兽类学报 ,2007,27 (3):209 - 214 Acta Theriologica Sinica Hoarding of walnuts by David s rock squirrels Sciurotamias ’ ( davidianus within enclosure ) 1 ,2 2 LU Jiqi ,ZHANG Zhibin Department of Bioengineering Zhengzhou University Zhengzhou China (1 , , 450001, ) State Key Laboratory of Integrated Management of Pest Insects and Rodents Institute of Zoology the Chinese Academy of Sciences Beijing (2 , , , China 100080 , ) Abstract :A variety of animals store food to cope with temporally variable or unpredictable food supplies. We have little Sciurotamias davidianus knowledge of the food hoarding behavior of David’s rock squirrels ( ),a species endemic to China and mainly distributed in the hilly temperate zone in northern China. We constructed semi-natural enclosures in the Donglingshan mountains area in which we investigated the squirrels’food hoarding behavior by providing them with tagged Juglans regia walnuts ( ). The results showed that David’s rock squirrels exhibited both larder and scatter hoarding,and the latter seemed to be their preferred choice. Artificial pilferage of hoarded food items had no significant effect on the hoarding behavior of squirrels. Within the enclosures,squirrels tended to select certain sites to scatter hoard walnuts,and no walnuts were consumed at the location where they were provisioned. The possible factors affecting food hoarding of Da- vid’s rock squirrels were discussed. Key words Sciurotamias davidianus :Donglingshan Mountains; ;Larder hoarding;Scatter hoarding;Walnuts 围栏条件下岩松鼠对核桃的贮藏 路纪琪1 ,2 张知彬 2 郑 州大 学生物 工程系 郑 州 中国科 学院 动物研 究所 农业虫鼠害综合治理国家重点实验室 北京 (1 , 450001)(2 , , 100080) 摘要 许多动物都能够贮藏食物以应对一定时期的食物短缺 岩松鼠是中国特有的一种啮齿动物 主要 分布于 : 。 , 华北山地和丘陵地区 对于其食物贮藏行为还了解不多 我们在北京东灵山地区建立了半自然围栏 在 围栏一 , 。 , 角设置一木质巢箱供其休息 在围栏中心设一食盘 给食 处 就岩 松鼠 对核 桃 已 预先 标记 的 贮藏特 征进 , ( ), ( ) 行了观察 每只受试动物在实验开始前 断 食 于 左右 随机 选择 只岩 松鼠 将其 放入 围 栏中 适应 。 6 h , 13 ∶ 00 , 1 , 随后 在给食处放置 枚已标记的核桃 于第二天同一时间进入围栏 检查并记录岩松鼠对核桃的处 2 ～ 3 h。 , 20 。 , 理情况 将埋藏 取食和剩余的核桃全部移出 另 置 枚新 的核 桃 继续 实验 第 三天 重 复上 述 检查 和记 , 、 , 20 , 。 , 录 将岩松鼠及被其处理的核桃全部移出 清理巢箱 整理围栏 随后放 入第二只岩松 鼠 重复上述实 验过程 , , 、 。 , , 如遇恶劣气候 则实验顺延 直至实验结束 结 果表 明 岩松鼠兼具集中贮藏和分散贮藏两种食物贮藏方式 , , 。 : , 并且分散方式是其主要的食物贮藏方式 岩松鼠在围栏中选择一定的位置贮藏食物 文中还讨论了可能影响岩 ; ; 松鼠食物贮藏的因素 。 关键词 岩松鼠 集中贮藏 分散贮藏 核桃 东灵山 : ; ; ; ; 中图分类号 文献标识码 文章编号 :Q958 1 :A :1000 - 1050 (2007) 03 - 0209 - 06 A wide variety of animals hoard food for later con- large concentrations of stored food (larders)are com- sumption during periods of food scarcity. Stored food pelled to space food items widely and hide them care- items are distributed in a variety of ways,from highly fully (i e ,scatter hoarding ),so they cannot easily clumped to highly dispersed. The extremes of this be found by other animals (Vander Wall and Jenkins, spectrum of cache-dispersion patterns have been 2002). Food hoarding has an advantage of increasing termed larder hoarding and scatter hoarding (Smith food availability during winter and early spring (Wau- et al and Reichman, 1984; reviewed by Vander Wall, ters ,1995),it also decreases the likelihood that 1990 ). Food hoarding animals that cannot defend other foragers will find the food (Anderson and Krebs, Foundation item :The key project (G2000046802) of the Ministry of Science and Technology of China; the key project (KSCX2 - SW - 103 ) of the Chinese Acadeny of Sciences Biography :LU Jiqi (1964 - ),male, doctor,professor, is engaged in animal ecdogy . E - mail:lujq@ zzu edu cn Received date Accepted date :2007 - 01 - 31; :2007 - 05 - 24 correspondence author,E - mail:zhangzb@ ioz ac cn 兽 类 学 报 卷 210 27 1978; Smith and Reichman, 1984; Stapanian and verely disturbed due to extensive artificial cutting and Smith,1984;Brodin and Ekman,1994). Under nat- grazing by livestock for almost a century. Since the ural conditions,larder hoarding and scatter hoarding 1990’s,all villagers were relocated to allow for resto- may exert different roles in plant regeneration,the lat- ration and conservation of the local ecosystem. Lia- Quercus liaotungensis ter will playing an important role in this aspect odong oak ( ), wild apricot P armeniaca Vitex negundo Prunus davidiana (Vander Wall, 1990; Forget and Vander Wall, ( ), and Elymus excel 2001). Rodents in Family Sciuridae are among the are common shrubs. Under the shrubs, - sus Poa Elsholtzia stauntoni most studied food hoarders. Hoarding behaviour of red , spp , are commonly seen Sciurus vulgaris Larix principis rupprechtii squirrels ( )(Rice-Oxley 1993;Jiang, grass species. Larch ( - ),and P tabulaeformis 1995;Wauters and Casale,1996;Lee,2002;Wau- Chinese pine ( )have been planted in et al Sciurus carolinen ters ,2002 );grey squirrels ( - small areas by a local reforestation farm. Wild apricot sis )(Thompson and Thompson, 1980; Kraus, typically set fruits from June to August,while walnuts Sciurus niger et al J regia 1983);fox squirrels ( )(Nixon , ( ) are available from September to October. 