Canine detection of free-ranging brown treesnakes on Guam

Abstract

HLQYHVWLJDWHGFDQLQHWHDPV��GRJVDQGWKHLUKDQGOHUV��RQ�*XDPDVDSRWHQWLDOWRROIRU�oQGLQJ� invasive brown treesnakes (Boiga irregularis) in the wild. Canine teams searched a 40 × 40 m forested area for a snake that had consumed a dead mouse containing a radio-transmitter. To avoid tainting the target or target area with human scent, no snake was handled or closely approached prior to searches. Trials were conducted during the morning when these nocturnal snakes were usually hidden in refugia. A radiotracker knew the snake's location, but dog handlers and search navigators did not. Of 85 trials conducted over four months, the WZRFDQLQHWHDPVKDGDQDYHUDJHVXFFHVVUDWHRI�����RIFRUUHFWO\�GHoQLQJDQDUHD�i���O���PWKDW� FRQWDLQHG� the transmittered snake; the team with more experience prior to the trials had a success rate of 44% compared with 26% for the less experienced team. Canine teams also found 11 shed skins from wild snakes. Although dogs alerted outside the vicinity of transmittered snakes, only one wild, non-transmittered snake was found GXULQJWKHWULDOV��SRVVLEO\�UH?HFWLQJWKHGLIoFXOW\�KXPDQVKDYHLQORFDWLQJQRQWUDQVPLWWHUHGEURZQWUHHVQDNHV� LQUHIXJLD���:HHYDOXDWHGVXFFHVVDW�oQGLQJVQDNHVDVDIXQFWLRQRIFDQLQHWHDP��QXPEHURISULRUWULDOV��LH�� H(SHULHQFHJDLQHGGXULQJWKHWULDOV���UHFHQWFDQLQHVXFFHVVDW�oQGLQJDWDUJHWVQDNH��YDULRXVHQYLURQPHQWDO� conditions, snake perch height, and snake characteristics (snout-vent length and sex). Success rate increased over the course of the trials. Canine team success also increased with increasing average humidity and decreased with increasing average wind speed. Our results suggest dogs could be useful at detecting brown treesnakes in refugia, particularly when compared to daytime visual searches by humans, but techniques are needed to help KXPDQV�oQGDQGH(WUDFWVQDNHVRQFHDGRJKDVDOHUWHG