The assessment of arboreal insect fauna: comparisons of knockdown sampling and faunal lists

Abstract. 1. A comparison is made between the fauna of six British tree species sampled by pyrethrum knockdown and the faunal lists in the literature for the same tree species.
2. Conspecific trees vary both in abundance of arthropods and their proportional distribution across taxa, but there are important overriding differences between tree species.
3. The percentage similarity in faunal composition between tree species reflects the ecological specificity of the arthropod groups used for the comparison.
4. The similarity in species composition between tree species is least for phytophages, the guild most closely associated with particular tree species, The two species of Salix are most similar in their fauna for most guilds.
5. About 40% of the entirely phytophagous species in the faunal lists for native trees were found in the knockdown samples.
6. The proportion of individuals of predominantly phytophagous taxa collected that belong to the relevant faunal lists ranges from 0.39 to 0.99.
7. Those species found in the knockdown samples which are not included in faunal lists none the less contribute to the trophic web of the tree.
8. The relative species richness of arboreal faunas assessed from knockdown samples parallels that derived from faunal lists.
9. The two approaches to the categorization of arboreal faunas, knockdown sampling and faunal lists, provide comparable data.     

Guild composition and mustelid morphology – character displacement but no character release

Aim  Competition is hypothesized to lead to the evolution of reduced morphological overlap between competitors. Within guilds, this is believed to lead to overdispersed size ratios of the trophic apparatus of adjacent-sized species. In allopatry, conditions are believed to favour character release. We examined whether character displacement is prevalent in mainland musteline guilds and sought evidence for character release in adjacent island guilds.
Location  Holarctic, from Japan through western Europe to Pacific North America.
Methods  We measured skulls and canines of members of the mustelid subfamily Mustelinae and examined whether size ratios tend towards equality. We then examined whether insular guilds are characterized by larger size ratios and a higher degree of sexual size dimorphism than mainland guilds, and whether this reflects evolution towards the size of missing guild members.
Results  We found equal ratios between skull lengths but not canine diameters in all mainland guilds. Few insular guilds showed equal ratios for either trait. There was scant evidence for character release: insular mustelines do not evolve towards the size of a missing guild member, nor is sexual size dimorphism greater on islands. There was no evidence for a lower limit on the size similarity of co-existing mustelids.
Main conclusions  We propose that different guild compositions in different localities produce different evolutionary trajectories. Similar sizes on islands and mainlands can be explained by similar prey sizes in both settings. Morphological evidence suggests that competition is probably not a ubiquitous force in the assembly and evolution of musteline guilds.     

Host specificity of ambrosia and bark beetles (Col., Curculionidae: Scolytinae and Platypodinae) in a New Guinea rainforest

Abstract.  1. Bark and ambrosia beetles are crucial for woody biomass decomposition in tropical forests worldwide. Despite that, quantitative data on their host specificity are scarce.
2. Bark and ambrosia beetles (Scolytinae and Platypodinae) were reared from 13 species of tropical trees representing 11 families from all major lineages of dicotyledonous plants. Standardised samples of beetle-infested twigs, branches, trunks, and roots were taken from three individuals of each tree species growing in a lowland tropical rainforest in Papua New Guinea.
3. A total of 81 742 beetles from 74 species were reared, 67 of them identified. Local species richness of bark and ambrosia beetles was estimated at 80–92 species.
4. Ambrosia beetles were broad generalists as 95% of species did not show any preference for a particular host species or clade. Similarity of ambrosia beetle communities from different tree species was not correlated with phylogenetic distances between tree species. Similarity of ambrosia beetle communities from individual conspecific trees was not higher than that from heterospecific trees and different parts of the trees hosted similar ambrosia beetle communities, as only a few species preferred particular tree parts.
5. In contrast, phloeophagous bark beetles showed strict specificity to host plant genus or family. However, this guild was poor in species (12 species) and restricted to only three plant families (Moraceae, Myristicaceae, Sapindaceae).
6. Local diversity of both bark and ambrosia beetles is not driven by the local diversity of trees in tropical forests, since ambrosia beetles display no host specificity and bark beetles are species poor and restricted to a few plant families.     

