Movement of Free-Ranging Koalas in Response to Male Vocalisation Playbacks.

Alex Zijian Jiang,Peter Murray,William Ellis,Clive Phillips,Andrew Tribe

doi:10.3390/ani12030287

Abstract

Simple SummaryConservation management is critical for threatened wildlife species and an effective conservation approach relies on good understanding of animal behaviour in natural habitat. Currently, koalas are listed as vulnerable to extinction in Australia with declining populations, but their social and breeding system remains unclear. Male koala vocalisations, known as bellows, are believed to be closely related to their breeding behaviour. Bellows incorporate callers’ body size information which can be perceived by other koalas. In this study, we tested the behavioural responses of 20 GPS-collared free ranging koalas to bellow recordings collected from small (<6 kg) and large (>8.5 kg) adult male koalas. We report evidence of intra-male competition, with adult males approaching bellow playbacks, particularly those from small-sized males. In contrast, juvenile males under three years of age showed avoidance of the playbacks. No patterns in the response of females were detected. Our results provide the strongest evidence yet that bellows are primarily a means by which males occupy and control habitat space during the breeding season. Future studies are required to see if female response to bellows depends on their reproductive status.Effective conservation strategies rely on knowledge of seasonal and social drivers of animal behaviour. Koalas are generally solitary and their social arrangement appears to rely on vocal and chemical signalling. Male koala vocalisations, known as bellows, are believed to be closely related to their breeding behaviour. Previous research suggests that oestrous female koalas use bellows to locate unique males to mate with, and that males can similarly use bellows to evaluate the physical attributes of their peers. We tested the behavioural responses of 20 free ranging koalas to bellow recordings collected from small (<6 kg) and large (>8.5 kg) adult male koalas. Individual koala movement was reported by hourly-uploaded GPS coordinates. We report evidence of intra-male competition, with adult males approaching bellow playbacks, particularly those from small-sized males. In contrast, males under three years of age were averse to the playbacks. No patterns in the response of females were detected. Our results provide the strongest evidence yet that bellows are primarily a means by which males occupy and control space during the breeding season. Future studies are required to see if female response to bellows depends on their reproductive status.

Highlights

Vocalisations have been found to serve a number of purposes; for example, they facilitate recognition of kin [1,2,3,4,5,6,7], warn of predators [8,9], confirm territories [10,11], solicit sexual attention from conspecifics [12,13,14] and permit assessment of rivals [15]
Koala response behaviour towards bellow playbacks was primarily impacted by koala’s class, whereas other factors including the animal’s sex, age and body mass, breeding season, playback source and sequence had no significant effects on their behaviour
The results demonstrated that dependent on the koala’s class, bellow playbacks significantly affected koala movement, activity level, and time spent near speakers

Summary

Introduction

Vocalisations have been found to serve a number of purposes; for example, they facilitate recognition of kin [1,2,3,4,5,6,7], warn of predators [8,9], confirm territories [10,11], solicit sexual attention from conspecifics [12,13,14] and permit assessment of rivals [15]. Phascolarctos cinereus, are vocal marsupials, using bellows to communicate in vast Australian eucalypt forests. They use a novel vocal organ, an extra pair of vocal folds [16,17], to produce extra low-pitched vocalisations. Bellows are unique and reliable signals of size in koalas [17]. Bellows are typically produced by male koalas during their breeding season (southern hemisphere spring through summer) [18,19,20], peaking in frequency during mating activity [21]. Koala bellowing has been associated with movement [20] and intraspecific interactions [19]

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