Evidence for acoustic niche partitioning depends on the temporal scale in two sympatric Bornean hornbill species

• Published in: Biotropica 2023-03, Vol.55 (2), p.517-528
• Main Authors: Kennedy, Amy G., Ahmad, Abdul Hamid, Klinck, Holger, Johnson, Lynn M., Clink, Dena J.
• Format: Article
• Language: English
• Subjects: Acoustic data; Acoustic measurement; Acoustics; Avoidance; bioacoustics; Buceros rhinoceros; Calling behavior; Communication; Competition; Conservation areas; Diurnal; Ecological distribution; ecology; Habitat preferences; Habitat selection; Habitats; helmeted hornbill; Malaysia; Niche overlap; Niches; Partitioning; rhinoceros hornbill; Rhinoplax vigil; Species; Sympatric populations; Sympatry; Time; vocal communication
• ISSN: 0006-3606; 1744-7429
• DOI: 10.1111/btp.13205

Understanding niche partitioning of closely related sympatric species is a fundamental goal in ecology. Acoustic communication space can be considered a resource, and the acoustic niche hypothesis posits that competition between species may lead to partitioning of communication space. Here, we compare the calling behavior of two sympatric Bornean hornbill species—the rhinoceros hornbill (Buceros rhinoceros) and the helmeted hornbill (Rhinoplax vigil)—to test for evidence of acoustic niche partitioning. Both hornbill species emit calls heard over many kilometers and have similar habitat preferences which is predicted to result in interspecific competition. We collected acoustic data on sympatric populations of both hornbill species using 10 autonomous recording units in Danum Valley Conservation Area, Sabah, Malaysia. We found that there was substantial spectral overlap between the calls of the two species, indicating the potential for competition for acoustic space. To test for evidence of acoustic niche partitioning, we investigated spatial and temporal patterns of calling in each species. Both hornbills were strictly diurnal and called throughout the day, and we were equally likely to detect both species at each of our recorders. We did not find evidence of temporal acoustic avoidance at a relatively coarse timescale when we divided our dataset into 1 h bins, but we did find evidence of temporal acoustic avoidance at a finer timescale when we used null models to compare the observed duration of overlapping calls to the expected amount of overlap due to chance. in Malay is available with online material. Memahami pembahagian nic dalam kalangan spesies simpatrik yang berkait rapat adalah hal yang fundamental dalam bidang ekologi. Ruang komunikasi akustik boleh dianggap sebagai sejenis sumber, justeru hipotesis nic akustik menegaskan bahawa persaingan di antara spesies boleh membawa kepada pembahagian ruang komunikasi. Di sini, kami membandingkan tingkah laku memanggil di antara dua spesies burung enggang Borneo yang simpatrik – enggang badak (Buceros rhinoceros) dan enggang tebang mentua (Rhinoplax vigil) – untuk diuji bagi menentukan bukti kewujudan pembahagian nic akustik. Bunyi panggilan kedua‐dua spesies enggang ini boleh kedengaran sejauh beberapa kilometer dan kedua‐duanya memilih habitat yang sama. Maka dijangkakan kedua‐dua hal ini boleh mengakibatkan persaingan antara spesies. Kami mengumpulkan data akustik daripada populasi dua spesies enggang si