Fitness consequences of diet choice in waterbirds of agricultural and natural landscapes

最近的农业做法导致栖息地多样性减少，从而改变了野生动物的食物供应。高质量的食物是繁殖的主要因素，而繁殖又反过来推动人口发展。虽然农业生境的食物丰富度一般较高，但食物多样性往往较低。食物供应如何共同影响个人层面上的健身很少被评估，主要是由于难以估计个人的饮食选择。这项拟议中的研究将首次提供经验证据，说明个人的健康状况如何随饮食选择而变化，以及不同栖息地的食物供应如何影响饮食选择的宽度。目标物种将是哑天鹅天鹅，一种显然从农业中获利的水鸟。该项目将调查自然和农业栖息地的天鹅种群，在这些栖息地中，天鹅可能依赖特定的栖息地觅食。在这些群体中，将通过比较潜在食物中的稳定同位素比率与雏鸡和亚成体血液和组织中的稳定同位素比率来评估个体饮食选择。因此，个人的饮食选择将衡量特定生境的食物供应，并在人口之间进行比较。此外，通过同时测量雏鸡的生长轨迹、免疫能力和存活率，饮食选择水平可以直接与适合度相关。此外，涉及生殖成功的长期数据可以概括饮食选择如何影响健身以及人口如何科普农业景观中的食物供应。

Recent agricultural practices lead to a decrease in habitat diversity and thereby changed food availability for wild animals. High-quality food is a major factor for reproduction, which in turn drives population development. Although food abundance is generally high in agricultural habitats, food diversity tends to be low. How food availability jointly affects fitness on the individual level has rarely been assessed, mainly due to difficulties in estimating individual diet choice. The proposed study will for the first time provide empirical evidence for how an individual¿s fitness varies with its diet choice and how food availability in different habitats affects diet-choice width. The target species will be Mute Swan Cygnus olor, a waterfowl that has apparently profited from farming. The project will investigate swan populations of natural and agricultural habitats, where individuals may rely on specific habitats for foraging. In these populations, individual diet choice will be assessed by comparing stable-isotope ratios in potential food with stable-isotope ratios in blood and tissues of chicks and subadults. Thus, individual diet choice will be measured with respect to habitat-specific food availability, and compared between populations. Furthermore, the level of diet selection can be directly related to fitness by simultaneously measuring chick growth trajectories, immunocompetence and survival of chicks. Additionally, involving longterm data of reproductive success allows generalisations of how diet choice affects fitness and how populations cope with food availabilities in agricultural landscapes.