Publisher: Bachudo Science Co. Ltd

Breeding Losses In Cattle Egret, Bubulcus Ibis L. Causes and Repercussion On Generational Propagation In Arid Ecology

H. A. Sharah, E. A. Ali
KEYWORDS: Storms, aggression, infanticide. starvation. predators. egg failure to hatch. poaching, generational propagation


The study was carried out in three sites. (Mbodewa, in the Sahel Savannah zone and Jebra and Konduga in Sudan Savannah zone of Northeastern Nigeria) m 2002 and 2003. The aim was to study the causes of breeding losses of the nestling Cattle egrets and its effect on the generational propagation of these birds m the zone. Counting of losses of all stages began the first week nest construction started and continued at weekly intervals until nest site abandonment at ten (10) weeks by both parents and offspring at the end of fledging (67-70 days) from nest construction. Total of 45.421 nests were involved in the three heronries. with a total of 17,714 losses recorded; 10,850 (61 3%) in Mbodewa, 5,701 (32.2%) in Jebra and 1, 163 (6 61%) Konduga. Mean egg losses accounted for 9,078 (51.3%), nestlings 6,662(37 6%) and adults 1,974(11.1%) of the total losses for the two breeding seasons. The main causes of losses were storms, egg failure to hatch, poaching, aggression, predation and starvation Losses were higher in Sahelian zone with few and little tree canopy cover in the nesting colony trees and where wind speed was high (69km/hr), than Jebra (54.4km/hr.) and Konduga (58.5km/hr.) in the Sudan Savannah with good colony tree canopy cover and low (x = 56.5km/hr) wmd speed. Nests an.d breeding birds population on each site reduced with years due to reduced and even spread of rainfall m subsequent years. Account of other salient mortality factors are described.

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