scholarly journals The function of nonlinear phenomena in meerkat alarm calls

2010 ◽  
Vol 7 (1) ◽  
pp. 47-49 ◽  
Author(s):  
Simon W. Townsend ◽  
Marta B. Manser
Keyword(s):  
Alarm Call ◽  
Alarm Calls ◽  
Nonlinear Phenomena ◽  
Behavioural Responses ◽  
Linear Medium ◽  
Suricata Suricatta ◽  
Naturally Occurring ◽  
Animal Vocalizations ◽  
Human Animal

Nonlinear vocal phenomena are a ubiquitous feature of human and non-human animal vocalizations. Although we understand how these complex acoustic intrusions are generated, it is not clear whether they function adaptively for the animals producing them. One explanation is that nonlinearities make calls more unpredictable, increasing behavioural responses and ultimately reducing the chances of habituation to these call types. Meerkats ( Suricata suricatta ) exhibit nonlinear subharmonics in their predator alarm calls. We specifically tested the ‘unpredictability hypothesis’ by playing back naturally occurring nonlinear and linear medium-urgency alarm call bouts. Results indicate that subjects responded more strongly and foraged less after hearing nonlinear alarm calls. We argue that these findings support the unpredictability hypothesis and suggest this is the first study in animals or humans to show that nonlinear vocal phenomena function adaptively.

scholarly journals Discrimination of Acoustic Stimuli and Maintenance of Graded Alarm Call Structure in Captive Meerkats

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3064
Author(s):  
Sebastian Schneider ◽  
Sarah Goettlich ◽  
Charlette Diercks ◽  
Paul Wilhelm Dierkes
Keyword(s):  
Clustering Algorithm ◽  
Escape Behavior ◽  
Cooperative Behavior ◽  
Alarm Call ◽  
Acoustic Signals ◽  
Alarm Calls ◽  
Call Structure ◽  
Graded Structure ◽  
Suricata Suricatta ◽  
In Captivity

Animals living in human care for several generations face the risk of losing natural behaviors, which can lead to reduced animal welfare. The goal of this study is to demonstrate that meerkats (Suricata suricatta) living in zoos can assess potential danger and respond naturally based on acoustic signals only. This includes that the graded information of urgency in alarm calls as well as a response to those alarm calls is retained in captivity. To test the response to acoustic signals with different threat potential, meerkats were played calls of various animals differing in size and threat (e.g., robin, raven, buzzard, jackal) while their behavior was observed. The emitted alarm calls were recorded and examined for their graded structure on the one hand and played back to them on the other hand by means of a playback experiment to see whether the animals react to their own alarm calls even in the absence of danger. A fuzzy clustering algorithm was used to analyze and classify the alarm calls. Subsequently, the features that best described the graded structure were isolated using the LASSO algorithm and compared to features already known from wild meerkats. The results show that the graded structure is maintained in captivity and can be described by features such as noise and duration. The animals respond to new threats and can distinguish animal calls that are dangerous to them from those that are not, indicating the preservation of natural cooperative behavior. In addition, the playback experiments show that the meerkats respond to their own alarm calls with vigilance and escape behavior. The findings can be used to draw conclusions about the intensity of alertness in captive meerkats and to adapt husbandry conditions to appropriate welfare.

Vocalize to localize

2005 ◽  
Vol 5 (3) ◽  
pp. 327-344 ◽  
Author(s):  
Marta B. Manser ◽  
Lindsay B. Fletcher
Keyword(s):  
Visual Cues ◽  
Gaze Direction ◽  
Alarm Calls ◽  
General Behaviour ◽  
Acoustic Structure ◽  
Suricata Suricatta ◽  
High Urgency ◽  
High Stimulus ◽  
Functionally Referential ◽  
Stimulus Specificity

