May-Collado Laura J, Wartzok Douglas
Department of Environmental Science and Policy, George Mason University, MSN 5F2, Fairfax, Virginia 22030, USA.
J Acoust Soc Am. 2009 Feb;125(2):1202-13. doi: 10.1121/1.3058631.
Knowledge of the whistle structure in Guyana dolphins comes mostly from Brazilian populations where recordings have been made using limited bandwidth systems (18 and 24 kHz). In Brazil, Guyana dolphin whistle frequency span is 1.34-23.89 kHz, but authors have suggested that limits of their recording system may underestimate frequency span. Whistles of Guyana dolphins from Costa Rica were studied using a broadband recording system. How bandwidth limitations affect the understanding of whistle structure and species classification between sympatric dolphin species was evaluated. In addition, whistles were compared to Brazilian populations. Guyana dolphin whistle frequency span was 1.38 up to 48.40 kHz, greater than previously reported. Bandwidth limitations explained 89% of the whistle variation between studies, and increase in bandwidth improved the whistle classification of Guyana dolphins. Whistle duration and minimum frequency were the most important variables in dolphin species classification. Finally, after accounting for differences in recording systems, Costa Rican Guyana dolphins whistled with significantly higher frequency than Brazilian populations, providing evidence for a postulated increase in frequency from south to north. The study concludes that equipment with an upper frequency limit of at least 50 kHz (150 kHz for harmonics) is required to capture the entire whistle repertoire of the Guyana dolphin.
对圭亚那海豚哨声结构的了解大多来自巴西种群，在那里使用有限带宽系统（18千赫和24千赫）进行了录音。在巴西，圭亚那海豚哨声频率范围为1.34 - 23.89千赫，但作者认为他们录音系统的局限性可能低估了频率范围。使用宽带录音系统对来自哥斯达黎加的圭亚那海豚的哨声进行了研究。评估了带宽限制如何影响对同域海豚物种间哨声结构和物种分类的理解。此外，还将哨声与巴西种群的进行了比较。圭亚那海豚哨声频率范围为1.38至48.40千赫，比之前报道的要大。带宽限制解释了不同研究之间89%的哨声差异，带宽增加改善了圭亚那海豚哨声的分类。哨声持续时间和最低频率是海豚物种分类中最重要的变量。最后，在考虑了录音系统的差异后，哥斯达黎加的圭亚那海豚哨声频率明显高于巴西种群，为推测的从南到北频率增加提供了证据。该研究得出结论，需要上限频率至少为50千赫（谐波为150千赫）的设备来捕捉圭亚那海豚的整个哨声曲目。
