凉水自然保护区松鼠（Sciurus vulgaris）贮食生境选择

2003年10月~2004年4月,在黑龙江省小兴安岭凉水国家级自然保护区,应用跟踪观察法、样线调查法、样方调查法等研究方法,采用Vanderploeg和scavia选择系数Wi和选择指数Ei作为衡量指标,对松鼠贮食红松种子生境选择进行了研究。研究表明,松鼠贮食对生境具有选择性:以主要林型为划分标准,松鼠偏爱贮食生境依次为:原始红松林,云杉林,人工云杉林,针叶混交林,人工落叶松林,针阔混交林,阔叶混交林,次生白桦林和人工红松林。在原始红松林内,松鼠对微生境的利用存在选择性差异:松鼠对郁闭良好(郁闭度大于0.6)、灌丛密度中等、倒木和枯立木密度中等(1~5个)、盗食动物活动较弱(大林姬鼠Apodemus peninsulae为主要盗食动物)的原始红松林生境表现出较强的选择性(Ei>0.2);而对坡度小于5°、基质为霉菌土、倒木和枯立木密度较高(大于5个)、草本盖度较高、盗食动物活动中等(花鼠Eutamias sibiricus为主要盗食动物)的原始红松林生境表现出较强的负选择性(Ei<-0.2),对阴坡表现出强烈的回避性(Ei=-0.5368)。     

凉水自然保护区松鼠和星鸦贮食生境选择差异

2003 年9 月30 日～2005 年10 月8 日,在黑龙江凉水国家级自然保护区,应用样方调查法, 采用Vanderploeg和Scavia 选择系数Wi和选择指数Ei作为衡量指标,对松鼠和星鸦贮食生境选择进行了研究。结果表明, 二者贮食生境选择优先顺序略有不同,松鼠偏爱的贮食生境依次是: 云杉林、原始红松林、人工红松林、针阔混交林、人工云杉林、白桦林、针叶混交林、人工落叶松林、阔叶混交林、冷杉林和其它。星鸦对贮食生境的偏爱程度依次为: 人工红松林、原始红松林、云杉林、人工云杉林、针阔混交林、阔叶混交林、白桦林、针叶混交林、人工落叶松林、冷杉林和其它。在对贮食微生境因子的选择利用上, 二者大致相同,只是在对优势灌丛的选择上略有差异, 松鼠优先选择在狗枣猕猴桃优势灌丛内贮藏红松种子, 而星鸦优先选择在刺五加优势灌丛内贮食。松鼠和星鸦贮食生境选择的差异将对随后的红松天然更新过程产生不同的影响。     

The effects of hoarding habitat selection of Eurasian red squirrels (Sciurus vulgaris) on natural regeneration of the Korean pines

Cone-cores discarded by Eurasian red squirrels were used to study the habitat selection of Korean pine-seeds hoarding, in forest patch Nos. 16 and 19 in Liangshui Nature Reserve, China. Ten transects with a total length of 15 km were uniformly set, and data from 343 valid samples were collected in a 369 hm² area. One hundred and eighty four were hoarding samples which were determined according to the cluster analysis based on the number of the cone-cores, while the other 159 were control samples. The principal component analysis, using 11 habitat factors, suggested that the distance from Korean pine forest, forest type, number of Korean pine seedlings, density and type of bush significantly influenced the habitat selection of hoarding by Eurasian red squirrels. The results of Bailey’s method indicated that the squirrels showed (1) preference for natural coniferous forest, natural fir and spruce forest and planted spruce forest; (2) avoidance of planted Korean pine forest and planted larch forest; and (3) random use of natural Korean pine forest. Moreover the distance from the Korean pines in the range of 150–600 m showed no effect on the habitat selection of hoarding by the Eurasian red squirrels. More than 50% of the cone-cores were discarded in either fringe or gap of the Korean pine forest with more cone-cores found at <300 m than at 300 m away (One-Way ANOVA; df = 3, 183, F = 5.76, p = 0.0009). This demonstrated that the Eurasian red squirrels could take the cone-cores out of the Korean pine forest. The density of bushes in samples of hoarding area was significantly lower than that in control samples (Kruskal–Wallis test; df = 1, χ² = 83.99, p < 0.0001). The number of the Korean pine seedlings in samples of hoarding area was significantly higher than that in the control samples (Kruskal–Wallis test; df = 1, χ² = 104.13, p < 0.0001). This illustrated that the hoarding habitat favoured the germination of the Korean pine seedlings. In conclusion the behavior of hoarding Korean pine seeds by the Eurasian red squirrels can promote the regeneration and dispersal of the Korean pines.     

