Hermit Hummingbirds Research Articles

Foraging, Fear and Behavioral Variation in a Traplining Hummingbird

Traditionally, foraging behavior has been explained as the response to a trade-off between energetic gain from feeding resources and potential costs from concomitant risks. However, an increasing number of studies has shown that this view fails to explain an important fraction of the variation in foraging across a variety of taxa. One potential mechanism that may account for this variation is that various behavioral traits associated with foraging may have different fitness consequences, which may depend on the environmental context. Here, we explored this mechanism by evaluating the foraging efficiency of long-billed hermit hummingbirds (Phaethornis longirostris) with regard to three behavioral traits: (a) exploration (number of feeders used during the foraging visit), (b) risk avoidance (latency to start feeding) and (c) arousal (amount of movements during the foraging visit) in conditions at two different levels of perceived risk (low—control and high—experimental, with a threatening bullet ant model). Foraging efficiency decreased in response to threatening conditions. However, behavioral traits explained additional variation in foraging efficiency in a condition-dependent manner. More exploration was associated with a higher foraging efficiency under control conditions, but this was reversed when exposed to a threat. Regardless of the conditions, arousal was positively associated with foraging efficiency, while risk avoidance was negatively related. Importantly, exploratory behavior and risk avoidance were quite repeatable behaviors, suggesting that they may be related to the intrinsic traits of individuals. Our findings highlight the importance of taking into account additional behavioral dimensions to better understand the foraging strategies of individuals.

Specificity and influence of climatic factors on the pollination of south-eastern Brazilian Sinningia

Ornithophily is a widespread pollination syndrome that has evolved independently several times along the evolution of plants. It is reported in sixty-five plant families, including Gesneriaceae. One of the most diverse genera within gesneriads is Sinningia, which comprises species pollinated by bees, hummingbirds and bats. However, little is known about the reproduction biology of either species or on pollinator specificity in this genus. Based on investigations on flowering phenology, flower morpho-anatomy, volume and concentration of floral nectar, pollinators, and breeding system, this paper reports the reproduction and the pollinator specificity of Sinningia douglasii and Sinningia araneosa in natural areas in Brazil. Both species offer nectar as a resource and are exclusively pollinated by a single species of hermit hummingbird. Nectar is produced by glands around the ovary. Pollen is deposited between the base of the beak and the head feathers. Both species are self-compatible and pollinator-dependent. In both Sinningia species, the combination of protandry, pollinator specificity, due to long corolla tubes that exclude the visitation of short-billed hummingbirds. The presence of particular flower features influence the occurrence of pollination by specific pollen vectors, such as hermit hummingbirds, in deterrence of illegitimate visitors (i.e. territorial hummingbirds), protection against vigorous foraging, and accurate placement of pollen on legitimate pollinators. In addition, the foraging of Phaethornis on flowers of Sinningia is independent of relative humidity and air temperature, whereas the main factor influencing hummingbird visits is the luminosity.

To overlap or not to overlap: context-dependent coordinated singing in lekking long-billed hermits

When using signals to attract mates or defend resources, animals often overlap the voices of other individuals in close proximity. In such contexts signal masking is likely and animals would benefit by adopting behavioural strategies that modify the timing of signals to minimize the negative effects of masking or take advantage of its signalling value. Indeed, temporal coordination has been commonly described in a wide variety of taxa, but compelling evidence demonstrating that it arises as an active process is scarce. Here we investigate the degree of coordinated singing by lekking long-billed hermit hummingbirds, Phaethornis longirostris, in the Neotropics, using randomization tests to study the timing of vocal signals. We first demonstrate that a randomization statistical approach is robust at detecting coordinated singing in simulated data. Then, we show that long-billed hermits engage in vocal interactions in which either song alternation or song overlap is used. Furthermore, we show that singing behaviour varies with the distance between singers: hermits alternate their songs when they are in close proximity, and they overlap songs at farther distances. Birds achieve these two behaviours by modifying the time intervals between signals. The association between pattern of coordination and distance is not fully explained by any of the current hypotheses for song overlap and suggests that multiple context-dependent singing strategies could be involved. Our findings provide compelling evidence on vocal coordination as an active process in this species and validate an analytical approach that could be extended to investigate similar patterns in other taxa.

