Activity Patterns, Sex Ratio, and Social Organization of the Bare-Faced Curassow (Crax fasciolata) in the Northern Pantanal, Brazil

Abstract

Among Neotropical cracids (Galliformes), many taxa are declining rapidly in population size and facing local extinction. However, in the Brazilian Pantanal, several species occur sympatrically and in abundant numbers to allow for long-term studies. Therefore, the study was intended to collect data and statistically evaluate the life history patterns of Bare-faced Curassow (Crax fasciolata), a high-conservation-priority species. Additionally, the effect of applying commonly used independence filters on camera trap data was evaluated. The study was conducted in the SESC Pantanal, Baía das Pedras, Mato Grosso, Brazil, a private protected area of approximately 4200 ha. Between July 2015 and December 2017 (4768 sampling days), 37 sampling locations were monitored with camera traps placed in a regular grid with a spacing of 1 km. Crax fasciolata was detected at 26 (70.27%) of them, with 357 independent captures (554 individuals). Capture success differed among the four seasonal periods, being highest during the receding and lowest during the high-water period. The seasonal difference was more pronounced in the savanna, with significantly lower activity during the rising period and higher activity during the receding period, while it was more uniform in forest-dominated areas. Groups with offspring were more active during the period of receding water, indicating the peak of reproductive activity in the months before. The daily activity of the species followed a bimodal pattern, with peaks between 06:00 and 07:00 and 16:00 and 17:00. Daily activity rhythms were similar when compared between seasonal periods, sexes, and adults with or without offspring and differed between two habitats (more homogeneous in the forest). The mean detected group size was 1.55 ± 0.81 SD, with four animals exhibiting the largest observed aggregation. Larger unisexual aggregations of adults were not observed. The offspring sex ratio was significantly female-skewed at 0.51:1.00, while the adult sex ratio was considered equal at 1.05:1.00 (male:female). The use of different independence filters did not alter the BFC general activity pattern estimates. Cracids can be considered important bioindicators of habitat quality. The results of this study outline the importance of the Pantanal as a stronghold for this species and the privately protected areas with low anthropogenic activity as highly beneficial to its populations.