The effects of variation in anthropogenic noise on anti-predator behaviours in dwarf mongooses (Helogale parvula)

Abstract

Escalating urbanisation and globalisation of our planet is placing increasing pressure on nature. Anthropogenic noise, an increasingly widespread pollutant, is becoming a key concern. Extraneous noise is known to have detrimental effects on human health and although there is growing recognition of the impacts of noise on wildlife, research has largely focused on acoustic communication with field-based studies comprising only a minor proportion. Here, I address some shortfalls in the current literature by way of field-based experimental playbacks to investigate whether variation in temporal characteristics of noise differentially affects foraging–vigilance trade-offs in wild dwarf mongooses (Helogale parvula). I show that during playback of either intermittent or continuous traffic-noise, foragers show increased vigilance (headscans and sentinel behaviour) compared to an ambient-sound control. There was no difference in vigilance levels between intermittent or continuous traffic-noise. However, sentinel bout frequency increased following playback of continuous traffic noise but decreased after playback of intermittent noise. These responses could be due to differences in overall noise exposure, with continuous noise presenting a greater stimulus or ‘threat.’ If noise is analogous to a predation threat, greater investment in vigilance may be adaptive as individuals assess their surroundings for danger. However, if noise persists, or if noise distracts individuals from real threats, survival could be compromised. Additionally, playback of traffic noise at sleeping burrows significantly delayed group emergence and departure. In this context, entire groups may suffer lost foraging time with associated declines in individual fitness. Grooming rates were also influenced by noise, with greater frequency but not duration observed in traffic noise. Further research would benefit from using several behavioural measures and conducting longer-term studies to investigate changes in responses over time and to assess where individuals may be able to compensate for costs incurred by noise exposure.

Date of Award	1 Oct 2019
Original language	English
Awarding Institution	University of Bristol
Supervisor	Andrew N Radford (Supervisor) & Innes C Cuthill (Supervisor)