Six-male field study documents two advertisement call types in the treefrog Gracixalus weii

A field study of six male Gracixalus weii treefrogs recorded two forms of advertisement call, one of which resembled the song of the Black-breasted Thrush, Turdus dissimilis. The observations provide an initial acoustic description of the newly described species but do not establish its complete vocal repertoire.

Researchers recorded 182 spontaneous calls from six males at the species’ type locality, Leigongshan Nature Reserve in Leishan County, Guizhou Province, China. Recordings were collected from April 20 to 26, 2025, between 19:00 and 23:00, at about 1,570 metres above sea level. Air temperature ranged from 15.7°C to 20.5°C and humidity from 85% to 97%.

The males were observed calling on or within bamboo in dense forest near streams. Each isolated individual was recorded within one metre using a Sony ICD-PX470 digital recorder operating at 44.1 kHz with 16-bit resolution. Only calls with a high signal-to-noise ratio and without overlap from nearby males were analyzed.

Acoustic measurements were made in Raven Pro 1.6. Temporal properties were derived from waveform displays, while spectral properties were calculated by averaging the spectrum across each call. Analyses used a 512-sample fast Fourier transform, 50% overlap and a Hann window. Principal component analysis examined variation among the recorded calls.

Type A calls were produced by two males and accounted for 33 of the 182 recordings. Each comprised an introductory note followed by two click notes. Total duration ranged from 547 to 862 milliseconds, with a mean and standard deviation of 727 ± 119 milliseconds. The introductory note lasted 262–386 milliseconds, while the click notes lasted 39–75 and 38–92 milliseconds.

Type A calls contained harmonics spanning approximately 2.0–21.0 kHz and had a mean dominant frequency of 2.46 ± 0.10 kHz. All six males produced the 149 Type B calls, each consisting of an introductory note and one click note. These calls lasted 374–680 milliseconds, with a mean of 481 ± 77 milliseconds, and had a mean dominant frequency of 2.58 ± 0.15 kHz.

The first two principal components accounted for 82.49% of measured variation. The first component explained 52.62% and was associated most strongly with note number, third-note duration and total call duration. The second explained 29.87% and was primarily associated with second-note duration. Type B calls clustered together with limited variation among individuals, while Type A and Type B calls were clearly distinguishable.

The bird comparison used the “CNG Field Guide to the Birds of China,” consultation with local ornithologists, and oscillograms and spectrograms. The selected Black-breasted Thrush song segment lasted 726 milliseconds and had a dominant frequency of 2.07 kHz. Its longer note followed by two shorter notes resembled a Type A frog call, although the researchers stressed that the signals were not identical. They described the resemblance as a possible case of acoustic convergence, but its functional significance was not tested.

Comparisons with previously described calls also distinguished G. weii from other Gracixalus species. Its two or three notes exceeded the single notes reported for G. huaping and G. tianlinensis but were far fewer than the 40–72 notes of G. nonggangensis. Its click notes were longer than those reported for G. gracilipes, G. quangi and G. supercornutus, while its 2.0–21.0 kHz range was broader than ranges reported for four other species. The authors said these acoustic differences support the taxon’s differentiation, complementing morphological and mitochondrial 16S identification. Because the sample comprised six males at one locality over seven nights, with Type A calls detected in only two, broader behavioral and population-level tests remain necessary.

Subject of Research: Acoustic characterization of advertisement calls in the newly described treefrog Gracixalus weii

Article Title: A bird-like vocalization in a treefrog ( Anura , Rhacophoridae ): Analysis of advertisement call characteristics in Gracixalus weii

Article References: Peng, C., Shen, T., Li, S., Liu, J., Ye, R., Li, D., Chen, J., Tang, X., & Su, H. (2026). A bird-like vocalization in a treefrog (Anura, Rhacophoridae): Analysis of advertisement call characteristics in Gracixalus weii. Herpetozoa, 39, 7-15. https://doi.org/10.3897/herpetozoa.39.e175324

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.39.e175324

Keywords: Gracixalus weii, treefrog, advertisement calls, bioacoustics, animal behavior, field recording, Guizhou China, acoustic convergence, rhacophorid frogs, bird-like, vocalization, Anura