Tropical Forest Fragmentation Limits Movements, but Not Occurrence of a Generalist Pollinator Species.

Habitat loss and fragmentation influence species distributions and therefore ecological processes that depend upon them. Pollination may be particularly susceptible to fragmentation, as it depends on frequent pollinator movement. Unfortunately, most pollinators are too small to track efficiently which has precluded testing the hypothesis that habitat fragmentation reduces or eliminates pollen flow by disrupting pollinator movement. We used radio-telemetry to examine space use of the green hermit hummingbird (Phaethornis guy), an important ‘hub’ pollinator of understory flowering plants across substantial portions of the neotropics and the primary pollinator of a keystone plant which shows reduced pollination success in fragmented landscapes. We found that green hermits strongly avoided crossing large stretches of non-forested matrix and preferred to move along stream corridors. Forest gaps as small as 50 m diminished the odds of movement by 50%. Green hermits occurred almost exclusively inside the forest, with the odds of occurrence being 8 times higher at points with >95% canopy cover compared with points having <5% canopy cover. Nevertheless, surprisingly. the species occurred in fragmented landscapes with low amounts of forest (~30% within a 2 km radius). Our results indicate that although green hermits are present even in landscapes with low amounts of tropical forest, movement within these landscapes ends up strongly constrained by forest gaps. Restricted movement of pollinators may be an underappreciated mechanism for widespread declines in pollination and plant fitness in fragmented landscapes, even when in the presence of appropriate pollinators.

Reproductive biology of a hummingbird-pollinated Billbergia: light influence on pollinator behaviour and specificity in a Brazilian semi-deciduous forest.

Ornithophily has evolved in parallel several times during evolution of angiosperms. Bird pollination is reported for 65 families, including Bromeliaceae. One of the most diverse bromeliad is Billbergia, which comprises species pollinated mainly by hummingbirds. Based on investigations on flowering phenology, morpho-anatomy, volume and concentration of nectar, pollinators and breeding system, this paper explores the reproductive biology and pollinator specificity of B.distachia in a mesophytic semi-deciduous forest of southeastern Brazil. The results have show that B.distachia is pollinated by a single species of hermit hummingbird, Phaethornis eurynome, which search for nectar produced by a septal nectary, where the secretory tissue is located above the placenta. The species is self-incompatible. The combination of pollinator specificity, due to long corolla tubes that exclude visitation of short-billed hummingbirds, complete self-incompatibility and non-territorial behaviour of pollinators, it is very important to reduce pollen loss and increase gene flow within population. Our results indicate that studies on pollination biology and reproduction are essential to understand the evolutionary history of pollination systems of plants since, at least in Billbergia, variation in the pollinator spectrum has been recorded for different habitats among Brazilian forests. Furthermore, according to our data, foraging of Phaethornis on flowers is independent of air temperature and humidity, while the main factor influencing hummingbird visitation is daylight. Considering current knowledge on climatic parameters influencing hummingbird foraging, pollination and reproductive biology of Neotropical flora and environment of the hermit hummingbird in tropical forests, new insights on plant-pollinator interaction are provided.

WarbleR: an r package to streamline analysis of animal acoustic signals

Summary Animal acoustic communication is one of the most fruitful research areas in behavioural and evolutionary biology. Work in this area depends largely on quantifying the structure of acoustic signals, which has often depended upon closed‐source or graphical user interface (GUI)‐based software. Here, we describe the r package warbleR, a new package for the analysis of animal acoustic signal structure. The package offers functions for downloading avian vocalizations from the open‐access online repository Xeno‐Canto, displaying the geographic extent of the recordings, manipulating sound files, detecting acoustic signals or importing detected signals from other software, assessing performance of methods that measure acoustic similarity, conducting cross‐correlations, measuring acoustic parameters and analysing interactive vocal signals, among others. Functions working iteratively allow parallelization to improve computational efficiency. We present a case study showing how warbleR functions can be used in a workflow to evaluate the structure of acoustic signals. We analyse geographic variation in long‐billed hermit hummingbirds (Phaethornis longirostris) songs obtained from Xeno‐Canto. The code in warbleR can be executed by less experienced r users, but has also been thoroughly commented, which will facilitate further customization by advanced users. The combination of the tools described here with other acoustic analysis packages in r should significantly expand the range of analytical approaches available.

