Anthony Di Fiore, a primate biologist at New York University, writes from Ecuador, where he is using GPS technology and camera traps to study the behavior of male spider monkeys.
Wednesday, Jan. 12
Success! After three days of following the spider monkeys waiting for a perfect opportunity to capture a male, we finally got our first chance. Now Poto, one of the oldest males in our main study group, is outfitted with a new high-tech collar that combines a traditional radio transmitter (which will help us find and follow him more regularly when we have a telemetry receiver with us in the forest) and a data-logging GPS unit (which uses satellites to pinpoint and record its location and will let us collect data on Poto’s ranging patterns, even when we are focusing on other individuals). These collars are one of the new tools we’re using to study male cooperation and competition among spider monkeys.
In most places where they have been studied, male spider monkeys move farther and faster each day than females do, and they typically use more of the group’s entire home range. By contrast, females spend most of their time in their own smaller “core” areas, which may overlap with those of other females.
Spider monkey biologists think there are several key reasons for males’ peripatetic habits. First, males wander over their own group’s range to regularly visit females and check out their reproductive status. (Are those females pregnant? Do they still have a dependent offspring? Or are they sexually receptive and maybe looking to mate?) Second, males cooperatively engage in defense of the group’s range (and the set of females that use it) by traveling together on long patrols of their territory boundaries. They also sometimes raid the territories of adjacent groups. During patrols and raids, when males from another group are encountered, a raucous and sometimes violent showdown usually occurs...