Corresponding authors: Shari Limbo Guerra (
Academic editor: Yasen Mutafchiev
The role of vocalisation for the Philippine hornbills' ecology and speciation and their implication in understanding speciation is not well understood. We described and compared recorded calls of seven hornbill taxa in captivity namely Mindanao Wrinkled hornbill (
Hornbills (
The resounding vocalisations of hornbills aids their communication interaction with conspecifics and sympatrics in dense forest habitats, defence, territory and threat (
Studies by
Observations took place during the day and the advertisement calls were recorded on an opportunistic basis with a Sony PBR-330 parabolic reflector, Uniso UC-0163 hands-free microphone and Sony IC recorder ICD-BX140. During the recording of the calls, the microphone was approximately 8 to 10 metres away from the hornbill species in captivity. The male hornbills, used in the study, were inside the cages with the other hornbills of the same species. The majority of the vocal sampling was derived from captive hornbills due to the limitations of recording vocalisations of Philippine hornbills in the wild. For comparison, analysis was supplemented by recordings available from online databases.
Adult male captive hornbills in Avilon Zoo, Rodriguez, Rizal were used in this study (Fig.
Each individual had six to ten replicates and the non-overlapping vocalisations with the lowest background noise were used for analysis. The editing and noise reduction tools were utilised in Audacity 2.1.3 to eliminate unnecessary noise. Recordings were digitised and analysed using waveforms and spectrograms generated by Raven Pro 1.2 software. The vocalisations were quantified following the criteria proposed by
For each individual in the sample, the individual average for each parameter was determined. Thereafter, the mean and standard deviation were used to calculate the effect size index (
Vocalisations of hornbills were found to reveal information on the individual (
For this study, there were six individuals for
The effect sizes for
On the other hand,
The magnitude of the strongest temporal and strongest spectral characters were 2 and 3, respectively. In total, a score of 5 was given to
Between
However,
Lastly,
There were five individuals for
Between
The species-pairs of
The species pair of
A small effect size was obtained for the minimum frequency between
In comparison with the
As seen in Table
Amongst the endemic Philippine Tarictic hornbills, small effect sizes for the minimum frequency were evident between
The above acoustic analyses of the trumpeting calls of Philippine Tarictic hornbills, belonging to the endemic genus
The large effect sizes in the acoustic data, observed amongst subspecies of
Male captive Philippine hornbill species.
Summary of Cohen’s
The summary of Cohen’s
The summary of Cohen’s
Waveform and spectrogram.
Waveform and spectrogram.
Waveform and spectrogram.
Summary of phenotypic scoring procedures (
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Morphology (biometrics) | Strongest increase and strongest decrease only | Effect size: 0.2-2 | Effect size: 2-5 | Effect size: 5-10 | Effect size: >10 |
Acoustics | Strongest temporal and spectral character only | Effect size: 0.2-2 | Effect size: 2-5 | Effect size: 5-10 | Effect size: >10 |