In this study of the functionally referential alarm calls in the meerkats (Suricata suricatta), we tested the hypothesis that the ability to refer to a specific location was an important factor in the evolution of discrete vocalizations. We investigated what information receivers gained about the location of the predator from alarm calls with high stimulus specificity compared to alarm calls with low stimulus specificity. Furthermore, we studied whether visual cues about the localization of the predator may be available from the posture of the caller. We described the general behaviour of the caller, the caller’s posture, and in particular its gaze direction. We then observed receivers responding to the different call types, to determine whether the acoustic structure of the calls was enough for them to respond in the appropriate way, or whether they used additional visual cues from the caller. We tested this with specific manipulation experiments, using three set ups of playback experiments: (1) no caller visible; (2) model guard with specific gaze direction; and (3) live sentinel. Natural observations and experiments confirmed that in high urgency situations the meerkats have enough information from the acoustic structure of the call to respond appropriately. When hearing low urgency calls that are less stimuli specific, meerkats used visual cues as an additional source of information in a few cases. This may indicate that functionally referential calls evolved to denote the location of the predator, rather than the predator type or its velocity of approach. However, when discussing this result in comparison to other functionally referential calls, such as the food associated calls and recruitment calls, this localization hypothesis does not appear to apply to the functionally referential calls in general.

scholarly journals Alarm calls elicit predator-specific physiological responses

2010 ◽  
Vol 6 (5) ◽  
pp. 623-625 ◽  
Author(s):  
Jill M. Mateo
Keyword(s):  
Information Processing ◽  
Physiological Responses ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Cortisol Response ◽  
Behavioural Responses ◽  
Cortisol Responses ◽  
Cortisol Increase ◽  
Physiological Reactions ◽  
Very High

Glucocorticoids regulate glucose concentrations and responses to unpredictable events, while also modulating cognition. Juvenile Belding's ground squirrels ( Urocitellus beldingi ) learn to respond to whistle and trill alarm calls, warning of aerial and terrestrial predators, respectively, shortly after emerging from natal burrows at one month of age. Alarm calls can cause physiological reactions and arousal, and this arousal, coupled with watching adult responses, might help juveniles learn associations between calls and behavioural responses. I studied whether young show differential cortisol responses to alarm and non-alarm calls, using playbacks of U. beldingi whistles, trills, squeals (a conspecific control vocalization) and silent controls. Trills elicited very high cortisol responses, and, using an individual's response to the silent control as baseline, only their response to a trill was significantly higher than baseline. This cortisol increase would provide glucose for extended vigilance and escape efforts, which is appropriate for evading terrestrial predators which hunt for long periods. Although whistles do not elicit a cortisol response, previous research has shown that they do result in bradycardia, which enhances attention and information processing. This is a novel demonstration of two physiological responses to two alarm calls, each appropriate to the threats represented by the calls.

scholarly journals Drought decreases cooperative sentinel behavior and affects vocal coordination in meerkats

2019 ◽  
Vol 30 (6) ◽  
pp. 1558-1566 ◽  
Author(s):  
Ramona Rauber ◽  
Tim H Clutton-Brock ◽  
Marta B Manser
Keyword(s):  
Small Groups ◽  
Cooperative Behavior ◽  
Drought Condition ◽  
Drought Period ◽  
Suricata Suricatta ◽  
Naturally Occurring ◽  
Dry Conditions ◽  
Group Members ◽  
Fitness Benefits ◽  
Cooperative Behaviors

Abstract Cooperative breeding often evolved in harsh and arid habitats characterized by high levels of environmental uncertainty. Most forms of cooperative behavior have energetic costs and previous studies have shown that the contributions of individuals to alloparental provisioning are conditional on their food intake. However, the effect of naturally occurring, extreme environmental conditions on the persistence of costly forms of cooperative behaviors and their coordination by communication remain unknown. Here, we show that in meerkats (Suricata suricatta) the probability to act as sentinel, a cooperative vigilance behavior, was the same for typically occurring dry and wet conditions, but significantly reduced during a drought condition with almost no rain, especially in young individuals, members of small groups and groups with pups. The duration an individual stayed on sentinel guard, however, was most reduced during dry conditions. Besides reductions in sentinel behavior, the vocal coordination of foraging meerkats differed when comparing drought and wet conditions. Individuals responded more strongly to playbacks of sentinel “all-clear” calls and close calls, resulting in less vigilance and more foraging behavior during the drought condition. We conclude that while meerkats are adapted to commonly occurring dry periods with low rainfall, the extreme drought period with almost no rain, led to a decrease of the frequency of costly forms of cooperative behaviors in favor of behaviors that maximize direct fitness benefits and also affected the vocal coordination among group members.

scholarly journals Heterospecific alarm-call recognition in two warbler hosts of common cuckoos

