Van de Waal, E. | Search bioRxiv

bioRxiv2026

Chorus Synchrony as a Cue: Influence of Chorus Howl Synchrony from Unfamiliar Packs on Wolves' Behaviour

Chorus howls play a central role in wolves' (Canis lupus) social communication, shaping both intra- and inter-pack interactions. While synchrony has been shown to influence perceived threat from outgroups in birds and humans, whether the synchrony of an outside pack's chorus howl plays a role in wolf pack behaviour remains unclear. This study investigated behavioural responses of 19 zoo-housed wolf packs to playbacks of synchronous and asynchronous chorus howls from unfamiliar packs, in comparison to a dove control call. We hypothesized that packs would show stronger intra-pack cohesion and greater spatial withdrawal in response to more synchronous, and thus cohesive - and potentially more formidable - sounding vocalisations. Alternatively, asynchronous howls might elicit stronger responses due to their ambiguity and the "Beau Geste" effect (where asynchronous signals make it harder to infer the number of callers). Synchronous howls resulted in more distance from the sound source and less activity compared with asynchronous howls. This could be interpreted as a more cautious response towards a perceived threat. However, since there was no effect on pack-directed behaviour and no difference between the synchronous and control sound, lower interest or motivation to engage with the stimulus cannot be excluded. In contrast, wolves spent more time near the sound-source after hearing asynchronous howls, approached it more, and oriented towards it for longer compared to synchronous playbacks, a pattern consistent with threat-investigation. In how far these reactions result from a more difficult localisation of synchronous howls or more ambiguity in pack size in the asynchronous playbacks, as well as how this translates to wild wolf behaviour, remains to be investigated.

animal behavior and cognition↗

bioRxiv2026

Collateral effects of lethal management operations: biologging reveals multiscale responses in non-target vervet monkeys

Lethal wildlife management operations are typically evaluated through their direct effects on target species, yet their disturbance footprint may extend to non-target animals sharing the same landscape. We opportunistically used a large-scale helicopter-assisted culling event targeting ungulates at Mawana Game Reserve, South Africa, as a natural experiment to examine how such an operation affected the behaviour and space use of non-target vervet monkeys (Chlorocebus pygerythrus). Using GPS and tri-axial accelerometry from 21 collared individuals across seven habituated social groups, we quantified behavioural and spatial responses around the culling event, including changes in activity budgets, circadian activity patterns, short-term walking and running responses, daily space use, and habitat composition. Vervets showed fear-consistent responses that differed among behaviours, social groups, and temporal scales. Foraging declined at the population level, with the strongest reduction occurring in the morning, when helicopter and shooting activity were the most intense. Inactivity increased during culling and remained elevated afterwards, suggesting both disturbance-related change and seasonal background effects, while social behaviour showed a transient increase consistent with a possible social-buffering response. Walking and running showed little consistent change in daily averages across the culling period, but finer-scale analyses revealed short-lived deviations concentrated in specific groups and time windows. Spatially, groups remained within existing ranges but showed divergent responses, from contraction and increased use of dense vegetation to greater movement in more open areas, highlighting how population-level inference can obscure context-dependent responses when heterogeneity among groups, individuals, or habitats is not explicitly considered. Together, our findings show that lethal management can generate multiscale, context-dependent responses in non-target wildlife, and that overlooking these effects may lead to systematic underestimation of their ecological consequences.

ecology↗