Tackling pollination of tubular flowers in Rutaceae and a case study of Conchocarpus rubrus (Galipeinae, Rutaceae)

Tubular flowers are only found in two distantly related groups in Rutaceae: the mainly Australian tribe Boronieae and the Neotropical subtribe Galipeinae. It is assumed that these nectar-rewarded, tubular flowers arose from convergent evolution driven by pollinator pressures. However, there are few empirical studies on pollen vectors of Neotropical Rutaceae. We explored the floral biology and pollination of Conchocarpus rubrus (A.St.-Hil.) Bruniera and Groppo (Galipeinae), including details about its nectar-secreting floral structures. We also compared the available records on floral biology and pollination of Boronieae and Galipeinae, aiming to provide a better understanding of the factors that influenced their floral evolution. Conchocarpus rubrus was pollinated by a single species of hermit hummingbird (Phaethornis idaliae Bourcier and Mulsant 1856) and by butterflies (Pyrginae and Pierinae), which take nectar accumulated at the bottom of the tube. Floral features and pollination data indicate that the convergent evolution of floral tubes in Rutaceae resulted from phenotypic specialization toward a subset of nectar-foraging pollinators with long mouth parts. Specifically, while in the Australian Boronieae the evolutive pathway toward sympetaly was likely influenced by Meliphagidae birds, in the Galipeinae, it was influenced by hummingbirds, butterflies, and settling moths. Besides a floral tube, floral features also linked to phenotypic specialization toward Meliphagidae pollination in Boronieae were related not only to birds’ attraction (nectar features, attractive colors, etc.), but also to insect impediments (sensory exclusion, absence of landing platforms, etc.), occurring together with other ornithophilous features. In Galipeinae, floral features are more diverse, and functionally linked to the different groups of pollinators herein found.

Nectar robbery by a hermit hummingbird: association to floral phenotype and its influence on flowers and network structure

Interactions between flowers and their visitors span the spectrum from mutualism to antagonism. The literature is rich in studies focusing on mutualism, but nectar robbery has mostly been investigated using phytocentric approaches focused on only a few plant species. To fill this gap, we studied the interactions between a nectar-robbing hermit hummingbird, Phaethornis ruber, and the array of flowers it visits. First, based on a literature review of the interactions involving P. ruber, we characterized the association of floral larceny to floral phenotype. We then experimentally examined the effects of nectar robbing on nectar standing crop and number of visits of the pollinators to the flowers of Canna paniculata. Finally, we asked whether the incorporation of illegitimate interactions into the analysis affects plant-hummingbird network structure. We identified 97 plant species visited by P. ruber and found that P. ruber engaged in floral larceny in almost 30% of these species. Nectar robbery was especially common in flowers with longer corolla. In terms of the effect on C. paniculata, the depletion of nectar due to robbery by P. ruber was associated with decreased visitation rates of legitimate pollinators. At the community level, the inclusion of the illegitimate visits of P. ruber resulted in modifications of how modules within the network were organized, notably giving rise to a new module consisting of P. ruber and mostly robbed flowers. However, although illegitimate visits constituted approximately 9% of all interactions in the network, changes in nestedness, modularity, and network-level specialization were minor. Our results indicate that although a flower robber may have a strong effect on the pollination of a particular plant species, the inclusion of its illegitimate interactions has limited capacity to change overall network structure.