2019 ◽  
Vol 22 (6) ◽  
pp. 1149-1157 ◽  
Author(s):  
Jiangping Yu ◽  
Hailin Lu ◽  
Wei Sun ◽  
Wei Liang ◽  
Haitao Wang ◽  
...  
Keyword(s):  
Alarm Call ◽  
Alarm Calls ◽  
Reed Warbler ◽  
Cuculus Canorus ◽  
Common Cuckoo ◽  
Playback Experiments ◽  
Call Recognition ◽  
Accipiter Nisus ◽  
Main Host ◽  
The Common

Abstract Species facing similar selection pressures should recognize heterospecific alarm signals. However, no study has so far examined heterospecific alarm-call recognition in response to parasitism by cuckoos. In this study, we tested whether two sympatric host species of the common cuckoo Cuculus canorus, Oriental reed warbler Acrocephalus orientalis (ORW, main host), and black-browed reed warbler Acrocephalus bistrigiceps (BRW, rare host), could recognize each other’s alarm calls in response to cuckoos. Dummies of common cuckoo (parasite) and Eurasian sparrowhawk Accipiter nisus (predator) were used to induce and record alarm calls of the two warbler species, respectively. In the conspecific alarm-call playback experiments, ORW responded more strongly to cuckoo alarm calls than to sparrowhawk alarm calls, while BRW responded less strongly to cuckoo alarm calls than to sparrowhawk alarm calls. In the heterospecific alarm-call playback experiments, both ORW and BRW responded less strongly to cuckoo alarm calls than sparrowhawk alarm calls. BRW seemed to learn the association between parasite-related alarm calls of the ORW and the cuckoo by observing the process of ORW attacking cuckoos. In contrast, alarm calls of BRW to cuckoos were rarely recorded in most cases. BRW with low parasite pressure still developed recognition of heterospecific parasite-related alarm call. Unintended receivers in the same community should recognize heterospecific alarm calls precisely to extract valuable information.

scholarly journals Specific responses of cuckoo hosts to different alarm signals according to breeding stage: a test of the offspring value hypothesis

2020 ◽  
Vol 66 (6) ◽  
pp. 649-655 ◽  
Author(s):  
Jiaojiao Wang ◽  
Canchao Yang
Keyword(s):  
Alarm Call ◽  
Host Responses ◽  
Alarm Calls ◽  
Attack Behavior ◽  
Brood Parasite ◽  
Reed Warbler ◽  
Defense Strategies ◽  
Breeding Stage ◽  
Accipiter Nisus ◽  
Streptopelia Orientalis

Abstract The selective pressure exerted by avian brood parasites forces their hosts to evolve specific defense strategies. When subject to brood parasite attack, avian hosts will often emit alarm calls. To date, few studies have examined whether and how host responses to different alarm calls indicative of different enemies vary with the host’s breeding stage. We carried out alarm call playback experiments during both the egg and nestling stages of the oriental reed warbler Acrocephalus orientalis, a host of the common cuckoo Cuculus canorus. The playback exemplars were selected from recorded alarm calls of the warbler to the presence of common cuckoos, sparrowhawks Accipiter nisus, and oriental turtle doves Streptopelia orientalis, which represented brood parasite, predator, and harmless control, respectively. The results showed that the oriental reed warblers did not discriminate alarm calls issued to different intruder types, but the intensity of the response was significantly higher in the nestling stage than in the egg stage. Attack behavior related to sparrowhawk alarm calls was absent in the egg stage, but aggressive behavior increased dramatically and exceeded the attack frequency in response to the cuckoo alarm call in the nestling stage, implying a shift in the tradeoff between the parents’ own survival and the loss of offspring. Alarm calls attracted a larger number of conspecifics than members of other species. In general, the oriental reed warbler had consistently stronger responses to different alarm calls in the nestling stage than in the egg stage, supporting the offspring value hypothesis.