1968; Stapanian and Smith, 1984 ) and Japanese The area is considered within the natural distribution Sciurus lis et al S davidianus squirrels ( )(Tamura ,1999 ) have region of David’s rock squirrels ( ) et al been studied. (Shou,1962,Chen ,2002) Sciurotamias davidianus David’s rock squirrel ( ), 1 2 Enclosure design an endemic species in China,occurs widely in moun- Four enclosures (9 m × 9 m × 1 m ) were con- tainous and hilly areas throughout northern China. structed on abandoned cultivated land. The tops were They usually inhabit relativly open habitats such as covered with strips of wire mesh (2 5 cm × 2 5 cm) broad-l afed ores s,co ifer oress,fr it foests nd to prevent experimental animals from crawling out. s rubs andae con ider dtobesemi-arboreal (Shou, The floor within each enclosure was cemented to pre- et al 1962;Chen ,2002). Similar to other Holarctic vent animals escaping by burrowing. We then spread a tree squirrels,David ’s rock squirrels do not hiber- layer (about 20 cm)of mixed soil and sand (1 ∶ 1)to nate. They exhibit a diurnal activity pattern,with ac- allow a matrix in which food could be cached. A tivity peaks in the early morning and late afternoon. wooden nest box (30 cm × 20 cm × 20 cm)was placed David’s rock squirrels preferred to eat oleaginous seeds in a corner of each enclosure. All food items were pro- Pinus tabulaeformis and nuts of Chinese pine ( ),wal- vided in a wooden feeder located at the enclosure cen- Juglans regia Prunus armenia nuts ( ),wild apricot ( - ter. The central feeder location forced animals to cross ca et al )(Shou,1962,Chen ,2002). We expected open ground to acquire food items and then again to them to scatter hoard food as a behavioural strategy to potential hoarding sites. A water bottle was placed survive over the period of food shortage, that is, next to the nest box. Enclosures were divided in four through the long winter and early spring,and to pre- equal quadrants with the feeder as the origin to ease vent their hoarded food from being pilfered by intra-and mapping the cache locations inter-species individuals. It has been suggested that 1 3 Experimental animals David’s rock squirrel stores some nuts in tree holes Adult experimental animals were live captured et al (Chen ,2002 ). However,the detail of food from the study area. The mean (± SD)body mass of n hoarding behaviour in this species remains unknown David ’s rock squirrels ( = 14 ) was 274 24 ± We conducted a series of tests to develop an un- 18 31 g. Their previous dietary experience was pre- derstanding of hoarding behaviour of David’s rock sumed to have consisted primarily of the predominate squirrels,The main goals of this study were:1)to de- vegetation. Following capture animals were weighed, termine the hoarding strategy of David’s rock squirrels examined to ensure they were healthy and to determine on walnuts (larder vs scatter hoarding);and 2)to test gender, and tagged for subsequent identification. how squirrels respond to perceived pilferage on hoarded Then, all David’s rock squirrels were individually food. housed in cages made of steel mesh (45 cm × 30 cm × Material and Methods 1 20 cm). Animals were given free access to rabbit pel- 1 1 Study area lets or peanuts and water throughout the holding peri- The study area,Liyuanling village (40° 00′ N, od. Lighting reflected natural day lengths during the 115°30′E)in Mentougou District,lies at an altitude of study period from September to October,2003 about 1 100 m,about 120 km northwest of Beijing, 1 4 Walnuts collection and marking China. This area belongs to the Donlingshan Food items offered squirrels during the study were Mountains region and has a warm temperate continental walnuts. During fruiting periods (September), ma- monsoon climate. The local ecosystem has been se- tured intact walnuts were collected,and kept hermeti- 期 et al Sciurotamias davidianus 3 LU Jiqi .:Hoarding of walnuts by David’s rock squirrels ( ) within enclosure 211 cally until experimental use. We selected walnuts for After checking and recording,all food items were use because they are wildly available, and are impor- removed from enclosure. The procedures were then re- tant in the diet of David ’s rock squirrels at the study peated with new walnuts (20). Subjects were removed area ,and are relatively large and easy to experimental- at the end of each trial and the nest box,feeder,and ly manipulate. Squirrels caught in the area were pre- the enclosure were thoroughly cleaned. An additional sumed to have had prior experience with walnuts. 4 squirrels were then randomly assigned to the enclo- n Fresh mass of walnut averaged 10 74 ± 1 42 g ( = sures and the test repeated. Subjects were tested only 50). Individual walnuts were marked following Zhang once. During every experimental day,a total 280 wal- and Wang (2001 ). A tiny hole was drilled at the nuts were provided. spine of each nut,and a small,light tin-tag (3 cm We defined those food items transported into nest- long and 1 cm wide) was connected with a fine wire boxes as larder hoarding,while any food items buried 3 cm long.