Ecological differences between two sympatric species of armadillos (Xenarthra, Mammalia) in a temperate region of Argentina

Abstract

Structural and functional foraging specializations that enhance the ability to use certain food types, may also entail costs of being less efficient in exploiting other food resources (Darwin 1859). Foraging specialization not only affects daily food composition but other behavioural [35] Acta Theriologica 55 (1): 35-44, 2010. Abba A. M. and Cassini M. H. 2010. Ecological differences between two sympatric species of armadillos (Xenarthra, Mammalia) in a temperate region of Argentina. Acta Theriologica 55: 35-44.Morpho-physiological specialization related to foraging can act as constraints on behaviour and ecological patterns of abundance and distribution. We tested this prediction in two species (weeping or screaming hairy armadillos Chaetophractus vellerosus Gray, 1865 and mulitas Dasypus hybridus Desmarest, 1804) that represent the two subfamilies of armadillos (Dasypodidae, Xenarthra): Euphractinae and Dasypodinae. The first subfamily possesses a well-developed masticatory apparatus that is considered primitive within the Xenarthra, while Dasypodinae show reductions in various aspects of cranial morphology. We sampled signs (burrows and foraging holes) and captured both species on 34 farms randomly selected in the north-eastern Pampas region of Argentina. We analyzed several niche dimensions. The two species showed significant differences in habitat use, seasonal patterns and diet. Weeping armadillos were generalists in their diet and active throughout the year. They were associated with calcareous-sand soil, as expected for a burrowing animal of the deserts. They tolerated a wide range of environmental conditions. We found that mulitas are myrmecophagous, and that they demonstrated a reduction in body temperature and activity during the cold season. As expected from their geographical distribution, mulitas used mainly vegetation with high cover and were associated with humic soils. Niche segregation between the two species of armadillos appeared to originate from different degrees of dietary specialization.

Comparative histology and ontogenetic change in the carapace of armadillos (Mammalia: Dasypodidae)

“…Euphractus sexcinctus apparently prefers semi-arid environments (Schaller 1983). Chaetophractus vellerosus is distributed in southeast Bolivia, northwest Paraguay, and central Argentina, occupying arid regions with loose and sandy soil, and semiarid conditions (Cabrera 1957;Carlini and Vizcaíno 1987;Greegor 1985;Wetzel 1985;Soibelzon et al 2006;Abba et al 2007;Abba and Cassini 2010). Zaedyus pichiy and C. villosus are the species with the southernmost distributions.…”

Diet and prey selectivity of the specialist myrmecophage, Temminck's ground pangolin

“…25 species are obligate myrmecophages (Redford, ). Dietary specialization often has a knock‐on effect on biological and ecological traits, including social and population dynamics (Abba & Cassini, ), and as Temminck's ground pangolin Smutsia temminckii is one of the most widespread African myrmecophages it is an ideal model to explore the consequences of dietary specialization on strict myrmecophagous mammals.…”

Morphological characterization and sex-related differences of the mandible of the armadillos Chaetophractus vellerosus and Zaedyus pichiy (Xenarthra, Dasypodidae), with consideration of dietary aspects

“…Greegor, 1980;Soibelzon et al, 2007;Superina et al, 2009) do not allow substantiating our results. However, some support in favour of this hypothesis may come from the comparison of the mandible of Z. pichiy with that of the long-nosed armadillos of the genus Dasypus, which have been also indicated as non-selective opportunistic feeders (Breece & Dusi, 1985) but with a strong component of insectivory (mainly myrmecophagy) (Talmage & Buchanan, 1954;Redford, 1985;Smith & Redford, 1990;da Silveira Anacleto, 2007;Abba & Cassini, 2010). Excepting by the condylar height and the number of teeth (both reduced in the long-nosed armadillos), the general configuration of the mandible of these species show noticeable similarities; whether this "insectivore" morphotype can be considered as derivative or not for armadillos seems to be a controversial matter in light of the contradictory results of the major phylogenetic studies conducted to date (e.g.…”