Global patterns of guild composition and functional diversity of spiders

The objectives of this work are: (1) to define spider guilds for all extant families worldwide; (2) test if guilds defined at family level are good surrogates of species guilds; (3) compare the taxonomic and guild composition of spider assemblages from different parts of the world; (4) compare the taxonomic and functional diversity of spider assemblages and; (5) relate functional diversity with habitat structure. Data on foraging strategy, prey range, vertical stratification and circadian activity was collected for 108 families. Spider guilds were defined by hierarchical clustering. We searched for inconsistencies between family guild placement and the known guild of each species. Richness and abundance per guild before and after correcting guild placement were compared, as were the proportions of each guild and family between all possible pairs of sites. Functional diversity per site was calculated based on hierarchical clustering. Eight guilds were discriminated: (1) sensing, (2) sheet, (3) space, and (4) orb web weavers; (5) specialists; (6) ambush, (7) ground, and (8) other hunters. Sixteen percent of the species richness corresponding to 11% of all captured individuals was incorrectly attributed to a guild by family surrogacy; however, the correlation of uncorrected vs. corrected guilds was invariably high. The correlation of guild richness or abundances was generally higher than the correlation of family richness or abundances. Functional diversity was not always higher in the tropics than in temperate regions. Families may potentially serve as ecological surrogates for species. Different families may present similar roles in the ecosystems, with replacement of some taxa by other within the same guild. Spiders in tropical regions seem to have higher redundancy of functional roles and/or finer resource partitioning than in temperate regions. Although species and family diversity were higher in the tropics, functional diversity seems to be also influenced by altitude and habitat structure.     

The arthropod community of an Australian rainforest tree: Abundance of component taxa,species richness and guild structure

Abstract The arthropod community within the crowns of Argyrodendron actmophyllum (Sterculiaceae) in a subtropical rainforest near Brisbane, Australia, was investigated during a 2 year study using interception traps and restricted canopy fogging. The total arthropod density was 34 individuals m^?2 of leaf area. Spiders, psyllids, thrips, psocids and chrysomelids were most abundant. The most diverse families included Curculionidae, Cicadellidae, Staphylin-idae, Cerambycidae, Theridiidae, and Chrysomelidae. The arboreal community of A. actinophyllum exhibited several features common to arthropod communities from temperate and tropical rainforest trees. Affinity with temperate trees was suggested by the relatively high densities of certain species, by high proportions (in terms of individuals) of sap-suckers and non-insect predators, and by a low proportion of ants. Affinity with tropical rainforest trees was expressed by high proportions of scavenging fauna, particularly wood-eaters and fungalfeeders.     

Spatial covariance of herbivorous and predatory guilds of forest canopy arthropods along a latitudinal gradient

In arthropod community ecology, species richness studies tend to be prioritised over those investigating patterns of abundance. Consequently, the biotic and abiotic drivers of arboreal arthropod abundance are still relatively poorly known. In this cross‐continental study, we employ a theoretical framework in order to examine patterns of covariance among herbivorous and predatory arthropod guilds. Leaf‐chewing and leaf‐mining herbivores, and predatory ants and spiders, were censused on > 1000 trees in nine 0.1 ha forest plots. After controlling for tree size and season, we found no negative pairwise correlations between guild abundances per plot, suggestive of weak signals of both inter‐guild competition and top‐down regulation of herbivores by predators. Inter‐guild interaction strengths did not vary with mean annual temperature, thus opposing the hypothesis that biotic interactions intensify towards the equator. We find evidence for the bottom‐up limitation of arthropod abundances via resources and abiotic factors, rather than for competition and predation.     

Community structure and assembly rules in a dune slack: Variance in richness,guild proportionality,biomass constancy and dominance/diversity relations

There is still disagreement as to whether plant communities can be described as conforming to certain assembly rules. We searched for such rules in the vegetation of four dune slacks in west Wales by examining variance in richness, guild proportionality, biomass constancy and dominance/diversity relations. To test for the occurrence of niche limitation, variance in quadrat species-richness was compared to null models of species occurrence. Using an Overall-model, one site showed a deficit of variance, but this disappeared when a Patch-model analysis was used. It therefore seems likely that the effect observed was due to equality in the species pools adapted to different microenvironments. The proportional representation of functional guilds was examined, in guilds based on morphology and life history. Significant constancy of guild proportions was seen for the annual guild in the only site in which it occurred, perhaps reflecting a regeneration niche. Total biomass per quadrat was examined, and compared to a model in which the biomass of each species was determined at random from the biomasses of that species at the site. Surprisingly, the observed biomasses showed no departure from the null model. However, there was considerable discrepancy from an alternative null model in which biomasses were allocated at random irrespective of species. This would imply that competition limits species coexistence, rather than performance. Examination of the proportions of species from different potential-size classes in each quadrat gave limited confirmation. The local abundance of species (mean biomass) was significantly correlated with the frequency of the species within a site, parallelling the geographical-range/local-abundance correlation previously reported. Five dominance/diversity models were fitted to the biomass data. The best fits were given by the Geometric or the General Lognormal models, though which fitted best varied between and within sites. Between sites, there was some indication of a consistent difference in Preston's gamma. Most of the results are compatible with Gleason's Individualistic concept of the plant community, though there are several pointers that assembly rules have some impact on community structure.     

