Seasonal variation in attention and spatial performance in a wild population of the African striped mouse (Rhabdomys pumilio)
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Cognitive flexibility describes the reversible changes of cognition in response to environmental changes. Although various environmental factors such as temperature, photoperiod and rainfall change seasonally, seasonal variation in cognitive performance has been reported in merely a few birds and mammals. We assessed whether cognitive performance in a wild population of African striped mice Rhabdomys pumilio, from the Succulent Karoo semidesert of South Africa, differed between summer and winter. In order to measure cognitive performance, striped mice were trapped in the field, tested under laboratory conditions at our research station and returned to the field within 5 h. We measured attention and spatial memory using the standardized orientation response test and the Barnes maze test. Males tested during summer oriented faster toward a predator-stimulus but made more errors and took longer to locate a shelter than males tested during winter. In contrast, females’ performance did not differ between the two seasons. We discuss how the faster orientation in males during winter might be the consequence of lower temperatures and/or prolonged food restriction. We suggest that the enhancement of spatial performance during winter might be due to a greater motivation for future dispersal in male striped mice, as spring represents the breeding season.
KeywordsCognitive flexibility Seasonality Orientation response Spatial memory Sex differences
This research was supported by a fellowship (to CS) of the University of Strasbourg Institute for Advanced Study. This study was made possible by the administrative and technical support of the Succulent Karoo Research Station (registered South African NPO 122-134), where fieldwork took place. We thank Ivana Schoepf, Chi-Hang Yuen, Patrick Brunner and Andrea Del Mela Gorrino for assistance in data collection. We also thank Bernard Thierry for helpful discussions about the methodology.
Compliance with Ethical Standards
Animal ethical clearance was provided by the University of the Witwatersrand, Johannesburg, South Africa (No. 2013/50/2A). All procedures were in accordance with the ethical standards of the institution or practice at which the studies were conducted. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
Conflict of interest
The authors declare that they have no conflict of interest
Orientation response test. A mouse (identified with ear tags and red/blonde hair dye) placed in a transparent box facing a white screen, orients its head toward the raptor-stimulus that appeared at the left bottom of the screen and slides in a rightward motion. The raptor-stimulus presentation lasts 5 s. (MP4 8310 kb)
Barnes maze test—bat trial. A mouse (placed in transparent circular box at the center of the Barnes maze) is released, nose-pokes 4 incorrect holes and then locates the correct hole providing access to an escape box. A bat toy hanging above the maze mimics the presence of a flying predator. Pictures of rocks and plants (photographed in the natural habitat of the population of mice tested) that are placed on the walls and curtains surrounding the maze provide visual landmarks to the mice. (MP4 2635 kb)
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