EAGER: Utilizing arthropod prey species' phenology, availability, and life history at the deciduous-boreal ecotone to assess bird range geographic shifts

虽然有很多证据表明，植物和动物正在改变它们的栖息地，以应对气候的变化，但它们是如何做到这一点的，以及一个物种的变化是否会影响其他物种的变化，目前还不清楚。例如，鸟类可以很容易地从一个地区迁徙到另一个地区，但它们赖以为生的植物和昆虫却不能。这个项目探索的可能性是，鸟类可能会在一个新的地区找到合适的气候条件，但由于它们通常以植物和昆虫为食，无法迁移到那里，因此无法迁移到那里。缅因州的研究人员将使用DNA来测量一种森林停止而另一种森林开始的广阔区域内鸟类的饮食。他们将测试两种可能的解释，以解释为什么一些鸟类正在向一种以前没有出现过的森林类型扩张，而另一些物种似乎被困在一个地方并正在经历衰退。第一种解释是，鸟类所使用的食物类型对于数量增加的物种比数量减少的物种更容易获得。第二种解释是，有食物的时间和数量减少的物种开始繁殖的时间不匹配。研究人员将让本科生、公民科学家和公立学校的孩子参与这个项目；每个人都将共同努力，收集数据，发现鸟类、它们的食物和气候之间的联系。利用16S线粒体和细胞色素氧化酶I基因的元条形码技术，对北方落叶交错带内鸟类食用的昆虫和蜘蛛进行鉴定。将对三组食虫森林鸟类进行采样：“前沿”物种（那些从南部/落叶范围扩展的物种），“后缘”物种（那些正在减少并且通常出现在北方森林的物种）和栖息地通用型物种（那些在整个区域或栖息地类型中更广泛地出现的物种）。将根据时间（物候）和地点（生境）对食物的供应和利用进行评估。猎物的生活史、范围和行为特征将被用来比较三种鸟类的饮食。食物使用的措施也将与繁殖时间和繁殖鸟类调查的区域长期人口趋势进行比较，以审查食物供应和使用对人口可能产生的影响。

While there is much evidence that plants and animals are changing where they live in response to shifts in climate, it remains unclear how they do so and whether changes in one species affect those in other species. Birds, for example, can move easily from one region to another, but the plants and insects they depend on for food cannot. This project explores the possibility that birds may find suitable climatic conditions in a new area but be deterred from moving there because the plants and insects they typically feed on have not been able to move there. Researchers in Maine will use DNA to measure the diets of birds in a broad area where one type of forest stops and another type begins. They will test two possible explanations for why some birds are expanding into one of the forest types where they did not occur previously, while others species appear stuck in one place and are experiencing declines. The first explanation is that the type of food used by the birds is more available for the expanding species than for the declining species. The second explanation is that there is a mismatch in timing between the when food becomes available and when the declining species start to breed. Researchers will engage undergraduate students, citizen scientists, and public school children in the project; everyone will work together to collect data and to discover the links between birds, their food, and climate. The insects and spiders consumed by birds within the boreal-deciduous ecotone will be identified using metabarcoding of 16S mitochondrial and cytochrome oxidase I genes. Three groups of insectivorous forest birds will be sampled: "leading edge" species (those that are expanding from a southern/deciduous range), "trailing edge" species (those that are declining and typically occur in boreal forest), and habitat generalists (those that occur more broadly across the region or habitat types). Food availability and use will be assessed relative to both time (phenology) and place (habitat). Life history, range, and behavioral characteristics of prey items will be used to compare the diets of the three bird groups. Measures of food use will also be compared to timing of breeding and regional long-term population trends from the Breeding Bird Survey to examine possible effects of food availability and use on demography.