PROVISION OF SUPPLEMENTARY NEST MATERIAL TO COLONIAL EGRETS

Colonies of tree-nesting birds are unable to occupy the same site for long periods if the nesting substrate dies and does not provide nest p lacement opportunities. One way vegetation is damaged is defoliation b y birds collecting nest material. If birds accept supplementary nestin g material from outside the colony site they would not need to take as many sticks from live trees in it. This trial was designed to determi ne if supplementary sticks would be taken by Great Ardea alba, Interme diate A. intermedia, Little Egretta garzetta and Cattle A. ibis Egrets and, if so, whether there was a preference for particular species; fr om what locations within the colony sticks were taken, and at what sta ge of the nesting season? Sticks of several species were taken by all four egrets immediately nesting began, and during the height of nest c onstruction the egrets collected sticks from dry land plots placed up to 5 m from the colony edge. Such nest material supplementation may re duce tree defoliation and lead to greater nest attentiveness, with enh anced breeding success in larger nests through fewer eggs and chicks f alling out and greater thermal insulation.