Ignacio Barberis

Seasonal and interannual variation in waterbird abundance and species composition in the Melincué saline lake, Argentina

We conducted 14 bird surveys in the Melincué saline lake from 1992 to 2002 (7 in winter and 7 in summer), and we detected 223,643 individuals belonging to 71 species from 17 families. The more abundant species were Fulica leucoptera, Larus maculipennis, Phoenicopterus chilensis, Plegadis chihi, Anas platalea, Himantopus mexicanus, and Rollandia rolland. Bird abundance was similar in winter and summer, whereas species composition differed between seasons. We recorded 65 species in summer and 59 in winter. P. chilensis and A. sibilatrix were more abundant in winter, whereas Ajaia ajaja, Phalacrocorax olivaceus, Ardea ibis, Sterna nilotica, Egretta thula, Mycteria americana, Charadrius collaris, A. versicolor, Calidris fuscicollis, and Ciconia maguari were more abundant in summer. Bird abundance in each survey was positively associated with the lake level. In summer surveys, the highest variation in species composition through the years was associated with water level fluctuations. Shorebirds predominated in those years with lower level, whereas the species that fed mainly on plants or vertebrates predominated in years with higher levels. Those species that fed on invertebrates (not shorebirds) and those that fed on invertebrates and plants predominated in years with intermediate level. The omnivorous species predominated in years of lower level. There were differences among transects in the proportion of different trophic groups. Short-term studies that do not take into account the particular dynamic of these systems may lead to erroneous generalisations. Thus, the long-term information of this study may be useful for management and conservation of species and system.

Morphological variation of Aechmea distichantha (Bromeliaceae) in a Chaco forest: habitat and size-related effects

Plants show different morphologies when growing in different habitats, but they also vary in their morphology with plant size. We examined differences in sun- and shade-grown plants of the bromeliad Aechmea distichantha with respect to relationships between plant size and variables related to plant architecture, biomass allocation and tank water dynamics. We selected vegetative plants from the understorey and from forest edges of a Chaco forest, encompassing the whole size range of this bromeliad. Plant biomass was positively correlated with most architectural variables and negatively correlated with most biomass allocation variables. Understorey plants were taller and had larger diameters, whereas sun plants had more leaves, larger sheath area, sheath biomass and sheath mass fraction. All tank water-related variables were positively correlated with plant biomass. Understorey plants had a greater projected leaf area, whereas sun plants had higher water content and evaporative area. Plasticity indices were higher for water-related than for allocation variables. In conclusion, there were architectural and biomass allocation differences between sun- and shade-grown plants along a size gradient, which, in turn, affected tank water-related variables.

Lead pollution from waterfowl hunting in wetlands and rice fields in Argentina.

The pollution of wetlands by lead derived from waterfowl hunting with lead shot was investigated. We determined soil pellet density and Pb concentration in soil, water and vegetation in natural wetlands and rice fields in central-eastern Santa Fe province, Argentina. Pellet density varied greatly among hunting sites (between 5.5-141 pellets/m(2)) and pellets were present in some control sites. Soil Pb concentration in most hunting sites (approximately 10-20 mg kg(-1)) was not much higher than in control sites (~5-10 mg kg(-1)), with the exception of the site with highest pellet density, which also had a high Pb soil concentration. In water, on the other hand, Pb concentration was similar in all sites (~4-7 μg L(-1)), both control and hunting, and higher than reference values for aquatic media. Lead was also present in vegetation, including grasses and rice crops, in almost all cases. Most soil-collection sites were slightly acidic, and were frequently flooded. These results strongly suggest that metallic Pb from spent shot is oxidized and dissolved due to wetland conditions. Thus, the pollutant is readily mobilized and distributed across all wetland areas, effectively homogenizing its concentration in locations with and without hunting activities. The replacement of lead by nontoxic materials in pellets appears to be the only effective way to prevent Pb pollution in wetlands.

A New Record of James's Flamingo (Phoenicoparrus jamesi) from Laguna Melincué, a Lowland Wetland in East-Central Argentina

Abstract Jamess Flamingos (Phoenicoparrus jamesi), also known as Puna Flamingos, are distributed primarily in the Andean wetlands of southern South America during the breeding season, and dispersed through the lowland wetlands in Argentina during the non-breeding season. However, the main sites where they concentrate during the non-breeding season still remain unknown. Here, we report the first records of Jamess Flamingos observed in two consecutive years (two adults in Aug 2010, one adult and two subadults in Jul 2011) at Laguna Melincué, a Ramsar site in Santa Fe Province, Argentina (33° 25′ S, 61° 28′ W, 84 m asl). Jamess Flamingos were feeding in a mixed flock of Andean and Chilean flamingos (Phoenicoparrus andinus and Phoenicopterus chilensis, respectively). Our observations constitute the southernmost record for presence of this flamingo species at any lowland site and indicate the high dispersal ability of this species and its plasticity in occupying different wetland types during the non-breeding season.

Reproductive traits and floral visitors of Aechmea distichantha plants growing in different habitats of a South American xerophytic forest

Aechmea distichantha, a widely-distributed facultative epiphytic bromeliad species, is present from rainforests to xerophytic forests. At its southernmost distribution (Humid Chaco) it grows in the understory and forest edges. This animal-pollinated bromeliad shows high phenotypic plasticity on its vegetative traits, but there is no information about plasticity on its reproductive traits. Infructescences from shade plants were heavier, had longer rachis, more spikelets, higher number of fruits/spikelet and higher number of seeds/fruit than those from sun plants, but they presented similar number of open flowers. The number of visitation events was similar in both habitats, but more flowers were visited in the sun than in the shade. Flowers were visited by seven species (six insects and one hummingbird). In the sun, the carpenter bee was the most frequent visitor and visited almost all flowers, whereas in the shade different species of visitors attained similar proportion of visits and number of visited flowers. Despite visitation events were similar in both habitats, plants growing in the shade set more seeds/fruit than plants growing in the sun. The higher proportion of visits accomplished by carpenter bees compared to hummingbirds is probably a consequence of the climatic conditions in the austral location of these populations.

Infructescence size has a larger effect than light environment on the abundance of different arthropod feeding guilds dwelling on the infructescences of a terrestrial bromeliad in a xerophytic forest

ABSTRACT Bromeliads are a conspicuous feature of many Neotropical xerophytic forests. Bromelia serra is an understory bromeliad living in xerophytic forests of the Humid Chaco, which shows high phenotypic plasticity when exposed to different environmental conditions. Its infructescences carry many fleshy fruits that are colonized by arthropods from different feeding guilds. We used structural equation modeling and redundancy analysis to evaluate the influences of light environment, plant size, and infructescence size on the abundance of five different feeding guilds of arthropods dwelling on the infructescences (‘fruit-secretion feeders,’ ‘infructescence-detritus feeders,’ ‘predators,’ ‘pulp feeders’ or ‘seed feeders’). Plant size was negatively associated with canopy openness, whereas infructescence size was positively associated with plant size. The abundance of all feeding guilds, except fruit-secretion feeders, were positively associated with infructescence size.

Non-passerine birds from Laguna Melincué Ramsar Site, Santa Fe province, Argentina

We present a waterbird inventory of the Laguna Melincue Ramsar Site in southern Santa Fe province, Argentina. We record 109 species from 28 families of non-passerine birds, including the 14 Nearctic species, four southern austral migrant species, three northern austral migrants, 17 partial migrants, and two altitudinal migrants. The eight most abundant species belong to different families and trophic groups. Thirty-six species were observed nesting or rearing chicks. This baseline knowledge of non-passerine birds will be useful to assist future conservation studies in this highly threatened area.