Nesting habitats of free-ranging Indian peafowl, Pavo cristatus, revealed by sniffer dogs in Okinawa, Japan

The Indian peafowl, Pavo cristatus, is the largest of the pheasants and ground-nesting bird. Because this species was introduced in Okinawa, Japan about 40 years ago and is now increasingly recognized as a pest in the Yaeyama region, and the extermination of this species has been promoted for ecosystem conservation. It was thought that there is need to develop a method to reduce the peafowl population and dogs were trained to detect them. We faced two difficulties in developing sniffer dogs to detect peafowl nests as below; (i) it is difficult to obtain a sufficient number of eggs to train the detection dogs, (ii) another difficulty is that the nesting period of peahens and the preferred vegetation used for nesting in Okinawa have not been reported. At first, we screened and trained two dogs of Welsh Corgi Pembroke and one dog of Brittany Spaniel for peafowl nest detection dogs with peahen feathers instead of peahen eggs. These dogs demonstrated a 100% sensitivity rate and there were no false-positives of their precision test. In second step, display survey of peacock to predict the nesting period of peahen was conducted in Kohama (KHM) and Kuroshima (KRS) islands, and the earliest dates of trail displays were observed in late February between 2014 and 2019 in both Islands. We predicted that the eggs would begin hatching in early April. We surveyed peahen nests for a total of 837 h and 1153 km on 962 transects with sniffer dogs and detected 423 peahen's nests in KHM and KRS islands between 2014 and 2019. Peahens made her nests mainly in Poaceae or Asteraceae plants in research areas. The peak hatching was between mid-April and early May. In this study, we were able to detect peahen nests in the field by dogs trained with peahen feather, and we also identified the exact nesting season and preferred vegetation in Okinawa to control of Indian peafowl as an invasive species.