Experimental evidence for delayed post-conflict management behaviour in wild dwarf mongooses

In many species, within-group conflict leads to immediate avoidance of potential aggressors or increases in affiliation, but no studies have investigated delayed post-conflict management behaviour. Here, we experimentally test that possibility using a wild but habituated population of dwarf mongooses (Helogale parvula). First, we used natural and playback-simulated foraging displacements to demonstrate that bystanders take notice of the vocalisations produced during such within-group conflict events but that they do not engage in any immediate post-conflict affiliative behaviour with the protagonists or other bystanders. We then used another playback experiment to assess delayed effects of within-group conflict on grooming interactions: we examined affiliative behaviour at the evening sleeping burrow, 30–60 min after the most recent simulated foraging displacement. Overall, fewer individuals groomed on evenings following an afternoon of simulated conflict, but those that did groomed more than on control evenings. Subordinate bystanders groomed with the simulated aggressor significantly less, and groomed more with one another, on conflict compared to control evenings. Our study provides experimental evidence that dwarf mongooses acoustically obtain information about within-group contests (including protagonist identity), retain that information, and use it to inform conflict-management decisions with a temporal delay.

A desert songbird with no confamilials in the Western Hemisphere (Verdin, Auriparus flaviceps) investigates divergent conspecific songs

Most birds that show geographic variation in their songs discriminate between local and foreign songs, which may help them avoid unnecessary conflicts with vagrant individuals or similar-sounding congeners. However, some species respond equally to foreign and local songs, which may be useful if foreign individuals present territorial threats or if there are no sympatric congeners to avoid. Species without sympatric congeners are not commonly tested in playback studies, but they offer an opportunity to see how song variation and recognition unfolds when the pressure to avoid similar congeners is absent. Here, we use Verdins (Auriparus flaviceps), a monotypic genus of songbird with no confamilials in North America, to explore song variation and recognition in a species living without close relatives. We assessed geographic variation in song across the Verdin range and conducted a playback experiment using exemplars from 2 acoustically divergent and geographically distant regions as treatments. We found significant geographic variation in song that mapped well onto ecologically distinct desert regions. We found that Verdins had stronger vocal responses to local-sounding songs, but had equal movement responses to local-sounding and foreign songs. These results are similar to results found in other species without sympatric congeners and provide an example of a species that investigates acoustically divergent conspecific songs, despite recognizing salient differences in those songs.

Experimental evidence for delayed post-conflict management behaviour in wild dwarf mongooses

In many species, within-group conflict leads to immediate avoidance of potential aggressors or increases in affiliation, but no studies have investigated delayed post-conflict management behaviour. Here, we experimentally test that possibility using wild dwarf mongooses (Helogale parvula). First, we used natural and playback-simulated foraging displacements to demonstrate that bystanders take notice of the vocalisations produced during such within-group conflict events. We then used another playback experiment to assess delayed effects of within-group conflict on grooming interactions. Overall, fewer individuals groomed on evenings following an afternoon of simulated conflict, but those that did groomed more than on control evenings. Subordinate bystanders groomed with the simulated aggressor significantly less, and groomed more with one another, on conflict compared to control evenings. Our study provides experimental evidence that dwarf mongooses acoustically obtain information about within-group contests (including protagonist identity), retain that information and use it to inform conflict-management decisions with a temporal delay.

Effective conspecific communication with aberrant calls in the common cuckoo (Cuculus canorus)

The obligate brood parasitic common cuckoo (Cuculus canorus) is best known for its two-note “cu-coo” call, which is uttered repeatedly by adult males during the breeding season. This call advertises the male’s claim for his territory. A rare, aberrant version (“cu-kee”) was discovered in a population of cuckoos in central Hungary. In a playback experiment, we simulated conspecific territorial intrusions using either aberrant call sequences or normal calls (as control). Cuckoos responded to both calls similarly by approaching the speaker, flying around it several times, and perching on nearby trees. To identify the role of each note of these cuckoo calls, we also played sequences of the first (“cu”) or second (“coo” or “kee”) notes of the calls. Territorial males responded to first notes at similarly high frequencies as to each of the full calls, whereas responses toward either second note type were nearly absent. Thus, the first notes of both typical and aberrant cuckoo calls contain sufficient information to recognize conspecific males and the novel calls did not reduce the efficiency of male-male communication in cuckoos because the aberration occurred in the less functional second note. Significance statement Birds use songs and calls to communicate with each other, including advertising their territories to keep competitors away. However, when the acoustic signal is atypical and distorted, the receiver individual may not process it correctly. Common cuckoos recognize a territorial intruder by their well-known “cu-coo” calls. We studied a rare, aberrant version of the common cuckoo call (“cu-kee”), which differed from the normal call in the second note of the two-partite call. However, cuckoos responded similarly to both of the normal and aberrant calls in a playback experiment. When the first or second parts of the different calls were played separately, only the first part of the cuckoo calls was effective in eliciting territorial defence. Consequently, the aberrant second note did not reduce cuckoos’ communication efficiency.

White-handed gibbons discriminate context-specific song compositions

White-handed gibbons produce loud and acoustically complex songs when interacting with their neighbours or when encountering predators. In both contexts, songs are assembled from a small number of units although their composition differs in context-specific ways. Here, we investigated whether wild gibbons could infer the ‘meaning’ when hearing exemplars recorded in both contexts (i.e. ‘duet songs’ vs. ‘predator songs’). We carried out a playback experiment by which we simulated the presence of a neighbouring group producing either its duet or a predator song in order to compare subjects’ vocal and locomotor responses. When hearing a recording of a duet song, subjects reliably responded with their own duet song, which sometimes elicited further duet songs in adjacent groups. When hearing a recording of a predator song, however, subjects typically remained silent, apart from one of six groups which replied with its own predator song. Moreover, in two of six trials, playbacks of predator songs elicited predator song replies in non-adjacent groups. Finally, all groups showed strong anti-predator behaviour to predator songs but never to duet songs. We concluded that white-handed gibbons discriminated between the two song types and were able to infer meaning from them. We discuss the implications of these findings in light of the current debate on the evolutionary origins of syntax.

3. The Effect of Audio Recording for Playback Experiment to the Alteration of Orangutan’s Territorial Behavior

The aim of this study was to find an alternative method to prevent the conflict between the orangutan and human with the utilization of audio recording as biofence. The location of this study was in Leuser National Park on Bukit Lawang, Langkat, North Sumatra using 16 orangutans as the subject of this study. The method used in this study was a simulation and playback experiment which were using long call, spontaneous call, predator voice, and siren sound in the audio recording of non-alpha orangutans. The respond was observed using binocular and recorded using camera recorder. The data obtained were analyzed using Krustal Wallist test. The result showed that 87% of orangutan showed an interest in the attractor, on the other hand, 13% showed disinterest to the attractor. The facial expression shown by orangutan was fear, submission, aggression, and worry. The statistical analyzing result showed that long call and the spontaneous call was very significant (P0.01), while the predator and siren voice were insignificant (P0.05). The result can be concluded that long call and spontaneous calls showing the effective result to the alteration of territorial behavior on orangutan and have a potential as a biofence that is used as an alternative method to prevent the conflict between orangutan and human.