Mixed-Species Flocking and Foraging Behavior of Four Neotropical Warblers in Panamanian Shade Coffee Fields and Forests

The Auk ◽  
2003 ◽  
Vol 120 (4) ◽  
pp. 1000-1012 ◽  
Author(s):  
Lars Y. Pomara ◽  
Robert J. Cooper ◽  
Lisa J. Petit
1973 ◽  
Vol 51 (12) ◽  
pp. 1275-1288 ◽  
Author(s):  
John R. Krebs

The experiments described in this paper show that two species of chickadees learn from one another about the location and nature of potential feeding places when they are foraging together in mixed flocks in large aviaries. In the first experiment, I show that when an individual of one species finds a single food item, members of the other species modify their foraging behavior over the next few seconds so that they put more effort into searching near the site of the find. This applies to both species. Further, members of both species modify their foraging behavior when a bird of the other species searches in a place unsuccessfully. This response to an unsuccessful search is similar to, but weaker than, the response to a food find. The second experiment shows that when the two species are trained to forage in different positions in the experimental trees, they converge in their foraging behavior when they are put in mixed flocks, This is a result of copying. The third experiment shows that individuals of both species are more likely to discover a completely new foraging place if they are in the presence of an experienced bird of the other species.I discuss these results in relation to theories on the adaptive significance of flocking, and conclude that learning about potential feeding places from other species is an important function of mixed flocks, at least for some species. This does not exclude the possibility of other functions of mixed flocks.


The Auk ◽  
2003 ◽  
Vol 120 (4) ◽  
pp. 1000-1012
Author(s):  
Lars Y. Pomara ◽  
Robert J. Cooper ◽  
Lisa J. Petit

Abstract We quantified foraging rates and foraging visibility metrics for four Neotropical warblers—Slate-throated Redstart (Myoborus miniatus), Golden-crowned Warbler (Basileuterus culicivorus), Wilson's Warbler (Wilsonia pusilla), and Black-and-White Warbler (Mniotilta varia)—under flocking and solitary conditions in western Panama to test hypotheses regarding the relative influences of predation pressure and social facilitation on foraging behavior. We also compared foraging behavior in primary forests and in traditionally managed shade coffee fields for two species (Slate-throated Redstart and Wilson's Warbler) to estimate spatial variation in foraging behavior and compare it to variation due to social situation (flocking or solitary). We then assessed the contribution of spatial variation in flocking propensity to the total spatial variation in foraging rates within species. We observed very little overall within-species variability in foraging behavior between social situations or study locations. Only Slate-throated Redstart's behavior was consistent with the hypothesis that flock membership reduces predation pressure and therefore reduces the amount of foraging time spent being vigilant against predators, allowing birds to forage more quickly and find more prey items per minute. No species' behavior supported the hypothesis that flocking birds forage more efficiently than solitary birds by obtaining useful information from flock mates about the location or suitability of foraging resources or techniques. The effort required to find prey items did not vary between study locations (forest and coffee field plots) for Wilson's Warbler. Because flocking also had no effect on foraging behavior of Wilson's Warbler, a reduction in flocking propensity in coffee habitat, relative to forest, did not cause further foraging behavior differences between study locations. Spatial variation in Slate-throated Redstart's foraging behavior independent of a flocking effect was minor; but flocking affected foraging rates, and flocking propensity was lower in coffee fields than in forest, so that location and flocking effects combined to widen foraging rate differences between locations. Thus, variations in flocking behavior and foraging behavior interacted differently for those two species.


The Condor ◽  
2000 ◽  
Vol 102 (4) ◽  
pp. 958-962 ◽  
Author(s):  
Jason Jones ◽  
Paolo Ramoni Perazzi ◽  
Erin H. Carruthers ◽  
Raleigh J. Robertson

Abstract We examined the use of Venezuelan shade-coffee plantations by the Cerulean Warbler (Dendroica cerulea) and other Neotropical migrants. Cerulean Warblers were commonly observed as pairs in mixed-species flocks. Average (± SE) flock size was 13 ± 2 species with 22 ± 3 individuals. Average flock territory size was 2.5 ± 0.2 ha. No differences were detected in foraging behavior (maneuvers, location, or success) among adult males, adult females, and immature birds. Adult males were often observed visiting flowers of canopy trees. The results of this study indicate that shade coffee plantations may provide suitable wintering habitat for Cerulean Warblers although comparisons with other habitats are needed.


2021 ◽  
Vol 8 ◽  
Author(s):  
Priti Bangal ◽  
Hari Sridhar ◽  
Kartik Shanker

Animals that live in groups may experience positive interactions such as cooperative behavior or negative interactions such as competition from group members depending on group size and similarity between individuals. The effect of group size and phenotypic and ecological similarity on group assembly has not been well-studied. Mixed-species flocks are important subsets of bird communities worldwide. We examined associations within these in relation to flock size, to understand rules of flock assembly, in the Western Ghats of India. We examined the relationship between phenotypic clumping and flock richness using four variables—body size, foraging behavior, foraging height and taxonomic relatedness. Using a null model approach, we found that small flocks were more phenotypically clumped for body size than expected by chance; however, phenotypic clumping decreased as flocks increased in size and approached expected phenotypic variation in large flocks. This pattern was not as clear for foraging height and foraging behavior. We then examined a dataset of 55 flock matrices from 24 sites across the world. We found that sites with smaller flocks had higher values of phenotypic clumping for body size and sites with larger flocks were less phenotypically clumped. This relationship was weakly negative for foraging behavior and not statistically significant for taxonomic relatedness. Unlike most single-species groups, participants in mixed-species flocks appear to be able to separate on different axes of trait similarity. They can gain benefits from similarity on one axis while mitigating competition by dissimilarity on others. Consistent with our results, we speculate that flock assembly was deterministic up to a certain point with participants being similar in body size, but larger flocks tended to approach random phenotypic assemblages of species.


