Historic changes in Mid-winter use of Laguna Cuyutlán, Colima, Mexico, by Waterfowl

To understand changes in winter waterfowl abundance at Laguna Cuyutlán, we analyzed data from the U.S. Fish and Wildlife Service Midwinter Waterfowl Surveys. Data exhibited the plummeting of waterfowl abundance in this lagoon in 1955, which had no equivalence in other estuarine systems in southern Mexico. The species involved did not exhibit range-wide population reductions either. Most likely, this reduction was caused by man deriving the greatest part of fresh water from the Ayuquila-Armería watershed for human use, mostly agriculture, causing the loss or deterioration of ecological processes in the lagoon. The role of freshwater supply to Laguna Cuyutlán has been neglected by researchers and managers alike, while, conversely, they supported the opening of the lagoon to the sea. The effects of freshwater flow into Laguna Cuyutlán, as well as the supposed benefit of artificial connections with the sea, should be examined much more thoroughly, to provide sounder management actions for the conservation or restoration of the lagoon's ecological characteristics. Accepted 30 January 2009. © The Neotropical Ornithological Society