The nutritional ecology of small mammals

我们研究了阿尔伯塔省西南部短夏环境中鹿鼠和田鼠的生活史，那里的成熟年龄往往推迟到一岁，雏鸟的存活率可变，成虫的存活率很高。这些人口很容易受到干扰，因为周转率和从下降中恢复的速度很慢。新陈代谢速率由环境温度决定，当温度接近零时，新陈代谢速率接近最高可持续水平，将繁殖限制在短暂的夏季。夏季的繁殖没有能量上的限制。我们的食物补充研究发现，营养限制了雏鸟的生长、成熟和春季繁殖的开始，但对雏鸟或成鸟的存活没有影响。我们目前的研究调查了鹿、老鼠和田鼠对天然饲料质量变化的人口统计学反应。鹿鼠是杂食性动物(主要是种子和无脊椎动物，无脊椎动物代表着高质量的饮食)，毛发样本中稳定的氮同位素被用来识别它们饮食质量的季节和年度差异。田鼠主要是草食性和肉食性，种子和绿色植被的适口性(以及植物种类的可获得性)正被用来确定它们饮食质量的季节和年度差异。我们未来的研究将特别集中在小鼠和田鼠对针叶树种子生产的人口和种群反应，植物次生化合物的生物化学，食物储存在改善难吃植物物种质量方面的作用，以及不同窝大小的田鼠之间的饮食质量比较。

We study the life histories of deer mice and voles in short-summer environments in southwestern Alberta, where age at maturation is often delayed to one year of age, survival of nestlings is variable, and survival of adults is high. These populations are vulnerable to disturbance because turn-over rates and recovery from declines are slow. Rates of metabolism are dictated by ambient temperatures and approach maximum sustainable as temperatures approach zero, constraining reproduction to a short summer season. There are no energetic constraints on reproduction during the summer. Our food supplementation studies have identified nutritional constraints on nestling growth, maturation, and the initiation of breeding in the spring but no effect on nestling or adult survival. Our current research investigates the demographic responses of deer mice and voles to changes in the quality of natural diets. Deer mice are omnivorous (mostly seeds and invertebrates, with invertebrates representing a high quality diet) and stable isotopes of nitrogen in hair samples are being used to identify seasonal and annual differences in their diet quality. Voles are mostly herbivorous and granivorous and the palatability of seeds and green vegetation (and the availability of plant species) are being used to identify seasonal and annual differences in their diet quality. Our future research will focus specifically on demographic and population responses of mice and voles to conifer seed production, the biochemistry of plant secondary compounds, the role of food storage in improving the quality of unpalatable plant species, and a comparison of diet quality among voles with different litter sizes.