红松结实量与松果可利用量对松鼠和花鼠贮食行为的影响

植物通过每隔几年产生大量种子的丰年策略提高贮食动物传播种子效率,但人为采摘活动降低了种子的可利用量,从而影响贮食动物行为及种群动态。为研究红松球果采摘如何通过降低松果可利用量而影响贮食动物行为,我们基于黑龙江凉水自然保护区2003-2012年红松结实量和采摘量的变化,比较分析了结实大小年间松鼠贮点大小、贮点深度、贮食密度和贮藏量、松鼠花鼠种群以及2010年和2011年花鼠洞穴贮藏量的差异。结果显示：结实大年松鼠的平均贮点大小显著高于小年,大贮点比例增加,贮食密度和贮藏量也明显高于结实小年,但随着结实量的增大,球果采摘量增加,使松果可利用量减少,由此结实大年2011年松鼠贮食密度并未随结实量增加而增加,反而低于2003年和2008年,松鼠遇见率也没有在该结实大年有所增长。而花鼠种群和洞穴松籽贮藏量在结实大年和小年间没有显著差异。研究表明红松球果采摘对松果可利用量和松鼠贮食行为有较大影响,应合理确定大年的采摘量以保证贮食动物的食物丰度,维系红松生态系统健康。     

Seed dispersal of the Korean pine,Pinus koraiensis,by the red squirrel,Sciurus vulgaris

Seed hoarding behavior of the red squirrel,Sciurus vulgaris, was studied in relation to the amount of dispersed seeds of the Korean pine,Pinus koraiensis, and the distribution of its seedlings. After removing a cone from a tree, squirrels sat on the ground and ripped off its cone scales before transporting it. A mean of 3.2 seeds were scatter-hoarded per hole. Of 7.7×10⁴ mature seeds produced in a 0.21 ha planted Korean pine forest, 22% were estimated to be directly eaten by four squirrels, 9% were hoarded by them in the pine forest and 65% were cached outside the forest. Squirrels rediscovered hoarded seeds frequently, until the ground was covered with snow, during the period from snow fall until seed germination the next spring, few hoarded seeds were utilized. Korean pine seedlings were found up to 600 m from their mother trees. Scatter-hoarding by squirrels extensively contributes to seed dispersal to places suitable for the regeneration of the Korean pine. The large size of the cone, the absciss-layer at the cone penduncle, the infrequent dehiscence of cone scales, the large and wingless seeds, and the thick seed-coats have probably all been specialized to facilitate utilization by GenusSciurus.     

动物与红松天然更新关系的研究综述

红松球果成熟后,种子自身不能脱落到达适宜的萌发地,因而无法自身完成天然更新而要依赖动物帮助传播种子。捕食红松种子的动物包括啮齿类、鸟类和一些大型兽类。其中,松鼠、星雅和普通币鸟具有分散贮藏的行为,以前两者为重要。这些动物从球果中取出种子,吃掉一部分后,靠颊囊或舌下囊搬运至贮藏地,将种子埋藏在地被物下准备冬、春食物缺乏时再重新捕食。搬运的距离远达数百米至几公里。分散贮藏的贮点数量很大。每个贮点有一至数粒种子。贮点小生境比较适合红松种子的萌发,因此大量的未被重新发现和捕食的贮点的种子在20个月后可能萌发。虽然动物贮藏的生境适合幼苗的萌发,但是不一定适合幼苗的继续生长。由于动物的捕食和贮藏行为,阔叶红松林内红松种子运转途径在4个层次（树上、地面、地被物下和洞穴）进行,最后只有少数种子萌发为幼苗。幼苗的生长过程同样受到动物的捕食和破坏。由于红松结实的丰欠年度变化,动物种群也随之变动。     

