Volodina E., Volodin I.,. Klenova A., Khudjakova T., Matrosova V., Filatova O., 2004, Bioacoustical sexing and individual identification provide alternatives to capture both in zoos and in the wild // Advances in Ethology. Contributions to the 5-th International Symposium on Physiology, Behaviour and Conservation of Wildlife. Berlin. V. 38, p. 90.
In the last decade bioacoustical methods proved their great value both in captive and wildlife management. Alongside with other applications, acoustic-based identification of sex and individuality may be recognized as one of the most important for many bird and mammal species.
The task of distant sexing is actual for many bird taxa with lack of sexual dimorphism, such as geese, cranes, rallies, raptors, owls, parrots, auks, etc. Methods that are already in use (DNA-analysis, laparoscopy, cloak inspection) all demands capture, taking blood or feather samples or other stressing manipulations and are very limited in their application in free-living populations. However, the vocal-based sexing may by very reliable. Our researches showed, that in the white-faced whistling duck, Dendrocygna viduata, male loud whistles significantly lower in frequency, than the female ones. These differences provide 100% reliability of sexing by a single call. Also, preliminary data showed, that loud whistle patterns of three other Dendrocygna species (D. bicolor, D. autumnalis and D. arborea) demonstrate high intersexual differences. For cranes, bioacoustical sexing is actual in relation with programs of captive breeding and reintroduction into nature. Current practice of chick sexing is based on gene analysis, not earlier 3-month age. Accordingly to our data, tonal calls of the Red-crowned crane (Grus japonensis) chicks provide up to 90% reliability of sexing as early as in first two weeks of their life. Also, the Siberian crane (G. leucogeranus) calls emitted in response to handling provide reliable sexing (over 97% of correct assignment to sex) in chicks during first two months of life.
Development of individual identification by voices for monitoring of free-living populations and reintroduced animals has two stages. First one is search of individual differences in calls, second one is estimation of their stability over years. We received data on individual differences for captive white-faced whistling ducks (94% correctly assigned calls for 14 birds); for captive red-breasted geese Branta ruficollis (85,6% correctly assigned calls for 22 birds), for free-living spotted ground squirrels Spermophillus suslicus (96% correctly assigned calls for 13 animals) and for captive dholes Cuon alpinus (96% correctly assigned calls for 6 animals). However, preliminary cross-validation data, received for the red-breasted goose and for spotted ground squirrel suggest substantial decrease of individual discrimination from year to year. Now we continue to gather and to analyse representative material concerning sustainability of individual and sexual differences over years.