A Social Bird Species Ending Solitary: Flocking and Breeding Aspects of Greater Rheas (Rhea americana) in the Brazilian Dry Forest Region

Authors: Tubelis DP* and Costa FMO

DOI: 10.23880/izab-16000486

Volume 6, Issue 4

Abstract

Populations of numerous bird species have been declining around the world due to factors such as habitat loss and hunting. This involves the reduction of flock size of social species in non-protected landscapes. The Greater Rhea (Rhea americana) historically occurred in flocks of up to 30 individuals in the Caatinga, the Brazilian dry forest region. The objective of this study was to examine the composition of flocks of the Greater Rhea in the Caatinga through citizen science data. Breeding aspects also were studied. Searches for photographic records were done in the WikiAves platform in April 2023. As some birds could be out of frame, the authors of photographs were consulted to confirm flock size. A total of 112 records of Greater Rheas, including eight with breeding evidence, were found and included in this study. Most of them have been obtained by citizens in central and eastern Caatinga. Among the 104 records with only adults, most (n = 77; 74%) showed a single adult, while 23 (22%) had a pair, and only three (3%) showed three adults; these percentages referred to 38%, 20% and 15% when considering only those records (n = 45) with flock size confirmed by authors of photographs. Only three records had 20-25 adults confirmed by authors. Breeding records comprised a nest with six eggs, a nest with an incubating adult, and six families with 1-2 adults and 1-8 young. Our results indicate that Greater Rheas currently found in non-protected landscapes in the Caatinga tend to occur solitary or in small groups. If this situation persists or get worse, Greater Rheas might become extinct in numerous Caatinga regions. We suggest that conservation programs reintroduce the subspecies R. americana americana in protected and non-protected landscapes throughout Caatinga regions where it originally occurred. Educational programs also are welcome to reduce or avoid their hunting in current and future areas of occurrence in this dry forest region.

Keywords: Birdwatchers; Caatinga; Citizen Science; Flock Size; Reproduction

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