behavior, reproductive biology, diet and competition with native species in Brazil, particularly in the Cerrado biome, can be helpful in providing information for management actions to control the invasion of bullfrogs.

Figure 1. Some of the sampled water bodies. (A) Artificial pond around three meters deep; (B) Artificial pond around two meters deep; (C) Artificial pond approximately seven meters deep; (D) Natural water body about two meters deep.

Effects of introduction and decline of a Bullfrog population in Central Brazil 265

Acknowledgements. We thank Camila Both and anonymous reviewer for comments on manuscript. We also thank Débora Silvano for valuables suggestions and Emanuel Teixeira for providing us a pre-peer review. We are grateful to Vinícius Santos for helping us with the pictures and Elba Albuquerque for the English review.

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Accepted by Mirco Solé; Managing Editor: Vinicius Caldart