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

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.

2019 ◽  
Vol 22 (6) ◽  
pp. 1149-1157 ◽  
Author(s):  
Jiangping Yu ◽  
Hailin Lu ◽  
Wei Sun ◽  
Wei Liang ◽  
Haitao Wang ◽  
...  

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.


2021 ◽  
Vol 9 ◽  
Author(s):  
Jiaojiao Wang ◽  
Laikun Ma ◽  
Xiangyang Chen ◽  
Canchao Yang

Cuckoo nest parasites lay eggs in host nests and thereby transfer all reproduction costs to the hosts. This greatly reduces host fitness. Parasitism has selected for the evolution of anti-parasitic strategies in hosts, including nest defense. The dynamic risk assessment hypothesis holds that nest parasitism only threatens the nests during the egg stage, so hosts should reduce the level of defense against nest parasites after the egg stage. We studied the behavioral and acoustic responses of oriental reed warblers (Acrocephalus orientalis), during both the egg and nestling stages, toward the common cuckoo (Cuculus canorus), sparrowhawks (Accipiter nisus) and oriental turtle doves (Streptopelia orientalis). A. orientalis can visually distinguish cuckoos from sparrowhawks and doves, indicating that hawk mimicry did not work for the cuckoos. The behavioral response of hosts in the nestling stage was stronger than in the egg stage, which supports the offspring value hypothesis and suggests that cuckoos may also act as nest predators. However, there was no difference in the alarm calls A. orientalis produce in response to different invaders, indicating that different types of alarm calls may not contain specific information.


Behaviour ◽  
2016 ◽  
Vol 153 (5) ◽  
pp. 591-606 ◽  
Author(s):  
Lynne A. Isbell ◽  
Laura R. Bidner

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.


2012 ◽  
Vol 58 (5) ◽  
pp. 773-780 ◽  
Author(s):  
James F. Hare ◽  
Kurtis J. Warkentin

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.


1999 ◽  
Vol 3 (2) ◽  
pp. 135-147 ◽  
Author(s):  
Daniel T. Blumstein

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.


Behaviour ◽  
1987 ◽  
Vol 102 (1-2) ◽  
pp. 15-39 ◽  
Author(s):  
Peter Marler ◽  
Roberta Pickert ◽  
Marcel Gyger

AbstractVocal alarm signals of male domestic fowl given in the presence of predators and other ground and aerial objects were recorded and analyzed. Studies were conducted under semi-naturalistic conditions and a telemetric technique was used to facilitate high quality sound recording. Cockerels gave ground alarm calls specifically to objects moving on the substrate and aerial alarm calls to objects moving above in free space. Vocalizations were associated with both dangerous and harmless objects. We therefore investigated variation in sound structure of aerial alarm calls with reference to flying predators and non-predators. A multidimensional contingency table analysis revealed a significant tendency for qualitatively different aerial alarm calls to be associated with flying predators and non-predators. Differences in call structure were restricted to the two first units of the alarm call. We tested the hypotheses that variation in aerial alarm call structure might be affected by either the distance separating the bird from the object or the angular size of the object projected onto the retina of the cockerel. Statistical analysis showed that the angular size was a good predictor of variation of the second unit of alarm call. The distance it self was less predictive. The first unit of the alarm call was not affected by either the distance or the angular size of the object. We propose that this part of the call has a more general function of alerting the conspecific companions. We conclude that alarm vocalizations of male domestic fowl refer specifically to a certain type of stimulus object, either moving on the ground or flying. For alarm calls correlated with aerial stimuli the specific angular size of a stimulus object moving in the air is a good predictor of call structure. We suggest that this way of dealing with flying objects as stimuli for alarm calls is the result of a predator detection strategy in which the benefits of an expanded field of vision, an important adaptation for ground-dwelling birds, exceed the costs of alarming to harmless birds and other aerial objects.


