Seasonal and geographical variation in resident waterbird populations along the Paraguay River
1996; Volume: 14; Issue: 3 Linguagem: Inglês
10.56178/eh.v14i3.993
ISSN1850-4884
Autores Tópico(s)Mosquito-borne diseases and control
ResumoI conducted 47 censuses of resident waterbirds at the Bahía de Asunción, a shallow "bay" of the Paraguay River, from October 1987 to October 1989. I also conducted four shipboard censuses of waterbirds along 859 km of the Paraguay River between Asunción and Bahía Negra during June, August and October 1988 and January 1989. Forty-seven species of waterbirds were recorded during these censuses. Virtually all species of waterbirds were most common during periods of low water levels, from November to March; lower water levels presumably expose a larger surface area of potential feeding habitat. Interannual variation in abundance appears to be related to local patterns of precipitation and habitat availability. The densities of several species increased toward the north as the Paraguay River narrowed. Waterbird populations are good indicators of environmental changes, and should be further censused in order to monitor the effects of chemical contamination and other changes due to the proposed Hidrovia waterway in the river's watershed.
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