Gender identification using acoustic analysis in birds without external sexual dimorphism

Zoo and wildlife management faces a problem with bird sexing,as many bird taxa have indiscernible gender differences in size and coloration.Problematic groups are geese,cranes,rails,raptors,owls,parrots,doves,auks,shearwaters and some passerines.Commonly accepted invasive sexing techniques based on genetics,laparoscopy,morphometric and on cloacal inspection,are all needed in bird capturing and handling.Capturing and subsequent manipulations may be inapplicable for free-ranging birds,whereas distant voice-based sexing is relevant for many species.This review evaluates the potential for noninvasive sexing by separate calls or duet calls,for adult birds of 69 species from 16 orders and for chicks of 11 species from 7 orders.For adult birds of 25 species,a single call per individual was sufficient for 100 % reliable sexing by ear or using spectrographic analysis.For chicks,the potential for voice-based sexing seems to be very limited.For birds calling rarely or unpredictably,we propose a simple way of provoking vocalization using playbacks of species-specific calls that are available from sound libraries.We conclude that sexing by voice may represent a feasible alternative to the classical sexing techniques,both in the wild and in captivity.

Phylogenetic relationship and variation of alarm call traits of populations of red-cheeked ground squirrels(Spermophilus erythrogenys sensu lato)suggest taxonomic delineation

Distribution area and taxonomic borders within the species complex Spermophilus erythrogenys sensu lato re­main questionable.Early evidence suggests that red-cheeked ground squirrels of Southeast Kazakhstan are re­markably different in terms of the acoustic structure of their alarm calls from the red-cheeked ground squirrels of the Kurgan region in Russia.In this study,we analyzed the differences in the acoustic structure of the alarm call and mitochondrial DNA(complete control region,1005-1006 bp and complete cytochrome b gene,1140 bp)in 3 populations of red-cheeked ground squirrels(Tara,Altyn-Emel and Balkhash),all located within ar­eas isolated by geographical barriers in Southeast Kazakhstan.We found that the alarm call variables were sim­ilar between the 3 study populations and differed by the maximum fundamental frequency(8.46±0.75 kHz)from the values(5.62±0.06 kHz)reported for the red-cheeked ground squirrels from the Kurgan region of Rus­sia.Variation in mtDNA control region was only 3%and variation in cytochrome b gene was only 2.5%.Phylo­genetic trees based on cytochrome b gene polymorphism of 44 individuals from the study area and adjacent ter­ritories indicated 3 clades with high(98-100%)bootstrap support:“intermedius,”“brevicauda”and“iliensis”).We conclude that the 3 study populations in Southeast Kazakhstan belong to the clade intermedius and suggest a taxonomical revision of the species complex Spermophilus erythrogenys sensu lato,including analyses of nu­clear DNA and alarm calls for populations of the brevicauda and iliensis clades.