**1. Introduction**

Species distribution mapping and modeling has been described as "measuring, weighting and studying the behaviour of ghosts" [1]. Subjected to natural and anthropic range contraction or expansions—besides anthropic extirpations makes species ranges a shapeshifting subject that challenges scientific inquiry [2, 3]. The greater rhea (*Rhea americana*) is a species described as occurring in the "Neotropical Dry Diagonal" of open savanna landscapes in South America [4–6], composed by the Caatinga, Cerrado, Chaco and Pampa [4, 6]. Given that those ecosystems are under high rates of destruction [7], and that the surrounding close canopy forests are also being cleared by the expansion of cattle ranching [8, 9] leading to the savannization of their faunas [10], the understanding of greater

rhea reaction to those drivers is of great interest. For instance, other species associated with open landscapes, such as the maned wolf (*Chrysocyon brachyurus*), have expanded their distribution towards the degraded sections of Atlantic Forest and Amazon Forest [11, 12]. Greater rheas by their time are known to have successfully established populations out of their range, most notably in Germany [13].

Greater rheas are the biggest birds in the Americas averaging 1.4 m and 23 kg, reaching 40 kg in large males [14]. They lay eggs during the dry season from June to September, which hatch in the beginning of the rain season from September to November [15]. Males are polygynous while females are polyandrous: females will move around during breeding season, mating and depositing their eggs with a male, and then mating with other males [16]. Males are sedentary, incubating and raising the hatchlings on their own [16]. Each nest is thus visited by several females, containing up to 80 eggs; each female lay 5–10 eggs per breeding season [17]. The average clutch size is 26 eggs per nest, laid by seven females on average [17]. Nests are shallow depression on soil, cleaned of vegetation debris [17]. Out of the breeding season, both sexes are social, and form flocks up to a 80 individuals [18], which facilitate vigilance toward predators [19].

As many large-sized species [20], greater rheas are of ecological importance. Feeding mainly on broad-leaved herbs, they occasionally eat fruit and invertebrates [21]. They are seed predators for many plant species in Cerrado, while dispersing seeds in a few cases [22]. They are occasional prey for pumas (*Puma concolor*), jaguars (*Panthera onca*) and solitary eagles (*Buteogallus coronatus*) [23, 24], while their eggs serve as food for several armadillo species [25]. Association with pampas deer (*Ozotocerus bezoarticus*) and guanacos (*Llama guanicoe*) is common on open fields for predator vigilance [26–28]. The species is considered Near Threatened by IUCN, because of habitat loss to agriculture and cattle ranching, which makes little sense (since the species occur in both pastures and plantations) and by poaching [29]. Furthermore, greater rhea distribution as shown by IUCN is grossly mistaken, showing the species occurring all over the Atlantic Forest [29].

The greater rhea is of high cultural importance in South America. Princess Therese of Bavaria [30] mentions the species' occurrence in a public garden of northeastern Brazil as early as 1888, and greater rheas remains nowadays as ornamental wildlife in Alvorada Palace, Brazil's presidential residence [31]. Greater rhea was an important source of feathers for dusters historically [5], and name a Brazilian national park [32], inspired music and several popular expressions.

In this paper, my aim is to describe the current distribution of rheas in South America, including their range expansion, introductions and extirpations. With this, I hope to provide basis to management and conservation activities dedicated to the species. An accessible, handy, single-source database approaching the species current distribution range is still missing from scientific literature, and is of prime interest in the context of wildlife conservation in anthropic landscapes.