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。     

The role of birds and mammals in Korean pine (Pinus koraiensis) regeneration dynamics

This study examined the interrelationships of the fall seed-foraging guild with Korean pine (Pinus koraiensis) and its regeneration. The study took place in old-growth and secondary-growth forests in Northeastern China. Foraging behavior, seed transportation distance, and cache location of various birds and mammals were observed. Regeneration characteristics of Korean pine were also analyzed using plots in various vegetation cover types, successional stages, and topographical situations. Ten species of vertebrates were able to harvest seed from the closed-cone Korean pine. Of these, the Eurasian nutcracker, Eurasian nuthatch, red squirrel, and Siberian chipmunk were found to be potential seed dispersal agents. The nutcracker was the most important dispersal agent, easily acquiring seed with its large pointed bill, carrying up to 62 seeds in one trip, carrying seed at least 4 km, and placing seed in a variety of sites 2.5–3 cm deep in the soil. The Eurasian nuthatch carried a single seed per trip at distances less than 50 m, needed nutcrackers to open the cones and expose seed before they could acquire seed, and occasionally cached seed in the soil. Red squirrels were uncommon visitors to the tree tops of Korean pine, carried cones shorter distances than nutcrackers, and were only found under forest canopies. Human harvest of cones by knocking off branches also affected squirrel behavior and reduced future cone crops. Siberian chipmunks also collected seed from cones in trees and appeared to transport seed less than 50 m. Six other species were observed in this study successfully harvesting seed from cones but were not potential seed dispersers. Natural seedling establishment was found to be over 1000 seedlings/ha except on old-growth pine-hardwood sites. Squirrels were commonest here, but few seedlings survived past the 2nd year due to the intense shading. Second-growth forest types, including aPicea plantation where nutcrackers cached seed daily, and an old-growth pine-hardwood selective-harvest site, had the greatest regeneration. In conclusion, most natural regeneration of Korean pine in this part of its range is due primarily to the Eurasian nutcracker. Nutcrackers can aid forest managers in reaching desired stocking levels after disturbance, as well as a more natural-appearing forest. Squirrels, chipmunks, and nuthatches are minor seedling establishment agents. Korean pine seed is an important food source used by at least 22 species of forest wildlife.     

A predator's perspective of nest predation: predation by red squirrels is learned,not incidental

Nest predation has been used to explain aspects of avian ecology ranging from nest site selection to population declines. Many arguments rely on specific assumptions regarding how predators find nests, yet these predatory mechanisms remain largely untested. Here we combine artificial nest experiments with behavioural observations of individual red squirrels Tamiasciurus hudsonicus to differentiate between two common hypotheses: predation is incidental versus learned. Specifically, we tested: 1) whether nest survival could be explained solely by a squirrel's activity patterns or habitat use, as predicted if predation was incidental; or 2) if predation increased as a squirrel gained experience preying on a nest, as predicted if predation was learned. We also monitored squirrel activity after predation to test for evidence of two search mechanisms: area‐restricted searching and use of microhabitat search images. Contrary to incidental predation and in support of learning, squirrels did not find nests faster in areas with high use (e.g. forest edges). Instead, survival of artificial nests was strongly related to a squirrel's prior experience preying on artificial nests. Experience reduced nest survival times by over half and increased predation rates by 150–200%. Squirrels returned to and doubled their activity at the site of a previously preyed on nest. However, neither area‐restricted searching nor microhabitat search images can explain how squirrels located artificial nests more readily with experience. Instead, squirrels likely used cues associated with the nests or eggs themselves. Learning implies that squirrels could be increasingly effective predators as the density or profitability of nests increases. Our results add support to the view that nest predation is complex and broadly influenced (e.g. by predator experience, motivation), and is unlikely to be predicted consistently by simple relationships with predator activity, abundance or habitat.     

