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Breeding Records Suggest a Year-round Barn Swallow Population in Imphal Valley

Adult barn swallows sampled in Imphal Valley, Manipur
Research · Ecology

Field surveys in Manipur documented a breeding population of barn swallow (Hirundo rustica) in the Imphal Valley that the researchers identified as resident throughout the year. Published on 30 March 2026, the study describes this as the first documented resident breeding population of the species in northeast India.

Researchers surveyed Manipur in 2022 and 2023. In 2023 they located barn swallow nests at about 50 properties in the central Imphal Valley and captured 45 adults during the non-breeding season, including 26 males and 19 females. Plumage and morphometric measurements were compared with published and museum information for barn swallow subspecies reported from India.

Map of barn swallow breeding and nest locations in Manipur and Imphal Valley
Breeding and nest records used to place the Imphal Valley population in its regional context. Figure 2 from Kaur & Kumar (2026), Journal of Wildlife Science, CC BY 4.0.

Morphology did not resolve the subspecies identity

Male wing length ranged from 111 to 123 millimetres and female wing length from 111 to 122 millimetres. The measurements overlapped with available museum data for H. r. rustica, H. r. gutturalis and H. r. tytleri, so the researchers could not assign the Imphal Valley birds unambiguously to a single subspecies. The birds also showed substantial variation in throat, breast-band and underpart coloration.

Plumage variation in adult barn swallows sampled in Imphal Valley, Manipur
Plumage variation among adult barn swallows sampled in the Imphal Valley. Figure 3 from Kaur & Kumar (2026), Journal of Wildlife Science, CC BY 4.0.

Evidence supported year-round residency

The population was identified as year-round resident from the continued presence of adults at nesting sites during both breeding and non-breeding seasons, information from property owners, and ringing of adults with uniquely coded metal bands that confirmed site fidelity over time.

The authors propose two non-mutually exclusive hypotheses for the population’s origin. One is a secondary colonisation involving H. r. tytleri and possible historical genetic exchange with H. r. erythrogaster. The other is a shift in migratory strategy in which Barn Swallows wintering in northeast India reduced or abandoned long-distance migration and became sedentary. Favourable climate and available nesting sites may also have helped the breeding population establish, but these ideas remain to be tested.

They recommend geolocators or stable isotopes to examine individual movements in more detail, genomic analyses to clarify subspecies identity and relationships with other populations, and long-term demographic monitoring to assess recruitment and persistence of the breeding population.

Sources and image credit

  1. Kaur, A., & Kumar, R. S. (2026). Barn swallows of the Imphal Valley – a potential case of past climatic events leading to year-round residency in the population in Northeast India. Journal of Wildlife Science, 3(1), 35–40. https://doi.org/10.63033/JWLS.GXZU3002Primary open-access article published 30 March 2026 under CC BY 4.0. Surveys in Manipur in 2022 and 2023 documented a resident breeding population in the Imphal Valley; 45 adults were captured and morphometric overlap prevented unambiguous subspecies identification.

Image: Kaur & Kumar (2026), Figure 3 / Journal of Wildlife Science — adult barn swallows sampled in Imphal Valley, Manipur; photographic crop from the study figure. · CC BY 4.0 · Source

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