A dataset of migration, reproduction, and morphological traits of breeding barn swallow (Hirundo rustica) populations in the tropical region of South China

<p indent="0mm">Understanding the geographic variation among different populations of widely distributed species is crucial for revealing the mechanisms of their adaptive evolution. The Barn Swallow (<italic>Hirundo rustica</italic>), as a model species in ecological research, has limited available data on the breeding and migration ecology of its tropical breeding populations. This gap limits a comprehensive understanding of the species′ adaptive potential, population dynamics, and genetic structure. Based on systematic research conducted between 2021 and 2023 on Barn Swallows breeding in the northern margin of the tropical region of South China (Zhanjiang, Guangdong), this study integrated light-level geolocator-based migration tracking, standardized breeding monitoring, and individual morphological measurements. For the first time, it has constructed a multi-dimensional ecological dataset encompassing the migration paths, breeding parameters, and morphological traits of 20 individual barn swallows, along with three years of baseline breeding ecological parameters at the study site. The dataset is organized into three key subsets: 1) migration trajectory data, which record raw light intensity fluctuations information collected by light-level geolocators along migration routes; 2) reproductive data, detailing crucial parameters such as egg-laying dates, clutch size, number of nestlings; and 3) morphological trait data, which includes ten key morphological indicators, such as body mass, wing length, and tail length. All data were obtained through strict quality control and standardized measurement protocols, ensuring accuracy and comparability. This study contributes essential baseline data on the ecology of barn swallow populations at the northern edge of the tropical region of China. This dataset serves as a valuable resource for exploring key questions in avian adaptive evolution, life-history strategies, and migratory ecology. The publication of this dataset will facilitate cross-population comparative studies of migratory birds, and provide data support for research on migration ecology along the East Asian-Australasian Flyway.