2008 ◽  
Vol 4 (5) ◽  
pp. 472-475 ◽  
Author(s):  
Sarah Papworth ◽  
Anne-Sophie Böse ◽  
Jessica Barker ◽  
Anne Marijke Schel ◽  
Klaus Zuberbühler

Male blue monkeys ( Cercopithecus mitis stuhlmanni ) of Budongo Forest, Uganda, produce two acoustically distinct alarm calls: hacks to crowned eagles ( Stephanoaetus coronatus ) and pyows to leopards ( Panthera pardus ) and a range of other disturbances. In playback experiments, males responded to leopard growls exclusively with a series of pyows and to eagle shrieks predominantly with hacks. Responses to playbacks of these alarm call series matched the responses to the corresponding predators, suggesting that the calls conveyed something about the nature of the threat. When responding to a series of hacks, indicating an eagle, males responded predominately with hacks, but produced significantly more calls if their group members were close to the playback stimulus than far away, regardless of their own position. When responding to a series of pyows, indicating a range of disturbances, males responded with pyows, but call rates were independent of the distance of other group members. The results suggest that males took into account the degree of danger experienced by other group members.


Behaviour ◽  
2010 ◽  
Vol 147 (9) ◽  
pp. 1201-1218
Author(s):  
Shannon Digweed ◽  
Drew Rendall

AbstractNorth American red squirrels are a small-bodied and solitary-living species that faces a diversity of predators and produces two different variants of alarm calls in response to them. Recent studies have yielded conflicting interpretations of the predator-specific and functionally referential nature of these alarm call variants. We undertook a systematic set of playback experiments to quantify the responses of red squirrels to alarm calls produced by other squirrels during encounters with different predators. The experiment was designed to test a core requirement of functionally referential alarm calls, namely that different alarm call types induce distinct and functionally appropriate escape responses in listeners. Results indicated that squirrels registered and responded to alarm calls produced by others; however, their responses were not differentiated according to the type of alarm call they heard and, thus, did not provide evidence that the different alarm call variants hold any predator-specific, referential value. These outcomes are discussed in light of complementary work on alarm call production in red squirrels and broader aspects of this species' life history in an effort to better understand the necessary and sufficient pressures promoting the evolution of referential call systems in animals.


2012 ◽  
Vol 8 (3) ◽  
pp. 379-381 ◽  
Author(s):  
Ben O. Brilot ◽  
Melissa Bateson

The majority of bird taxa perform water bathing, but little is known about the adaptive value of this behaviour. If bathing is important for feather maintenance then birds that have not bathed should have poorer feather condition, compromised escape ability and therefore increased responsiveness to cues of predation. We conducted two experiments examining the behaviour of captive starlings responding to conspecific alarm calls. Birds that had no access to bathing water showed a decreased willingness to feed and increased their vigilance behaviour following an alarm call. We argue that birds denied access to bathing water interpreted an ambiguous cue of threat as requiring more caution than birds that had access, consistent with higher levels of anxiety. Our results support the provision of bathing water for captive birds as an important welfare measure.


2021 ◽  
Vol 2 ◽  
Author(s):  
Vanessa Morris ◽  
Benjamin James Pitcher ◽  
Anthony Chariton

Translocation programmes implying the movement of animals from one place to another aim to sustain endangered populations in the wild. However, their success varies greatly, with predation being a major contributing factor. This is particularly prevalent in released captive-raised individuals which have a reduced or lost awareness of predators. Alarm calls are an immediate response made toward a predator, mostly studied in highly predated, social vertebrates. These warning vocalizations are a vital part of a prey species' anti-predator behavior, enhancing the individuals' and surrounding listeners' survival. To date, most translocation programmes have not considered this behavior for release success. Here we review the literature summarizing alarm communication systems of wild and captive vertebrates, aiming to establish recommendations and actions which could encourage alarm communication behavior in captive vertebrate species. Observations of wild animals show that alarm-call understanding is gained through the experience of predation pressure from a young age, amongst conspecific and heterospecific social groups, which captive individuals can lack. This information, combined with consideration of a programme's accessible resources and captive individual's developmental history, is pivotal to efficiently guide appropriate actions. Focusing on preserving behaviors in captivity, we provide a list of recommendations and actions to guide the reinforcement of alarm communication throughout the translocation process. Ensuring predator awareness and the maintenance of alarm communication in translocated individuals may greatly improve the likelihood of release success.


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