Chaco Chachalaca (Ortalis canicollis, Wagler, 1830) feeding ecology in a gallery forest in the South Pantanal (Brazil).

J Ragusa-Netto

doi:10.1590/1519-6984.07113

Abstract

Cracids are generalist frugivores, which often exploit plant food resources such as flowers and leaves, mainly when fruit production declines. The Chaco chachalaca (Ortalis canicollis) is the most abundant cracid in the Pantanal (Brazil), and particularly common in the gallery forests. However, the factors related to their occurrence in this habitat type are unclear. In this study I describe the feeding habits and feeding niche breadth fluctuations of the Chaco chachalaca in relation to food resources abundance and diversity at the Miranda river gallery forest (Southern Pantanal). I also analyzed the relationships between Chaco chachalacas feeding activity and food resources abundance. This parameter (flowers and fruits) exhibited significant seasonal differences of abundance in which flowers were plentiful at the end of the dry, while fruits were abundant during the early wet season. However, food resources diversity to Chaco chachalacas exhibited no seasonal difference. Their feeding activity paralleled the availability of food resources, so that when some items were massively available an enhanced number of Chaco chachalacas foraged in the gallery forest, particularly during the prolonged dry season when they extensively used flowers and Genipa americana fruits. In fact, the Chaco chachalaca feeding niche breadth value presented low values in this period, while high values were common in the rest of the year. The flexible diet of this cracid, potentially favors their year round presence in the gallery forest, mainly during the prolonged dry season when the propensity for famine might be high. Since the Chaco chachalaca is among the largest and most abundant canopy frugivores in the gallery forest, it may contribute to forest regeneration, an underscored role due to the impact of annual floods and meandering dynamics on tree loss.

Highlights

Several Neotropical vertebrate species rely on plant food resources
This study was developed in the Southern Pantanal flood plain at the gallery forest of the Miranda river (Municipality of Corumbá, State of Mato Grosso do SulBrazil, 19° 35’S, 57° 2’W, altitude ±100 m)
I recorded 29 tree species in the phenology transects, which belong to 18 families. Both species and trees with fleshy fruits predominated in the phenology sample (66%, and 80%, respectively, n = 370 trees), while the occurrence of species with dry fruits was smaller (10 species, and 76 trees)

Summary

Introduction

Several Neotropical vertebrate species rely on plant food resources. frugivorous vertebrates are the dominant group in the neotropical forests and, in some areas, comprised much of the mammalian and avian biomass (Fleming et al, 1987, Terborgh et al, 1990). While in markedly seasonal areas fleshy fruit production declines during the dry season, flowering is often pronounced, so that flowers may turn an important food resource both for sedentary (Ferrari and Strier, 1992), and mobile frugivores (Galetti, 1993; Ragusa-Netto, 2004, 2005, 2007, 2008b). Fruits form most of their diet, so that the most exploited plant families are Moraceae, Arecaceae, Rubiaceae, Fabaceae, Cecropiaceae and Lauraceae, a total of 113 families have been reported (Muñoz and Kattan, 2007). They often forage on flowers, leaves, seeds, and arthropods (Caziani and Protomastro, 1994; Galetti et al, 1997; Sick, 1997). Due to their generalist feeding habits, they often resort to feeding on those items when fruits are scarce (Muñoz and Kattan, 2007)

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Conclusion