Out of 39 currently known southern ground hornbill nests in the Kruger National Park (KNP), only seven live chicks were found when the nests were checked in mid-February. The ground hornbill breeding season usually coincides with the rainy season, and a survey of the nests last November found only one chick and 15 nests showing potential breeding activity, with green leaves in the nest and adult ground hornbills nearby.
Peter Shepherd, field researcher with the Percy Fitzpatrick Institute at the University of Cape Town, comments, "Compared to our knowledge of ground hornbill breeding, this represented either a poor breeding season, or an exceptionally late start to the season." According to LD van Essen, Ground Hornbill Working Group (GHWG) manager for the Endangered Wildlife Trust (EWT), ground hornbills suffer the highest mortality in their first year of life.
A third survey is proposed for later this year, and the Percy Fitzpatrick Institute will be submitting a proposal to do further research in Kruger to find out more about the conservation requirements of the ground hornbill. The known nests in the park were discovered by Dr Alan Kemp during a research project many years ago, as well as from more recent information gathered by Kruger's field rangers using the Cybertracker system.
The number of known nests has dropped from around 50 to the current 39, and the field study showed that several of the nests have become non-viable recently, with nest bottoms falling out, trees falling over or branches breaking off. Van Essen believes that there could be many more undiscovered nests, as the birds are very secretive in their nesting behaviour.
At a Population Habitat Viability Assessment carried out for southern ground hornbills in February 2005, it was estimated that there are between 620 and 720 birds in the park, which could translate into about 200 nests, especially as the birds often have more than one nesting site in their territory.
Van Essen says that preliminary data shows that Cybertracker information on ground hornbill sightings could help lead researchers to new nest sites. He is hoping to make adaptations to the recording system on the hand-held computers that will allow field rangers to input when they see birds with nesting material or with food offerings for nesting birds and chicks.
He adds that the public can also help the researchers by regularly reporting sightings of this distinctive bird in the sightings books in the various camps. Researchers can then go through the books to find out where the hornbills are most frequently seen.
He asks that members of the public spotting the birds record exactly where they saw the birds (GPS readings if possible), how many birds were seen, whether juvenile or adult and if they appeared to be carrying nesting material. For more information, or to report a sighting directly to L.D. van Essen via SMS, call 082 320 6620.
By Melissa Wray
Learn more about Kruger Park birdlife