Species co-occurrence, nestedness and guild–environment relationships in stream macroinvertebrates

1. Describing species distribution patterns and the underlying mechanisms is at the heart of ecological research. A number of recent studies have used null model approaches to explore mechanisms behind spatial variation in community structure.
2. However, unexplored questions are the degree to which single guilds of potentially competing stream macroinvertebrate species show: (i) interspecific segregation among-stream sites (i.e. occur together less often than expected by chance), suggesting competitive interactions; (ii) interspecific aggregation (i.e. occur together more often than expected by chance), suggesting similar responses to the environment; (iii) comply with nestedness, suggesting the existence of selective extinctions or colonisations and (iv) show similar environmental relationships.
3. The present analyses showed that guilds of stream macroinvertebrates exhibit non-random co-occurrence patterns that were generally contingent on the weighting of sites by stream size. Despite significant segregation of species, each guild also showed significantly nested patterns. Species richness was correlated with different environmental factors between the guilds, although these correlations were relatively low. By contrast, correlations between the major ordination axes and key environmental variables were slightly stronger in canonical correspondence analysis, and generally the same factors were most strongly correlated with variation in the species composition of each guild.
4. The present findings are the first to show that species within each stream macroinvertebrate guild show significant negative co-occurrence at the among-stream riffle scale. These findings present challenges for future studies that aim to disentangle whether these patterns comply with the habitat checkerboard or the competitive checkerboard explanations.     

Feeding guild structure of beetles on Australian tropical rainforest trees reflects microhabitat resource availability

1.?We tested the hypotheses that feeding guild structure of beetle assemblages changed with different arboreal microhabitats and that these differences were consistent across rainforest tree species. 2.?Hand collection and beating techniques were used from the gondola of the Australian Canopy Crane to collect beetles from five microhabitats (mature leaves, flush leaves, flowers, fruit and suspended dead wood) within the rainforest canopy. A simple randomization procedure was implemented to test whether the abundances of each feeding guild on each microhabitat were different from that expected based on a null hypothesis of random distribution of individuals across microhabitats. 3.?Beetles from different feeding guilds were not randomly distributed, but congregated on those microhabitats that are likely to provide the highest concentrations of their preferred food sources. Herbivorous beetles, in particular, were over-represented on flowers and flush foliage and under-represented on mature leaves and dead wood. Proportional numbers of species within each feeding guild were remarkably uniform across tree species for each microhabitat, but proportional abundances of feeding guilds were all significantly non-uniformly distributed between host tree species, regardless of microhabitat, confirming patterns previously found for arthropods in trees in temperate and tropical forests. 4.?These results show that the canopy beetle community is partitioned into discrete assemblages between microhabitats and that this partitioning arises because of differences in feeding guild structure as a function of the diversity and the temporal and spatial availability of resources found on each microhabitat.     

Variability in species richness and guild structure in two species-rich grasslands

It has been suggested that variation in the proportion of species in guilds (=guild proportionality) indicates community structuring by guilds in biotic communities. This hypothesis was tested on a subthermophilous grassland and a mesotrophic meadow at a scale of 0.09 m² based on a five-year data set. Further, variation in the total number of species, variation in the number of species belonging to a guild and non-randomness in species composition of guilds were studied. A number of criteria for guild definition were used, such as life form, Grime's C-S-R strategy, phenology, plant height, pollination and dispersal syndromes, leaf shape and anatomy and taxonomy at the family level. The observed variation in the number of guild species corresponded to the null model in which species assemblages with fixed species richness per square were randomly generated from the species pool. The observed variation in the number of guild species was often higher than the variation calculated for randomly distributed species whereas the variation in the proportion of guild species was in some cases lower than the variation calculated for randomly distributed species with fixed frequencies. Possible reasons for the discrepancy in the results based on different models are discussed. It is concluded that there is little evidence of guilds in the organization of grasslands. *** DIRECT SUPPORT *** A02DO006 00012     

