围栏条件下岩松鼠对核桃的贮藏

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6 h断食,于13∶ 00 左右,随机选择1 只岩松鼠,将其放入围栏中适应2 ～ 3 h。随后,在给食处放置20 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理情况,将埋藏、取食和剩余的核桃全部移出,另置20 枚新的核桃,继续实验。第三天,重复上述检查和记录,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。     

岩松鼠的食物贮藏行为

食物贮藏是许多动物对不可预见的食物供应变化的一种重要适应.岩松鼠(Sciurotamias davidianus)为中国特有物种,广泛分布于华北地区的山地和丘陵地带.作者在北京市东灵山地区建造半自然围栏(4 m×3 m× 1 m),以核桃(Juglans regia)和山杏(Prunus armeniaca)种子为备选食物,对岩松鼠(12只)的食物贮藏行为进行了研究.数据的统计分析采用SPSS for Windows进行.研究结果表明1)岩松鼠表现出集中和分散两种食物贮藏方式,而分散贮藏是其偏好的贮藏方式;2) 当遇到贮藏食物被盗窃时,岩松鼠倾向于搬运更多的食物进行集中和分散贮藏;3)岩松鼠没有在食盘就地取食任何一种食物;把食物搬离后,岩松鼠所取食的山杏种子数量明显多于所取食的核桃数量;4)岩松鼠只选择核桃进行分散贮藏;5)岩松鼠对核桃的搬运距离大于山杏种子.本研究结果提示,在自然条件下,岩松鼠对核桃和山杏的天然更新起着不同的作用[动物学报 51(3)376-382,2005].     

围栏条件下影响岩松鼠寻找分散贮藏核桃种子的关键因素

在北京东灵山地区半自然围栏内,通过将核桃(Juglans regia)种子用塑料袋封闭处理减弱嗅觉信号和埋藏处理阻断视觉信号,研究了岩松鼠(Sciurotamias davidianus)对置于地表、埋藏、封闭后置于地表和封闭后埋藏核桃种子的发现率,以探讨岩松鼠找寻种子的主要方式;同时还研究了岩松鼠对自己埋藏和其他个体埋藏种子的发现率,以探讨空间记忆在岩松鼠找寻自己埋藏种子时是否有重要作用。岩松鼠对各组种子的发现率为:埋藏组59.5±27.6%,地表组53.3±27.7%,封闭埋藏组31.0±27.2%,封闭地表组26.3±28.6%;其中埋藏组与地表组较高,差异不显著(Z=-0.356,P=0.722),封闭埋藏组和封闭地表组较低,差异也不显著(Z=-0.493,P=0.622),即通过埋藏处理阻断视觉信号对岩松鼠的种子发现率没有显著影响;埋藏组显著高于封闭埋藏组(Z=-2.943,P=0.003),地表组显著高于封闭地表组(Z=-2.084,P=0.037),即通过封闭处理减弱嗅觉信号显著减少了岩松鼠对种子的发现率;当种子被封闭且埋藏时,有31.0%的种子被找到,即当通过封闭处理减弱嗅觉信号,埋藏处理阻断视觉信号后,岩松鼠仍能通过随机探索找到部分种子。自埋组(57.9±21.8%)和他埋组(54.4±33.9%)的种子发现率都较高,且差异不显著(Z=-0.157,P=0.875),即岩松鼠在找寻自己埋藏的种子时没有明显优势。这些结果表明:围栏条件下,嗅觉在岩松鼠找寻贮藏种子时起主要作用,然后随机探索也具有一定意义,而视觉和空间记忆意义不大。     

贮藏种子的啮齿动物对油茶种子沉积形式的影响

种子沉积的质量常常涉及种子扩散作用者(如鸟类和小型啮齿动物)对生境和微生境的选择以及种子沉积的形式(如种子埋藏)。然而,很少的研究涉及到种子在离开母树后被这些动物沉积在何处。在四川省都江堰一个实验林场的2个林分(次生林和原生林)内,通过追踪用带编号的金属薄片标记的油茶(CamelliaoleiferaAbel.)种子的命运,研究了贮藏种子的啮齿动物对种子沉积的影响。研究发现在2个林分内,80%以上的种子被很好地埋藏在0~60mm深的土壤中,而小部分种子则被放置在地表(但有少量落叶遮盖)。小型啮齿动物喜好在灌丛下或灌丛边缘贮藏和取食种子,可能是在这样的微生境下它们在觅食时将遭遇较小的捕食风险。研究还发现,贮藏点的微生境分布随贮藏点等级而逐渐变化在两个林分内较高等级的贮藏点(如次贮藏点和三级贮藏点)比初级贮藏点有更多的种子被贮藏在灌丛下或灌丛边缘。这表明,啮齿动物对油茶种子的埋藏可能更有益于种子的存活、萌发以及幼苗的建成。啮齿动物将散落在母树下或其附近的油茶种子扩散到不同的微生境,这可能有利于他们遭遇到更多的适宜环境而萌发,实现幼苗补充。     

