Alarm Calling in Sri Lankan Mixed-Species Bird Flocks

Abstract Vocal alarm calls are important to the vigilance and likely the organization of mixed-species flocks, but community-wide studies of alarm calling in flocks are lacking. We investigated which species alarm-call, and the characteristics of their calls, in a large flock system of a Sri Lankan rainforest. We recorded naturally elicited alarm calls during several attacks by Accipiter hawks and while following flocks for 10 h. We then artificially elicited alarms by throwing a stick to the side of the flock, in a total of 70 trials at 30 flock sites. The Orange-billed Babbler (Turdoides rufescens) was the most frequent caller to both the artificial and natural stimuli, followed by the Greater Racket-tailed Drongo (Dicrurus paradiseus). Several other species also called, and multiple species often called to the same stimulus (in 23 trials, and in all of the hawk attacks). The species differed in their rapidity of response and in their sensitivity to different natural stimuli. Calls of the gregarious babbler usually provided a first, unreliable warning of an incoming threat, whereas later calls of other species emphasized the seriousness of the threat. We suggest that birds in mixed-species flocks may be particularly aware of aerial predators for two reasons: (1) a “numbers effect,” whereby nongregarious species are more aware of predators when surrounded by large numbers of other species; and (2) an “information effect,” whereby species differ in the information available in their alarm calls, leading to an accumulation of information in a mixed-species flock. Llamadas de Alarma en Bandadas Mixtas de Aves en Sri Lanka

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Context-specific behavior serves as a mechanism of interspecific cohesion in mixed-species flocks

The Auk ◽

10.1093/ornithology/ukab046 ◽

2021 ◽

Author(s):

Sean M Williams ◽

Catherine A Lindell

Keyword(s):

Flight Distance ◽

Species Flock ◽

Mixed Species ◽

Specific Behavior ◽

Call Type ◽

Interspecific Associations ◽

Mixed Species Flocks ◽

Context Specific ◽

Species Flocks

Abstract We investigated whether context-specific behavior is responsible for the cohesion of mixed-species flocks of antshrikes and antwrens in Amazonian Peru. Antshrikes perform a behavior while spatially repositioning, to which antwrens respond by approaching. The cohesion of interspecific associations requires communication, although the mechanisms often are unexplored. In monospecific groups, cohesion among individuals is maintained with actions or vocalizations given in a certain context. Dusky-throated Antshrikes (Thamnomanes ardesiacus) vocalize while in flight and the number of times they vocalize covaries with the flight distance. We refer to this pairing of flight and vocalization as repositioning behavior. Furthermore, antshrikes pair a different call type with perching, which we refer to as perching behavior. We followed Long-winged (Myrmotherula longipennis) and White-flanked Antwrens (M. axillaris) and recorded their response following natural vocalizations (no playback used) given by the antshrikes. Long-winged Antwrens, but not White-flanked, flew toward an antshrike significantly sooner and were more likely to approach the antshrikes after the repositioning behavior than after perching behavior. In addition, Long-winged Antwrens, but not White-flanked, flew toward an antshrike sooner after a longer series of repositioning calls than after a shorter series. We did not distinguish between the Long-winged Antwrens’ response as a function of movement vs. vocalizations of the antshrikes, although we argue that vocalizations are likely a more important communication component of repositioning behavior than movement. It remains unclear whether the antshrikes are deliberately signaling the Long-winged Antwrens or the antwrens are taking advantage of the repositioning behavior; active signaling is possible since antshrikes benefit from antwrens. White-flanked Antwrens may be less responsive to the antshrikes since they have a lower propensity to occur in a mixed-species flock. The results indicate that the repositioning behavior of Dusky-throated Antshrikes is a key mechanism of interspecific cohesion of Amazonian mixed-species flocks of the understory.

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Structure and Dynamics of Mixed-Species Flocks in a Hawaiian Rain Forest

The Auk ◽

10.1093/auk/120.1.82 ◽

2003 ◽

Vol 120 (1) ◽

pp. 82-95

Author(s):

Patrick J. Hart ◽

Leonard A. Freed

Keyword(s):

