Hummingbirds

Exotic species can threaten biodiversity by disrupting ecological interactions among native species. Highly-attractive exotic species can exert a 'magnet effect' by attracting native pollinators, which may have either competitive or facilitative effects on co-flowering native plants. However, those effects may be context-dependent. We used a mistletoe-hummingbird pollination system in the Valdivian rainforest (southern Chile) to test whether the exotic tree Eucalyptus globulus (a highly attractive species to pollinators) acts as a magnet species, affecting the co-flowering native mistletoe. We compared humming-bird abundance, visitation rates, and activity patterns between native forest and abandoned E. globulus plantations. We found that hummingbirds were more abundant and visited more flowers at the plantation irrespective of E. globulus flowering. We observed a significant change of pollinator activity at the native habitat during E. globulus flowering, as hummingbirds visited mistletoe flowers more frequently early in the morning at the plantations and in the afternoon at the native forests. Our results showed that E. globulus acts as an exotic magnet species and can alter pollinator abundance and behavior. Our findings demonstrate the importance of considering local-and landscape-scale processes to understand the effects of magnet species on native plants and suggest that magnet species may influence even highly-attractive plants.

1. Ecological interactions are the glue of biodiversity, structuring communities and determining their functionality. However, our knowledge about ecological interactions is usually biased against cryptic interactions (i.e. overlooked interactions involving inconspicuous species). Mosses are a neglected component in community ecology despite being diverse and abundant in boreal and temperate forests. Therefore, the cryptic relationships of trees as hosts for epiphytic mosses, and vertebrates using mosses as nesting material, may have important consequences for community structuring. 2. We built species-and individual-based ecological networks to characterise tree-moss associations in 120 tree individuals representing 13 species, which hosted 19 moss species. We also used those ecological networks to simulate the effects of non-random extinctions due to selective logging, to assess the presence of moss species in hummingbird nests (30 nests), whether these mosses were a subset of those found on the trees if moss diversity varies with tree height and whether these moss-tree relationships are phylogenetically constrained. 3. We found a nested pattern in the tree-moss network. Taller trees were the most connected, with tree height positively related to number of moss species, network degree and centrality. Extinction simulations showed changes in network topology, with the strongest effect from the removal of the most connected tree species. However, tree and moss networks were not influenced by phylogenetic relatedness. The hummingbird Sephanoides sephaniodes selectively collected mosses; the moss species used as nesting material by hummingbirds were a subset of available species. These complex relationships among trees, birds and mosses underpin the importance of neglected components in the community. 4. We found that tree-moss associations were non-random, showing a positive relationship between tree height and moss diversity. Those associations are the reflection of preferences beyond relative abundances in the forest, and the removal of certain tree species (due to selective logging) may have cascade effects in the community. Furthermore, the lack of phylogenetic correspondence suggests that tree-moss associations are governed by ecological factors (host tree preferences). Moss-hummingbird associations are non-random, as hummingbirds (that pollinate

En el bosque montano de los Andes del norte existe un vacío en el conocimiento sobre interacciones ecológicas de los colibríes. Los factores que pueden determinar la estructura de la red planta-colibrí y sus características son abundancia, fenología o restricciones morfológicas. Estudié colibríes y las plantas que visitan en el bosque de Unchog (Departamento de Huanuco, Perú) de 2011 a 2014. La red de colibríes fue construida con observaciones directas. Una interacción se definió cuando visitaron y consumieron el néctar. La abundancia de aves fue determinada usando redes de niebla y la de plantas contando flores. La fenología se midió cuando una especie de planta y una de colibrí estaban presentes. Las restricciones morfológicas provocan "interacciones prohibidas", que se determinaron midiendo el pico del colibrí y comparándolo con la longitud de las flores. La teoría de redes se aplicó utilizando R y algoritmos desarrollados por investigadores con las mismas preguntas ecológicas. Los visitantes más importantes en la red fueron los colibríes Metallura theresiae y Pterophanes cyanoptera. Tomando en cuenta todas las aves que visitaron las plantas con flores, el perforador de flores, Diglossa mystacalis fue abundante. Las plantas más visitadas fueron el arbusto Brachyotum lutescens y el muérdago Tristerix longebracteatus. El análisis demostró que la fenología es el mejor predictor de la estructura de la red. Algunos colibríes superan interacciones prohibidas tal vez por el efecto de perforadores de flores; por lo que la morfología no fue el principal impulsor de la estructura de la red. Considerando interacciones legales o ilegales en la red; la fenología fue en ambos casos el predictor más importante de la estructura de la red. Con el inminente efecto del cambio climático causando desajuste fenológico en la biodiversidad de las montañas tropicales, estos resultados refuerzan la necesidad de protección de los colibríes y sus hábitats.

