Diet and trophic niche of Lithobates catesbeianus (Amphibia: Anura)

Abstract

. Lithobates catesbeianus (Shaw, 1802) is an invasive anuran introduced in Brazil that is associated with the displacement and the decline of populations of native species worldwide. There is evidence that biological invasions are facilitated by certain attributes of the invading species, for instance niche breath, and that invasive species have a broader ecological niche with respect to native ones. We designed a study to ascertain the temporal, ontogenetic, and sex differences in the niche dynamics of the American bullfrog. We sampled monthly from June 2008 to May 2009 in the state of Paraná, southern Brazil. For each individual, we gathered biometric and stomach content data. We then estimated the niche breath of the juveniles and adults, and compared it between the sexes. A total of 104 females and 77 males were sampled. Lithobates catesbeianus has a generalist diet, preying upon invertebrates and vertebrates. Even though the diet of the studied population varied seasonally, it did not differ between the sexes nor did it respond to biometric variables. Niche breadth was more restricted in the winter than in the autumn. The trophic niche of juveniles and adults did not overlap much when compared with the trophic niche overlap between males and females. Adult males and females had a considerable niche overlap, but females had a broader trophic niche than males in the winter and in the spring. These niche characteristics point to an opportunistic predation strategy that may have facilitated the process of invasion and establishment of this species in the study area.

Aspectos ecológicos de una comunidad de anuros en un ambiente tropical estacional en Guanajuato, México

“…Las especies de género Lithobates suelen considerarse de alta plasticidad al invadir y explotar variados ambientes, y los hábitos reproductivos asociados a charcas o pozas les brinda mayor independencia de fuentes de agua permanentes. Al respecto, Leivas et al (2012) mencionan que L. catesbeianus presenta una alta plasticidad tanto trófica como en el uso de microhábitats, siendo una especie con un alto éxito ecológico y tolerante a distintos ambientes. Una situación similar podría ocurrir con L. neovolcanicus, ya que se observó con una amplia distribución y que a pesar de tener preferencia por pozas de agua aledañas al río Colorado y dentro del mismo río, usa una gran cantidad de microhábitats.…”

Histopathological aspects of the liver of free-living and farmed bullfrogs (Lithobates catesbeianus)

“…Because free-living bullfrogs feed only by preying on insects, other invertebrates, and small vertebrates and its animal protein intake is consequently low (Hirai, 2004;Silva et al, 2009;Leivas et al, 2012), this protein-mineral deficiency is practically not observed.…”

“…The diet of free-living bullfrogs is based on invertebrates and small vertebrates (Hirai, 2004;Silva et al, 2009;Leivas et al, 2012). By contrast, captivity-reared bullfrogs consume balanced diets containing ingredients of animal and plant origins (Olvera-Novoa et al, 2007;Rodrigues et al, 2007;Castro et al, 2008).…”

Species Composition, Conservation Status, and Sources of Threat of Anurans in Mosaics of Highland Grasslands of Southern and Southeastern Brazil

“…The main threats to anurans in highland grasslands seem to be: erosion and soil instability due to anthropogenic activities, deforestation, biological invasion, fire, removal of ornamental plants, mining, urban expansion, climate change, installation of power transmission lines (Martinelli 2007, Mocochinski & Scheer 2008. Based on our field experience and on the recent literature (e.g., Leivas et al 2012, Rodriguez et al 2014, "[apparently the main threats for anuran fauna in highland grasslands seem to be: fire, disease, expansion of disturbed areas associated with human activities] MV Garey (personal communication)".…”

“…The only area of highland grasslands where there are records of an exotic species (Lithobastes catesbeianus) is the Campos do Jordão State Park in the Serra da Mantiqueira (Gomes 2009). This species has been introduced in many localities in Brazil for commercial purposes (Both et al 2011) and has many negative impacts on native anuran populations by competing (Kupferberg 1997) with preying (Leivas et al 2012) upon native species and transmitting pathogens (Schloegel et al 2010), which promoted the decline of some amphibian populations (Kats & Ferrer 2003). This species was also recorded in areas of Montane Rain Forest (between 700 and 800 m) of the Curucutu section of the Serra do Mar State Park (Malagoli 2013), which suggest the imminent risk to anurans in this region.…”