Pollination and breeding system of Canna paniculata(Cannaceae) in a montane Atlantic Rainforest: asymmetric dependence on a hermit hummingbird

We studied the pollination biology of Canna paniculata (Cannaceae), a plant species common in the Atlantic Rainforest of southeastern Brazil. The species presents specialized ornithophilous flowers, which in our study area are solely pollinated by the hermit hummingbird Phaethornis eurynome. Although C. paniculata is capable of bearing fruit after self-pollination, it requires pollinators for reproduction. We discuss the importance of hermit hummingbirds for the reproduction of specialized ornithophilous plants such as C. paniculata, including their asymmetric dependence on hermit hummingbirds - core pollinators in Neotropical forest ecosystems.

Evolution of sexual dimorphism in bill size and shape of hermit hummingbirds (Phaethornithinae): a role for ecological causation

Unambiguous examples of ecological causation of sexual dimorphism are rare, and the best evidence involves sexual differences in trophic morphology. We show that moderate female-biased sexual dimorphism in bill curvature is the ancestral condition in hermit hummingbirds (Phaethornithinae), and that it is greatly amplified in species such as Glaucis hirsutus and Phaethornis guy, where bills of females are 60 per cent more curved than bills of males. In contrast, bill curvature dimorphism is lost or reduced in a lineage of short-billed hermit species and in specialist Eutoxeres sicklebill hermits. In the hermits, males tend to be larger than females in the majority of species, although size dimorphism is typically small. Consistent with earlier studies of hummingbird feeding performance, both raw regressions of traits and phylogenetic independent contrasts supported the prediction that dimorphism in bill curvature of hermits is associated with longer bills. Some evidence indicates that differences between sexes of hermit hummingbirds are associated with differences in the use of food plants. We suggest that some hermit hummingbirds provide model organisms for studies of ecological causation of sexual dimorphism because their sexual dimorphism in bill curvature provides a diagnostic clue for the food plants that need to be monitored for studies of sexual differences in resource use.

Biologia floral de Cleistes macrantha (Barb. Rodr.) Schltr. (Orchidaceae: Vanilloideae: Pogoniinae)

Cleistes macrantha (Barb. Rodr.) Schltr. is widely distributed in Atlantic rain forests in south and southeastern Brazil, occurring in anthropogenic disturbed areas and in restinga vegetation. Aspects of the floral biology of C. macrantha were investigated in the Intervales nature reserve, in the interior of Sao Paulo state. This species offers nectar as reward and is pollinated principally by bumblebees. The nectar is secreted before the anthesis of the flowers, with no posterior secretion. Hermit hummingbirds can also act as pollinators. A previous visit of a bumblebee, however, is necessary for pollen deposition on their bills. Bumblebees are responsible for most cross-pollinations. The hummingbirds perform mainly self-pollination. Preliminary treatments reveal that C. macrantha is self-compatible, but a pollinator is necessary for successful pollination. In spite of the self-compatibility observed, ecological factors favor cross-pollination in this species. This study makes too, a comparison of the floral biology of C. macrantha with what is known about the genera of the North American-Asiatic clade in Pogoniinae.

Hummingbird‐Pollinated Floras at Three Atlantic Forest Sites1

ABSTRACTWe studied 86 species of hummingbird‐pollinated flowers and their pollinators at a coastal lowland site and two highland rain forest sites in southeastern Brazil. The Jaccard index for hummingbird‐pollinated floras showed greater floristic similarity between the two highland communities than between floras of high altitudes and that of near sea level. The lowland site had slightly greater richness than either of the two highland sites. Bromeliaceae was the most important family, accounting for ca. 36 percent of the bird‐pollinated species and comprising 33 percent of the richest flowers. The plant populations bloomed annually for the most part. Both the wet lowland and the dry highland floras showed flowering seasonality, whereas the cloud highland flora had aseasonal flowering. A hermit hummingbird was the major pollinator in the lowland community. A hermit and a non‐hermit hummingbird shared most of the floral resources in the two highland communities. Hermit hummingbirds are the major pollinators of hummingbird‐pollinated floras in the Atlantic rain forests of southeastern Brazil. These areas may be as rich as Central and other South American areas in hummingbird‐pollinated flowers, and altogether present an older development history when compared to the North American flora.