贮藏种子的啮齿动物对油茶种子沉积形式的影响

种子沉积的质量常常涉及种子扩散作用者(如鸟类和小型啮齿动物)对生境和微生境的选择以及种子沉积的形式(如种子埋藏).然而,很少的研究涉及到种子在离开母树后被这些动物沉积在何处.在四川省都江堰一个实验林场的2个林分(次生林和原生林)内,通过追踪用带编号的金属薄片标记的油茶(Camellia oleifera Abel.)种子的命运,研究了贮藏种子的啮齿动物对种子沉积的影响.研究发现:在2个林分内,80%以上的种子被很好地埋藏在0～60 mm深的土壤中,而小部分种子则被放置在地表(但有少量落叶遮盖).小型啮齿动物喜好在灌丛下或灌丛边缘贮藏和取食种子,可能是在这样的微生境下它们在觅食时将遭遇较小的捕食风险.研究还发现,贮藏点的微生境分布随贮藏点等级而逐渐变化:在两个林分内较高等级的贮藏点(如次贮藏点和三级贮藏点)比初级贮藏点有更多的种子被贮藏在灌丛下或灌丛边缘.这表明,啮齿动物对油茶种子的埋藏可能更有益于种子的存活、萌发以及幼苗的建成.啮齿动物将散落在母树下或其附近的油茶种子扩散到不同的微生境,这可能有利于他们遭遇到更多的适宜环境而萌发,实现幼苗补充.     

岩松鼠和松鸦对辽东栎坚果的捕食和传播

脊椎动物对栎属(Ｑｕｅｒｃｕｓ)坚果的捕食和传播是栎属通过实生苗更新的关键因子,栎属中一些物种坚果的分布格局以及动物对坚果的捕食作用已有较多研究[1～6]。一般情况下,栎属的坚果成熟落地后立即开始发芽,落在地表的坚果里的种子胚根长出后,由于地表枯落物的阻碍作用...     

岩松鼠和松鸦对辽东栎坚果的捕食和传播

Predation and dispersal of Quercus liaotungensis Koidz. acorns by Chinese Rock squirrel (Sciurotamias davidianus) and Eurasian jay (Garrulus glandarius) were examined in a Pinus tabulaeformis Carr. forest in Dongling Mountain. Both of them were important acorn dispersal agents. Chinese Rock squirrels frequently forage food in this forest. They consumed a small portion of acorns in situ, while they transported large quantities of acorns in their big cheek pouches. Eurasian jays have great capacity to transport acorns, although they were uncommon visitors to this forest. They carry acorns in their sublingual pouches to other forest. Of the 18 acorns scatterhoarded by a Chinese Rock squirrel, only 3 remained in two different caches 111 days after they were cached. These results indicate that vertebrates play an important role in acorn dispersal and seedling establishment of Quercus liaotungensis.     

围栏条件下同域分布三种鼠对两种种子的贮藏行为差异

种子贮藏是啮齿动物利用食物资源的一种适应性行为。同域分布的啮齿动物可能进化出不同的贮藏方式和策略。为了解同域分布的啮齿动物的贮藏策略及种子特征在动物贮藏行为决策中的作用,于2014年10-12月,通过半自然围栏实验,在秦岭南坡的佛坪国家级自然保护区内调查了同域分布社鼠、中华姬鼠和甘肃仓鼠对板栗和锐齿槲栎种子的贮藏策略差异,并探讨了2种种子特征在鼠类贮藏行为决策中的作用。结果显示：1）社鼠主要集中贮藏板栗种子,未分散贮藏任何种子;中华姬鼠未贮藏板栗种子,对锐齿槲栎种子同时表现出集中和分散贮藏行为,以集中贮藏为主;甘肃仓鼠对2种种子均表现出集中贮藏行为,未表现分散贮藏行为。2）社鼠和甘肃仓鼠均倾向于集中贮藏有较高营养价值（高蛋白和脂肪）且单宁含量较低的板栗种子;中华姬鼠倾向于分散贮藏单宁含量高的锐齿槲栎种子。3）3种鼠均喜好取食有较高营养价值且单宁含量低的板栗种子,很少取食单宁含量高的锐齿槲栎种子。结果表明同域分布鼠类对不同种子的贮藏方式有所不同,种子特征影响鼠类的取食和贮藏策略。     

