Breeding site selection by colonial waterbirds given various combinations of constructed or natural alternatives over a 10-year period

Abstract

Understanding breeding site preferences is important for management of colonial waterbirds. The number of active colonial waterbird nests at a  series of four small constructed wetlands in Cape Town was counted monthly from 1999 to 2008. In total 491 pairs belonging to 11 waterbird species were involved. Between 1997 and 2004 a number of different artificial structures were used to attract colonial waterbirds to breed at one of the constructed wetlands. The changes in use of the different artificial structures, and of natural reedbeds, for nesting revealed the site preferences of different waterbird species. Structures that simulated  flooded dead trees were most successful in attracting breeding waterbirds. Reedbeds were used for nesting when the number of such  artificial structures was reduced. When the reedbeds were removed some birds returned to the artificial structures, whereas others moved to a more distant wetland. Some species were pioneers that provided  public information about safety from predation that apparently  encouraged birds in other species to settle. Safety from potential  mammalian predators was clearly the prime consideration in breeding  locality selection. Adverse winds and human disturbance were less important factors.

OSTRICH 2010, 81(3): 197–203