Janete de Fátima Martins Scherer

Trace elements concentrations in Buff-breasted Sandpiper sampled in Lagoa do Peixe National Park, Southern Brazil

Cadmium, cobalt, chromium, copper, manganese, nickel, zinc and lead concentrations were detected in feathers of Buff-breasted Sandpipers (Calidris subruficollis) captured during the non-breeding season and analyzed with relationship to body mass. Of these metals tested for, only copper levels (2.28 µg/g) were positively correlated with bird body mass. Zinc levels showed higher concentration (67.97 µg/g) than the other metals, and cadmium levels showed the lowest concentration (0.14 µg/g). Trace element concentrations were below toxicity levels for all tested chemicals and we suggest that this probably reflects that essential elements are maintained there by normal homeostatic mechanism and that no excessive environmental exposure to these elements during migration or on the wintering area is suggested by these results.

Sexual dimorphism and body condition of wintering White-rumped Sandpipers in southern Brazil

ABSTRACT We used discriminant function analysis (DFA) of a series of external morphometric measurements, with confirmation by genetic methods, to develop a simple method to determine the sex of adult White-rumped Sandpipers (Calidris fuscicollis) wintering in southern Brazil. In total, we evaluated the sexual size dimorphism (SSD) of 82 males and 102 females captured with mist nets during the non-breeding period from 2010–2012 using eight morphological measurements. We found significant sex differences: females are significantly larger than males in bill and total head and wing lengths (% SSD 1.0–6.2%). The SSD in skull and bill lengths showed a tendency to maximize the bill length in females, while males exhibited a greater skull length than females (2.6%). Both males and females showed similar body mass, and heavier birds were found in the fall before the northward migration. Body condition showed no difference between the sexes but was higher in the fall than the spring. Molecular sexing showed that DFA would lead to misclassification of sex. Given this, the use of morphological measurements for sexing non-breeding birds of this species in the wintering area should be avoided.

Sexual Dimorphism, Habitat Use and Molt in Wintering Black Skimmers (Rynchops niger) in the Lagoa do Peixe, Southern Brazil

Abstract. Sexual dimorphism is the phenotypic difference between males and females of the same species, characterized by different body size and plumage. Black Skimmers (Rynchops niger, n = 44 adults, n = 14 juveniles) were captured between December 2010 and April 2012 with mist nets during the non-breeding period in the Lagoa do Peixe estuary, southern Brazil. Black Skimmers showed conspicuous sexual size dimorphism, with males being significantly larger than females. Males were 29% heavier than females and significantly larger in six measurements (% sexual size dimorphism = 7–26%). We developed two discriminant functions, both correctly identifying the sex of > 97.7% of the individuals tested and found that head + bill length alone was sufficient to predict the adult sex. The preferred habitat of Black Skimmers in this area was the barra region of the Lagoa do Peixe, where they can take advantage of the abundance of fish in the shallow water. Active molt was recorded in 62.5% of captured Black Skimmers. The molt scores of the primaries and the capture date showed a positive correlation, with lower scores observed in November/December and the highest scores in March/April. We found the intensity of red coloration of the culmen was not a good method for Black Skimmer sex determination in the field compared to molecular sexing, misclassifying 31.0% of individuals overall.

Vertical nest stratification of four heron species in southern Brazil

Herons generally breed in mixed flocks and their nests are made in shrub wetlands and on islands. Waterbirds can select different tree species in the heronries which can influence the vertical stratification of the heron nests. The aim of the present study was to determine the vertical nest stratification among four Ardeidae species in heronries in southern Brazil. The study was carried out during four breeding seasons between 2004 and 2009. No significant species-specific difference in mean nest height was observed between the three heronries. However, there was some variation in nest heights per species in the four years of the study and among the heron species. Nest height was correlated with the body size of the heron species. The smaller species, Bubulcus ibis, Egretta thula, and Nycticorax nycticorax, occupied mainly the lower stratum and the largest, Ardea alba, the higher stratum. The colonist species B. ibis did not show a clear preference, occupying both Mimosa bimucronata and Cephalanthus glabratus for nest building, while the other three herons selected mainly M. bimucronata if the two tree species were available.