岩松鼠贮藏种子的空间记忆研究

通过在岩松鼠自身埋藏种子附近选择相同生境人工埋藏种子的方法,研究岩松鼠对自身埋藏种子和人工埋藏种子的找回率有无差异,从而部分揭示记忆如何在岩松鼠找回贮藏种子过程中发挥作用。数据的统计分析采用SPSS for Windows(version 19.0)进行。结果显示:1)岩松鼠喜欢将种子贮藏在灌丛下方,但对埋藏基质没有明显偏好;2)埋藏微生境和埋藏基质对岩松鼠在对人工埋藏种子的找回过程中没有明显影响;3)岩松鼠对人工埋藏的核桃种子在种子找回过程中与自身埋藏的核桃种子有显著差异(Z=-2.499,P=0.014),对人工埋藏的胡桃楸种子在找回过程中与自身埋藏的胡桃楸种子有极显著差异(Z=-6.557,P<0.001)。     

Substrate selection by juvenile Atlantic cod (Gadus morhua): effects of predation risk

Although predator avoidance has been proposed as one possible factor influencing the distribution of fish among substrate types, no study has addressed this question directly. Groups of juvenile Atlantic cod were offered a choice between pairs of the following three substrates: sand, gravel-pebble and cobble. Their distribution on these substrates was compared prior to, during and following exposure to a predator (i.e. a larger conspecific). With no apparent risk of predation, juvenile cod preferred sand or gravel-pebble. When cobble was present, juveniles hid in the interstitial spaces of this substrate in the presence of a predator. With no cobble present, juveniles showed no preference between sand and gravel-pebble, and did not seek refuge from predation in association with these substrates. Following exposure to a predator (i.e. 2.5 h later) larger juvenile cod again showed a preference for the finer-grained substrates, but smaller individuals continued to associated with the cobble. The presence of cobble resulted in fewer juveniles being captured and a significant increase in the latency until the first juvenile was captured by the predator. Results are discussed with respect to the effects of predation on the distribution and survival of fishes among substrate types.     

Evidence of effects of human disturbance on alert response in Père David's deer (Elaphurus davidianus)

To understand effects of human disturbance on alert response of Père David's deer, we carried out an experiment in the Dafeng Père David's Deer Reserve (32°59′–33°03′N, 120°47′–120°53′E), China. In the spring and summer, we observed alert responses (including stare, walking away, and flee) of deer and recorded the intensity of tourist disturbance in a small display pen using a laser‐range finder to measure the alert distance of a free‐ranging group in a large enclosure. We also recorded the pattern of head orientation when deer were resting in these two deer groups. After statistical analysis, we found that: 1) in small pen, the frequency of alert response was significantly different among different intensities of human disturbance; strong disturbance resulted in higher frequency of alert response; 2) stare distance in the free‐ranging group in summer was significantly longer than that in spring, but the distance of walking away and the distance of flee showed no significant difference between the two seasons; and 3) in free‐ranging group, there was no significant directional difference in head orientation, whereas in display group, there was a significant directional difference in head orientation. We suggest that: 1) under the captive situation, human disturbance may be one of the factors that affect alert response in Père David's deer; and 2) Père David's deer adopted different alert response to adapt to human disturbance under different circumstance. We recommended that relationships between alert response and human disturbance should be considered in ex situ conservation of this field extinct deer. Zoo Biol 26:461–470, 2007. © 2007 Wiley‐Liss, Inc.     

Habitat shift in roach (Rutilus rutilus) induced by pikeperch (Stizostedion lucioperca) introduction: predation risk versus pelagic behaviour

Changes in the fish community structure and habitat use were followed after the introduction of pikeperch (Stizostedion lucioperca) to the roach-dominated Lake Gjersjøen. Quantitative echosounding showed that the density of juvenile roach (Rutilus rutilus) was dramatically reduced in pelagic areas, from 12 000–15 000 fish/ha to 250 fish/ha, while total fish density remained unchanged in littoral areas. At the same time, the habitat segregation between different size groups of roach was altered as larger roach utilized the pelagic zone after pikeperch introduction. The loss of the pelagic refuge for juvenile roach increased the availability of juvenile roach to littoral predators, notably perch. In littoral areas, the fish community changed from one dominated by roach (> 95%) to one dominated by perch (> 50%).     

