Four-years of monitoring a breeding colony of black-necked stilt (Himantopus mexicanus ) on the Rio Grande do Norte State coast, Brazil

Mendonça, M. L. AElias, A. P. RLunardi, D. GLunardi, V. O

The black-necked stilt (Himantopus mexicanus Statius Müller, 1776) is the widest distributed Recurvirostridae species of the Americas, with resident and wintering populations in many wetlands. Researches on behavior, population ecology and threats of this shorebird species have focused on Northern Hemisphere populations, and comparatively little about these topics is known of its southernmost populations (Robinson et al., 1999). In 2013, we registered and described the first breeding colony of black-necked stilt in northeastern Brazil, in a non-natural saline area of the Apodi-Mossoró River Estuary (AMRE), Rio Grande do Norte State (Lunardi et al., 2015). In the current study, we presented data of a four-years (2012-2016) of monitoring the site used as breeding colony to provide additional information regarding seasonality and breeding success of the species in the northeastern Brazil. The study site comprised an artificial saline area (145 ha) located at the mouth of the AMRE (04°57’ S, 37°08’ W), Rio Grande do Norte State, Brazil. The study site consists of 54 continuous saline ponds (1-2 ha each) limited by small dikes (1-2 m wide) and two unpaved roads (5-7 m wide; used for salt transportation and not used by birds). The black-necked stilt reproductive colony occupied an area of ~106 ha in the study area (Lunardi et al., 2015). Between August 2012 and July 2016, two researchers conducted two fortnightly counts (during high and low tide periods, in consecutive days) of black-necked stilts (n = 192 counts), in 54 fixed observation sites, located on the two unpaved roads and in front each one of the 54 ponds. In each count, the same two researchers walked (~3 km/h) between the fixed observation sites only on the unpaved roads to avoid disturbing black-necked stilts. The data obtained in the 54 fixed points were added up to each count and it was used as an estimate of the total number of black-necked stilts present in the study area. Two binoculars (8×40 mm/Bushnell) and a digital camera (DSC-H100/Sony) were used in the counts. Each count was conducted in ~2 h. Annual fluctuation in abundance between the studied years was analyzed with KruskalWallis nonparametric test (H) and Dunn’s post-tests were performed. In this study, each studied year corresponded to the period between July and August.(AU)