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].     

采伐对长白山阔叶红松林生态系统碳密度的影响

采伐对森林生态系统碳密度和固碳能力有重要的影响,且影响的程度因采伐强度和方式不同而有巨大差异。以长白山地区原始阔叶红松林在不同采伐方式、采伐强度干扰后形成的次生林为研究对象,通过对2007至2009年建立的11块1 hm2永久样地中植被层、凋落物层和土壤层碳密度在采伐前后变化特征的分析,研究了采伐强度与恢复时间对阔叶红松林生态系统碳密度的影响。结果表明:在短期内,采伐导致了植被层和土壤表层(0—20cm)碳密度值的减少,其中植被碳密度与采伐强度有显著的线性负相关关系(y=-0.9x+91.17,R2=0.626,P<0.01),而后,随着植被的恢复,生态系统碳密度增加,其中植被、土壤层碳密度呈显著线性正相关关系。根据植被碳密度与恢复时间之间的相关关系,确定以生态系统恢复、木材生产与固碳三者兼顾的合适采伐强度为30%,轮伐期为45a。     

帽儿山3种森林生态系统土壤动物与土壤呼吸及其相互关系研究

土壤呼吸是森林生态系统碳循环的关键过程,土壤动物可通过自身代谢及影响微生物活动调控土壤呼吸,因此研究土壤动物与土壤呼吸的相互关系对进一步揭示生态系统碳循环的规律和机理具有重要意义。通过野外定点,以帽儿山3种森林生态系统的土壤呼吸及土壤动物为研究对象,探讨不同森林生态系统的土壤呼吸、土壤动物个体密度和生物量的时间变化规律及二者相互关系。结果表明:(1)3种森林生态系统土壤总呼吸速率与土壤异养呼吸速率均呈现先增强后减弱的时间动态变化(P<0.05),且不同森林生态系统土壤异养呼吸速率差异显著(P<0.05),表现为硬阔叶林最高,红松人工林最低;(2)3种森林生态系统土壤动物生物量也具有显著的时间动态变化(P<0.05),均在9月份达到最大,且不同森林生态系统土壤动物个体密度显著不同(P<0.05),蒙古栎林土壤动物个体密度显著小于红松人工林与硬阔叶林;(3)通过回归分析可得,土壤动物数量及生物量的增加抑制了土壤呼吸速率,尤其在生长季初期、末期。研究表明土壤动物可通过抑制微生物生命活动和降低根系呼吸从而对土壤总呼吸及异养呼吸产生负反馈作用,三者是不可分割的整体,与土壤温度、水分等环境因子共同调控着土壤呼吸。     

NEOSQUIRREL: a data set of ecological knowledge on Neotropical squirrels

相似文献   

贮食动物的盗食与反盗食行为策略

食物贮藏是许多动物应对食物短缺、保障其生存和繁衍的一种适应性行为。保护好贮藏食物以供食物短缺期利用,是食物贮藏成功的标志和进化动力。同种或异种动物盗食是贮藏食物损失的重要原因。嗅觉、视觉与空间记忆、随机搜寻等是动物搜寻和盗取食物的重要手段;避免盗食、阻止盗食和容忍盗食是动物反盗食的重要策略。动物通常采用多种行为策略进行盗食和反盗食,分配食物资源,形成相对稳定的种内、种间关系。盗食与反盗食互作及其对贮食行为进化的意义已成为行为生态学的研究热点和前沿之一,针对鸟类和哺乳类动物的研究尤为丰富。本文总结了贮食动物常见的盗食和反盗食行为策略及其相互作用的研究进展,主要内容涉及贮食动物利用嗅觉、视觉与空间记忆、随机搜寻等盗取其他个体食物的盗食策略,以及通过隐藏、转移、保卫、容忍等方式减少被盗食,保护贮藏食物的行为策略。针对现有研究状况,从种间盗食与反盗食及其与物种共存的关系,种间非对称盗食关系及其适应意义,盗食与反盗食最适行为策略及其与贮食动物适合度的关系等方面对今后研究提出了建议。     

