Date of this Version
Carlson, Glenn. "Individual Identification and Sex Determination of Whooping Cranes by Analysis of Vocalizations.", In: Stahlecker D. W., ed. 1992. Proceedings of the Sixth North American Crane Workshop, Oct. 3-5, 1991, Regina, Sask. (Grand Island, NE.: North American Crane Working Group, 1992), 176.
I analyzed 3 temporal and 2 frequency features of whooping crane (Grus americana) guard calls from 4 locations to determine if vocalizations could be used as a means of sex determination and individual identification in this species. Wild birds were recorded at Grays Lake, Idaho, and Aransas National Wildlife Refuge, Texas, and captive birds were recorded at Patuxent Wildlife Research Center, Maryland, and the International Crane Foundation, Wisconsin. Discriminant analysis provided an overall success rate of 98.8% in classifying individual calls to the appropriate sex of Whooping crane. This success rate is comparable to that of the current method, karyotyping, but sexing by vocal analysis is preferable because it is non-intrusive and much less expensive. In addition, an audible difference exists in the perceived pitches of male and female Whooping cranes and may provide a means of sex determination in field situations when the calls cannot be recorded for analysis. Discriminant analysis for individual identification produced a successful classification rate of only 64.4%, making individual identification by vocal analysis inappropriate for whooping cranes at this time. Significant differences existed in whooping crane guard call features between locations and may have developed in as little as 2 years. These differences are most likely a result, either directly or indirectly, of varying conditions under which the cranes live. This could pose problems to reintroduction efforts if guard call features convey important information among whooping cranes concerning the calling stimulus, be it another whooping crane or a potential threat. Evidence from Grays Lake and elsewhere suggests that Whooping crane guard calling contains a learned component. At the very least, the acoustic environment at captive facilities and the calls which birds are exposed to at these facilities need to be taken into consideration for whooping cranes and other cranes that are being bred for release.