CONICET | Buscador de Institutos y Recursos Humanos

In desert environments, some small mammals have been shown to be diurnal in the field and nocturnal when transferred to the laboratory. Epigeous rodents also presented seasonality in their daily activity rhythms. Both features were observed in the activity pattern of subterranean rodents from Monte desert, Argentina (Ctenomys aff. knighti, tuco-tucos), but using distinct recording methods: light exposure (surface activity) in semi-natural enclosures, wheel running in laboratory and body temperature in both conditions. Here we present the first activity data obtained using accelerometers, miniature devices (0.7g; 460 days, 1Hz samples) that record activity levels even of small animals in both field and laboratory conditions. During summer and winter, accelerometers and light-loggers were tied to 9 freshly caught animals (5 males, 4 females; 178±39g). Three of them were also implanted with temperature loggers. Animals with sensors were kept inside enclosures (12m×6m×1,5m) for one month. Environmental temperature was recorded simultaneously. Recaptured animals were transferred to laboratory and kept in constant conditions for 10 days. In summer, general activity inside enclosures was observed throughout the day and presented peaks when crepuscular surface activity occurred. In winter, both activity components became diurnal. Independent of season, transition from enclosures to laboratory caused general activity to become concentrated at night. Inside laboratory, body temperature rhythm coincided with general activity rhythm, differently from enclosures. Comparison between animal and environmental records indicates that nocturnal/diurnal switch and seasonality of activity patterns can be partially due to masking by environmental temperature.

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