Habitat-mediated influence of water-level fluctuations on waterbird occurrence in floodplain wetlands of the Parana River, Argentina

LORENZÓN, R.E.; BELTZER, A.H.; PELTZER, P.M.; OLGUIN, P.F.; LEÓN, E.J.; SOVRANO, L.; RONCHI-VIRGOLINI, A.L.

RIVER RESEARCH AND APPLICATIONS

JOHN WILEY & SONS LTD

Año: 2017 p. 1 - 12

1535-1459

AbstractResponses of waterbirds to habitat variation could account for their responses to fluctuations inriver levels because hydrological fluctuations influence habitat availability across floodplains.Relationships between water level and waterbird occurrence were examined in floodplainwetlands of the Middle Paraná River to assess (a) whether occurrences of waterbird specieswere associated with water‐level fluctuations of the river, (b) which habitats were associatedwith species that showed a relationship with water level, (c) the influence of water level onthese habitats, and (d) whether influence of water level on these species was related towater‐level influence on habitats. Through the use of regressions and structural equationmodels, we assessed whether direct relationships between each species and water levelremained important after considering the influence of habitat variation. Of 21 species analysed,occurrences of 12 species showed an association with water‐level fluctuations. Indirect effectsof water level through habitats fully accounted for this association in 5 species. Variation inhabitat conditions did not, however, fully account for responses of 6 species, suggesting thatalthough habitat variation can be an important factor, other variables are necessary to explainresponses of some species to water level. One species was not associated with any habitatand therefore was not included in this analysis. Our results agreed with the idea that an importantfraction of waterbird responses to hydrological fluctuations is related to the effects ofthese fluctuations on the availability of habitats across the floodplain. Our results provide datathat help delimit groups of waterbird species that respond in similar ways to hydrologicalfluctuations.