Ecophysical Limits to Northern Breeding Distributions of Arctic Sandpipers

9423522 Ricklefs北极高纬度地区的环境对生物的生长有两个关键限制， 多种生命形式的存在。 其中之一包括极端的物理环境条件：寒冷的温度，高风速和低降水。 另一个是生长季节的干旱。 这种环境对鹬（Scolopacidae）来说尤其严酷，它们在北极的繁殖地只呆两个月，而且它们的雏鸟是最小的温血动物之一。 该研究项目将利用详细测量的生长和发育，能量，热环境，食物供应，和父母的照顾，发现这些鸟类如何利用北极环境如此成功。 寒冷的温度需要产生代谢热的高能力;短繁殖季节需要快速生长。因此，低温和短季节的综合压力似乎会推动小型恒温动物 在高纬度的北极地区达到极限。 解决生长速率和产热这两个相互冲突的功能之间的折衷问题，是理解生物体的设计如何与其环境设置相关联的一个很好的模型。现场和实验室测量将用于确定关系的形式，并量化在一个数学模型中的系数的阿托珀酸小鸡。 该模型的基本要素包括小鸡的内部组织和小鸡与环境的关系。该模型随着雏鸡的生长而不断变化，并且通过将生长速率与组织的功能能力和功能能力与达到的成年尺寸的比例相关的表达式来模拟生长。 实验室和现场工作将提供数据，以评估阿托匹酸鸡模型。 实验室调查将集中在能量预算的组成部分，小鸡产生热量的能力 响应于冷应激，从B体损失热量，包括 由呼吸道表面的蒸发和身体冷却的耐受性引起的。对散养雏鸡的观察 自然的家庭群体，在可行的情况下使用无线电标记的个体，将有助于验证围栏鸟类的结果。 将不断监测热环境条件和食品供应情况，以提供有关牧场的数据。 以及这些因素的时间变异性。

9423522 Ricklefs The environment of the high arctic imposes two critical limits to the existence of many forms of life. One includes the extreme physical conditions of the environment: cold temperatures, high wind velocities, and low precipitation. The other is the briefness of the growing season. This environment is especially stringent for sandpipers (Scolopacidae), which occupy their arctic breeding grounds for as little as two months, and whose chicks are among the smallest of warm-blooded animals. This research project will utilize detailed measurements of the growth and development, energetics, thermal environment, food supply, and parental care of scolopacid chicks to discover how these birds exploit the arctic environment so successfully. Cold temperatures require a high capacity for generating metabolic heat; short breeding seasons require rapid growth. Therefore, the combined stresses of low temperature and short season would seem to push small homeotherms to the limit in the high arctic. The problem of resolving compromises between the conflicting functions of growth rate and heat generation is an excellent model for understanding how the design of the organism relates to its environmental setting. Field and laboratory measurements will be used to determine the forms of relationships and quantify the coefficients in a mathematical model of the scolopacid chick. The essential elements of the model encompass the internal organization of the chick and the relationship of the chick to its environment. The model changes continuously as the chick grows, and growth is simulated by expressions relating growth rate to functional capacity of tissues and functional capacity to the proportion of adult size achieved. Laboratory and field work will provide data to evaluate the scolopacid chick model. Laboratory investigation will focus on components of energy budgets, capacity of chicks to generate heat in response to cold stress, loss of heat from the b ody, including that caused by evaporation from the respiratory surfaces, and tolerance of body cooling. Observations of free-ranging chicks in natural family groups, using radio-tagged individuals where practical, will help to validate the results from penned birds. Conditions of the thermal environment and the availability of food items will be monitored continuously to provide data on the range and temporal variability of these factors.