复合因子对东方田鼠能量收益的作用

One of the classical abstractions in foraging theory, the patch model, predicts that animals would reside in patches as long as their instantaneous food intake rate exceeds the average intake rate across patches available. Therefore, intake rate has been generally recognized as a key indicator of herbivore's energy gains and residence time in food patch. Mammalian herbivores functional responses models that describe the relationship between intake rate and plant availability includ only two behavioral parameters, biting time and handling (chewing and swallowing) time. In small herbivores, however, food selection, vigilance driven by nature and predation risk, and kinship that partly occupy its foraging time, may also affect the functional response and energy gains. Previous studies of large herbivores showed little effect of vigilance on intake rate; they assumed that the handling time is often compatible with vigilance. However, these assumptions are not fit to small herbivore animal's foraging process. Here we have derived two new mechanism models, the model of functional response and the model of gain function, both of them incorporate the food selection time, the foraging interruption time initiated by instinctive vigilance, kinship and vigilance under predation risk, and the handling time that is compatible with vigilance. These models allow for the status that food selection, foraging interruption and handling prove entirely incompatible. To investigate whether food selection, kinship and predation risk would affect the functional response and energy gains in a small mammalian, reed vole (Microtus fortis), we plan to catch voles in the area of Dongting Lake of Hunan province. The wild - caught individuals are brought to the laboratory and breed. Mother and F1 are applied in experiment. The predator siberian weasel (Mustela sibirica) will also be caught there. We plan to measure behavioral parameters of vole foraging in artificial patches of spatial food heterogeneity integrated with kinship and predation risk. Using focus sampling method, we record foraging process of single vole or target individual of a family in patch with a camera. The nitrogen content of the food would be measured with Half a trace KaiShi method, and the fiber content of the food with Conventional stalling method. Thus, we achieve all the foraging behavioral parameters such as foraging time, residence time, intake rate, energy gains, and et al. We design three model tests. First, we examine whether these models are statistically fit to the data. Second, we examine whether these behavioral parameters like intake rates, energy gains and residence time were affected by selecting, cropping, handling, or foraging interruption. Finally, we compare observed parameters with those predicted by the mechanism models.

植食性哺乳动物功能反应描述了采食和处理食物对摄入率的制约作用，但未能反映小型动物食物选择时间和觅食中断时间对摄入率、能量收益及停留时间的影响。探讨复合因子食物空间异质性、亲缘关系及捕食风险对功能反应格局和能量收益的作用，有助于揭示小型动物觅食行为的适应性策略。本项目拟以东方田鼠为研究对象，在调控食物空间异质性条件下，整合亲缘关系和捕食风险因子，采用焦点取样摄像技术、半微量凯氏法和常规静置法，测定觅食行为参数食物选择时间、采食和处理食物时间、觅食中断时间、觅食回合时间、摄入率、能量收益和停留时间等；建立新的功能反应机制模型和能量收益函数机制模型；分析模型拟合效果；检验食物空间异质性、亲缘关系及捕食风险对东方田鼠觅食行为参数摄入率、能量收益和停留时间及功能反应格局的独立及交互作用；检验和评价功能反应模型和能量收益函数模型的预测性。

植食性小型哺乳动物的觅食行为是其对特定生境的适应性产物。其在觅食活动中伴有各种警觉行为动作如扫视、静听、嗅闻等。复杂多变的觅食环境是否通过作用于动物觅食和警觉行为而影响其能量收益。实验条件下，人工构建均质性食物斑块，测定东方田鼠觅食行为过程，检验视野受阻对东方田鼠觅食行为及摄入率的影响；构建空间异质性食物斑块，检验空间异质性食物资源对东方田鼠食物选择及能量收益的作用；以流浪猫（Felis catus）作为捕食风险源检验捕食风险对东方田鼠食物选择及能量收益的作用。. 结果发现，① 个体在不同程度视野受阻条件下食物摄入率无显著差异。在不同视野受阻条件下，个体能通过调整各采食回合内警觉行为动作的发生频次和持续时间，维持觅食回合内总的觅食中断时间的稳定，进而保证进食时间的稳定。东方田鼠在不同程度的视野受阻条件下均能通过行为变异和优化使摄入率保持稳定。说明，东方田鼠在警觉强度上的变化不能反映觅食中断所带来的食物收益减损的代价，但觅食活动中各警觉动作的持续时间的变异却能够明确指示个体摄入率的动态变化。② 空间异质性食物斑块能显著性降低动物的能量收益。异质性斑块中，动物对优质食料植物表现出极强的选择性。因个体搜寻、辨识、选择较为优质的食物项目，降低了采食率，个体采食口量亦显著性减低。雄体的采食口量及能量收益显著高于雌体的雌体的。说明，小型植食性哺乳动物觅食过程中的搜寻、辨识和选择行为能明显降低能量收益；东方田鼠对空间异质性食物的反应存在性别差异。③ 捕食风险能显著降低东方田鼠对优质食料植物的选择性，使其采食的食物项目更加种类广泛；捕食风险能显著降低实验个体的扫视行为时间，增大盯视捕食者时间；东方田鼠能通过警觉行为动作优化，保持觅食中断时间的稳定，尽可能地维持其能量收益。.①在视野受阻程度不同的觅食斑块上，东方田鼠可通过觅食活动中警觉行为动作的变异和优化，使其摄入率维持稳定；②小型植食性哺乳动物觅食过程中搜寻、辨识和选择食料项目的行为动作，会延长 觅食下一口食物的时间，降低个体单位时间能量摄入效率；③捕食者存在时，个体通过减少扫视行为持续时间，增加视觉盯视捕食者的行为时间，维持觅食中断时间的稳定，以便尽可能维持能量摄入效率。因此，以觅食活动中警觉引起的觅食中断时间代价为线索，检验其对能量摄入率的影响，是评价植食性小型哺乳动物在不同生境觅食适应性策略的有效方法。