# Landscape Structure and Breeding Site Conditions Shape the Urban Distribution of the Two Frog Species, Dryophytes japonica and Rhacophorus schlegelii

## TL;DR

This study explores how landscape and breeding site conditions affect two frog species in urbanized areas of Japan, finding that one species is more vulnerable to habitat changes.

## Contribution

The study reveals species-specific responses to urban stressors, emphasizing the need for tailored conservation strategies.

## Key findings

- Both frog species benefit from nearby forests and water retention in paddy fields.
- R. schlegelii relies on specific soil channels for breeding, making it vulnerable to concreting.
- Conservation strategies should address both landscape and microhabitat needs for amphibians in urban areas.

## Abstract

Urbanization poses significant threats to amphibians through habitat loss, fragmentation, and degradation of breeding sites. This study investigated the distribution of two frog species, Dryophytes japonica and
Rhacophorus schlegelii
, which have relatively similar ecological traits in paddy fields in high‐populated, i.e., heavily urbanized areas of Tokyo and Kanagawa, Japan, focusing on landscape‐ and microhabitat factors simultaneously. Calling surveys were conducted at approximately 100 sites over 2 years (2022–2023) during the breeding season to identify key environmental variables influencing species occurrence. As a landscape factor, both species were positively associated with surrounding forest, suggesting the importance of landscape connectivity between forest as habitats and paddy fields as breeding sites. As a microhabitat factor, water retention in the paddies was a significant factor for both species. Notably,
R. schlegelii
depended on microhabitat features, in specific soil channels, whereas
D. japonica
did not. These findings suggest that while both species benefit from nearby forests in urbanized areas, only
R. schlegelii
is vulnerable to concreting that disrupts soil channels as breeding sites. The study underscores the need for conservation strategies that address both landscape‐ and microhabitat requirements to support amphibians in urbanizing agricultural regions. Importantly, species with similar ecological niches may respond differently to urban stressors, requiring species‐specific management strategies.

Both frog species can persist in urbanized areas if forest habitats and paddy fields used for breeding remain. However, breeding site requirements differ between the species; concreting disproportionately impairs the reproductive success of
R. schlegelii
. While habitat loss is often emphasized as a key driver of amphibian decline, this study highlights the need to consider the entire life history when assessing threats.