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

The Auk ◽  
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.

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

The Auk ◽  
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.

scholarly journals Alarm Calling in Sri Lankan Mixed-Species Bird Flocks

The Auk ◽  
2005 ◽  
Vol 122 (1) ◽  
pp. 108-120 ◽  
Author(s):  
Eben Goodale ◽  
Sarath W. Kotagama
Keyword(s):  
Alarm Call ◽  
Alarm Calls ◽  
Species Flock ◽  
Sri Lankan ◽  
Mixed Species ◽  
Alarm Calling ◽  
Natural Stimuli ◽  
Mixed Species Flocks ◽  
Multiple Species ◽  
Species 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

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

2019 ◽  
Vol 7 (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.).

Using playback to test leadership in mixed-species flocks and compare flocking with mobbing

2021 ◽  
Vol 180 ◽  
pp. 151-166
Author(s):  
Liping Zhou ◽  
Indika Peabotuwage ◽  
Kang Luo ◽  
Rui-Chang Quan ◽  
Eben Goodale
Keyword(s):  
Mixed Species ◽  
Mixed Species Flocks ◽  
Species Flocks

Why Do Brown-Headed Cowbirds Perform the Head-Down Display?

The Auk ◽  
1983 ◽  
Vol 100 (1) ◽  
pp. 139-148 ◽  
Author(s):  
Thomas W. Scott ◽  
Judith M. Grumstrup-Scott
Keyword(s):  
Observational Data ◽  
Agonistic Behavior ◽  
Mixed Species ◽  
House Sparrows ◽  
Mixed Species Flocks ◽  
Free Ranging ◽  
Species Flocks

Abstract Four hypotheses for the function of the head-down display performed by Brown-headed Cowbirds were tested with observational data from free-ranging and captive cowbirds. Free-ranging cowbirds performed 284 interspecific and four intraspecific displays during 59.2 daylight hours while roosting in mixed-species flocks adjacent to feeding areas. The most common recipients of displays, female Red-winged Blackbirds and House Sparrows, preened cowbirds during 25 displays. Cowbirds that had just been preened displayed more often than those that had not recently been preened. Captive cowbirds displayed intraspecifically 475 times during 13.3 h, and dominant captive birds displayed more often than their subordinates. The following hypothesis was proposed to explain the display's function: the head-down display of Brown-headed Cowbirds is an appeasing agonistic behavior, the displayor is most often dominant to the recipient, and subsequent displaying is stimulated by interspecific preening. The display may function in: (a) obtaining food, (b) minimizing roosting energetics, and/or (c) establishing flock order.

Temperature and vegetation complexity structure mixed-species flocks along a gradient of elevation in the tropical Andes

The Auk ◽  
2021 ◽  
Author(s):  
Flavia A Montaño-Centellas ◽  
Harrison H Jones
Keyword(s):  
Species Richness ◽  
Abiotic Stress ◽  
Environmental Gradients ◽  
Bird Community ◽  
Taxonomic Diversity ◽  
High Elevation ◽  
Tropical Andes ◽  
Mixed Species ◽  
Mixed Species Flocks ◽  
Species Flocks

Abstract Mixed-species flocks constitute community modules that can help test mechanisms driving changes to community composition across environmental gradients. Here, we examined elevational patterns of flock diversity (species richness, taxonomic diversity, species, and guild composition) and asked if these patterns were reflections of the full bird community at a given elevation (open-membership hypothesis), or if they were instead structured by environmental variables. We surveyed both the overall avian community and mixed-species flocks across an undisturbed elevational gradient (~1,350–3,550 m) in the Bolivian Andes. We then tested for the role of temperature (a surrogate for abiotic stress), resource diversity (arthropods, fruits), and foraging niche diversity (vegetation vertical complexity) in structuring these patterns. Patterns for the overall and flocking communities were similar, supporting our open-membership hypothesis that Andean flocks represent dynamic, unstructured aggregations. Membership openness and the resulting flock composition, however, also varied with elevation in response to temperature and vegetation complexity. We found a mid-elevation peak in flock species richness, size, and Shannon’s diversity at ~2,300 m. The transition of flocking behavior toward a more open-membership system at this elevation may explain a similar peak in the proportion of insectivores joining flocks. At high elevations, increasing abiotic stress and decreasing fruit diversity led more generalist, gregarious tanagers (Thraupidae) to join flocks, resulting in larger yet more even flocks alongside a loss of vegetation structure. At lower elevations, flock species richness increased with greater vegetation complexity, but a greater diversity of foraging niches resulted in flocks that were more segregated into separate canopy and understory sub-types. This segregation likely results from increased costs of interspecific competition and activity matching (i.e., constraints on movement and foraging rate) for insectivores. Mid-elevation flocks (~2,300 m) seemed, therefore, to benefit from both the open-membership composition of high-elevation flocks and the high vegetation complexity of mid- and low-elevation forests.

Do racket-tailed drongos make tree guards for their nest trees?

Behaviour ◽  
2020 ◽  
Vol 157 (14-15) ◽  
pp. 1239-1244
Author(s):  
Samira Agnihotri ◽  
Marian Kethegowda ◽  
Jadeswamy
Keyword(s):  
Tropical Forest ◽  
Cognitive Abilities ◽  
Forest Trees ◽  
Tree Trunk ◽  
Mixed Species ◽  
Old World ◽  
Mixed Species Flocks ◽  
Old World Tropics ◽  
Species Flocks ◽  
Nesting Season

Abstract Greater racket-tailed drongos are renowned for their splendid mimicking abilities, and for their significant roles within mixed species flocks in the Old World tropics. Yet, we know little about their basic ecology and breeding behaviour. Here we describe a set of unique behaviours of these drongos during their nesting season. Racket-tailed drongos nested in trees in an open patch of forest, often returning to the same tree year after year. The nesting pair also smoothened the bark of the nest tree trunk with their beaks. These findings suggest that the nest tree is a crucial resource for this species, and have implications for the cognitive abilities of drongos, as well as for hitherto unknown interactions between an avian species and tropical forest trees.

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