Insects as Important Delicacy for Birds: Expanding our Knowledge of Insect Food Ecology of Birds in the Tropics

Abstract

Eighty percent of birds include insects in their diet. The species of insect more or less consumed often depend on the bird species and its stage in life. In terms of nutritional value, insect diet is adequate; because of its rich and easily digestible protein and fat although the digestibility of various parts largely depends on their chitin content. This study was carried out in three sites; Kurra Falls Forest (9023’N, 8042’E), the Fobur Forest (9051’N, 9001’E) and the Jos Wildlife Park (09° 52', 08° 53') all located in Plateau State, Nigeria. In general all the study sites constitute similar vegetation structure and lanscape. All sites are typically savanna woodlands interspersed with gallery forests, patches of grasslands and rocky outcrops. Insect diet of insectivorous passerines and cattle egret Bubulcus ibis were studied through faecal sample analysis. The methods generally involved collection of faecal droppings from roost sites and mist-netting. Insects were also sampled using sweep net and pitfall traps to correlate results of field and faecal sample data. Results showed that the Order hymenoptera, orthoptera and coleoptera constitutes main insect Orders whose fragments were found in the diet of insectivorous passerines and the cattle egret. Analyses of faecal droppings of the study species generally revealed that birds preyed primarily on the insect Orders hymenoptera (36%), coleoptera (23%), orthoptera (12%) and diptera (9%) which together represent 80% of the avian insect diet. The study concludes therefore, that tropical birds may show a direct correlation between habitat resource availability and utilization which perhaps confirm that birds choose food opportunistically.