Microhabitat Segregation of Co‐Existing Nightjar Species in The Gambia

TL;DR

This study shows that two similar nightjar species in The Gambia avoid each other at small scales but coexist at larger scales, suggesting niche partitioning and highlighting the importance of rice fields for their foraging.

Contribution

The study provides the first evidence of spatial niche partitioning in nightjars and emphasizes rice fields as critical foraging habitats in tropical ecosystems.

Findings

Long-tailed Nightjars were more abundant than Standard-winged Nightjars, especially inside rice fields.

The two species co-occurred at landscape scales but avoided each other at finer spatial scales (<500 m).

Rice fields were identified as important foraging habitats for both nightjar species.

Abstract

The coexistence of nocturnal bird species in tropical ecosystems remains poorly understood, primarily due to the difficulty of detecting and monitoring these elusive organisms. We studied the spatial distribution of two ecologically similar nightjar species, the Long‐tailed Nightjar
Caprimulgus climacurus
and Standard‐winged Nightjar
Caprimulgus longipennis
, in The Gambia. Under the assumption that competition is particularly intense among closely related species, we aim to investigate the degree of spatial overlapping between the two nightjar species as a preliminary test of spatial niche partitioning in nightjars. During the early dry season of 2021, we recorded the location of nightjars sitting on dirt tracks at night inside and outside of a rice field area in the Central River Region in The Gambia. We analysed the abundance, density and spatial distribution pattern of nightjars to determine if the two species segregate in space along tracks or occur together. The density of Long‐tailed Nightjar was higher than that of Standard‐winged Nightjar (9:1), and density was higher inside the rice field (4.41 nightjars/km) than outside of it (0.58 nightjars/km). The spatial analysis suggested that both species tended to co‐occur at the landscape scale (> 500 m) and avoided each other over finer spatial scales (< 500 m). This study identifies, for the first time, the potential for niche partitioning and spatial segregation at the community level in caprimulgids, although larger scale studies are needed to confirm the generality of the observed patterns. Moreover, our research highlights the magnitude of the utilisation of rice fields for foraging by nightjars in this novel study of this habitat type in The Gambia. Understanding the role of land use management patterns and the interaction of poorly studied nocturnal birds in (sub)tropical areas has important implications to support decision‐making in species conservation planning and land management.

We studied the spatial distribution and habitat use of Long‐tailed Nightjar (
Caprimulgus climacurus
) and Standard‐winged Nightjar (
Caprimulgus longipennis
) in The Gambia to test the hypothesis of spatial niche partitioning. Our findings reveal that while the species co‐occur at the landscape scale, they avoid each other at finer spatial scales, highlighting potential niche partitioning. This study underscores the importance of rice fields as key foraging habitats for nightjars and provides insights into the implications of land‐use management for nocturnal bird conservation in tropical ecosystems.

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