Bird's nesting success and eggs predation within Arusa National Park, Arusha, Tanzania
Nesting success and eggs predation is among the factors that affect the population dynamics of bird species. The study was carried out to determine predation impact on selected bird species population in Arusha National Park, Arusha, Tanzania. Specifically the study assessed the potential predators to ground (Scaly Francolin) and (Ruppell’s Robin- Chat, Striped-cheeked Greenbul, Tambourine Dove and Tropical Boubou) to establish if nesting success and eggs predation vary with habitat fragments types and nesting heights. Artificial nests were constructed in three different heights, and both artificial and true eggs were put on the nests in eleven habitat fragments and their associated forests. Identification of predators was obtained indirectly through punched signs left by predators on artificial and true eggs. Observation was done daily and data were analyzed both qualitatively and quantitatively. The study showed no significant difference in predation effect on eggs in glade versus glade edge X2 = 3.08, Df = 1, P > 0 .05, glade edge versus forest interior X2 = 0.04, Df = 1, P > 0 .05, while glade versus forest interior showed to differ significantly X2 = 0.08, Df =1, P < 05). Predation effect on nesting position at three levels showed no significant difference X2 = 6.75, Df = 3, P > 0 .05 in level 1, X2 = 3.81, Df = 2, P > 0.05 at level 2 and X2 = 0.67, Df = 2, P > 0. 05 at level 3. The percentage egg failure was 41.54 % with predation effects contributing 92% of the total impact, followed by floods 5% and trampling 3%. Although habitat predation varied among habitat types and vertical levels, the type of predators did not vary. However, among predators rodents contributed the highest level of predation effects. Nesting failure was a result of predation, trampling and flooding with the later two affecting more the ground nester birds’ species.
Key words: Predators, birds’ population, edge effects, Tanzania