Data for: Behavioural responses of songbirds to preen oil odour cues of sex and species

DATA: Results from 3 behavioural trials and 2 analsyes of similarities (of preen oil chemical composition).

Experiment 1: Conspecific preen oil versus absence of preen oil odour cues
We presented subjects with a two-choice test involving same-sex preen oil in one maze arm, and residual solvent only in the other arm.

Experiment 2: Opposite-sex versus same-sex conspecific preen oil
We presented subjects with a two-choice test involving opposite-sex preen oil in one maze arm and same-sex preen oil in the other arm.

Experiment 3: Cowbird preen oil versus absence of preen oil odour cues
We presented subjects with a two-choice test involving preen oil from a female cowbird in one maze arm and residual solvent only in the other arm.

Preen Oil Analysis:
We quantified the relative size of each chromatogram peak identified by GC-FID, retaining for analysis only peaks that comprised ≥ 0.1% of the total chromatogram area. To prevent large peaks from disproportionately influencing distance measures, we normalized the data using the ‘range’ method in the decostand function in the ‘vegan’ package in R. We log x + 1 transformed the normalized dataset then constructed pairwise matrices of Bray-Curtis dissimilarity, which we interpret as chemical distances between samples. To assess the statistical significance of chemical differences between the sexes and between species, we used nonparametric analysis of similarities (ANOSIM) with 10,000 iterations.

数据集说明：3项行为学试验与2项羽油化学成分相似性分析的结果。

实验1：同种羽油与无羽油气味线索
本研究为受试对象设置双选择实验：将同性同种羽油置于迷宫一侧臂，另一侧臂仅放置残留溶剂。

实验2：异性同种羽油与同性同种羽油
本研究为受试对象设置双选择实验：将异性同种羽油置于迷宫一侧臂，另一侧臂放置同性同种羽油。

实验3：牛鹂羽油与无羽油气味线索
本研究为受试对象设置双选择实验：将雌性牛鹂的羽油置于迷宫一侧臂，另一侧臂仅放置残留溶剂。

羽油化学成分分析：
我们对气相色谱-火焰离子化检测器（GC-FID）识别出的各色谱峰的相对面积进行定量，仅保留占总色谱面积≥0.1%的峰用于后续分析。为避免大峰对距离度量造成不成比例的影响，我们采用R语言'vegan'包中`decostand`函数的极差标准化（range）方法对数据进行归一化处理。我们对归一化后的数据集进行log(x+1)对数转换，随后构建布雷-柯蒂斯（Bray-Curtis）相异度成对矩阵，并将该矩阵视为样本间的化学距离。为评估性别间与物种间化学差异的统计学显著性，我们采用置换次数为10000次的非参数相似性分析（ANOSIM）进行检验。