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Nocturnal animals like raccoons are active at night. Diurnal creatures, like humans, are up and about during the day. But what about cathemeral animals? I'm Jim Metzner, and this is the Pulse of the Planet. Luke Dollar is a Doctoral Fellow in ecology at Duke University's Nicholas School of the Environment.

"There are a number of primates on Madagascar, and other animals as well, that are active on about a three hour on, four hour off schedule -- it’s called cathemerality. It’s active both day and night. An animal that's cathemeral is active almost all the time, except during the extremes of temperature or the dead of night. Coldest time of night, it’s not moving. The hottest time of the day, it’s not moving. I’ve been tracking it in those times. I don’t want to move either, so it makes perfect sense."

The Fossa, one of Madagascar's most elusive animals operates on such a schedule. And its status as a ruthless predator fits with the cathemeral profile.

"Fossa have about two periods of activity per day. They’ll get up before dawn and they will start traveling. They'll find a hunting ground, and as animals are either going back to the nest or waking up, they’re gonna start hunting. Once a fossa finds a prey item, could be a lemur, could be a lizard, could be both, the fossa’s going to be locally active for a while. It’s going to eat that meal. And then it’s going to bed down, as the heat of the day comes along. When things start to get a little bit cooler, up it goes. It’ll hunt maybe a little bit locally, and then it’ll start traveling again. Find another hunting ground as the things that are nocturnal are just waking up. The things that are diurnal are going to sleep. And do it all over. And it does that every day. Over and over and over and over."

Our thanks to Earthwatch. Pulse of the Planet is presented with support provided by the National Science Foundation. I'm Jim Metzner.

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