2005 ◽  
Vol 83 (6) ◽  
pp. 880-890 ◽  
Author(s):  
Ya-Fu Lee ◽  
Yen-Min Kuo ◽  
Eric K Bollinger

Foraging behavior that balances feeding efficiency with predation risk avoidance may be selected for; thus, foraging animals may choose among sites and achieve various giving-up densities under different feeding conditions. We compared the frequency and duration of visits and the feeding efficiency of a mixed-species wintering bird flock among feeders set up at three heights within woods, at the edge between woods and dense shrub, and in open fields to investigate the feeding height preference of birds and its relationship to the extent of openness of the sites. Carolina chickadees (Parus carolinensis Audubon, 1834) and tufted titmice (Parus bicolor L., 1766) accounted for 96% of the total number of visits to feeders and 95.9% of the total time spent on feeders. Birds tended to visit higher feeders and feeders in the woods and at edge sites more frequently than they visited lower feeders and feeders in open fields. Birds also spent more time on higher feeders and feeders in the woods and at edge sites than on lower feeders and feeders in open fields. However, the feeding height preference changed over the course of observations, and different patterns were observed at different sites. In the woods and at the edge, bird visits shifted to the lower feeders earlier; in contrast, birds preferred higher feeders throughout the period of observation in open fields. Feeding efficiency was lower at open sites than in woods and at edge sites, but birds spent the least time per seed on low feeders at open sites. Seeds on higher feeders and in woods or at edge sites were removed faster. Regardless of the height and locality of feeders, birds preferred energy-rich oil-type seeds over energy-poor striped seeds.


The Auk ◽  
2020 ◽  
Vol 137 (2) ◽  
Author(s):  
Harrison H Jones ◽  
Mitchell J Walters ◽  
Scott K Robinson

Abstract Mixed-species flocks are ubiquitous in forest bird communities, yet the extent to which positive (facilitative) or negative (competitive) interactions structure these assemblages has been a subject of debate. Here, we describe the fine-scale foraging ecology and use network analysis to quantify mixed-species flocking interactions of an insectivorous bird community in hardwood forests of north-central Florida. Our goal was to determine if similarly foraging species are more (facilitation hypothesis) or less (competition hypothesis) likely to associate in flocks, and if foraging ecology can explain intraspecific abundance patterns within flocks. We quantified attack maneuvers, foraging substrate, and foraging microhabitat of all 17 common insectivorous species in these forests and characterized the composition of 92 flocks encountered. Flocking was important in our community; 14 of 17 species joined more than 5% of flocks, and 10 species had flocking propensities of over 0.80. Our results supported both hypothesized mechanisms structuring flock composition. Species had distinct, well-defined foraging niches during the nonbreeding season, but foraging niche overlap among flocking species was greater than expected by chance. Consistent with the facilitation hypothesis, we found that similarly foraging species were significantly more likely to associate in flocks, a result driven by lower association strengths in large-bodied woodpeckers. We found no evidence of assortment by foraging behavior, however, likely because foraging behavior and substrate use showed strong niche partitioning at the fine scale within our community. Intraspecific abundance patterns were significantly linked to foraging substrate use, with live leaf use correlated with high within-flock abundance and relative abundance at study sites. Species that specialized on comparatively less abundant substrates (tree trunks, epiphytes, dead leaves) joined flocks as singletons, showed lower relative abundance, and may exhibit nonbreeding territoriality. Our results highlight the importance of foraging substrate use and mixed-species flocks in structuring the nonbreeding ecology of migratory birds.


2018 ◽  
Vol 29 (2) ◽  
pp. 232-248 ◽  
Author(s):  
LAURA N. CÉSPEDES ◽  
NICHOLAS J. BAYLY

SummaryThe Canada Warbler Cardellina canadensis is a steeply declining Neotropical migratory bird and > 50% of its non-breeding range is within the Colombian Andes. Despite being an abundant migrant in Andean forests, the species’ elevational distribution and non-breeding ecology have yet to be studied, thereby precluding the design of effective conservation actions. During four non-breeding periods (2012–2016), we surveyed Colombia’s three Andean ranges, carrying out passive 5-minute point counts between 700 and 3,150 m asl in five habitats (mature forest, secondary growth, forest edges/riparian forest, shade coffee, sun coffee), recording the perpendicular distance, sex, foraging height, and association with mixed species flocks of Canada Warbler. Habitat variables were recorded at each point. Based on 819 passive point counts, Canada Warblers occupied elevations between 750 and 2,300 m, being more abundant between 1,000 and 2,200 m. Relative densities were higher in mature forest compared to shade coffee and secondary forest, and accordingly abundance increased with canopy height. There was no evidence for a difference in elevation or habitat use by males and females. Within forests, birds foraged at mid-levels, 5–15 m above the ground, and the probability of Canada Warblers occurring in mixed species flocks increased with elevation. Models of variation in relative density throughout the Eastern Andes showed a positive relation with cloud cover and above-ground forest biomass, implying a preference for humid, forested regions. Of the areas in the Eastern Andes with high predicted relative density, ∼ 14% overlapped with protected areas and we identify priority areas where protective measures could benefit the conservation status of the species. For maximum effectiveness, conservation actions should focus on protecting forest fragments and initiating reforestation projects at mid-elevations (1,000–2,200 m), as well as supporting agroforestry practices in humid regions of the Colombian Andes.


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