Stable isotope analysis reveals shifts in diet of a breeding montane bird

Insectivorous breeding birds require access to high quality prey to produce a successful nest. A lack of suitable prey (e.g., low nutritional quality or low invertebrate availability) that fulfill energetic demands can negatively affect nestling growth and survival. In high elevation ecosystems (>900 m), cooler and wetter climates can have negative influences on invertebrate availability which in turn can affect bird diets. Yet we lack studies of how diet composition changes over elevation gradients. Here, we assessed the diet of Swainson’s Thrush (Catharus ustulaus) within the White Mountains, New Hampshire using stable isotope analysis and DNA metabarcoding. We found that the proportion of detritivore arthropods in thrush diets increased with elevation, while the proportion of predatory arthropods and overall niche-width declined. Further, we show that high-elevation thrushes had diets that were different in composition, but similar in diversity to thrushes at low-elevation sites. ..., , , # Description of the data and file structure

This data describes how we used stable isotope mixing models (MixSIAR) to determine the proportion of dietary prey items within the diet of a montane breeding bird, the Swainson's Thrush along an elevation gradient. We collected prey items (invertebrates) and took blood samples of consumers across an elevational gradient to understand if dietary items changed with elevation. All helpful code is attached in the section below. Raw data used in code/analysis is all under \"Deckel_Data\" excel file, except for 3 .cvs files that were used in SIMPER dietary analysis (swth_community, swth_community2, and swth.whole). DNA metabarcoding data is labeled \"SWTH_diversity\" in the \"Deckel_Data\" excel file.

\##Detailed data context description
In the \"Deckel_Data\" excel file, below is a brief explanation for content and units used:
-Weight (milligrams [mg])
-Bin symbolizes 1 of 4 elevational bins that invertebrates or samples were put into, depending on wha...

食虫性繁殖鸟类需要获取高质量猎物方可成功育雏。无法满足能量需求的适宜猎物匮乏（如营养质量低下或无脊椎动物可获得性不足），会对雏鸟的生长与存活产生负面影响。在海拔高于900米的高海拔生态系统中，冷湿气候会对无脊椎动物的可获得性造成不利影响，进而影响鸟类的食谱组成。然而目前学界尚缺乏关于食谱组成随海拔梯度变化的相关研究。本研究以新罕布什尔州怀特山脉的斯温氏鸫（Catharus ustulaus）为研究对象，利用稳定同位素分析（stable isotope analysis）与DNA宏条形码（DNA metabarcoding）技术评估了其食谱组成。研究发现，鸫类食谱中腐食性节肢动物的占比随海拔升高而上升，而捕食性节肢动物占比与整体生态位宽度则随之下降。此外，本研究还表明，高海拔地区的斯温氏鸫，其食谱组成与低海拔种群存在差异，但食谱多样性与低海拔个体并无显著不同。

# 数据与文件结构说明
本数据集记录了本研究如何通过稳定同位素混合模型（stable isotope mixing models, MixSIAR），测算沿海拔梯度分布的山地繁殖鸟类——斯温氏鸫的食谱中各类猎物的占比。研究人员沿海拔梯度采集了猎物样本（无脊椎动物）以及消费者（斯温氏鸫）的血液样本，以探究食谱组成是否随海拔发生变化。下文附所有可用的分析代码。代码与分析中使用的原始数据均存放于"Deckel_Data"Excel文件中，仅3个用于SIMPER食谱分析的.csv文件除外，这三个文件分别为swth_community、swth_community2与swth.whole。DNA宏条形码数据在"Deckel_Data"Excel文件中以"SWTH_diversity"命名。

## 详细数据背景说明
在"Deckel_Data"Excel文件中，以下为各字段的内容与单位简要说明：
- 体重（单位：毫克[mg]）
- 分级编号（Bin）代表将无脊椎动物或样本归入4个海拔分级中的1个，具体划分依据为……