Rain Forest ◽

High Variability ◽

Species Flock ◽

Flock Size ◽

Mixed Species ◽

Individual Level ◽

Interspecific Associations ◽

Nuclear Species ◽

Mixed Species Flocks ◽

Species Flocks

Abstract Mixed-species flocks of native and introduced birds were studied for four years in an upper elevation Hawaiian rain forest. Those flocks were characterized by strong seasonality, large size, low species richness, high intraspecific abundance, a lack of migrants, and a general lack of territoriality or any sort of dominance hierarchy. There was high variability among years in patterns of occurrence at the species level, and high variability within years at the individual level. These flocks are loosely structured social groupings with apparently open membership. The fluid, unstable movement patterns, high degree of variability in size and composition, and lack of positive interspecific associations are not consistent with the “foraging enhancement” hypothesis for flocking. Two resident, endangered insectivores, the Akepa (Loxops coccineus) and Hawaii Creeper (Oreomystis mana) served as “nuclear” species. Flock composition was compared between two study sites that differed significantly in density of these two nuclear species. Flock size was similar at the two sites, primarily because the nuclear species were over-represented relative to their density. This observation suggests that birds are attempting to achieve a more optimal flock size at the lower density site.

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The frequency of vocal mimicry associated with danger varies due to proximity to nest and nesting stage in a passerine bird

Behaviour ◽

10.1163/1568539x-00003123 ◽

2014 ◽

Vol 151 (1) ◽

pp. 73-88 ◽

Cited By ~ 6

Author(s):

Eben Goodale ◽

Chaminda P. Ratnayake ◽

Sarath W. Kotagama

Keyword(s):

Sri Lanka ◽

Passerine Bird ◽

Alarm Calls ◽

Mixed Species ◽

Vocal Mimicry ◽

Young Offspring ◽

Mixed Species Flocks ◽

Species Specific ◽

Breeding Seasons ◽

Species Flocks

Several species of birds vocally imitate sounds associated with danger. Two anecdotal studies suggest that such ‘danger mimicry’ increases during nesting, but such a relationship has not been quantitatively demonstrated. Sri Lanka drongos (Dicrurus paradiseus lophorhinus) are known to imitate predators and other species’ mobbing and alarm calls in alarm contexts. Here we investigated whether drongos vary their production of danger mimicry in different nesting stages (building, incubation, nests with hatchlings, fledglings still outside of mixed-species flocks), and when foraging away from young in mixed-species flocks. We recorded drongos over two breeding seasons at 14 different nesting trees, used year-after-year. We found that of all the types of danger mimicry, imitation of predators was the most common and exclusive to drongos that had young offspring. Such predator mimicry was observed at a higher rate during the hatchling and fledgling stages compared to incubation or flocks. Danger mimicry did not, however, increase during this stage in isolation: drongo species-specific alarm calls also increased, and the close connection between these two types of calls did not appear to change. Although it is possible that the association between danger mimicry and species-specific alarm calls could help young birds learn sounds associated with danger, the performance of this behaviour does not seem exclusive enough to interactions between adult drongos and their offspring to meet functional definitions of teaching.

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The influence of a single species on the space use of mixed-species flocks in Amazonian Peru

Movement Ecology ◽

10.1186/s40462-019-0181-5 ◽

2019 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

Sean M. Williams ◽

Catherine A. Lindell

Keyword(s):

Space Use ◽

Single Species ◽

Species Flock ◽

Vegetation Density ◽

Utilization Distribution ◽

Mixed Species ◽

Use Patterns ◽

Mixed Species Flocks ◽

Predator Behavior ◽

Species Flocks

Abstract Background The drivers of space use patterns of multi-species groups have been poorly studied, although mixed-species avian flocks are common throughout the world. In a mixed-species flock, multiple species move together and maintain proximity. The different species may or may not have conflicting preferences of space use. We hypothesized that the space use patterns of the flock are driven by a single species. Methods We investigated the behavioral drivers of space use patterns of mixed-species flocks in Amazonian Peru by mapping 95% fixed-kernel home ranges of three flocks, which then we divided into high-use (inner 55% kernel utilization distribution) and low-use areas (lying outside the high-use area). We quantified the foraging and anti-predator behavior of individual birds in the flocks. We tested whether foraging and anti-predator behavior of different species were different in high use and low use areas of the flock. Results We collected 455 spatial points and 329 foraging and anti-predator behavior observations on three flocks. The single best model for explaining the space use patterns of the flocks contained only vegetation density that surrounded Dusky-throated Antshrikes. Conclusion The results are consistent with the hypothesis that a single species in mixed-species flocks has a disproportionately large influence on space use patterns. The surrounding vegetation density of the Dusky-throated Antshrike was the only driver of space use patterns of flocks supported by our data. The results may apply to flocks pantropically, many of which are led by species that behave similarly to the Dusky-throated Antshrike, e.g. Asian flocks led by drongos (Dicrurus spp.).

