Selection of Nuts by Gray Squirrels and Optimal Foraging Theory

Lewis, Allen R.

doi:10.2307/2425376

Cited by 50 publications

(28 citation statements)

References 18 publications

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“…Smith and Follmer (1972) and Lewis (1980Lewis ( , 1982 found that grey squirrels prefer BO acorns, and interpreted this as a response to their higher lipid content. These authors concluded that the squirrels are follow?…”

Section: Discussionmentioning

confidence: 73%

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Grey Squirrel Food Preferences: The Effects of Tannin and Fat Concentration

Smallwood¹,

Peters²

1986

Ecology

127

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Both tannin and fat concentration in acorns have been postulated to affect squirrel preferences and foraging strategy. Our study directly tests the effects of tannin and fat on the food preferences of free-ranging grey squirrels {Sciurus carolinensis). Using food items processed from white oak {Quercus alba) acorns with various amounts of tannin and fat added, we find that added tannin significantly reduces the probability that a food item will be eaten and the length of time spent eating it. The addition of fat is shown to attenuate the effects of tannin, but the overall effect is that squirrels do not forage in a manner that maximizes daily energy intake. These results are contrary to the findings of previous studies. A hypothesis is presented to account for the apparent contradiction: the squirrels may maximize energy intake over the entire fall/winter season rather than over a shorter period, such as each foraging bout or day.

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Section: Discussionmentioning

confidence: 73%

“…termine which group of acorns squirrels prefer, and have cited reasons for the preferences they observed. More recently, Lewis (1980) conducted a field study in which he also found squirrels to prefer BO (actually, red oaks). rels prefer BO over WO acorns.…”

Section: Ofcarcik and Burns 1971 Short And Epps 1976)mentioning

confidence: 99%

Grey Squirrel Food Preferences: The Effects of Tannin and Fat Concentration

Smallwood¹,

Peters²

1986

Ecology

127

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“…The selection of tree seeds by squirrels has been investigated using the optimal foraging theory (Smith 1970;Smith and Follmer 1972;Lewis 1982). The importance of behavioral adaptation to increased feeding rate has also been described; for example, the genus Sciurus cache acorns after killing the embryo to prevent germination (Fox 1982;Steele et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Population differences and learning effects in walnut feeding technique by the Japanese squirrel

Tamura¹

2011

J Ethol

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Feeding efficiency is an important factor explaining diet selection in seed-eating animals. Behavioral adaptation to process and consume the seed is advantageous to improve their feeding rate. The Japanese walnut (Juglans ailanthifolia), which has a nutritious kernel surrounded by a hard shell, is an important food for the Japanese squirrel (Sciurus lis) in lowland mixed-species forests in Japan. In the present study, population differences in feeding technique were examined. In all squirrels captured from the Takao population (with wild Japanese walnuts in their habitat), the optimal feeding technique for quickly opening the walnut shell was observed. However, only 8% of the squirrels from the Fuji population (without walnuts in their habitat) processed the walnuts by the optimal feeding technique. By a repetitive provision of walnuts for 50 days, 14% of squirrels from the Fuji population acquired the optimal feeding technique. Learning effects did not differ significantly between solitary (without a demonstrator) and social conditions (with a demonstrator). The effects of age on learning the feeding technique were examined using individuals from a zoo population that had been naïve for Japanese walnuts. All five individuals aged 6 months old, and half the individuals aged 1-2 years old, ate walnuts by the optimal feeding technique after a 2-month learning period, but none of the individuals older than 3 years did. Consequently, the walnut feeding techniques of the Japanese squirrel are not entirely genetically fixed behavior and can be improved by learning at a young age.

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“…Some plants may have evolved the abilities to influence the foraging behavior of the rodents, to increase the probability of seed removal and caching, and their seedling establishment (Vander Wall, 2010). For example, tannin and nutrient contents (especially fat) were usually positively related in rodent-dispersed seeds which co-affected rodent foraging preference (Lewis, 1982;Smallwood et al, 2001;Xiao et al, 2006). However, besides the seed attributes evaluated in this study, several other traits of plant seed, e.g., seed coat hardness, indigestible fibers, and diverse secondary chemicals may also play important roles in affecting scatter-hoarding rodent foraging behavior (Kollmann et al, 1998;Guimaraes et al, 2003;Vander Wall, 2010;Chen et al, 2012).…”

Section: Discussionmentioning

confidence: 99%