One of the ways of determining population density of some species of carnivore is to take advantage of their opportunistic nature and play calls of a distressed prey animal over loud speakers to attract them to the area. By working out how far the call can be heard, we can work out the area that is covered by the call, and so calculate the density of animals in the area. This must, of course, take into account that not all target animals will respond. Due to the differences in vegetation and topography, calibration onsite is essential, as the response distance here on Venetia may be quite different from in other places where the work has been carried out. Earlier this week, we tested this by sitting one vehicle with Tsotsi and Tsala, two lionesses at Venetia, and their cubs and another vehicle taking the call-up equipment (a public address system with loud speakers) to 5km away. In radio contact with the team sitting with the lions, Wendy and Azwafarwi moved closer until the lions pricked their ears up in the direction of the call. They responded at 3.5kms, and so this is the distance we use as the radius for locating our call-ups stations to ensure there is no overlap. To minimise the chance of counting the same animal twice, all the call-ups will be done as close together as possible. Watch this space to see what comes to the calls!

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