Plumage and bare parts | Three strongest characters | A slightly different wash or suffusion to all parts of any area | Distinctly different tone/shade to all or part of a significant area of feathering | Contrastingly different hue/colour to all or part of a significant part of a significant area of feathering | Radically different colouration or pattern to most of plumage (striking contrast in colour, shade, shape) |
Geographical relationship | n/a | Broad hybrid zone | Narrow hybrid zone | Parapatry | n/a |
Summary of mean, standard deviation, number of individuals, pooled variance, Cohen’s
Vocal Characters | Mean | SD | n | Mean | SD | n | Pooled variance | Cohen's d | Score | Total Score |
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Bandwidth | 4.6735 | 0.2377 | 6 | 5.5377 | 0.0907 | 4 | 0.1753 | 4.93 | 2 | 5 |
Duration | 0.1875 | 0.0148 | 6 | 0.1571 | 0.0091 | 4 | 0.01 | 2.63 | 2* | |
Minimum Frequency | 2.0346 | 0.2023 | 6 | 1.8686 | 0.071 | 4 | 0.1482 | 1.12 | 1 | |
Maximum Frequency | 6.7081 | 0.1495 | 6 | 7.4063 | 0.0841 | 4 | 0.1153 | 6.06 | 3** | |
Peak Frequency | 4.7272 | 0.1604 | 6 | 4.171 | 0.0811 | 4 | 0.1218 | 4.57 | 2 | |
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Bandwidth | 4.6735 | 0.2377 | 6 | 5.1882 | 0.1053 | 5 | 0.1724 | 2.99 | 2 | 6 |
Duration | 0.1875 | 0.0148 | 6 | 0.1244 | 0.0046 | 5 | 0.01 | 6.1 | 3* | |
Minimum Frequency | 2.0346 | 0.2023 | 6 | 1.3492 | 0.0995 | 5 | 0.149 | 4.6 | 2 | |
Maximum Frequency | 6.7081 | 0.1495 | 6 | 6.5374 | 0.15 | 5 | 0.1354 | 1.26 | 1 | |
Peak Frequency | 4.7272 | 0.1604 | 6 | 3.2542 | 0.1704 | 5 | 0.1492 | 9.88 | 3** | |
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Bandwidth | 4.6735 | 0.2377 | 6 | 4.1438 | 0.0929 | 4 | 0.1756 | 3.02 | 2 | 5 |
Duration | 0.1875 | 0.0148 | 6 | 0.2562 | 0.0345 | 4 | 0.02 | 3.18 | 2* | |
Minimum Frequency | 2.0346 | 0.2023 | 6 | 1.8855 | 0.0792 | 4 | 0.1495 | 1 | 1 | |
Maximum Frequency | 6.7081 | 0.1495 | 6 | 6.0293 | 0.0456 | 4 | 0.1086 | 6.25 | 3 | |
Peak Frequency | 4.7272 | 0.1604 | 6 | 3.8559 | 0.0806 | 4 | 0.1217 | 7.16 | 3** | |
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Bandwidth | 5.1882 | 0.1053 | 5 | 4.1438 | 0.0929 | 4 | 0.0884 | 11.82 | 4** | 7 |
Duration | 0.1244 | 0.0046 | 5 | 0.2562 | 0.0345 | 4 | 0.02 | 6.55 | 3* | |
Minimum Frequency | 1.3492 | 0.0995 | 5 | 1.8855 | 0.0792 | 4 | 0.0806 | 6.66 | 3 | |
Maximum Frequency | 6.5374 | 0.15 | 5 | 6.0293 | 0.0456 | 4 | 0.1034 | 4.91 | 2 | |
Peak Frequency | 3.2542 | 0.1704 | 5 | 3.8559 | 0.0806 | 4 | 0.1227 | 4.9 | 2 | |
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Bandwidth | 5.5377 | 0.0907 | 4 | 4.1438 | 0.0929 | 4 | 0.0795 | 17.53 | 4 | 6 |
Duration | 0.1571 | 0.0091 | 4 | 0.2562 | 0.0345 | 4 | 0.02 | 4.54 | 2* | |
Minimum Frequency | 1.8686 | 0.071 | 4 | 1.8855 | 0.0792 | 4 | 0.0651 | 0.26 | 1 | |
Maximum Frequency | 7.4063 | 0.0841 | 4 | 6.0293 | 0.0456 | 4 | 0.0586 | 23.51 | 4** | |
Peak Frequency | 4.171 | 0.0811 | 4 | 3.8559 | 0.0806 | 4 | 0.07 | 4.5 | 2 | |
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Bandwidth | 5.1882 | 0.1053 | 5 | 5.5377 | 0.0907 | 4 | 0.09 | 3.99 | 2 | 6 |
Duration | 0.1244 | 0.0046 | 5 | 0.1571 | 0.0091 | 4 | 0.01 | 5.39 | 3* | |