Geographical distribution and habitat of Trochilidae (Aves) in the state of Guerrero, Mexico. The distribution and abundance of species of Trochillidae family is usually influenced by the flowering and phenology of plants used as a feeding source, mainly in primary forest, so that changes in vegetation cover could impact their populations. We analyzed and characterized the geographical distribution and habitat for 22 species of resident hummingbirds in the state of Guerrero using the vegetation and the land use map of INEGI Series IV (2007-2010). Distribution models were generated with the Genetic Algorithm for Rule Set Production (GARP), using historical records of scientific collections and fieldwork (2001-2009), in combination with climatic and topographic variables. Of the 22 modeled species, six are endemic to Mexico, the same number of species found in a risk category. The highest concentration with regards to richness (14-20 species), endemism (5-6 species) and number of threatened species of hummingbirds (5-6 species) occurred in the biotic province of Sierra Madre del Sur. However, the potential distribution of most of the hummingbirds occurred in disturbed sites or agroecosystems, as a result of changes in land-use. For Campylopterus hemileucurus, Lamprolaima rhami and Heliomaster longisrostris, their potential distribution was highest in areas of primary vegetation. Areas of high hummingbirds presence do not coincide with the Important Bird Areas proposed for bird conservation in Guerrero, considering that, despite its diversity and its extreme popularity, from the conservation perspective hummingbirds have received relatively little attention. Rev. Biol. Trop. 64 (1): 363-376. Epub 2016 March 01.

El presente ofrecimiento educativo desea animar y activar el Desarrollo Dinámico y Dialéctico en el seno de las Comunidades Convivenciales para el DesarrolloInfantil.
Para iniciar, es importante advertir que este Proyecto de Transformación Educativa de las Comunidades Convivenciales abreva en tres fuentes originales. La primera responde a los propósitos de nuestro Programa Alternativo y Popular de Educación Preescolar (PAPEP), que enfoca y concentra su atención en la animación y activación del Desarrollo Dinámico y Dialéctico en Comunidad Convivencial; la segunda obedece a los análisis realizados por los distintos Colectivos Escolares sobre las diferentes realidades educativas de la Zona Escolar 03 de nivel Preescolar, pero también de las acciones emprendidas respecto a las necesidades y problemáticas que cotidianamente atienden las Comunidades Convivenciales.
La tercera emana de las Jornadas de animación y activación de las Comunidades Convivenciales para el Desarrollo Infantil.
La valoración de los procesos educativos y pedagógicos nos remitió a los distintos análisis realizados por los diferentes colectivos de la Zona Escolar, quienes desarrollaron sus proyectos educativos atendiendo la urgente necesidad de animar la conciencia ecológica —bioética—, como aglutinante de unidad, organización y trabajo en las Comunidades Convivenciales para el Desarrollo Infantil.
Igualmente, la valoración de los proyectos escolares subrayó la necesidad de involucrar activamente a las familias en los procesos educativos emprendidos por las Comunidades Convivenciales; esta relación entre familia y escuela debe necesariamente extenderse a la comunidad y el pueblo.
Es decir, en acto de conciencia, la Comunidad Convivencial de la Zona Escolar 03 se organiza para actuar responsablemente y emprender acciones culturales en bien de la vida libre, digna y plena (vida en desarrollo); las cuales, se constituyen en elementos fundamentales de los procesos necesarios al continuum del Desarrollo Dinámico y Dialéctico definido en nuestro Programa Alternativo y Popular de Educación Preescolar.
Las acciones culturales se concentran en animar y dinamizar la unidad, solidaridad, organización, trabajo, movilización y lucha de la Comunidad Convivencial; vigilando la puntualidad en los procesos y disciplinándose responsablemente en la conquista comunitaria de sus propósitos.
Para lograr ello, los colectivos escolares de la Comunidad Convivencial de la Zona Escolar 03 presentaron diferentes proyectos con enfoque ecopedagógico que incluyeron recolección de desperdicios, reciclado de envases y deshechos, cultivo de lombriz y producción de lombricomposta, huertos escolares, etc.
El Proyecto «Salvemos al colibrí» surge principalmente de las necesidades de desarrollo emanadas de las realidades sociales y educativas de nuestras Comunidades Convivenciales, pero también de otras necesidades específicas del desarrollo infantil, particularmente aquellas relacionadas con el desarrollo del pensamiento complejo y
la comunicación, corporalidad, alfabetización, identidad de género, comunalidad, concienciación, expresión artística y desarrollo espiritual.
Este Proyecto de Transformación y Desarrollo Educativo en Comunidad Convivencial no se piensa concluido ni determinado; todo lo contrario, lo ofrecemos a la sensibilidad de las distintas Comunidades Convivenciales de la Zona Escolar 03, especialmente de las educadoras, para que se apropien de él… lo recreen, transformen y trasciendan...
De hecho, la realización del Proyecto en el tiempo tendrá que ser definida por el Colectivo de la Zona Escolar; únicamente se sugiere que la primera actividad de convivencia se realice en los primeros días de la primavera para que los bebederos cumplan su propósito.
El Proyecto sólo será realidad concreta en la medida que generemos las condiciones que puedan hacerle posible y que ya han sido previamente definidas por el Colectivo Escolar: vida en dignidad y desarrollo, servicio, liberación, justicia, democracia, unidad, solidaridad, guelaguetza, humildad, etc.; definidos como principios comunitarios de la praxis popular de nuestro Programa Educativo.
Es importante también mencionar que la Telesecundaria de la comunidad “Cerro de las Huertas”, en Oaxaca, y el Centro Educativo MÍRAME, en Puebla, han decidido también animar y activar la Comunidad Convivencial conforme al Proyecto Educativo: «Salvemos al colibrí».
No resta sino alentar la concienciación política y bioética en praxis libre, responsable y voluntaria de las Comunidades Convivenciales. Este es, —y no otro—, el propósito de este Proyecto de Transformación y Desarrollo Educativo: «Salvemos al colibrí».

