African Wildlife & Environment Issue 82

FAUNA, FLORA & WILDLIFE

An Update on the BAT HAWK CAM PROJECT IN MPUMALANGA

Bat Hawks are small compact raptors, usually seen from a far distance just by their silhouette, foraging in riparian habitat like an F-16 Falcon, dominating the sky. Up close they reveal their short crest, mottled brown plumage, black streak down their brown and white throat, bluish feet and their bright yellow eyes with a white streak above and below the eye. They have exceptionally good eye-sight due to their tubular eyes and binocular vision and especially their Tapetum lucidum , a reflective layer at the back of their retina. They also have five times more light-sensitive rod cells in their retina compared to us helping them to see their bat prey in poor light conditions. Bat Hawks have an elongated middle toe, a special adaptation to hook the bats that they feed on. Prey is caught in the feet, transferred to the bill and swallowed whole in flight. They feed on 5-6 bats in 20-minute binges, at dawn and dusk. The male bird also brings bat food parcels to its mate as a nuptial gift (a trait normally associated more with kingfishers, bee-eaters and larks). Other adaptations for making them agile, super-efficient bat hunters are their light mass ( they weigh only 600-650 grams), straight pointed

wings (their ulna being considerably longer than even a lanner and peregrine falcon!), stiff unslotted feathers, strong pectoral muscles, a manoeuvrable tail. The bats themselves are often too pre occupied in honing their echolocation skills while foraging for katydids and other insects than to worry too much about the Bat Hawks. There are numerous species of these insect-eating bats (Microchiroptera) which differ from each other, mainly based on their wing morphology and echolocation strategy, different species emitting their own signature frequencies (many of which are beyond our hearing). It is thought that the Bat Hawks prey mainly on the free-tailed bats (Mollosidae) which have a similar wing shape to the hawks, and which also forage in the open. These bats have a lower frequency echolocation compared to some of the other bat families, which forage closer to the leaves using a higher frequency. However, any unsuspecting bat would be on the hawks’ menu. Some of the katydids the bats prey on emit an ultrasonic pulse to ‘jam’ the frequency of the bats, allowing them a split-second chance to escape!

26 | African Wildlife & Environment | Issue 82 (2022)