Hummingbird-Pollinated Floras at Three Atlantic Forest Sites1

We studied 86 species of hummingbird-pollinated flowers and their pollinators at a coastal lowland site and two highland rain forest sites in southeastern Brazil. The Jaccard index for hummingbird-pollinated floras showed greater floristic similarity between the two highland communities than between floras of high altitudes and that of near sea level. The lowland site had slightly greater richness than either of the two highland sites. Bromeliaceae was the most important family, accounting for ca 36 percent of the bird-pollinated species and comprising 33 percent of the richest flowers. The plant populations bloomed annually for the most part. Both the wet lowland and the dry highland floras showed flowering seasonality, whereas the cloud highland flora had aseasonal flowering. A hermit hummingbird was the major pollinator in the lowland community. A hermit and a non-hermit hummingbird shared most of the floral resources in the two highland communities. Hermit hummingbirds are the major pollinators of hummingbird-pollinated floras in the Atlantic rain forests of southeastern Brazil. These areas may be as rich as Central and other South American areas in hummingbird-pollinated flowers, and altogether present an older development history when compared to the North American flora.

Energy regulation by traplining hummingbirds

1. A published model of constant diurnal energy accumulation by territorial hummingbirds does not accurately reflect the temporal distribution of feeding behaviour of traplining hummingbirds, Phaethornis longirostris (Long‐Tailed Hermit Hummingbirds). 2. In an enclosure study, gross nectar intake by P. longirostris decreased through the day, mirroring nectar production rates in its natural food‐flowers and mimicking its natural foraging patterns. 3. Using a simulation model, the energetic consequences of constant and decreasing net energy intake rates for traplining hummingbirds are compared. 4. Given natural patterns of nectar production, model birds with decreasing diurnal net intake rates met their energetic needs with fewer flowers than those with constant net intake, and spent less time foraging. 5. It is concluded that P. longirostris do not satisfy the physiological assumptions of the published model, and that in this way they are different from the territorial species on which the model has previously been tested.

The hummingbird community of a lowland Amazonian rainforest

Between October 1987 and September 1989, the British Ornithologists' Union Colombia Expedition recorded 16 species of hummingbird at Matamatá in the Amacayacu National Park, Amazonas, Colombia. Most of these species were resident breeders at the study site although two appeared to be local migrants. Six species of hermit hummingbirds (subfamily Phaethornithinae) occurred at Matamatá; although very similar in general morphology and behaviour, they showed different preferences for habitat, food plants and foraging technique. Hermits were predominant in the forest, but in areas of secondary vegetation and along riverine borders, “typical” hummingbirds (subfamily Trochilinae) were more common. The study site consisted of terra firme and várzea forest and an area of riverine secondary vegetation and contained around 60 species of flowering plants visited by hummingbirds. In contrast with most groups of organisms, hummingbirds and hummingbird‐pollinated plants had similar species diversity in primary forest and secondary habitats. The overall abundance of hummingbirds and flowers was significantly higher in areas of riverine secondary growth. The hummingbird community at Matamatá is remarkably species rich when compared with study sites elsewhere in North and South America. However, random null model comparisons among Amazonian hummingbird communities reveal that they share many characteristics in their structure and show a high degree of species overlap.

Phylogeny of the hermit hummingbirds (Trochilidae: Phaethornithinae)

