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Asymmetry in food handling behavior of a tree-dwelling rodent (Sciurus vulgaris).

Polo-Cavia N, Vázquez Z, de Miguel FJ - PLoS ONE (2015)

Bottom Line: Asymmetry in motor patterns is present in a wide variety of animals.Many lateralized behaviors seem to depend on brain asymmetry, as it is the case of different tasks associated to food handling by several bird and mammal species.Red squirrels devote most of their daily activity to feeding, thus this species constitutes an appropriate model for studying asymmetry in food processing.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Universidad Autónoma de Madrid, 28049, Madrid, Spain; Department of Biodiversity and Evolutionary Biology, Spanish National Museum of Natural History (CSIC), 28006, Madrid, Spain.

ABSTRACT
Asymmetry in motor patterns is present in a wide variety of animals. Many lateralized behaviors seem to depend on brain asymmetry, as it is the case of different tasks associated to food handling by several bird and mammal species. Here, we analyzed asymmetry in handling behavior of pine cones by red squirrels (Sciurus vulgaris). Red squirrels devote most of their daily activity to feeding, thus this species constitutes an appropriate model for studying asymmetry in food processing. We aimed to explore 1) the potential lateralization in handling of pine cones by squirrels, 2) the dominant pattern for this behavior (left- vs. right-handed), and 3) whether this pattern varies among populations and depending on the pine tree species available. Results revealed that red squirrels handle pine cones in an asymmetrical way, and that direction of asymmetry varies among populations and seems to be determined more by local influences rather than by the pine tree species.

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Pinecones handled by red squirrels.A: ‘right’ cone. B: torn cone.
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pone.0118233.g002: Pinecones handled by red squirrels.A: ‘right’ cone. B: torn cone.

Mentions: The preliminary phase of the study consisted in direct observation of feeding behavior of red squirrels at the Breeding Centre of Red Squirrel in Casa de Campo (Madrid Province, Central Spain). This center is located in an extensive, suburban holm oak forest. Two pairs of red squirrels were housed in separate enclosures (8 x 8 x 6.5 m) equipped with feeders, drinkers and nest boxes (although squirrels often build their own nests), and habitually fed nuts, apples, carrots and pine cones. For the sessions, squirrels were supplied Aleppo (Pinus halepensis) or stone (Pinus pinea) pine cones collected in the field. Observations were distributed in 18 sessions from May to July 2010. Handling behavior of cones by squirrels was registered through pictures and videos and recorded in field notebooks. From direct observations of squirrels’ feeding behavior at the Breeding Center, we drew out a basic pattern of their handling of pine cones that we used later to accurately interpret lateralization of this behavior from gnawed cones found in the field. Thus, we noticed that squirrels started to gnaw pinecones at their base, holding them vertically on their apex (Fig. 1A). In this way, squirrels removed the pine scales at their base, often leaving a small ridge in the site of the extraction. Then squirrels placed the cone horizontally, holding the base with one of the forelegs and the apex with the other (Fig. 1B). This latter is used to revolve the cone, while gnawing the bracts. The action of the lower incisors on the bracts leaves an oblique track on the cone with the shorter edge closer to the hemimandible and the longer edge in the opposite side. Looking at the disposition of this track in gnawed cones collected in the field (Fig. 2A), we could distinguish between left-handed squirrels, which hold the cone with the apex towards the left (i.e., use the left hand to rotate the cone), and right-handed squirrels, which do the opposite. We assumed no bias between left- and right-handed squirrels in the proportion of cones they ate.


Asymmetry in food handling behavior of a tree-dwelling rodent (Sciurus vulgaris).

Polo-Cavia N, Vázquez Z, de Miguel FJ - PLoS ONE (2015)

Pinecones handled by red squirrels.A: ‘right’ cone. B: torn cone.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340868&req=5

pone.0118233.g002: Pinecones handled by red squirrels.A: ‘right’ cone. B: torn cone.
Mentions: The preliminary phase of the study consisted in direct observation of feeding behavior of red squirrels at the Breeding Centre of Red Squirrel in Casa de Campo (Madrid Province, Central Spain). This center is located in an extensive, suburban holm oak forest. Two pairs of red squirrels were housed in separate enclosures (8 x 8 x 6.5 m) equipped with feeders, drinkers and nest boxes (although squirrels often build their own nests), and habitually fed nuts, apples, carrots and pine cones. For the sessions, squirrels were supplied Aleppo (Pinus halepensis) or stone (Pinus pinea) pine cones collected in the field. Observations were distributed in 18 sessions from May to July 2010. Handling behavior of cones by squirrels was registered through pictures and videos and recorded in field notebooks. From direct observations of squirrels’ feeding behavior at the Breeding Center, we drew out a basic pattern of their handling of pine cones that we used later to accurately interpret lateralization of this behavior from gnawed cones found in the field. Thus, we noticed that squirrels started to gnaw pinecones at their base, holding them vertically on their apex (Fig. 1A). In this way, squirrels removed the pine scales at their base, often leaving a small ridge in the site of the extraction. Then squirrels placed the cone horizontally, holding the base with one of the forelegs and the apex with the other (Fig. 1B). This latter is used to revolve the cone, while gnawing the bracts. The action of the lower incisors on the bracts leaves an oblique track on the cone with the shorter edge closer to the hemimandible and the longer edge in the opposite side. Looking at the disposition of this track in gnawed cones collected in the field (Fig. 2A), we could distinguish between left-handed squirrels, which hold the cone with the apex towards the left (i.e., use the left hand to rotate the cone), and right-handed squirrels, which do the opposite. We assumed no bias between left- and right-handed squirrels in the proportion of cones they ate.

Bottom Line: Asymmetry in motor patterns is present in a wide variety of animals.Many lateralized behaviors seem to depend on brain asymmetry, as it is the case of different tasks associated to food handling by several bird and mammal species.Red squirrels devote most of their daily activity to feeding, thus this species constitutes an appropriate model for studying asymmetry in food processing.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Universidad Autónoma de Madrid, 28049, Madrid, Spain; Department of Biodiversity and Evolutionary Biology, Spanish National Museum of Natural History (CSIC), 28006, Madrid, Spain.

ABSTRACT
Asymmetry in motor patterns is present in a wide variety of animals. Many lateralized behaviors seem to depend on brain asymmetry, as it is the case of different tasks associated to food handling by several bird and mammal species. Here, we analyzed asymmetry in handling behavior of pine cones by red squirrels (Sciurus vulgaris). Red squirrels devote most of their daily activity to feeding, thus this species constitutes an appropriate model for studying asymmetry in food processing. We aimed to explore 1) the potential lateralization in handling of pine cones by squirrels, 2) the dominant pattern for this behavior (left- vs. right-handed), and 3) whether this pattern varies among populations and depending on the pine tree species available. Results revealed that red squirrels handle pine cones in an asymmetrical way, and that direction of asymmetry varies among populations and seems to be determined more by local influences rather than by the pine tree species.

Show MeSH
Related in: MedlinePlus