One of the main factors that allow the red squirrel (Sciurus vulgaris) to live in cities may be the availability of supplemental food provided by people. In this article, preferences of red squirrels in relation to supplemental food, how it is handled, and whether change seasonally, is investigated. A cafeteria test was performed, in which squirrels could choose one from six kind of nuts. Three types of nuts were used: walnuts, hazelnuts and peanuts, with unshelled and shelled nuts of each offered. In most cases squirrels took an offered nut. If a nut was not taken, it was mostly due to lack of interest, without signs of fear. Regardless of season, whole, unshelled walnuts were selected most frequently - the most high-energy and least perishable from offered food. The least frequently selected overall were peanuts. Caching behaviour changed seasonally - nuts were mostly eaten in spring and hoarded in autumn and it took less time to cache nuts in autumn and winter. It may reflect optimal caching strategy at the time when food is abundant and there is a desire to secure as big a store of food as possible. Results from the study suggest that supplemental food is an important component of squirrels' diet and have an impact on their caching strategies.

中文翻译：

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城市公园红松鼠辅食的选择与处理

允许红松鼠（Sciurus vulgaris）生活在城市的主要因素之一可能是人们提供的补充食物的可用性。在这篇文章中，研究了红松鼠对补充食物的偏好、如何处理以及是否随季节变化。进行了自助餐厅测试，松鼠可以从六种坚果中选择一种。使用了三种坚果：核桃、榛子和花生，每种都提供带壳和带壳的坚果。在大多数情况下，松鼠会吃掉提供的坚果。如果坚果没有被吃掉，那主要是因为缺乏兴趣，没有恐惧的迹象。无论季节如何，最常选择的是完整的、带壳的核桃 - 能量最高且最不容易从提供的食物中腐烂。总体上选择最少的是花生。贮藏行为随季节而变化——坚果主要在春季食用，秋季囤积，秋季和冬季贮藏坚果的时间较短。当食物充足并且希望获得尽可能大的食物存储时，它可能反映了最佳缓存策略。研究结果表明，补充食物是松鼠饮食的重要组成部分，对它们的缓存策略有影响。