Abstract A phylogeny of the hummingbirds of the genera Ramphodon, Eutoxeres, Glaucis, Threnetes, and Phaethornis is presented on the basis of external morphological characters. All 34 species of hermit hummingbirds are included in this study. Differences in 96 characters were examined with regard to their apomorphic (derived) or plesiomor‐phic (primitive) states, resulting in evolutionary trees drawn on the basis of cladistic principles. The most important results are: (1) “Ramphodon “ dohrnii is closer to Glaucis than to Ramphodon; (2) “Phaethornis” gounellei is the sister species to all Phaethornis and merits reevaluation as a separate genus, Anopetia; (3) Phaethornis philippii and P. koepckeae are the sister group to P. syrmatophorus, their straight bill having evolved independently of P. bourcieri; (4) the Phaethornis superciliosus/malaris species group includes P. longirostris as a third species; (5) Phaethornis subochraceus, P. pretrei, and P. augusti share a common ancestor, and (6) Phaethornis longuemareus (sensu Peters 1945) is polyphyletic, being comprised of four seperate species. Due to the lack of synapomorphies, the relationships of some species cannot be reliably determined on the basis of external morphological characters alone.

Phylogeny of the hermit hummingbirds (trochilidae: Phaethornithinae)*

A phylogeny of the hummingbirds of the genera Ramphodon, Eutoxeres, Glaucis, Threnetes, and Phaethornis is presented on the basis of external morphological characters. All 34 species of hermit hummingbirds are included in this study. Differences in 96 characters were examined with regard to their apomorphic (derived) or plesiomor‐phic (primitive) states, resulting in evolutionary trees drawn on the basis of cladistic principles. The most important results are: (1) “Ramphodon “ dohrnii is closer to Glaucis than to Ramphodon; (2) “Phaethornis” gounellei is the sister species to all Phaethornis and merits reevaluation as a separate genus, Anopetia; (3) Phaethornis philippii and P. koepckeae are the sister group to P. syrmatophorus, their straight bill having evolved independently of P. bourcieri; (4) the Phaethornis superciliosus/malaris species group includes P. longirostris as a third species; (5) Phaethornis subochraceus, P. pretrei, and P. augusti share a common ancestor, and (6) Phaethornis longuemareus (sensu Peters 1945) is polyphyletic, being comprised of four seperate species. Due to the lack of synapomorphies, the relationships of some species cannot be reliably determined on the basis of external morphological characters alone.

Passiflora loefgrenii (Passifloraceae), a New Species in Subgenus Passiflora from the Brazilian Atlantic Rainforest

A new species of Passiflora from the Brazilian Atlantic rainforest in the state of Sdo Paulo is described and illustrated. Passiflora loefgrenii is placed in subgenus Passiflora Lobatae. It is vegetatively similar to P. amethystina Mikan and R eichleriana Masters, the three species occurring sympatrically. Passiflora loefgrenii differs from these species primarily by flower character. At the type locality Passiflora loefgrenii is pollinated by hermit hummingbirds and large bees. The Passifloraceae were last studied comprehensively by Killip (1938). In his work, 45 species in subgenus Passiflora (subg. Granadilla sensu Killip) were described as occurring in Brazil. The subgenus Passiflora usually has large and verticillate floral bracts, showy flowers with campanulate or short-tubular calyx tubes, and coronas with at least three series of appendages. In recent studies, six new species of subgenus Passiflora have been described from Brazil (Sacco, 1966a, b, 1968, 1973, 1980). Fieldwork at (now Intervales State Park) in 1991 yielded the new species described here. Intervales State Park (Fig.1) is a 46,000-ha reserve in the state of Sdo Paulo, Brazil, and, along with Carlos Botelho, Alto do Ribeira, and Xitue reserves, comprises more than 130,000 ha of continuous Atlantic rainforest in the Serra de Paranapiacaba. While examining Passiflora collections at the SP herbarium, I found a specimen collected in 1894 by Albert Loefgren on the margins of the Ribeira River, situated in the lowlands in the vicinity of the reserves cited above. Nowadays the Ribeira region is mostly occupied by extensive plantations. This plant, identified by H. Harms as R amethystina, belongs in fact to the new species collected in 1991 at Intervales. The new species is dedicated to Albert Loefgren, the Swedish naturalist who worked in Brazil for 44 years and first collected this plant. Passiflora loefgrenii Vitta, sp. nov. TYPE: Brazil. Sao Paulo: Guapiara, Fazenda Intervales, estrada Sede-Carmo, na beira da mata, Sep. 1991, F A. Vitta & L. C. Passos 010 (holotype, SPF; isotypes, K, UEC). Figure 2. Passiflora ad Lobatae pertinens; stipulae reniformes; glandulis nectariferis stipitatis sex per paria dispositis instructus; lamina trilobata, lobis ovatis; pedunculi 11-20 cm longi; bracteae ellipticae, verticillatae; flores speciosi 9-11 cm diam.; hypanthium campanulatum; sepala extus vinosa, intus purpurea, manifeste