Characteristics of Mount Graham Red Squirrel Nest Sites in a Mixed Conifer Forest

Abstract: The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is constrained to the Pinaleño Mountains in southeastern Arizona, USA. The population's endangered status and extensive forest damage from insects and fire warrants a better understanding of habitat variables important for nest site selection. We examined characteristics of cavity (n = 91) and drey (n = 38) nests and compared these to random sites (n = 113). Dreys were found primarily in Engelmann spruce (Picea engelmannii) and corkbark fir (Abies lasiocarpa var. arizonica). Cavity nests occurred primarily in aspen (Populus tremuloides) and corkbark fir. Squirrels selected nest sites with higher canopy cover and more corkbark fir, decayed logs, and living trees. Forest management plans emphasizing thinning must consider how altering these habitat characteristics could affect availability and suitability of tree stands for nesting squirrels.     

三种温带森林大型土壤动物群落结构的时空动态

对帽儿山3种典型森林群落大型土壤动物进行了连续6个月的野外调查研究。通过系统分析,共获得大型土壤动物3604只,隶属于3门6纲17目50科。其中正蚓科(Lumbricidae)、线蚓科(Enchytraeidae)和石蜈蚣目(Lithobiomorpha)为优势类群,常见类群11类。结果表明:(1)水平分布上,密度和生物量红松人工林最高,其次为硬阔叶林,蒙古栎林最少;类群数硬阔叶林最多,蒙古栎林最少;香农指数和丰富度指数均为蒙古栎林最高,红松人工林最低;优势度指数与两者相反;均匀度指数蒙古栎林最高,硬阔叶林最低;(2)垂直分布上,个体密度、类群数及生物量均差异显著(P < 0.001)。3个样地大型土壤动物个体密度表聚性明显;类群数红松人工林自凋落物层向下减少,硬阔叶林和蒙古栎林0-10 cm最多;生物量在0-10 cm土层最大;香农指数随深度增加而减小,优势度指数则相反;(3)在时间变化上,5月和10月个体密度和类群数较多,9月生物量最大;香农指数和优势度指数差异显著(P < 0.01),其他指数各月间无明显差异;(4)与土壤环境因子关系上,总有机碳含量与类群数、个体密度及生物量显著正相关,容重与香农指数显著负相关;典型对应分析结果表明,不同类群大型土壤动物与环境相关性不同。     

Antipredator behaviour and predator recognition in Belding's ground squirrels

This study evaluates whether Belding's ground squirrels (Spermophilus beldingi) recognize predators under natural conditions. I observed these squirrels for 300 h during two consecutive summers, during which I described 1029 aerial and terrestrial interactions, including 299 interactions with animals known to prey on squirrels. Squirrels responded differentially to predators and non-predators, to predators that hunt differently, and to contextually different interactions with the same predator. Responses shown in encounters with predators included Trill and Chirp vocalizing, upright Posting, crouching, running to burrow entrances, entering burrows, Approaching or chasing predators, and doubling-back on pursuing predators. Ground squirrels appear to adjust their antipredator behaviour depending on the amount and kind of danger they face during an encounter.     

