BIOLOGY OF THE GREENSHANK IN SOUTHERN-AFRICA

The Greenshank Tringa nebularia is a widespread visitor to southern Africa but is only normally common at favoured coastal sites. First migrants arrive at the end of July and the last birds leave in early May. Small numbers overwinter. Birds in the interior are forced to move coastward or southwestward once the summer rains set in and rapidly inundate suitable habitat. Peak numbers occur in January at Port Alfred, a coastal site. Greatest concentrations of Greenshanks occur on eutrophic bodies of water in the interior while at coastal localities the density of prawns appears to determine Greenshank numbers. It is normally a diurnal feeder but will feed at night in tidal areas when fattening up for return migration. It roosts communally standing in shallow water. Birds can be aged on plumage condition and primary feather moult. Birds have a lean mass of about 170 g while the potential migratory range on fat deposits accumulated is calculated to carry birds from the Cape coast to the East African lakes and thence to the Mediterranean or Caspian Seas. There is a considerable disparity in mass between inland and coastal localities. One banding recovery in Cyprus is noted; a low retrap rate is gradually being improved by colour ringing. © 1979 Taylor & Francis Group, LLC.