Sexually differentiated effects of radio transmitters on predation risk and behaviour in kangaroo rats Dipodomys merriami

In a 12-year study involving 191 radio-tracked Merriam's kangaroo rats and 337 subcutaneous radio implantations, females were killed by predators at a rate of 0.0054 per radio-bearing night and males at a rate of 0.0116. Both the mortality rate and the sex difference therein declined over the course of several nights after radio implantation. Females reduced their excursions from the day burrow for the first few nights after radio implantation, whereas males exhibited little if any such inhibition of movement. This sexually differentiated behavioural response to the transmitters is a likely source of the sexually differentiated mortality patterns.