New records and model application in predicting distribution area of critically endangered Bufo Luchunnicus in Vietnam

02/10/2024

The Luchun - Bufo luchunnicus (Yang and Rao, 2008) has a narrow distribution range in southern China and northwestern Vietnam. The species is classified as Critically Endangered (CR) in the IUCN Red List, due to the impact of habitat loss. Lack of information on the distribution range and natural history is the main reason why conservation work has not been carried out. A group of Vietnamese scientists from the Institute of Genome Research, Institute of Ecology and Biological Resources, University of Natural Sciences has coordinated with Cologne Zoo, Germany to conduct a survey to record two new populations of the species in Vietnam and supplement biological and ecological information of the species. During the implementation process, the research team predicted the potential distribution area of the species through the use of the Maximum Entropy algorithm model (Maxent), thereby orienting the survey to record new populations and identify priority conservation areas.

The Luchun - Bufo luchunnicus was first discovered in Yunnan province, China. After that, this species was found in Lao Cai and Son La provinces, Vietnam. Surveying six locations in Lao Cai and Son La from 2021-2023, the research team discovered two new populations of B. luchunnicus, specifically in Van Ban district, Lao Cai and Phuc Yen district, Son La. In a period of 10 years, only two individuals were recorded in China and six individuals in Vietnam, so the population of Bufo luchunnicus is assessed as very small. The study described and supplemented the morphological characteristics of the species.

In terms of natural history, the Luchun is found at night, between 7pm and 10:30pm. The surrounding environment is evergreen forest with large and medium trees and shrubs. They are found at altitudes ranging from 960 to 2025 m above sea level. Relative humidity is high at 75-90% and ambient temperatures range from 22 to 30°C. The team found one adult male swimming in the water, a mating pair on a rock, one male on a large rock and two males on the ground along the stream. The stream is about 5 to 15m wide, with flat banks and slow currents.

Using species distribution coordinates and climate parameters from Worldclim data (https://www. worldclim.org/), species distribution models run on Maxent software, version v.3.4.1 (Phillips et al., 2006) (https://biodiversityinformatics.amnh.org/ opensource/maxent/) all gave very good distribution area prediction results (AUC value > 0.9). Specifically, the model predicted a suitable climate distribution area covering the current distribution range of the species in Yunnan province, China and Lao Cai and Son La provinces, Vietnam. In addition, potential distribution areas were recorded in Ha Giang, Lai Chau and Yen Bai provinces of Vietnam, and Hua Phan province of Laos. Notably, both sides of the Red River region recorded a climate range not suitable for the species, which may be a geographical barrier limiting species dispersal across the river.

Distribution map and predicted climate niche of Bufo luchunnicus

The new discovery by the research team of additional populations of B. luchunnicus in Vietnam, extending the range to less than 10,000 km2. With an estimated adult population of less than 2,500, the scientists propose to assess the species as Endangered (EN) in the IUCN Red List.

The study noted that the natural habitat of B. luchunnicus is severely degraded due to human impacts, including illegal logging, collection of other products (such as bamboo shoots, medicinal plants), livestock farming, forest fires and hydropower construction. Under the impacts of humans, conservation measures to protect the natural population of B. luchunnicus and its habitat need to be implemented immediately.

Translated by Tuyet Nhung
Link to Vietnamese version

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