Bioacoustics of Octodontomys gliroides

ECOLOGY Octodontomys gliroides is a typical species of dry areas. It lives in small burrows among rocks or cactus roots, with scattered vegetation, shrubs, and cacti ( Thomas 1913 ; Walker 1964 ; Ipinza et al. 1971 ; Díaz and Barquez 2007), where it feeds on vegetation, hides from terrestrial and aerial predators, and rears offspring ( Rivera 2013 ). In an ecological study of Leopardus jacobita in the Andean region of Jujuy Province ( Argentina ), O. gliroides was cited as an important food item of this Andean mountain cat because of their biomasses and relatively high frequencies ( Reppucci 2012 ). The openings of its burrows are connected by superficial tracks, and all the vegetation around the burrow is removed except thorny species ( Ipinza et al. 1971 ). In Chile , the vegetation where O . gliroides is distributed is dominated by the cacti Browningia candelaris , Cereus atacamensis , Polycereus , and Opuntia as well as shrubs and herbs such as Polyachyrus tarapacanus , Viguiera gayana , Piqueria pinifolia , Psila boliviensis , Trixis cacaloides , and Mentzelia ignea (Muñoz-Pedreros 2000) . According to some authors, O . gliroides is nocturnal (e.g., Ipinza et al. 1971 ; Wilson and Kleiman 1974 ; Mares and Ojeda 1982), whereas other authors consider it diurnal ( Thomas 1913 ; Mann Fischer 1978 ; Díaz and Barquez 2007). Díaz and Barquez (2007) mentioned that it may remain active during the first hours of darkness. On the other hand, Rivera et al. (2014) used radiotelemetry to determine that the females and males were more active during nighttime than daytime. In Jujuy ( Argentina ), O . gliroides was captured with other mammalian species such as the white-bellied akodont Akodon albiventer , Andean mouse Andinomys edax , common yellowtoothed cavy Galea musteloides (now Galea leucoblephara ), yellow-rumped leaf-eared mouse Phyllotis xanthopygus (Rodentia) , and the white-bellied fat-tailed mouse opossum Thylamys pallidior (Didelphimorphia—Díaz and Barquez 2007) . Based on an isotopic study of hair from animals inhabiting the Andean region of Jujuy Province ( Argentina ), it was determined that O. gliroides represents the first active link of the local food chain (Panarello and Fernández 2002). It is an herbivorous species with a diet rich in cellulose, with the composition of its diet changing from cacti in the winter to an apparently graded mixture of CAM (Crassulacean acid metabolism) species with a proportion of up to 30% of C3 grasses during the summer; it uses the watery tissues of the cacti Cereus and Opuntia as water source (Muñoz-Pedreros 2000; Panarello and Fernández 2002). Other plants eaten by O. gliroides included: Maihueniopsis glomerata , M. boliviana , Tarassa , Gnaphalium lacteum , and Senecio graveolens (Panarello and Fernández 2002) . This species can suffer from otitis caused by Pseudomonas aeruginosa ; clinically, the tympanic membrane varied from mild hyperemia to dull opacification with collection of fluid behind it; radiographically, an increase in radiodensity and thickening of the wall and septa of the bulla characterize the infection ( Heller et al. 1976 ). Trypanosoma cruzi , the hemoflagellate responsible for Chagas disease, has been recorded in specimens of O. gliroides . It is thought that O . gliroides may have been involved with the domestic cycle of transmission with humans since prehistoric times ( Schweigmann et al. 1992 ). Recently, Buitrago et al. (2016) , in a study developed in Bolivia , mentioned that O. gliroides is the predominant blood meal sources of wild populations of T. infestans (36%) and also revealed that there may be links between wild and domestic cycles of the T. cruzi transmission. Regarding ectoparasites, O. gliroides hosts fleas of 2 species of the genus Ectinorus : E . nomisis in Argentina and Chile and E. simonsi in Bolivia and Chile ( Smit 1987 ; Beaucournu et al. 2013 , 2014 ). It has been suggested that E. nomisis should likely be regarded as a subspecies of E. simonsi ( Beaucournu et al. 2013 ) . Other species of fleas reported on O. gliroides are: Neotyphloceras crassispina hemisus , Nonnapsylla rothschildi , and Hectopsylla suarezi ( Beaucournu et al. 2014 ) . A louse of O . gliroides , Ferrisella disgrega ( Phthiraptera, Anoplura ), has been recorded from Zapahuira and Chuzmiza ( Chile ), Oruro ( Bolivia ), and Jujuy (Argentina—Castro and Cicchino 1987 as Hopopleura disgrega ; Durden and Musser 1994 as H. disgrega ; Castro and Verzi 2002 ; Moreno Salas et al. 2005 ). BEHAVIOR Octodontomys gliroides has not been observed in a family group; it is likely that the male is not bound to the same burrow as the female, since O. gliroides is less social than the highly communal common degu Octodon degus ( Rowlands 1974 in Wilson and Kleiman 1974 ). Rivera et al. (2014) determined that ecological differences (abundance and distribution of food, predation risk, and burrowing costs) in 2 populations of O. gliroides did not translate into social differences (group size and range area), and they also indicated that sociality of O. gliroides had an ancient origin. In O . gliroides , mutual upright body position with incisor interlocking and riding has been observed as part of social play; all members of families of O. gliroides also frequently sandbathed at the same location, often one after the other, and locomotor-rotational movements have also been observed (Wilson and Kleiman 1974 ). According to Emilio Budin in Thomas (1913:143) , the specimens “are not wild, and are easily shot.” In captivity, family groups (parents and young) immediately engage in intense social activity after awakening and do not eat until much later; this suggests that family groups may play together close to the nest site and then disperse to forage in nature (Wilson and Kleiman 1974 ). In O. gliroides , a pre-copulatory vocalization, a modified version of the alarm squeak, and gurgle or twitter similar to those produced by some birds have been reported ( Eisenberg 1974 ; Kleiman 1974 ). It emits low and middle frequency calls, and also several high frequency or ultrasonic vocalizations ( Eisenberg 1974 ), although the range of vocalizations of subterranean rodents is predominantly of low frequency ( Schleich et al. 2007 ).