An Ant Mosaic Revisited: Dominant Ant Species Disassemble Arboreal Ant Communities but Co-Occur Randomly

The spatial distributions of many tropical arboreal ant species are often arranged in a mosaic such that dominant species have mutually exclusive distributions among trees. These dominant species can also mediate the structure of the rest of the arboreal ant community. Little attention has been paid to how diet might shape the effects of dominant species on one another and the rest of the ant community. Here, we take advantage of new information on the diets of many tropical arboreal ant species to examine the intra- and inter-guild effects of dominant species on the spatial distribution of one another and the rest of the tropical arboreal ant community in a cocoa farm in Bahia, Brazil. Using null model analyses, we found that all ant species, regardless of dominance status or guild membership, co-occur much less than expected by chance. Surprisingly, the suite of five dominant species showed random co-occurrence patterns, suggesting that interspecific competition did not shape their distribution among cocoa trees. Across all species, there was no evidence that competition shaped co-occurrence patterns within guilds. Co-occurrence patterns of subordinant species were random on trees with dominant species, but highly nonrandom on trees without dominant species, suggesting that dominant species disassemble tropical arboreal ant communities. Taken together, our results highlight the often complex nature of interactions that structure species-rich tropical arboreal ant assemblages.     

Arthropod Distribution in a Tropical Rainforest: Tackling a Four Dimensional Puzzle

Quantifying the spatio-temporal distribution of arthropods in tropical rainforests represents a first step towards scrutinizing the global distribution of biodiversity on Earth. To date most studies have focused on narrow taxonomic groups or lack a design that allows partitioning of the components of diversity. Here, we consider an exceptionally large dataset (113,952 individuals representing 5,858 species), obtained from the San Lorenzo forest in Panama, where the phylogenetic breadth of arthropod taxa was surveyed using 14 protocols targeting the soil, litter, understory, lower and upper canopy habitats, replicated across seasons in 2003 and 2004. This dataset is used to explore the relative influence of horizontal, vertical and seasonal drivers of arthropod distribution in this forest. We considered arthropod abundance, observed and estimated species richness, additive decomposition of species richness, multiplicative partitioning of species diversity, variation in species composition, species turnover and guild structure as components of diversity. At the scale of our study (2km of distance, 40m in height and 400 days), the effects related to the vertical and seasonal dimensions were most important. Most adult arthropods were collected from the soil/litter or the upper canopy and species richness was highest in the canopy. We compared the distribution of arthropods and trees within our study system. Effects related to the seasonal dimension were stronger for arthropods than for trees. We conclude that: (1) models of beta diversity developed for tropical trees are unlikely to be applicable to tropical arthropods; (2) it is imperative that estimates of global biodiversity derived from mass collecting of arthropods in tropical rainforests embrace the strong vertical and seasonal partitioning observed here; and (3) given the high species turnover observed between seasons, global climate change may have severe consequences for rainforest arthropods.     

Species richness of phytophagous beetles in the tropical tree Brosimum utile (Moraceae): the effects of sampling strategy and the problem of tourists

Abstract.  1. Phytophagous beetles on six mature living trees and two dead trees of Brosimum utile (Moraceae) were surveyed during 1 year in a tropical wet forest in Panama. The dead trees were surveyed both as suspended in the canopy and after falling down to the understorey.
2. Canopy access was provided by a construction crane and sampling was performed by beating and hand-collecting. The same amount of time was spent on each tree in order to standardise sampling effort. A list of all species associated with the tree is presented.
3. A total of 3009 individuals representing 364 species were collected. Tourists were excluded from the analyses by recording host associations directly and by probability assessments of host associations based on abundance categories. A total of 2603 individuals and 244 species were associated with the tree. The proportion of tourists in the trees increased with sample size.
4. A single mature living tree had on average 58.5 ± 6.5 species. The local species richness of B. utile was estimated as 2.5 times higher than in a single mature tree; however, a substantial increase in species richness was attained when dead wood habitats were included. Saproxylic species made up 82% of the total material.
5. The investigated habitat types of B. utile constituted distinct, complementary species assemblages. Similarity between saproxylic species of dead suspended wood and dead understorey wood of the same tree was 0.2 (Morisita–Horn index), confirming a prominent vertical stratification among this guild.     

