Sexual dimorphism does not translate into foraging or trophic niche partitioning in Peruvian boobies (Sula variegata)

Intraspecific competition can lead to sexual segregation of diets or foraging behaviors in seabirds, and in some species the resulting niche partitioning is facilitated by sexual dimorphism. However, environmental stochasticity can mediate intraspecific competition and thus the extent of sex-based partitioning. The Peruvian booby (Sula variegata) is a sexually dimorphic seabird endemic to the Humboldt Current System (HCS), a highly variable environment due to El Niño Southern Oscillation. To determine the extent of sexual partitioning in this species, we quantified the foraging and trophic niches of breeding Peruvian boobies at Isla Guañape Norte, Peru in two years with different oceanographic conditions and nesting propensity. Morphometrics, GPS-tracked foraging behaviors, diets via regurgitates, and isotopic niches were compared between sexes and years where sample sizes permitted. Although females were larger and in better body condition than males, breeding Peruvian boobies in our s..., We sampled Peruvian boobies from Isla Guañape Norte (8.545°S, 78.964°W), an island located approximately 9 km offshore of northern Peru, in December 2016 and in November 2019. According to the Índice Costero El Niño, birds were experiencing weak El Niño conditions (0.47) in December 2016, and neutral conditions (-0.40) in November 2019.
Morphometrics measurement collection and processing
We sampled Peruvian boobies in December 2016 and in November 2019. Breeding adults were captured at the nest soon after dawn (06:00–08:00) using a monofilament lasso attached to a 5-meter telescopic pole. In 2016, adults selected for capture (14 females and 4 males) had eggs and/or chicks less than 7 days old. In 2019, the selected adults (20 females and 12 males) had nests containing chicks between 3–8 weeks old and represented 2% of individuals found breeding on the study plot. Both parents were present at the nest during capture, ensuring that chicks or eggs were not left unattended. Sex, weight (g),..., , # Sexual dimorphism does not translate into foraging or trophic niche partitioning in Peruvian boobies (Sula variegata)

[https://doi.org/10.5061/dryad.kd51c5bdv](https://doi.org/10.5061/dryad.kd51c5bdv)

This dataset contains data collected in the field (GPS tracks, morphometrics, stable isotope, prey data) as well as processed data derived from field movement data through the use of various R packages (EMbC and foraging trip data).

## Description of the data and file structure

This dataset contains 6 data files ('data_PEBO_embc', 'data_PEBO_foraging_trips', 'data_PEBO_gps', 'data_PEBO_morphometrics_isotope', 'data_PEBO_prey_measurements', and 'data_PEBO_regurgitates'). Observations in separate data files are linked through an individual key ID \"bird_id\" and/or trip ID \"trip_id\". However, some unique observations appear only in 'data_PEBO_prey_measurements' and 'data_PEBO_regurgitates'.

###### 'data\_PEBO\_embc'

This file contains the individual GPS points of foraging trips along w...

种内竞争（intraspecific competition）可导致海鸟出现食性或觅食行为的性分化，部分物种的此类生态位分化（niche partitioning）由性二态性（sexual dimorphism）介导。然而，环境随机性可调节种内竞争，进而改变基于性别的生态位分化程度。秘鲁鲣鸟（Sula variegata）是具有性二态性的海鸟，为洪堡洋流系统（Humboldt Current System, HCS）的特有物种，该系统受厄尔尼诺-南方涛动（El Niño Southern Oscillation）影响，环境高度多变。为明确该物种的性生态位分化程度，我们于两个海洋环境条件与繁殖倾向均存在差异的年份，在秘鲁瓜纳佩北岛（Isla Guañape Norte）对繁殖期秘鲁鲣鸟的觅食与营养生态位进行了量化分析。当样本量允许时，我们对不同性别与年份的个体形态测量数据、GPS追踪（GPS-tracked）的觅食行为、反吐食物获取的食性数据以及同位素生态位进行了对比。尽管雌性个体体型更大、身体状况优于雄性，但本研究中的繁殖期秘鲁鲣鸟……我们于2016年12月与2019年11月，在秘鲁北部近海约9公里处的瓜纳佩北岛（8.545°S, 78.964°W）开展了秘鲁鲣鸟采样。根据厄尔尼诺海岸指数（Índice Costero El Niño），2016年12月调查区域处于弱厄尔尼诺状态（指数值0.47），2019年11月则为中性状态（指数值-0.40）。

形态测量数据的收集与处理
我们分别于2016年12月与2019年11月开展秘鲁鲣鸟采样。繁殖成鸟于黎明后（06:00–08:00）在巢位被捕获，使用固定于5米伸缩杆的单丝套索。2016年捕获的成鸟（14只雌性、4只雄性）的巢内卵或雏鸟日龄均小于7天；2019年捕获的成鸟（20只雌性、12只雄性）的巢内雏鸟日龄为3~8周，该采样个体占研究样地繁殖个体总数的2%。捕获时双亲均在场于巢位，确保雏鸟或卵不会被单独留置。性别、体重（g）……

# 性二态性未导致秘鲁鲣鸟（Sula variegata）出现觅食或营养生态位分化

[https://doi.org/10.5061/dryad.kd51c5bdv](https://doi.org/10.5061/dryad.kd51c5bdv)

本数据集包含野外采集数据（GPS轨迹、形态测量数据、稳定同位素（stable isotope）数据、猎物数据），以及通过多种R包（R package）（EMbC与觅食行程数据工具）对野外移动数据进行处理后得到的衍生数据。

## 数据与文件结构说明
本数据集包含6个数据文件：`data_PEBO_embc`、`data_PEBO_foraging_trips`、`data_PEBO_gps`、`data_PEBO_morphometrics_isotope`、`data_PEBO_prey_measurements`及`data_PEBO_regurgitates`。不同数据文件中的观测值通过个体唯一标识符`bird_id`和/或行程唯一标识符`trip_id`进行关联。但部分唯一观测值仅出现在`data_PEBO_prey_measurements`与`data_PEBO_regurgitates`中。

###### `data_PEBO_embc`
该文件包含觅食行程的个体GPS点数据……