- Title
- The acoustic niche and conservation status of the recently described Hogsback caco, Cacosternum thorini (Amphibia: Pyxicephalidae), Hogsback, Eastern Cape, South Africa
- Creator
- Kom, Nokuthula
- Subject
- Amphibians
- Date
- 2021-02
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10353/20429
- Identifier
- vital:45665
- Description
- Animals may compete for acoustic space (acoustic niche) in the same way they do for habitat space. The most intense competition involves individuals with the most similar resource requirements (i.e. conspecifics), but if competition is interspecific, then mate recognition must occur both within and between species. The coexistence of the bronze caco (Cacosternum nanum) and the Hogsback caco (C. thorini) in the Tor Doone area of Hogsback could be interpreted as a result of past competition, which drove acoustic partitioning by means of the evolution of specific calls that do not overlap in frequency. Frogs are known to coexist well with other frog species because of their highly specific advertisement calls, which differ even between closely related species. One of the main aims of the project was to record and provide a description of the call of the recently described Hogsback caco, C. thorini. I identified 30 calling males and recorded each for 10 min in February 2016, yielding a total of 235 calls. Summary values for the calls include duration of 40 ± 14 ms, with 16 ± 5 pulses produced at a pulse-rate of 46 ± 21 s-1 and a mean dominant frequency of 4.19 ± 0.58 kHz. The call of C. thorini differs from those of all other cacos, by its incremental structure (increased number of pulses within consecutive units). My second goal was to use playbacks to investigate the preferred habitat of C. thorini and to compare it with that of C. nanum. I conducted experiments to measure the propagation of C. thorini and C. nanum calls in three different habitats (C. thorini habitat, C. nanum habitat, and grassland with no water bodies). Finally, I investigated the effect of drought and flood on the pools used by males as calling sites, using a buried basin to which I added water in 10 litre aliquots. The optimal water level for call propagation in the artificial pools was half-full. Using playbacks, I tested whether the two species responded to each other’s calls. I found that, although the two species call at the same time and each call in response to the other’s calls, they do not recognise heterospecific calls; they simply respond to noise. I found no evidence of acoustic competition between the two species, and in fact, the abundant, dominant species, C. nanum, was rare in the C. thorini preferred habitat. The results of this study may assist efforts to conserve endemic amphibians in the Amatola Mountains.
- Description
- Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (61 pages)
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
- Rights
- All Rights Reserved
- Rights
- Open Access
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UFH Department of Zoology & Entomology
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Kom_Corrected thesis_Signed.pdf | 2 MB | Adobe Acrobat PDF | View Details Download |