Determination of sex and species in red and fallow deer by near infrared reflectance spectroscopy of the faeces

Near infrared reflectance spectroscopy (NIRS) of faeces is a non-invasive analytical technique that has been used to determine physiological status of free-ranging herbivores. Sixty-eight faecal samples collected in April of 2000 and 2002 from adult animals maintained on ryegrass (Lolium perenne L.) were used to determine the ability of NIRS to distinguish faeces by sex and/or species in red (Cervus elaphus) versus fallow (Dama dama) deer. Two-block partial least squares procedures indicate a high degree of discrimination (R² > 0.90) between groups within year. Discriminant equations developed from samples within either year were ineffective in identifying sex or species in the other year's samples (<60% correct). Dissimilar forage conditions (i.e. diet quality) between the 2 years probably contributed the greatest amount of variation in faecal spectra, thus diminishing any possible animal related effects. Combining both years samples yielded a high degree of discrimination (R² > 0.87) and, when the resultant discriminant equations were applied to validation samples withheld from calibration, correctly identified 80-100% of faecal samples grouped by sex, species, sex within species, and species within sex. Fecal NIRS successfully discriminated sex and species in red and fallow deer maintained in unisex groups on a monoculture pasture. The use of faecal NIRS to characterize wildlife population demographics and non-invasively monitor individual animal physiology should now be explored in free-ranging animals.