Effects of predation risk on mating behavior of the Kanzawa spider mite

In the Kanzawa spider mite, Tetranychus kanzawai, adult males locate pre-reproductive quiescent females and engage in precopulatory mate guarding. We found that re-reproductive quiescent females preferred to be near veins, rather than other leaf parts, and moreover, adult males spent more time along the vein than on other parts. Consequently, T. kanzawai males found more quiescent females along veins than those on other parts. However, the predatory mite Neoseiulus womersleyi also found more quiescent T. kanzawai females along veins than those on other parts. Moreover, N. womersleyi found more guarding males than solitary males of T. kanzawai. Thus, we experimentally examined the effects of predation risk on the mating behavior of T. kanzawai. The presence of N. womersleyi reduced T. kanzawai female preference for vein vicinity as a quiescent site. Although the predation risk of guarding T. kanzawai males was lower than that of solitary males after detection by predators, the presence of N. womersleyi also reduced the proportion of guarding T. kanzawai males. These results suggest that the possible benefits of preferring vein vicinity as quiescent sites by T. kanzawai females is outweighed by predation risk in the presence of predators, and that the risk of detection by predators would be more important for T. kanzawai males than the risk of being preyed upon.     

剥夺食物对雄性长爪沙鼠贮食行为的影响

禁食导致一些啮齿动物的贮食量增加,但禁食处理后雄性长爪沙鼠贮食行为的变化则不一致。每天禁食22 h,长爪沙鼠的一些个体表现出高水平的贮食行为(禁食贮食组),而另一些个体则没有表现出贮食行为(禁食无贮食组)。延长禁食(22 h)持续的时间(连续重复3 d 和20 d)和增加禁食时间(禁食48 h),都没有使禁食无贮食组的动物表现出贮食行为。同样在自由取食条件下,长爪沙鼠的贮食行为也表现为二型性。在自由取食和禁食条件下,贮食量与体重、体脂含量和瘦素的浓度之间无明显相关关系。研究结果表明,禁食是诱导雄性长爪沙鼠贮食行为发生的一个重要条件,但增加禁食的程度并不改变其贮食行为的表现。     

捕食风险对不同饥饿状态下艾虎取食行为的影响

在室内条件下,将大鵟作为艾虎的天敌动物,通过双通道选择实验确定6 只成体艾虎在3 个捕食风险水平和4 种饥饿状态条件下的取食行为,探讨艾虎在取食过程中对饥饿风险与捕食风险的权衡策略。研究结果表明:在无捕食风险存在时,艾虎被剥夺食物0 d 和1 d 后对食物量不同的两个斑块中的取食量和利用频次均无明显不同(P > 0. 05),但对高食物量斑块的利用时间均明显高于低食物量斑块的(P <0.05),而艾虎被剥夺食物2 d和3 d后对高食物量斑块中的取食量和利用时间均明显高于低食物量斑块中的(P < 0.05),但在利用频次上均无明显差异(P > 0.05)。在面临低风险时,艾虎在4 种饥饿状态下均只利用无天敌动物存在的低食物量斑块,而基本不利用有天敌动物存在的高食物量斑块。在面临高风险时,艾虎不得不利用有天敌动物存在的食物斑块,被剥夺食物0 d 时艾虎对无风险、无食物量斑块的利用时间基本相同于对高风险、有食物量斑块的利用时间(P>0.05),而被剥夺食物1d、2 d 和3 d 后艾虎对高风险、有食物量斑块的利用时间明显高于无风险、无食物量斑块的(P< 0. 05)。在相同风险条件下,随着饥饿程度增加,艾虎在斑块中的取食量均明显增加(P< 0.05),而对斑块的利用时间和利用频次明显降低(P<0.05)。在相同的饥饿状态下,不同风险水平时,艾虎在斑块中的取食量无明显的差异(P>0.05),但在低风险和高风险时对斑块的利用时间和频次均明显低于无风险时的(P <0.05)。以上结果说明艾虎能够根据食物摄取率和自身的能量需求在捕食风险和饥饿风险之间做出权衡,当饥饿风险小于捕食风险时,艾虎趋于躲避捕食风险,当饥饿风险大于捕食风险时,艾虎趋于面对捕食风险,所采用的取食策略是减少活动时间和能量消耗,最大程度地提高单位时间内获得的能量。