The delayed effect of climatic conditions on pre-fledging nestling haematocrit in a suboscine species in Patagonia

Haematocrit, the proportion of blood comprising erythrocytes, is often used as a proxy of individual condition. Nestling haematocrit is influenced by several factors, but ambient temperature is generally agreed as a key driver. It is unclear which day(s) in embryonic or nestling development are most influential in determining pre-fledgling haematocrit. This is important, because if we are able to identify what day(s) nestlings are physiologically most vulnerable to climatic conditions, this may inform future conservation management and help mitigate the effects. We investigated the effect of ambient temperature, precipitation, body size, brood size, age, food abundance and habitat on nestling haematocrit in Aphrastura spinicauda (thorn-tailed Rayaditos). We collected this data from two climatically different locations in Chile: Northern Patagonia (Pucón) and Sub-Antarctic Patagonia (Navarino Island), located ~1800 km further south. We aimed to identify the key drivers of nestling haemat..., Data were collected from two climatically contrasting sites in Chile: one on Navarino Island (54.932° S, 67.605° W), which was ~5 km in radius, and the other is in Pucón (39.272° S, 71.977° W), which was ~10 km in radius and ~1800 km north of the other population. Data were collected in two years from September 2018 – February 2019 and from September 2019 – February 2020, during the Rayadito breeding season. These data were stored and processed in Microsoft Excel and R in RStudio v3.5.3 statistical software., Microsoft excel (CSV files) and R in RStudio v3.5.3 statistical software.

血细胞比容（Haematocrit）指血液中红细胞所占的体积比例，常被用作评估个体生理状态的替代指标。雏鸟血细胞比容受多种因素影响，但环境温度普遍被认为是关键驱动因子。目前尚不明确胚胎发育或雏鸟发育阶段的哪一（几）天，对确定出飞前雏鸟血细胞比容的影响最为显著。这一问题具有重要研究与应用价值：若能明确雏鸟在生理上对气候条件最为敏感的时段，可为未来的野生动物保育管理工作提供科学参考，并助力缓解气候变化带来的负面影响。
我们以棘尾雷雀（Aphrastura spinicauda，thorn-tailed Rayaditos）为研究对象，调查了环境温度、降水量、体型、窝雏数、日龄、食物丰度及生境对其雏鸟血细胞比容的影响。本研究的数据采集自智利两处气候差异显著的区域：北巴塔哥尼亚的普孔（Pucón），以及向南约1800公里的亚南极巴塔哥尼亚纳瓦里诺岛。
本次研究的实际采样样地为智利两处气候迥异的区域：一处位于纳瓦里诺岛（南纬54.932°，西经67.605°），样地半径约5公里；另一处位于普孔（南纬39.272°，西经71.977°），样地半径约10公里，两处种群的地理间距约1800公里。数据采集于两个年度的雷雀繁殖季：2018年9月至2019年2月，以及2019年9月至2020年2月。所有数据均通过微软Excel（Microsoft Excel，CSV格式）及RStudio v3.5.3版本的R统计软件进行存储与处理。