Armadillos represent the most diverse family of xenarthrans. Although many studies have been done on these mammals, several topics, such as their local distribution, natural history, behavioral ecology and conservation, remain poorly known. Chaetophractus villosus and Zaedyus pichiy are the most common armadillos in extra-Andean Patagonia, a vast area in southern Argentina and Chile that encompasses different ecosystems and has been modified by human activities, mainly by sheep grazing. In this work we present new data on the distribution, natural history, conservation, and ecology of C. villosus and Z. pichiy from central Patagonia (Chubut and Río Negro provinces, Argentina). We registered 60 localities for C. villosus and 35 for Z. pichiy that confirm their presence in wide sectors of central Patagonia. Furthermore, we confirmed that these two armadillo species suffer high rates of mortality due to their use as a protein source, hunting by dogs, road traffic, and poisoning, among others. We conclude that their populations are at risk of overexploitation and local extinction. The basic knowledge provided here will be a first step towards the conservation of these characteristic Patagonian mammals.
Armadillos (Mammalia: Dasypodidae) represent the most diverse family of recent xenarthrans (Wetzel, 1985a, b). Although many scientific publications exist on these species (see Superina, 2010), several topics, such as the natural history, local distribution, behavioral ecology, and conservation, remain poorly studied (McDonough and Loughry, 2008).
Extra-Andean Patagonia occupies an area of 750,000 km2 and encompasses different ecosystems, from grasslands to shrub-steppes and semi-desert. Phytogeographically, the area includes the Patagonian steppe, the Monte shrub-steppes, and scrublands (Cabrera, 1976). Human activities have modified most of the Patagonian region, most notably by sheep grazing on the natural vegetation. There is evidence that grazing by domestic herbivores has been modifying the vegetation and accelerating soil degradation processes since the beginning of the twentieth century (e.g., Beeskow et al., 1987; Rostagno and Del Valle, 1988; Bisigato and Bertiller, 1997).
Most of Patagonia is dominated by strong and constant west winds. Precipitation levels decrease from west to east; most of the region receives less than 200 mm per year. Mean annual temperature varies between 12°C in the northeastern part and 3°C toward the south (Paruelo et al., 1998). However, minimum temperatures in the Somuncurá plateau are among the coldest recorded for Argentina (-35°C in Maquinchao, Río Negro province).
Today, four species of armadillos are known to inhabit Patagonia (including Argentina and Chile): Chaetophractus vellerosus (Gray, 1865), C. villosus (Desmarest, 1804), Chlamyphorus truncatus (Harlan, 1825), and Zaedyus pichiy (Desmarest, 1804). Ch. truncatus and C. vellerosus occur only rarely (Abba and Vizcaíno, 2008), but C. villosus and, especially, Z. pichiy are two typical medium-sized mammals from Patagonia (Cabrera and Yepes, 1940; Daciuk, 1974). According to bibliographic records and voucher material from Argentinean mammal collections, only 51 localities have been reported for these two species in Patagonia (Abba and Vizcaíno, 2008; Abba, unpublished data).
In this work, we present data on new localities, natural history, conservation, and ecology of C. villosus and Z. pichiy from central Patagonia (Chubut and Río Negro provinces, Argentina).
Materials and Methods
Fieldwork was carried out during the summers of 2005 to 2007 as part of the dissertation research of two of the authors (MJN and DEUS) and in conjunction with the project “Postglacial Patagonia: evolutionary responses of small mammals to climate change” (National Geographic Society, grant number 7813-05). Data were collected opportunistically and through observation of individuals of Z. pichiy and C. villosus in different areas of central Patagonia, mainly the Chubut river basin, Somuncurá plateau, and Península Valdés. Additionally, we used information from interviews with rural settlers to obtain information on the behavior, habits, diet, abundance, and hunting of armadillos; the detailed results of these interviews are being analyzed and will be published elsewhere.
Collected material, such as skeletal remains, are in preparation and will be added to the Mammal Collection of Centro Nacional Patagónico, Chubut, Argentina. Additional evidence is registered in the field catalogue of Marcelo Carrera and Marcela J. Nabte.
Chaetophractus villosus Desmarest, 1804
Common name: large hairy armadillo, peludo, quirquincho grande.
Global and local conservation status: Least Concern (LC). Listed as LC because of its (1) wide distribution and thus, presumed large population; (2) occurrence in a number of protected areas; and (3) tolerance of a large degree of habitat modification. Also, it is unlikely to be declining fast enough to qualify for listing in a more threatened category (Fonseca and Aguiar, 2004).
Reported uses: hunting for food. Traffic accidents and poisoning with substances used to kill foxes were reported as other causes of non-natural mortality.
New records: 60 (see Table 1 and Fig. 1). Most records were observations of live individuals or collected carcasses. Only five animals could be captured and sexed; three were males and two were females. None of the latter was pregnant at the moment of capture in fall.
Habitat: this species was observed, captured, and reported in all habitat types (steppes, monte shrubsteppes, and scrublands), but was more common in the monte shrub-steppes.
Observations: local people list many negative impacts of C. villosus and frequently persecute it as a pest. One important complaint is related to its burrows, especially to the risk of livestock (sheep) and horses stepping into them and breaking their legs. Other common concerns include disease transmission and possible attacks on young sheep. In addition, C. villosus was found to negatively affect bird populations, both domestic (chicken) and wild (e.g., penguins in the northern part of Península Valdés at San Lorenzo ranch) because of their consumption of eggs and chicks.