Abundance and diversity of Homoptera in the canopy of a tropical forest

Abstract. 1. A series of samples of Homoptera was obtained by fogging the canopy of Luehea seemannii trees in tropical forest in the Panama Canal Zone at three different times of the year.
2. The peak of abundance occurs around July (at least 11.8 individuals/m²), in the early wet season, at a time when most of the trees in the forest, including Luehea are producing new leaves.
3. Minimum abundance occurs in March (at least 3.5 individuals/m²), in the late dry season.
4. The samples obtained are some 35% richer in species per given number of individuals than light trap samples taken simultaneously in a similar forest some 6 km away from the present sampling site.
5. The data show that the effect of intensive light trapping on the populations of Homoptera in the forest is virtually negligible.
6. For a given sample size the tropical samples are many times richer in species than samples from temperate areas.     

Ecological diatom guilds are useful but not sensitive enough as indicators of extremely changing water regimes

Classification of taxa into ecological guilds is based on the relation of respective taxa to nutrient enrichment and their resistance to physical disturbance. We hypothesized that ecological guild’s proportion and their taxa composition were strongly effected both by extremely changing water regime and nutrient contents. Diatom composition, guild dynamics and the diatom-based ecological status assessment index were studied in the Sebes-Körös River (South-East Hungary) in a year with extremely changing water regimes. There were highly pronounced changes in species composition during the whole vegetation period including the formation of running and standing water segments in autumn. While the proportions of ecological guilds showed no significant correlations with the studied environmental parameters, they were more balanced in high water discharge period than in the low water discharge period. Taxa compositions of segments were mainly determined by the preferences and strategies of a respective species and/or genera, regardless to their guild affiliation. These results point out that ecological guild characterisation should be refined using ecological knowledge at the subgenus level. We suggest to establish several subdivisions within the guilds to consider the differences in life strategies (CSR model) and life forms, and to implement the accumulated knowledge of nutrient preferences/indication of a respective taxa.     

The canopy beetle faunas of Gondwanan element trees in Chilean temperate rain forests

Aim To describe the coleopteran fauna occurring in canopies of temperate Gondwanan tree species in terms of their diversity and guild and taxonomic structures, and to test the proposition that this structuring reflects the Gondwanan origins of this fauna. Location The Andes and the coastal cordillera of temperate Chile. Methods Canopy fogging was used to sample beetles from 29 trees. The samples were statistically described using S_chao and the Simpson diversity index D. Cluster analyses and multi‐dimensional scaling (MDS) were performed. The taxonomic and guild structures of the Chilean coleopteran fauna were compared quantitatively with those found in other parts of the world using homogeneity chi‐square and t‐tests. Results A collection of 25,497 beetle specimens was obtained primarily from Nothofagus dombeyi, Nothofagus obliqua and Araucaria araucana. The specimens collected were distributed between 485 morphospecies and included 107 putative, new generic‐level taxa and 223 apparently undescribed species. Estimates of the size of the canopy beetle fauna showed that 600+ species were likely to be present. The communities found on a tree species differed markedly between years. MDS plots showed less community divergence between tree species for predators than for phytophages and xylophages. The guild structure was similar to that found on Australian ‘Gondwanan’ trees but differed significantly from the community structures found on ‘Laurasian’ tropical and temperate trees in supporting fewer phytophages and saprophages, but more xylophages. The predator guild showed a different pattern, with tropical faunas differing from those of more temperate regions, irrespective of hemisphere, as did the distribution of superfamilies. Main conclusions The beetle fauna found in the canopies of N. dombeyi, N. obliqua and A. araucana was large (600+ species), with about half of the species undescribed. S_chao was found to vary with sample size and to give lower estimates of S than species attenuation curves, raising the possibility that the two methods are estimating the sizes of different statistical communities. It is possible that the attenuation curve is estimating the number of species to be found on a particular tree species, while S_chao is estimating the ‘carrying capacity’ for beetle species of individual trees, and this varies from tree to tree. Care also needs to be taken in experimental design when monitoring temporal changes in forest insect communities given the difference in communities found between years in this study. The proportions of phytophages, saprophages and xylophages resemble those of a ‘Gondwanan’ rain forest from Australia and differ significantly from those of tropical and temperate ‘Laurasian’ forests.     