Minimum Frequency | 1.3492 | 0.0995 | 5 | 1.8686 | 0.071 | 4 | 0.08 | 6.66 | 3 | |
Maximum Frequency | 6.5374 | 0.15 | 5 | 7.4063 | 0.0841 | 4 | 0.11 | 7.82 | 3** | |
Peak Frequency | 3.2542 | 0.1704 | 5 | 4.171 | 0.0811 | 4 | 0.12 | 7.46 | 3 | |
*strongest temporal character | **strongest spectral character |
Summary of mean, standard deviation, number of individuals, pooled variance, Cohen’s
Vocal Characters | Mean | SD | n | Mean | SD | n | Pooled variance | Cohen's d | Score | Total Score |
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Bandwidth | 3.8984 | 0.0901 | 5 | 4.2894 | 0.1198 | 1 | 0.0736 | 5.31 | 3** | 6 |
Duration | 0.2878 | 0.0151 | 5 | 0.2 | 0.0145 | 1 | 0.01 | 7.14 | 3* | |
Minimum Frequency | 0.7293 | 0.041 | 5 | 0.6288 | 0.0189 | 1 | 0.0335 | 3 | 2 | |
Maximum Frequency | 4.6244 | 0.1046 | 5 | 4.9182 | 0.1284 | 1 | 0.0854 | 3.44 | 2 | |
Peak Frequency | 2.5908 | 0.1454 | 5 | 2.0413 | 0.364 | 1 | 0.1187 | 4.63 | 2 | |
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Bandwidth | 3.8984 | 0.0901 | 5 | 3.0039 | 0.1983 | 3 | 0.1179 | 7.59 | 4 | 7 |
Duration | 0.2878 | 0.0151 | 5 | 0.5875 | 0.0978 | 3 | 0.05 | 5.99 | 3* | |
Minimum Frequency | 0.7293 | 0.041 | 5 | 0.2261 | 0.0303 | 3 | 0.0327 | 15.38 | 4** | |
Maximum Frequency | 4.6244 | 0.1046 | 5 | 3.23 | 0.2017 | 3 | 0.1251 | 11.15 | 4 | |
Peak Frequency | 2.5908 | 0.1454 | 5 | 0.8506 | 0.1025 | 3 | 0.1149 | 15.15 | 4 | |
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Bandwidth | 4.2894 | 0.1198 | 1 | 3.0039 | 0.1983 | 3 | 0.1402 | 9.17 | 3 | 7 |
Duration | 0.2 | 0.0145 | 1 | 0.5875 | 0.0978 | 3 | 0.07 | 5.6 | 3* | |
Minimum Frequency | 0.6288 | 0.0189 | 1 | 0.2261 | 0.0303 | 3 | 0.0214 | 18.78 | 4** | |
Maximum Frequency | 4.9182 | 0.1284 | 1 | 3.23 | 0.2017 | 3 | 0.1426 | 11.84 | 4 | |
Peak Frequency | 2.0413 | 0.364 | 1 | 0.8506 | 0.1025 | 3 | 0.0725 | 16.43 | 4 | |
*strongest temporal character | **strongest spectral character |
Summary of mean, standard deviation, number of individuals, pooled variance, Cohen’s
Vocal Characters | Mean | SD | n | Mean | SD | n | Pooled variance | Cohen's d | Score | Total Score |
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Bandwidth | 2.1809 | 0.0945 | 3 | 2.493 | 0.0624 | 7 | 0.0642 | 4.86 | 2 | 3 |
Duration | 0.292 | 0.0226 | 3 | 0.2713 | 0.0038 | 7 | 0.01 | 1.97 | 1* | |
Minimum Frequency | 0.5065 | 0.0159 | 3 | 0.5035 | 0.0093 | 7 | 0.0101 | 0.29 | 1 | |
Maximum Frequency | 2.6873 | 0.0894 | 3 | 2.9965 | 0.0621 | 7 | 0.0626 | 4.94 | 2 | |
Peak Frequency | 0.8234 | 0.0123 | 3 | 0.9223 | 0.0248 | 7 | 0.02 | 4.95 | 2** | |
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Bandwidth | 2.1809 | 0.0945 | 3 | 4.6767 | 0.022 | 2 | 0.06 | 4.21 | 2 | 8 |
Duration | 0.292 | 0.0226 | 3 | 0.563 | 0.0434 | 2 | 0.02 | 11.23 | 4* | |
Minimum Frequency | 0.5065 | 0.0159 | 3 | 0.7911 | 0.023 | 2 | 0.01 | 13.02 | 4 | |
Maximum Frequency | 2.6873 | 0.0894 | 3 | 5.4678 | 0.0197 | 2 | 0.06 | 8.58 | 3 | |
Peak Frequency | 0.8234 | 0.0123 | 3 | 3.1199 | 0.3915 | 2 | 0.18 | 13.1 | 4** | |
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Bandwidth | 2.1809 | 0.0945 | 3 | 2.493 | 0.0624 | 7 | 0.0642 | 4.86 | 2 | 3 |
Duration | 0.292 | 0.0226 | 3 | 0.2713 | 0.0038 | 7 | 0.01 | 1.97 | 1* | |