Hummingbirds are very special birds. They are remarkable in many ways: very high metabolism, iridescence, extraodinary flight... Their well known belligerance and their speed in attack was perhaps a reason why some cultures perceived Hummingbirds as a symbol of War. The Moche iconography for example shows these birds flying around warriors. For Mexicas, Huitzilopochtli (Nahuatl: "Hummingbird on the Left") was the god of sun, war and human sacrifice.
But hummingbirds are also asociated with flowers. In many countries of Latin America, the bird taking the nectar from a flower is a symbol of Love, and a Don Juan is called "Picaflor" or "Chupaflor". Many Maya stories describe the sun turning into a hummingbird to seduce the moon.
This paper is in French. Good reading!

An important episode in Mesoamerican mythical narratives involves the abduction or impregnation of a tightly guarded maiden by a disguised god, against the will of her father or mother. This action precipitates major creational events that variously result in the origin of the sun, the moon, and human sustenance. Relying on a comparative analysis of versions recorded throughout Mesoamerica, this paper explores (a) representations of this episode in Maya art, where the suitor sometimes takes the shape of an insect; (b) the magical role of weaving and spinning, a recurrent theme in this mythical sequence; and (c) the relevance of Maya narratives for the interpretation of related passages in central Mexican mythology and ritual. Classic representations evidence the myth’s antiquity, while its numerous versions pose methodological problems, addressed in this paper through the analysis of synonymies in narrative, art, and performance.

In parts one and two of my three-part series on the atlatl weapon system I introduced or reintroduced readers to the basics of the atlatl or spear- thrower weapon system. I focused on the physics of the throw and the spear in flight. In part three, I am analyzing a surviving piece of an atlatl weapon system, an atlatl spur that was surface recovered on private land in Kings County, California by Connie Hudson prior to 1970.

1. Human observation is expensive and limits the breadth of data collection. For this reason, remotely placed video cameras are increasingly used to monitor animals. One drawback of field-based video recordings is extensive review time. Computer vision can mitigate this cost and enhance data collection by extracting biological information from images with minimal time investment. 2. MotionMeerkat is a new standalone program that identifies motion events from a video stream. After running a video, the user reviews a folder of candidate motion frames for the target organism. This tool reduces the time needed to review videos and accommodates a variety of inputs. 3. I tested MotionMeerkat using hummingbird-plant videos recorded in a tropical montane forest. To validate the optimal parameter set for finding motion events, I counted hummingbirds observed from direct video review compared to events found in images returned from MotionMeerkat. To show the generality of the approach, MotionMeerkat was tested on a set of terrestrial and underwater videos. To assess the performance of the background subtraction for further image analysis, I hand counted the number of frames with target organisms and compared them to the MotionMeerkat output. 4. MotionMeerkat was highly successful in finding motion events and often reduced the number of frames needed to capture hummingbird visitation by over 90%. Both background approaches effectively found a variety of organisms in ecological videos. I provide general recommendations for parameter settings and extending this approach in the future.