Behavioral, Ecological and Morphological Correlates of Foraging for Arthropods by the Hummingbirds of a Tropical Wet Forest

This paper seeks to clarify the ecological and evolutionary impacts of foraging for arthropods vs. nectar in hummingbirds, using data on morphology, sites, and tactics of arthropod foraging, and prey taken by 11 species of hummingbirds of La Selva, a Costa Rican lowland wet forest, as well as information on time budgets of male and female hummingbirds from two other sites. Hermit hummingbirds have long, curved bills and are nearly exclusively understory hover-gleaners that take mostly spiders. Most glean from webs but Threnetes ruckeri differs in foraging behavior and takes mostly jumping spiders. Non- hermits have shorter, straighter bills and employ a greater range of foraging tactics and sites, taking a wider variety of prey. In most species flycatching is frequent and flies and wasps are the predominant prey items, but some also take many spiders and ants; in particular, Heliothryx barroti is predominantly a hover-gleaner of the canopy and takes more spiders than flies. In Thalurania colombica, males and females differ in sites and tactics of arthropod foraging during the breeding season but not at other times. Breeding female hummingbirds spend much more time foraging for arthropods than do males in the same times and places, although flower visitation still constitutes the majority of foraging time. Among La Selva hummingbirds, bill curvature is strongly correlated with the proportion of gleaning vs. hawking, and with the proportion of prey taken from the substrate (spiders, ants) as opposed to volant prey (flies, wasps). Broad wings (low aspect ratio) and high wing disk loading are correlated with hovering, gleaning, and the proportion of spiders and ants in the diet; narrow wings and high wing disk loading, with flycatching. Except for the three species that engage in the most flycatching, females have broader wings than males and in virtually all species, females have higher wing disk loading. However, no parameter of wing morphology shows a clear relationship to strategies of nectar exploitation, probably reflecting the facultative nature of the latter. Hermits and nonhermits differ strongly in their preferred foraging levels in the vegetation, both for nectar and for arthropods, with the former using the understory almost exclusively, the latter using the canopy to a much greater extent, in both forest and second growth. Nevertheless, the two groups do not differ in the proportion of foraging attempts for nectar vs. arthropods, nor in the distribution of foraging through the day, in either habitat. In nearly all species, bills of females are longer than those of males, and this could increase their ability to forage for arthropods at least as much as for nectar. Much of the controversy regarding frequency and energetic importance of arthropod foraging vs. flower visitation reflects the biases inherent in observing each type of foraging or in interpreting data from stomach contents or emetic samples, or from failure to consider the specific tactics of foraging for arthropods. Reports that hummingbirds can exist for extended periods or breed without access to nectar or alternative sugar sources require confirmation, as does a report that availability of arthropods rather than nectar determines hummingbird breeding seasonality in dry areas. The major impact of arthropods in hum- mingbirds' diets appears to be at the daily, rather than seasonal, level. Data on arthropod prey do not support the notion that hummingbirds visit flowers for insects rather than nectar, and there is no evidence to suggest that their bills are specialized for extracting insects from

Lek-Verhalten vonPhaethornis guy in Südwestkolumbien

The Green Hermit Hummingbird, a polytypic trochilid, occurs in Trinidad, eastern Venezuela and from Costa Rica southwards through the Andes to Peru. Behaviour, display and song of lekking males from Yotoco, southwestern Colombia, are analyzed and compared to those of populations from Trinidad and Costa Rica. Strong differences in aerial displays ofPhaethornis guy males from southwestern Colombia support the subspecific status (emiliae) of this taxon.