Diversity and population densities of coraciiform birds in Zambezi riparian forest

Study Extent

The study area was located in the Zambezi Valley near Katima Mulilo in the Zambezi Region, NE Namibia. The study area comprised a forest stretching between the river and the international road from Zambia through Katima Mulilo to Botswana, lying on the left bank between the Wenela Bridge (border pass) and the Zambezi River lodge. This forest area is 7 km long and 200-700 m wide (mean = c. 400 m). The approximate surface area is therefore c. 280 ha. The natural vegetation is classified as Riparian Zambezi Forest (Mendelsohn et al., 2009). It is composed of large trees such as African teak Pterocarpus angolensis, albizias Albizia spp., apple leaf Lonchocarpus nelsii, baobab Adansonia digitata, Burkea Burkea africana, combretum Combretum spp., camel-thorn Acacia erioloba, corkwoods Commiphora spp., false mopane Guibourtia coleospermum, jackal berry Diospyros mespiliformis, knob-thorn Accacia nigrescens, makalani palm Hyphaene petersiana, manketti Schinziophyton rautanenii, marula Sclerocarya birrea, mopane Colophospermum mopane, pod mahogany Afzelia quanzensis, silver cluster-leaf Terminalia sericea, sausage tree Kigelia africana, sycomore fig Ficus sycomorus, white Bauhinia Bauhinia petersiana, Zambezi teak Baikiaea plurijuga. The forest is interlaced with pans covered with grass and sedges flooded almost on a yearly basis. About one quarter of the land has been converted into arable grounds and built-up areas, but large trees usually remain even in these converted areas.
The annual temperature for Katima Mulilo is 21˚C. The average maximum temperature during the hottest month (September) is 3 5˚C; the average minimum temperature during the coldest month (July) is 3 °C. Humidity is 80-90 % in the most humid month (February) and only 10-20 % in the least humid month (September). The average annual rainfall is c. 700 mm, the highest in Namibia. Median annual rainfall is 550-600 mm. Most rains fall between November and March. The rainfall was below the long-term average in 2014 and in 2015.

Sampling

A territory mapping method (Bibby et al., 2002) was used to assess the population densities of all coraciiform species nesting in the forest.

Quality Control

Special attention was paid to birds showing territorial behavior or breeding display. Recordings of two or three simultaneously calling males were important in interpreting the results. A bird or pair of the same species recorded at the same site in at least two out of the four months was interpreted as residential/breeding/territorial (following Bibby et al., 2002).

Method steps

1. The study area was divided into six sections. Birds were counted in each of the sections in one morning.Therefore, the whole study area was covered in six mornings. Such complete coverage was achieved four times in 2015, in August, September, October and November. During each count, all coraciiform birds seen or heard were plotted on the map 1: 500.

Diversity and population densities of coraciiform birds in Zambezi riparian forest

1. Coraciformes
   rank: order
2. Alcididae
   rank: family
3. Meropidae
   rank: family
4. Coraciidae
   rank: family
5. Upupidae
   rank: family
6. Phoeniculidae
   rank: family

The study area was located in the Zambezi Valley near Katima Mulilo in the Zambezi Region, NE Namibia. The study area comprised a forest stretching between the river and the international road from Zambia through Katima Mulilo to Botswana, lying on the left bank between the Wenela Bridge (border pass) and the Zambezi River lodge