Abstract—Interactions with pollinators are thought to play a significant role in determining whether plant species become invasive, and ecologically generalised species are predicted to be more likely to invade than more specialised species. Using published and unpublished data we assessed the floral biology and pollination ecology of the South American native Nicotiana glauca (Solanaceae) which has become a significant invasive of semi-arid parts of the world. In regions where specialised bird pollinators are available, for example hummingbirds in California and sunbirds in South Africa and Israel, N. glauca interacts with these local pollinators and sets seed by both outcrossing and selfing. In areas where there are no such birds, such as the Canary Islands and Greece, abundant viable seed is set by selfing, facilitated by the shorter stigma-anther distance compared to plants in native populations. Surprisingly, in these areas without pollinating birds, the considerable nectar resources are only rarely exploited by other flower visitors such as bees or butterflies, either legitimately or by nectar robbing. We conclude that Nicotiana glauca is a successful invasive species outside of its native range, despite its functionally specialised hummingbird
pollination system, because it has evolved to become more frequently self pollinating in areas where it is introduced. Its invasion success is not predictable from what is known of its interactions with pollinators in its home range.

Key words: Argentina, California, Canary Islands, Greece, hummingbird, invasive species, Israel, mutualism, Peru,
pollination, Solanaceae, South Africa, sunbird

Biannual cycles of reproduction and molt are rare in birds, with most species exhibiting a single annual cycle. We studied the breeding and molting phenology of the Cinnamon-bellied Flowerpiercer (Diglossa baritula), a nectar feeding passerine, in ...

Comparing ecological networks along environmental gradients can enable a better understanding of the environmental filtering and coexistence mechanisms that determine community assembly. In the present study, we assessed hummingbird-plant network metrics at three sites along an altitudinal gradient in the Sierra Madre Occidental corresponding to tropical forest (148 and 289 m a.s.l.), ecotone (1131 and 1423 m a.s.l.) and pine-oak forest (1800 and 2218 m a.s.l.). We evaluated variation in the specialization (d’) of the hummingbird species and their visited plant species across altitude. We determined if hummingbird species inside the modules of the general network were separated by biogeographical origin, migratory behavior, or morphology. We assessed whether the role in the modular partition of hummingbird and plant species in the general network was related to traits of species. Finally, determined which traits were associated with the importance of different species within the net...

El “ picaflor de Tacna” (Eulidia yarrellii) es considerada una especie endémica de los valles del sur de Perú y del extremo norte de Chile, siendo uno de los picaflores mas pequeños del mundo. La escasa información de la especie en el Perú motivó iniciar un estudio a fin de determinar el rango de ocurrencia de la especie (ocupación real) en el sur del Perú, así como estimar su abundancia poblacional, evaluando aspectos  ecológicos que motiven su presencia. Desde diciembre del 2005 a junio del 2006 se evalúo 11 zonas agrícolas y 01 zona urbana, entre los 0 a 2000 m.s.n.m., de Tacna y Moquegua. Se aplicó el método de conteo por puntos en doble banda con un radio de 30 m, conjuntamente con  búsqueda intensiva. Se evaluó 534 puntos, no encontrando la presencia del “ picaflor de Tacna” Eulidia yarrellii en las zonas establecidas. Las únicas especies halladas fueron Rhodopis vesper, Thaumastura cora y Mirtys fanny. La ausencia de E. yarrellii indicarí a que la especie tiene una presencia muy eventual en el Perú o que su población ha declinado drásticamente, como viene sucediendo en Chile, desapareciendo de esta parte de su distribución natural. La escasa vegetación silvestre y alteración del hábitat, uso indiscriminado de insecticidas y la competencia interespecí fica pueden ser las causas principales. Se recomienda mantener un monitoreo en el tiempo a fin de comprobar desplazamientos eventuales de la especie, y determinar si está asociado a factores ambientales u otros.

