Aquatic bird densities in two coastal lagoon systems in Chiapas State, Mexico, a preliminary assessment
- 1) Departamento ei Hombre y su Ambiente, Universidad Autonoma Metropolitana, Xochimilco, Mexico DF, Mexico
- 2) Av Purisima y Michoacan, Universidad Autonoma Metropolitana, Apdo., Postal 55-535, Iztapalapa, Mexico DF, Mexico
- 3) Canadian Wildlife Service, Environment Canada, Bedford Institute of Oceanography, P.O. Box 1006, B2Y 4A2, Dartmouth, N. S., Canada
Six bodies of water in two coastal lagoon systems were investigated in Chiapas State, Mexico between July, 1990 and February, 1991. The size of water bodies ranged from 102.5 to 847.5 ha. Salinity varied seasonally being the lowest in July during the rainy season (1.0‰) and highest in February (35.8‰). The waters are hypertrophic with total phosphorus concentrations as high 900 mg m?3. The number of bird species was the highest in February (N = 9 to 23) and the lowest in July (N = 2 to 15). The majority of birds present are resident species of Mexico but several species of northern birds were present in February (e.g. Lesser Scoup, Osprey, Peregrin Falcon). The number of birds observed in the waterbodies varied during the study period being as high as 2800 Cormorants, 2300 White Pelicans and 681 Limpkins, at a particular time, or expressed in terms of units surface area of each lagoon 8.0, 2.7 and 1.9 individuals per hectare respectively. The daily food requirements of White Pelicans at such a high density is about 4.1 kg ha?1 d?1. The hypertrophic state of Cerritos Lagoon allows a sufficient level of production to support such a high food requirement. Considering the limited survey time spent on the lagoons the bird population numbers are probably underestimated.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie