Temporal variation of bird assemblages in dynamic fluvial wetlands: seasonality and influence of water level and habitat availability

LORENZON, RODRIGO E.; BELTZER, ADOLFO H.; OLGUIN, PAMELA F.; LEON, EVELINA J.; SOVRANO, LORENA; ANTONIAZZI, CAROLINA; RONCHI VIRGOLINI, ANA LAURA

REVISTA DE BIOLOGíA TROPICAL

REVISTA DE BIOLOGIA TROPICAL

Lugar: Turrialba; Año: 2019 vol. 67 p. 1131 - 1145

0034-7744

Introduction: Study of temporal variation of bird assemblages may be particularly important inhighly dynamic ecosystems as fluvial wetlands to identify the factors that influence and contribute to maintainregional bird diversity. Objective: To study temporal variation in regional bird species composition (i.e. setof species that make up the assemblage) and richness (i.e. species number) and the factors that drive it, andquantify the importance of temporal-beta diversity to sustain bird regional diversity, in the fluvial system of theMiddle Paraná River in Argentina. Methods: We sampled birds on a regional scale by performing 16 repeatedsurveys roughly every 45 days across 2 years (2011-2013) at 60 point counts distributed along the fluvial system.Results: We recorded a total of 162 species and 12 738 detections, with a mean of 72.7 ± 1.9 species and796.1 ± 41 individuals per survey. Temporal beta diversity accounted for 57 % of regional bird species richness.Bird composition varied seasonally because of the species turnover (and not nestedness) between non-breedingand breeding periods; migrant species contributed to this issue but did not account for all these differences.Difference in bird composition between years was associated primarily to species turnover within non-breedingperiods and was related to changes in water levels. Temporal variation in availability of habitats across theregional extent of the fluvial system accounted for the highest proportion of temporal beta diversity. Speciesrichness neither varies seasonally nor was it related to fluctuations in water level or habitats. Conclusions: Theclimatic seasonality and environmental dynamics of the fluvial system, as a function of water-level fluctuationsand of variations in habitat availability, jointly influence regional composition of birds through temporal speciesturnover. These variations in regional composition were not related to variations in regional species richness.These results show the importance of the natural dynamic of the fluvial system to preserve the processes thatmaintain the regional assemblage of birds.