Gouldian Finches (Chloebia gouldiae) - Increase the Frequency of Head Movements with Increasing Risk at Water-holes but Prolong Interscan Intervals While Drinking

Sep 30, 2026

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Animals scan the environment to detect threats, yet vigilance is costly and must be adjusted to prevailing risk. This study examines how Gouldian finches modify drinking-time vigilance at predator-attracting waterholes by quantifying head-movement frequency and the interscan interval. Movement frequency rises from tree perching to ground and is highest at small waterholes. Interscan intervals vary with waterhole and group size, and head-movement frequency correlates positively with interscan interval, suggesting distinct check strategies under different risks.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages15

Reading Time38 min

AccessFree to download

Simple Summary

Abstract

Keywords

1. Introduction

Background on vigilance and cost-benefit tradeoffs

How animals adjust vigilance parameters

Evidence on interscan intervals and threat perception

Article Gouldian Finches (Chloebia gouldiae) Increase the Frequency of Head Movements with Increasing Risk at Water-holes but Prolong Interscan Intervals While Drinking: Two Different Strategies? Gerhard Hofmann 1 and Claudia Mettke-Hofmann 2, * Received: 15 November 2025 Revised: 13 December 2025 Accepted: 24 December 2025 Published: 28 December 2025 Copyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license. 1 Independent Researcher, Moreton CH46, UK; gerhard@hofmann-photography.de 2 School of Biological & Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK * Correspondence: [c.c.mettke-hofmann@ljmu.ac.uk](c.c.mettke-hofmann@ljmu.ac.uk) Simple Summary Animals scan their environment to detect predators. However, being vigilant is costly as animals must interrupt other activities. Here, we investigated vigilance at waterholes, which are dangerous sites as they attract predators. We assessed vigilance during drinking by measuring the frequency of head movements when the birds raised their head above the water surface and also measured the time taking-in water (interscan interval). The frequency of head movements was lower when the birds sat in trees when compared to being on the ground, indicating that the birds felt more vulnerable as they moved closer to the ground. While drinking, the frequency of head movements was highest at small waterholes when compared to larger waterholes, showing that small waterholes are perceived as more dangerous. This is concerning as droughts are predicted to increase. Furthermore, interscan interval was affected by waterhole size and group size in a complicating manner, showing that birds adjust their vigilance levels in response to specific situations. Finally, frequency of head movements and interscan interval were correlated. Individuals with a high frequency of head movements (high vigilance) had longer drinking bouts, whereas individuals with a lower frequency of head movements (lower vigilance) raised their head after shorter drinking intervals, possibly adjusting for the lower frequency of head movements. Abstract Animals scan their environment to detect threats. Such vigilance behaviour is costly, and animals adjust their vigilance to prevailing threats. Waterholes are dangerous places that attract predators, and require heightened vigilance. We investigated how Gouldian finches adjust their vigilance at waterholes by measuring the frequency of head movements and interscan interval while drinking. The frequency of head movements increased with increasing risk perception (a) from perching in the tree to being on the ground and (b) while drinking, with a higher frequency of movements recorded at small waterholes compared to medium and large ones. The latter adds to recent findings that small waterholes are perceived as more dangerous and require further investigation. With a predicted increase in droughts, birds will rely on small waterholes for longer during the dry season which might cause stress. Furthermore, interscan interval varied in terms of interaction with waterhole size and group size, indicating adjustments linked to perceived threat and social effects. Finally, frequency of head movements and interscan intervals were positively correlated. This might reflect different strategies to check the environment, with either a high frequency of head movements when scanning accompanied by long drinking bouts or looking in one direction for a longer time (lower vigilance) but repeating this behaviour at shorter intervals. Keywords: vigilance; social vigilance; alertness; birds; Estrildidae 1. Introduction Animals keep track of changes in their environment to avoid predation but also to monitor their companions to coordinate movement and avoid aggression by scanning their environment

FAQs

How did the researchers assess vigilance during drinking in Gouldian finches?

They measured the frequency of head movements when birds raised their heads above the water surface and recorded the time between successive vigilance events as the interscan interval.

What factors increased head-movement frequency at waterholes?

Head-movement frequency increased with risk perception, being higher on the ground than in trees, and was highest at small waterholes compared with medium and large ones.

How were head-movement frequency and interscan intervals related?

Frequency of head movements and interscan interval were positively correlated, indicating that individuals showing higher vigilance tended to have longer drinking bouts or different scanning patterns than less vigilant individuals.

Sep 30, 2026

Upload by Oliver