Scatter‐hoarding and cache pilfering of rodents in response to seed abundance

Seed caching and reciprocal cache pilferage play an important role in the coexistence of food‐hoarding animals. Understanding what affects seed caching and how cache pilferage occurs is an important question in seed dispersal ecology. However, tracking seed fate and cache pilferage presents substantial practical difficulties. Siberian chipmunks Tamias sibiricus always remove the entire pericarp when scatter‐hoarding acorns of Mongolian oak Quercus mongolica, whereas wood mice Apodemus peninsulae often store whole acorns in their caches. These differences in behavior provide an opportunity to investigate unilateral cache pilferage of T. sibiricus from A. peninsulae in response to seed abundance. In this study, tagged acorns were released at the peak and end periods of seed rain from Q. mongolica. This allowed us to investigate seed caching and unilateral cache pilferage at different seed abundances. We found that a higher proportion of acorns were cached at lower level of seed abundance (toward the end of seed rain), mainly because T. sibiricus rather than A. peninsulae scatter‐hoarded significantly more acorns at this time. Cache distances decreased with increasing seed abundance, indicating that acorns were cached further away and into smaller caches at lower seed abundance. Unexpectedly, unilateral cache pilferage by T. sibiricus was not significantly influenced by seed abundance—remaining at around 28% during both periods of high and low seed abundance.     

长白山云冷杉针阔混交林不同林隙下幼苗幼树密度及空间分布

2019年8月在云冷杉针阔混交林样地(0.36 hm²),对48个林隙及幼苗(0.2<更新高度RH<1 m)、幼树(RH≥1 m,胸径DBH<5 cm)进行调查,分析林隙大小(<20 m²,小;20～50 m²,中;50～120 m²,大;>120 m²,特大)对林隙内红松、鱼鳞云杉及冷杉幼苗幼树密度和生长指标(高、基径)的短期影响,并采用核密度估计法分析其空间分布规律。结果表明: 云冷杉更新的密度通常随林隙增大而降低,仅对幼树影响显著,小林隙下云冷杉幼树密度分别为0.34和1.74株·m^-2,红松密度不受林隙大小的影响。林隙大小对冷杉幼苗幼树生长指标的影响最大,对红松影响最小,平均最大值多出现在大林隙。红松和云杉幼树的基径和树高最大值均分布在小、中、大林隙东北部,在特大林隙中转移至冠空隙西北部。小林隙有助于幼苗的建立和萌发,可通过择伐冷杉创造小林隙,随后扩大林隙面积(>50 m²)促进幼树生长,需要持续监测来确定林隙大小对森林更新的长期影响。     

Sensitivity to Seed Germination Schedule by Scatter‐Hoarding Pére David's Rock Squirrels During Mast and Non‐Mast Years

Mast seeding by oaks (Quercus) and other seed species has fundamental impacts on the behavior of individual scatter‐hoarding animals as well as their population and community dynamics. Scatter‐hoarding squirrels are highly sensitive to acorn germination schedule and stop germination by removing the embryo of non‐dormant acorns to prevent losses of energy and nutrients by rapid germination. However, we know little about how this behavior is affected by mast seeding. We investigated foraging decisions made by free‐ranging Pére David's rock squirrel (Sciurotamias davidianus) with three species that produce non‐dormant seeds and two species that produce dormant seeds (Fagaceae) during mast and non‐mast years in Central China from 2007–2010. Consistent with the food perishability hypothesis that squirrels make decisions to minimize the perishability of their caches, non‐dormant seeds were hoarded at a lower rate, but had a higher probability of embryo removal than dormant seeds. Compared with non‐mast years, a lower proportion of seeds were harvested during mast years, but a higher proportion of the harvested seeds were hoarded. In addition, the probability of embryo removal in the hoarded seeds was higher during mast years. Squirrels also dispersed seeds at shorter distances during mast years. Moreover, the interactions between mast seeding and seed germination schedule had significant effects on squirrel foraging decisions, including embryo removal. This study is the first to demonstrate that squirrels show greater sensitivity to seed germination potential when seeds are abundant.