I provide the first description of the nest and juveniles of the Coppery Metaltail (Metallura theresiae), a hummingbird endemic to Peru. The locality of Unchog, in the elfin forest of the Carpish mountains in Huánuco, is where I found this species nesting. My descriptions are based on 4 nests found on different occasions (April 2013, January 2014, and Jul–Aug 2014). Coppery Metaltail used mainly moss, lichen, lycopodium, and twigs as materials to build their nests. I found 3 nest locations: a tree branch, creek banks, and an abandoned hut. The mean internal diameter of nests was 34.45 mm long by 42.52 mm wide (n = 4). I only measured the depth of 3 of them (mean = 33.83 mm). Metaltail eggs were white and had a mean of 12.93 by 8.3 mm (n = 2). Fledglings (n = 2) were observed in July and one of them reached up to 144% the mass of an adult. I comment on other cases of nestling obesity for different species of hummingbirds. The Coppery Metaltail selects different substrates for nesting and might reproduce throughout the year.

En el Cuarto el Ceibo de la Vereda la Chorrera del Municipio de Soatá, durante los meses de octubre de 2010 hasta enero de 2011 se caracterizaron y compararon algunos aspectos de las plantas explotadas como recurso alimenticio por Amazilia castaneiventris, especie endémica y en peligro que presenta una densidad poblacional aproximada de 5.7 individuos/ha en la zona de estudio.

Many birds spend important portions of their time and energy flying. For this reason, quantification of
metabolic rates during flight is of crucial importance to understanding avian energy balance. Measurement
of organismal gas exchange rates using a mask enclosing the whole head or respiratory orifices has served as
an important tool for studying animal energetics because it can free the rest of the body, permitting
movement. Application of so-called “mask respirometry” to the study of avian forward flight energetics
presents unique challenges because birds must be tethered to gas analysis equipment thus typically
necessitating use of a wind tunnel. Resulting potential alterations to a study organism's behaviour,
physiology, and aerodynamics have made interpretation of such studies contentious. In contrast, the study of
hovering flight energetics in hummingbirds using a specialized form of mask respirometry is comparatively
easy and can be done without a wind tunnel. Small size, hovering flight, and a nectarivorous diet are
characteristics shared by all hummingbird species that make these birds ideally suited for this approach.
Specifically, nectar feeders are modified to function as respirometry masks hummingbirds voluntarily respire
into when hover-feeding. Feeder-mask based respirometry has revealed some of the highest vertebrate
metabolic rates in hovering hummingbirds. In this review I discuss techniques for the successful
measurement of metabolic rate using feeder-mask respirometry. I also emphasize how this technique has
been used to address fundamental questions regarding avian flight energetics such as capacities for fuel use
and mechanisms by which ecology, behaviour and energy balance are linked.

Abstract
Aim: Among the world’s three major nectar-feeding bird taxa, hummingbirds are the
most phenotypically specialized for nectarivory, followed by sunbirds, while the honeyeaters
are the least phenotypically specialized taxa. We tested whether this phenotypic
specialization gradient is also found in the interaction patterns with their
floral resources.
Location: Americas, Africa, Asia and Oceania/Australia.
Methods: We compiled interaction networks between birds and floral resources for
79 hummingbird, nine sunbird and 33 honeyeater communities. Interaction specialization
was quantified through connectance (C), complementary specialization (H2
0),
binary (QB) and weighted modularity (Q), with both observed and null-model corrected
values. We compared interaction specialization among the three types of
bird–flower communities, both independently and while controlling for potential
confounding variables, such as plant species richness, asymmetry, latitude, insularity,
topography, sampling methods and intensity.
Results: Hummingbird–flower networks were more specialized than honeyeater–
flower networks. Specifically, hummingbird–flower networks had a lower proportion
of realized interactions (lower C), decreased niche overlap (greater H2
0) and greater
modularity (greater QB). However, we found no significant differences between
hummingbird– and sunbird–flower networks, nor between sunbird– and honeyeater–
flower networks.
Main conclusions: As expected, hummingbirds and their floral resources have
greater interaction specialization than honeyeaters, possibly because of greater phenotypic
specialization and greater floral resource richness in the New World. Interaction
specialization in sunbird–flower communities was similar to both
hummingbird–flower and honeyeater–flower communities. This may either be due
to the relatively small number of sunbird–flower networks available, or because sunbird–
flower communities share features of both hummingbird–flower communities
(specialized floral shapes) and honeyeater–flower communities (fewer floral
resources). These results suggest a link between interaction specialization and both
phenotypic specialization and floral resource richness within bird–flower communities
at a global scale.

ABSTRACT Marketing is part of our daily lives; however, it has become much more sophisticated. With the advanced tech-nology, nowadays Internet marketing is one of the most powerful marketing channels. Google has recently come up with a new algorithm, hummingbird, for all search results. It is designed more precisely to provide faster query results. This will promote both content and inbound marketing. In this essay, I will expound Google’s role in Internet marketing and how it promotes both content and inbound marketing.

