Dispersal of Brown Frogs Rana japonica and R. ornativentris in the Forests of the Tama Hills.

Abstract

For the conservation of forest frogs, it is important to conserve not only water sites for breeding but also forests for living in the non-breeding season. Therefore, the two species of brown frogs (Rana japonica and R. ornativentris) common to Japan were surveyed for their dispersal capability and the range of activity in the non-breeding season. The survey was conducted 16 times in forests on undeveloped land (about 28 ha) of the Tama Hills by the capture-and-mark method. The migrating distances were calculated from the sites of capture and spawning. As a result, 90% of the individuals were within the range of 200 to 270m (R. japonica) and 330 to 390 m (R. ornativentris). The maximum distance was about 500 m and both species were found capable of migrating at least 500 m. The migrating distances of recaptured individuals indicated that both species have specific summer habitat. Yearlings especially of both species grow rapidly between summer and fall in the forests. R. ornativentris was only rarely captured at the edge of the forest. The study demonstrated that the forest is the main habitat and main dispersion route for R. ornativentris in the non-breeding season. We discuss the conservation of both species from the viewpoint of landscape ecology.

Effects of Ecosystem Diversity on Species Richness and Ecosystem Functioning and Services: A General Conceptualization

“…Interestingly, this spatial scale is roughly consistent with the distance moved by adults of a closely related species Rana japonica from breeding sites (rice paddies) to nonbreeding sites (forests), as measured by individual marking (Osawa and Katsuno 2001).…”

Differential Responses of Two Anuran Species Breeding in Rice Fields to Landscape Composition and Spatial Scale

“…The montane brown frog lays jelly-like egg masses in the shallow water of rice fields (e.g., Osawa and Katsuno 2001), and the forest green tree frog lays frothy egg masses along rice-field margins on Sado Island (personal observation). We counted the number of egg masses, which were identified by eye, while walking along the paths surrounding rice fields.…”

“…As they lay a single egg mass in one breeding season (montane brown frog: Maeda and Ueda 2010, forest green tree frog: Kasuya et al 1996), the number of egg masses are a good measure for the relative abundance of each species breeding in a particular rice field. Adult montane brown frogs live on the forest floor in the non-breeding season (Osawa and Katsuno 2001), while adult forest green tree frogs spend their arboreal life in forests (Kusano 1998). The migration distances of the adults from the breeding sites to forests are known to differ, with the montane brown frog exhibiting a 500 m (Osawa and Katsuno 2001) and the forest green tree frog approximately 120 m (Kusano 1998) migration distance.…”

“…Adult montane brown frogs live on the forest floor in the non-breeding season (Osawa and Katsuno 2001), while adult forest green tree frogs spend their arboreal life in forests (Kusano 1998). The migration distances of the adults from the breeding sites to forests are known to differ, with the montane brown frog exhibiting a 500 m (Osawa and Katsuno 2001) and the forest green tree frog approximately 120 m (Kusano 1998) migration distance. Adults of both species exhibit site fidelity in forests across years in non-breeding season (Kusano 1998;Osawa and Katsuno 2001).…”

“…The migration distances of the adults from the breeding sites to forests are known to differ, with the montane brown frog exhibiting a 500 m (Osawa and Katsuno 2001) and the forest green tree frog approximately 120 m (Kusano 1998) migration distance. Adults of both species exhibit site fidelity in forests across years in non-breeding season (Kusano 1998;Osawa and Katsuno 2001).…”