Minimum Frequency | 0.5065 | 0.0159 | 3 | 0.5035 | 0.0093 | 7 | 0.0101 | 0.29 | 1 | |
Maximum Frequency | 2.6873 | 0.0894 | 3 | 2.9965 | 0.0621 | 7 | 0.0626 | 4.94 | 2 | |
Peak Frequency | 0.8234 | 0.0123 | 3 | 0.9223 | 0.0248 | 7 | 0.02 | 4.95 | 2** | |
*strongest temporal character | **strongest spectral character |
Phenotypic scores and molecular divergence (
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2 | 6 | 6 | 0 | 14 | 3.52 |
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3 | 6 | 6 | 0 | 15 | 4.53 |
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3 | 7 | 5 | 0 | 15 | 3.4 |
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2 | 5 | 5 | 0 | 12 | 2.06 |
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2 | 7 | 3 | 0 | 12 | 8.85 |
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2 | 7 | 8 | 0 | 17 | 11.56 |
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2 | 2 | 8 | 0 | 12 | 8.22 |
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3 | 6 | 6 | 0 | 15 | 5.36 |
Recording sources for the Philippine hornbill vocalisations.
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Frank Lambert | Zamboanga, Pasonaca Watershed Reserve, Cabonegro |
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Frank Lambert | Mt. Kitanglad, Mindanao |
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Paul Noakes | PICOP, Bislig, Mindanao |
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George Wagner | Baluno Station, Zamboanga Watershed, Mindanao |
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David Edwards | PICOP, Bislig, Mindanao |
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Shari Guerra | Avilon Zoo, Rodriguez, Rizal |
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David Edwards | Hamut, baliuag, Sierra Madre Mountains, Luzon |
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Shari Guerra | Avilon Zoo, Rodriguez, Rizal |
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Frank Lambert | Bacolod, Negros Occidental |
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Bram Demeulemeester | Rajah Sikatuna National Park, Bohol |
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Ross Gallardy | Rajah Sikatuna National Park, Bohol |
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Shari Guerra | Avilon Zoo, Rodriguez, Rizal |
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Shari Guerra | Avilon Zoo, Rodriguez, Rizal |
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Shari Guerra | Avilon Zoo, Rodriguez, Rizal |
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Shari Guerra | Avilon Zoo, Rodriguez, Rizal |
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Desmond Allen | Sitio Siete, South Cotabato Province, Mindanao |
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Ross Gallardy | PICOP, Bislig, Mindanao |
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Shari Guerra | Avilon Zoo, Rodriguez, Rizal |
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Frank Lambert | Chupukama Ridge, Guadalcanal |
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Patrick Abueg | Lolobata National Park, Halmahera, Indonesia |
Raw Data of Vocalization
Measurements of the vocal characters
File: oo_319775.docx
Spectrogram
Images of spectrogram
File: oo_319782.pdf