Species of street tree is important for southern hemisphere bird trophic guilds

Abstract Urban environments are highly modified with unique assemblages of bird species. Much of the research on urban bird assemblages comes from the northern hemisphere. Southern hemisphere bird assemblages differ from northern hemisphere assemblages in that they contain a large proportion of nectarivores. In this study we focus on bird use of street trees in Australia. We investigate the relative influence of tree species (plane tree, Platanus x acerifolia; red gums, Eucalyptus camaldulensis; jacaranda, Jacaranda mimosifolia; bottlebrush, Callistemon citrinus), season and the environment surrounding street trees, on the abundance and species richness of birds in Adelaide, South Australia. Our study considers birds in terms of granivore, nectarivore and insectivore trophic guilds. Nectarivores accounted for the greatest proportion of observations, in terms of abundance, in each of the tree species investigated. Species of street tree was a significant influence on bird use of the trees for all birds and each dietary guild. Red gums were used more than the other tree species by nectarivores, while plane trees were used more than the other trees by insectivores. Use of the tree species by granivores varied with the season. The measures of the environment surrounding street trees were largely unimportant with the exception of traffic for nectarivores in some cases. Urban avifauna use street trees and the species of tree will strongly influence its use by birds. However, the pattern of use of street tree species varied at different times of year and differed between different trophic guilds of birds. The dominance of nectarivores in the southern avifauna will likely produce different patterns of urban environment use to northern hemisphere avifaunas.     

Indicators of restoration success in riparian tropical forests using multiple reference ecosystems

Forest restoration by planting trees often accelerates succession, but the trajectories toward reference ecosystems have rarely been evaluated. Using a chronosequence (4–53 years) of 26 riparian forest undergoing restoration in the Brazilian Atlantic Forest, we modeled how the variables representing forest structure, tree species richness and composition, and the proportion of plant functional guilds change through time. We also estimated the time required for these variables to reach different types of reference ecosystems: old‐growth forest (OGF), degraded forest, and secondary forest. Among the attributes which follow a predictable trajectory over time are: the basal area, canopy cover, density and tree species richness, as well as proportions of shade tolerant and slow growing species or individuals. Most of the variation in density of pteridophythes, lianas, shrubs and phorophythes, proportion of animal‐dispersed individuals, rarefied richness and floristic similarity with reference ecosystems remain unexplained. Estimated time to reach the reference ecosystems is, in general, shorter for structural attributes than for species composition or proportion of functional guilds. The length of this time varies among the three types of reference ecosystems for most attributes. For instance, tree species richness and proportion of shade tolerant or slow growing individuals become similar to secondary forests in about 40 years, but is estimated to take 70 years or more to reach the OGF. Of all the variables considered, canopy cover, basal area, density, and richness of the understory—by their ecological relevance and predictability—are recommended as ecological indicators for monitoring tropical forest restoration success.     

Species packing and the competition function with illustrations from coral reef fish

This paper concerns the contrast between guilds whose species show resource partitioning and those that show extensive overlap. Using a Lotka-Volterra model, the ease of invasion by a third species into a guild already containing two species is examined for various shapes of resource utilization curves. I show that (a) a guild is more easily invasible and allows tighter packing if its member species have leptokurtic (thick-tailed) resource utilization curves than if they have platykurtic (thin-tailed) curves; (b) the distribution of niche separation distances is bimodal in a “thin-tailed” guild and is unimodal in a “thick-tailed” guild; (c) there are three-species guilds such that removal of one particular species leaves a two-species system in which one of the remaining species excludes the other. In this context, competition pressure is a force maintaining species diversity.Groupers (Serranidae) appear to be a thin-tailed guild, and Parrotfish (Scaridae) and Surgeonfish (Acanthuridae) together appear to be a thick-tailed guild, and these guilds show many properties predicted by the model. I conjecture that thick-tailed guilds form when the constituent species are selected to be generalists and apply this idea to tropical fruit- and flower-feeding birds.     

The Influence of Ants on the Foraging Behavior of Birds in an Agroforest1

Ants limit bird foraging success via interference or exploitative competition. We compared bird foraging (number and duration of visits, bird species visiting) on ant (Azteca instabilis)‐infested and ant‐free tropical trees (Inga micheliana and Alchornea latifolia). Ants did not affect the number of bird visits or the number of species visiting. Ant presence shortened visit duration (overall and for insectivores) only on A. latifolia where ant activity was higher. Ants may thus hinder bird foraging on some tropical trees potentially shaping how predators affect arthropod communities; yet ant effects depend on bird foraging guild and ant activity.