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Selective Alarm Calling by Downy Woodpeckers in Mixed-Species Flocks

The Auk ◽

10.2307/4086843 ◽

1985 ◽

Vol 102 (1) ◽

pp. 184-187 ◽

Cited By ~ 40

Keyword(s):

Mixed Species ◽

Alarm Calling ◽

Mixed Species Flocks ◽

Species Flocks

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Information Exploitation By Downy Woodpeckers in Mixed-Species Flocks

Behaviour ◽

10.1163/156853984x00128 ◽

1984 ◽

Vol 91 (4) ◽

pp. 294-311 ◽

Cited By ~ 95

Author(s):

Kimberly A. Sullivan

Keyword(s):

Feeding Rate ◽

Alarm Calls ◽

Feeding Rates ◽

Mixed Species ◽

Auditory Cues ◽

Picoides Pubescens ◽

Contact Calls ◽

Mixed Species Flocks ◽

Winter Flocks ◽

Species Flocks

AbstractDowny woodpeckers (Picoides pubescens) benefit from foraging in mixed-species winter flocks by decreasing their vigilance level and increasing their feeding rate. I investigated one mechanism, auditory cues, downy woodpeckers use to obtain information on the presence of other flock members and potential predators. Experiments with predator models and with recorded alarm calls and contact calls from flock members yielded the following results. Downy woodpeckers use the contact calls of other flock members to assess the presence of flocks members. Woodpeckers foraging alone but with the recorded contact calls of flock members showed lower vigilance levels and higher feeding rates than woodpeckers foraging alone with no recordings or with the control recordings. Woodpeckers respond to the other species' alarm calls as an indication of potential predators and also to their contact calls as an all clear signal afterwards. Downy woodpeckers decreased their vigilance levels and resumed foraging faster when the contact calls followed the presentation of predator models or alarm calls than when these were presented alone.

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Lesser spot-nosed monkeys coordinate alarm call production with associated Campbell’s monkeys

Behavioral Ecology and Sociobiology ◽

10.1007/s00265-021-03053-w ◽

2021 ◽

Vol 75 (8) ◽

Author(s):

Auriane Le Floch ◽

Alice Bouchard ◽

Quentin Gallot ◽

Klaus Zuberbühler

Keyword(s):

Alarm Call ◽

Predation Pressure ◽

Primate Species ◽

Alarm Calls ◽

Mixed Species ◽

Call Type ◽

Alarm Calling ◽

Calling Behaviour ◽

Vocal Behaviour ◽

Call Production

Abstract Forest monkeys often form semi-permanent mixed-species associations to increase group-size related anti-predator benefits without corresponding increases in resource competition. In this study, we analysed the alarm call system of lesser spot-nosed monkeys, a primate that spends most of its time in mixed-species groups while occupying the lowest and presumably most dangerous part of the forest canopy. In contrast to other primate species, we found no evidence for predator-specific alarm calls. Instead, males gave one general alarm call type (‘kroo’) to three main dangers (i.e., crowned eagles, leopards and falling trees) and a second call type (‘tcha-kow’) as a coordinated response to calls produced in non-predatory contexts (‘boom’) by associated male Campbell’s monkeys. Production of ‘kroo’ calls was also strongly affected by the alarm calling behaviour of male Campbell’s monkeys, suggesting that male lesser spot-nosed monkeys adjust their alarm call production to another species’ vocal behaviour. We discuss different hypotheses for this unusual phenomenon and propose that high predation pressure can lead to reliance on other species vocal behaviour to minimise predation. Significance statement Predation can lead to the evolution of acoustically distinct, predator-specific alarm calls. However, there are occasional reports of species lacking such abilities, despite diverse predation pressure, suggesting that evolutionary mechanisms are more complex. We conducted field experiments to systematically describe the alarm calling behaviour of lesser spot-nosed monkeys, an arboreal primate living in the lower forest strata where pressure from different predators is high. We found evidence for two acoustically distinct calls but, contrary to other primates in the same habitat, no evidence for predator-specific alarms. Instead, callers produced one alarm call type (‘kroo’) to all predator classes and another call type (‘tcha-kow’) to non-predatory dangers, but only as a response to a specific vocalisation of Campbell’s monkeys (‘boom’). The production of both calls was affected by the calling behaviour of Campbell’s monkeys, suggesting that lesser spot-nosed monkey vocal behaviour is dependent on the antipredator behaviour of other species. Our study advances the theory of interspecies interactions and evolution of alarm calls.

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