Vervet monkey (Chlorocebus pygerythrus) alarm calls to leopards (Panthera pardus) function as a predator deterrent

Behaviour ◽  
2016 ◽  
Vol 153 (5) ◽  
pp. 591-606 ◽  
Author(s):  
Lynne A. Isbell ◽  
Laura R. Bidner
Keyword(s):  
Alarm Call ◽  
Vervet Monkey ◽  
Camera Traps ◽  
Alarm Calls ◽  
Gps Data ◽  
Vervet Monkeys ◽  
Panthera Pardus ◽  
Predator Prey ◽  
Gps Collars ◽  
Chlorocebus Pygerythrus

Behavioural predator–prey interactions are difficult to study, especially when predators avoid humans. To gain greater understanding of their dynamism, we conducted a 14-month field study in which we minimized human presence by employing acoustic recorders and camera traps, along with GPS collars deployed on vervet monkeys (Chlorocebus pygerythrus) and leopards (Panthera pardus) in Laikipia, Kenya. Recordings at the vervets’ sleeping site revealed that they gave ‘leopard’ alarm calls most frequently near dusk and dawn, whereas photographs showed that leopards approached vervets more closely at night, when the monkeys alarm-called less often. GPS data showed that after vervets alarm-called, leopards within 200 m quickly moved away, changing direction, but when vervets did not alarm-call, leopards continued moving forward. These results reveal that vervets’ leopard alarm calls function as a predator deterrent in addition to a conspecific warning call.

scholarly journals The song remains the same: Juvenile Richardson’s ground squirrels do not respond differentially to mother’s or colony member’s alarm calls

2012 ◽  
Vol 58 (5) ◽  
pp. 773-780 ◽  
Author(s):  
James F. Hare ◽  
Kurtis J. Warkentin
Keyword(s):  
Adult Female ◽  
Escape Behavior ◽  
Alarm Call ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Digital Audio ◽  
Predator Detection ◽  
Postural Responses ◽  
Limited Opportunity ◽  
Predator Model

Abstract Alarm calls are emitted by Richardson’s ground squirrels Urocitellus richardsonii in response to avian and terrestrial predators. Conspecifics detecting these calls respond with increased vigilance, promoting predator detection and evasion, but in doing so, lose time from foraging. That loss can be minimized if alarm call recipients discriminate among signalers, and weight their response accordingly. For juvenile ground squirrels, we predicted that the trade-off between foraging and vigilance could be optimized via selective response to alarm calls emitted by their own dam, and/or neighboring colony members over calls broadcast by less familiar conspecifics. Alarm calls of adult female Richardson’s ground squirrels were elicited in the field using a predator model and recorded on digital audio tape. Free-living focal juveniles were subjected to playbacks of a call of their mother, and on a separate occasion a call from either another adult female from their own colony, or an adult female from another colony. Neither immediate postural responses and escape behavior, nor the duration of vigilance manifested by juveniles differed with exposure to alarm calls of the three adult female signaler types. Thus, juveniles did not respond preferentially to alarm calls emitted by their mothers or colony members, likely reflecting the high cost of ignoring alarm signals where receivers have had limited opportunity to establish past signaler reliability.

The evolution of functionally referential alarm communication

1999 ◽  
Vol 3 (2) ◽  
pp. 135-147 ◽  
Author(s):  
Daniel T. Blumstein
Keyword(s):  
Alarm Call ◽  
Referential Communication ◽  
Alarm Calls ◽  
Repertoire Size ◽  
Motor Abilities ◽  
Antipredator Responses ◽  
Tight Association ◽  
Functionally Referential ◽  
Alarm Communication ◽  
Call Repertoire

Many species produce specific alarm vocalizations when they encounter predators. There is considerable interest in the degree to which bird, ground-dwelling sciurid rodent, and primate alarm calls denote the species or type of predator that elicited the vocalization. When there is a tight association between the type or species of predator eliciting an alarm call, and when a played-back alarm call elicits antipredator responses qualitatively similar to those seen when individuals personally encounter a predator, the alarm calls are said to be functionally referential. In this essay I aim to make two simple points about the evolution of functionally referential alarm communication. Firstly, functionally referential communication is likely to be present only when a species produces acoustically distinct alarm vocalizations. Thus, to understand its evolution we must study factors that influence the evolution of alarm call repertoire size. Secondly, and potentially decoupled from the ability to produce acoustically distinctive alarm vocalizations, species must have the perceptual and motor abilities to respond differently to acoustically-distinct alarm vocalizations. Thus, to understand the evolution of functionally referential communication we also must study factors that influence the evolution of context-independent perception. While some factors may select for functionally referential alarm communication, constraints on production or perception may prevent its evolution.

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