DISSERTATION RESEARCH: Ecophysiology of Hummingbirds Along an Altitudinal Gradient: An Integrative Approach

论文研究：蜂鸟沿海拔梯度的生态生理学：综合方法

• 批准号: 9902155
• 负责人: Robert Dudley
• 金额: $ 0.99万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2001-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9902155&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Ecophysiology; Hummingbirds; Along

North American hummingbirds are specialized to feed on the energy-rich diet provided by flower nectar. These diminutive birds gain access to flowers through their unique form of locomotion: hovering flight. Hummingbirds are typically found in all North American habitats with abundant flowers,including very high altitude meadows such as those that occur in the Colorado Rocky Mountains. The rufous and broad-tailed hummingbirds compete for floral resources in the Rockies across a altitudinal range spanning 2500 meters. The two species weigh about the same but the wings of the rufous hummingbird are on average only 83% of the size of the broad-tailed hummingbird's wings. Because air is thinner in the mountains, species with large wings can more easily generate enough lift to fly at high altitudes. However, species with larger wings are at a disadvantage at low altitudes because they are less agile than species with small wings. Small-winged species outcompete large-winged hummingbirds at low altitudes, so there is a trade-off between competitive ability and altitudinal range. The PIs predict that rufous hummingbirds will outcompete broad-tailed hummingbirds at low elevations and thus dominate the best resources. Conversely, the rufous will be less competitive at high elevations due to high costs of flight and thus relegated to the less preferred resources. The PIs also predict that the increased costs of flight and related competitive behavior will be influenced by the density of the air rather than by oxygen availability.

北美蜂鸟专门以花蜜提供的富含能量的食物为食。这些小型鸟类通过其独特的运动形式获得花朵：盘旋飞行。蜂鸟是典型的发现在所有北美栖息地与丰富的鲜花，包括非常高海拔的草地，如那些发生在科罗拉多落基山脉。棕褐色和宽尾蜂鸟在落基山脉跨越2500米的海拔范围内争夺花卉资源。这两种蜂鸟的重量差不多，但棕褐色蜂鸟的翅膀平均只有宽尾蜂鸟翅膀大小的83%。由于山区的空气较稀薄，翅膀大的物种更容易产生足够的升力在高海拔地区飞行。然而，翅膀较大的物种在低空处于不利地位，因为它们不如翅膀较小的物种敏捷。在低海拔地区，小翅膀的蜂鸟比大翅膀的蜂鸟更有竞争力，所以在竞争能力和海拔范围之间存在权衡。PI预测，在低海拔地区，棕褐色蜂鸟将胜过宽尾蜂鸟，从而占据最好的资源。相反，红棕色在高海拔地区由于飞行成本高而竞争力较低，因此被降级为不太受欢迎的资源。PI还预测，飞行成本的增加和相关的竞争行为将受到空气密度的影响，而不是氧气的可用性。