Although local people view “peludos” as unclean because they eat carrion, garbage and pichis, many still use this armadillo as an important protein source. In many tourist areas (e.g., Punta Norte, Península Valdés) “peludos” are a favorite because they are neither aggressive nor shy, and will eat from the hand of people.
Zaedyus pichiy Desmarest, 1804
Common name: pichi, piche, piche de oreja corta, piche patagónico.
Local conservation status: Least Concern (LC). Species widespread and abundant (Diaz and Ojeda, 2000).
Global conservation status: Near Threatened (NT). This species is relatively widespread and is present in a great number of protected areas (Heinonen Fortabat and Chébez, 1997). However, it is hunted extensively, especially in the northern and eastern portion of its range, and local extinctions have been recorded in some areas (Fonseca and Aguiar, 2004; Superina, 2008; Superina and Members of the IUCN/SSC Edentate Specialist Group, 2008). Less information is available about declines in southern areas. Overall, this species is estimated to have declined significantly, primarily due to intense hunting (Fonseca and Aguiar, 2004).
Reported uses: hunting for food. Traffic accidents and hunting by domestic dogs were reported as other causes of non-natural mortality.
New records: 35 (see Table 1 and Fig. 1). Similar to C. villosus, most observations were of wild individuals that could not be captured. The gender of five animals was determined, four of them being males. One female captured during winter was not pregnant.
Habitat: Z. pichiy was observed, captured, and reported in all habitat types (steppes, monte shrubsteppes, and scrublands) but seemed to be more common in steppes.
Observations: in contrast to C. villosus, rural settlers eagerly hunt this species because it is “clean” (i.e., it does not ingest carrion) and its meat is more palatable. Many rural families will spend the afternoon hunting pichis and may catch four or five animals per day. They eat the meat and use the fat for frying.
In Península Valdés, pichis are more abundant in sandy areas. They are mainly found in the southern part of Península Valdés and become scarcer toward its northern portion. In central Patagonia, pichis are rarely seen aboveground during cold periods (fall and winter). Pichis are frequently observed eating plants, mainly Condalia microphylla and Arjona tuberose, and insect larvae (Tenebrionidae, Nyctelia spp.). Remains of several juvenile pichis were found below nests of Black-chested Buzzard-Eagles (Geranoetus melanoleucus), as observed by Saggese and De Lucca (1994).
Like all armadillos, C. villosus and Z. pichiy have low body temperatures, low basal metabolic rates, and high thermal conductances (McNab, 1985). Given the low ambient temperatures in Patagonia, these characteristics represent a major constraint on the behavior and ecology of large hairy armadillos and pichis. Perhaps related to this, interviews with locals indicate that both species are observed more often during the day and suggest that Z. pichiy enters hibernation during the cold season (cf. Superina and Boily, 2007).
The collected data suggest that in Patagonia, C. villosus is more common than Z. pichiy. The former is probably a new component of the Patagonian fauna that naturally immigrated into this area ca. 150 years ago (Poljak et al., 2010; Abba et al., in preparation).
Perhaps, its higher abundance is a consequence of its successful invasion of Patagonia (Williamson and Fitter, 1996).
On the other hand, Z. pichiy, the typical Patagonian armadillo, is registered in low frequencies and is intensely hunted. We therefore believe that the global conservation status (NT) is more realistic and/ or better reflects the current situation than the local status (LC; Diaz and Ojeda, 2000).
C. villosus has been described as a carnivore-omnivore (Redford, 1985; Casanave et al., 2003; Abba, 2008) that ingests, among others, meat and carrion. The observations presented here agree with the general type of food habits, but includes reports of consumption of lambs and birds (both domestic and wild), a behavior that has not been reported before for this species and is not easy to observe.
List of new records for Chaetophractus villosus and Zaedyus pichiy (see also Figure 1). NR= national route; PR = provincial route; Ea. = Estancia (farm, ranch).
The food habits reported for Z. pichiy in central Patagonia agree with the information presented by Superina et al. (2009) for Mendoza, who described this species as an opportunistic omnivore that ingests high proportions of insects, but also plant material.
The geographic distribution of neither species seemed to be restricted by altitude or vegetation type. This contrasts sharply with other inhabitants of the region, such as the Patagonian hare (Dolichotis patagonum), another medium-sized mammal that is not found above 1000 m, and the many small mammals of the central basaltic plateaus (such as Somuncurá; Andrade, 2007) whose distributions are strongly affected by plant composition.
To summarize, we confirmed the presence of C. villosus and Z. pichiy in wide sectors of central Patagonia. Both species suffer high mortality for many reasons: they are hunted for food, killed very frequently by dogs, hit by cars, poisoned with substances used to kill foxes, and must cope with the compaction of the soil by millions of sheep. These populations are therefore at risk of overexploitation and local extinction. Additional knowledge of localities, as well as of their ecology and natural history, will contribute to the conservation of these characteristic mammals of Patagonia.
The authors express their gratitude to Walter Udrizar Sauthier, Enrique Lessa, Guillermo D'Elia, Ulyses F. J. Pardiñas, Juan Andrés Martinez, Analía Andrade, Guido Bonnot, Cecilia Reeves, Florencia del Castillo Bernai, Virginia Burgi, Andrea Marino, Florencia Siri, German Cheli, Mónica Primost, Andrés Johnson, Sergio Saba, and all the rural settlers who helped us during field trips. Special thanks to Marcelo Carrera for allowing study of the collection under his care and to Jim Loughry for assistance with English-language editing. The National Geographic Society and the Administration of the Protected Area Península Valdés partially supported field work. CONICET provided financial support to the authors.