Estimation of the food consumption of fish-eating birds in the seasonally flooded savannas (llanos) of Alto Apure, Venezuela
Pinowski, J., Morales, L.G., Pacheco, J., Dobrowolski, K.A. and Pinowska, B. 1980. Estimation of the food consumption of fish-eating birds in the seasonally flooded savannas (Llanos) of Alto Apure, Venezuela. Bulletin de l’Académie Polonaise des Sciences, Série des Sciences Biologiques, 28: 163–170.
The study was carried out in savannas of southwestern Venezuela (7° 20' N, 69° 15' W). It was found that the density of fish-eating birds during the dry season (December–April) in managed savannas, where the water level is raised and many small artificial ponds (so-called prestamos) are created, is twice as high as in the natural savannas (Table I). In the rainy season (May–November), the fish-eating birds catch 10–25 kg fish per ha and 12–60 kg/ha in the dry season in the managed savannas (Table II). From the artificial water ponds (prestamos) formed in the areas where earth was taken to build dikes, these birds catch 18–500 kg/ha of fish, depending on fish densities, the dry season (Table III). The deepest ponds, never drying out (category III), have the highest fish densities (1279 kg/ha), and about one-third of the fish population is caught by birds. From shallower ponds (categories II and I), drying out during the dry season and with a smaller fish density, even all fish can be taken by the birds. Herons, storks and cormorants are the most important fish consumers in managed savannas (Figs 1 and 2).