In Brazil, studies focusing on reproductive biology and aspects of pollination in the genus Ruellia have demonstrated common characteristics such as pollination by hummingbird, the predominance of selffertility and spontaneous self-pollination. The objectives of this study were to describe the floral biology, nectar production, the reproductive system, the effect of pollination intensity and flowering phenology of Ruellia angustiflora, as well as keeping a record of the hummingbirds that visit the flowers of this species. Data collection was performed in a stretch of the Salobrinha stream in the Serra da Bodoquena, Mato Grosso do Sul, from August 2005 to July 2006. R. angustiflora flowered throughout most of the study period; it has diurnal anthesis and has increased nectar production in the morning hours with decreasing production rates during the day. The results of the reproduction experiments indicate self-fertility and pollen limitation in R. angustiflora. Among experiments with different pollination intensity there was no significant difference in fruit formation. Four hummingbird species were observed visiting the flowers of R. angustiflora, and Phaethornis pretrei was the most frequent followed by females of Thalurania furcata. According to its behavior and frequency of visits, P. pretrei can be considered the main pollinator of R. angustiflora in the study area. The experiments on flowers treated with different pollen loads indicate that most successful fruit formation in this species is obtained in flowers that received greater pollen loads on their stigmas. Besides, data suggest that major success in fruit set could be reached with more than three visits of P. pretrei.

Ecological communities that experience stable climate conditions have been speculated to preserve more specialized interspecific associations and have higher proportions of smaller ranged species (SRS). Thus, areas with disproportionally large numbers of SRS are expected to coincide geographically with a high degree of community-level ecological specialization, but this suggestion remains poorly supported with empirical evidence. Here, we analysed data for hummingbird resource specialization, range size, contemporary climate, and Late Quaternary climate stability for 46 hummingbird–plant mutualistic networks distributed across the Americas, representing 130 hummingbird species ( ca 40% of all hummingbird species). We demonstrate a positive relationship between the proportion of SRS of hummingbirds and community-level specialization, i.e. the division of the floral niche among coexisting hummingbird species. This relationship remained strong even when accounting for climate, furtherm...

Background: Relationships between floral biology and pollinator behavior are important to understanding species diversity of hemiparasitic Psittacanthus mistletoes (c. 120 species). We aimed to investigate trait divergence linked to pollinator attraction and reproductive isolation (RI) in two hummingbird-pollinated and bird-dispersed Psittacanthus species with range overlap. Methods: We investigated the phylogenetic relationships, floral biology, pollinator assemblages, seed dispersers and host usage, and the breeding system and female reproductive success of two sympatric populations of P. calyculatus and P. auriculatus, and one allopatric population of P. calyculatus. Flowers in sympatry were also reciprocally pollinated to assess a post-mating component of RI. Results: Hummingbird assemblages differed between calyculatus populations, while allopatric plants of calyculatus opened more but smaller flowers with longer lifespans and produced less nectar than those in sympatry. Bayesian-based phylogenetic analysis indicated monophyly for calyculatus populations (i.e. both populations belong to the same species). In sympatry, calyculatus plants opened more and larger flowers with longer lifespans and produced same nectar volume than those of auriculatus; populations shared pollinators but seed dispersers and host usage differed between species. Nectar standing crops differed between sympatric populations, with lower visitation in calyculatus. Hand pollination experiments indicated a predominant outcrossing breeding system, with fruit set after interspecific pollination two times higher from calyculatus to auriculatus than in the opposite direction. Conclusions: Given the low genetic differentiation between calyculatus populations, observed trait divergence could have resulted from changes regarding the local communities of pollinators and, therefore, expected divergence for peripheral, allopatric populations. Using RI estimates, there were fewer heterospecific matings than expected by chance in P. calyculatus (RI 4A = 0.629) as compared to P. auriculatus (RI 4A = 0.20). When considering other factors of ecological isolation that affect co-occurrence, the RI 4C values indicate that isolation by hummingbird pollinators was less effective (0.20) than isolation by host tree species and seed

Biological constraints and neutral processes have been proposed to explain the properties of plant–pollinator networks. Using interactions between nectarivorous birds (hummingbirds and flowerpiercers) and flowering plants in high elevation forests (i.e., ''elfin'' forests) of the Andes, we explore the importance of biological constraints and neutral processes (random interactions) to explain the observed species interactions and network metrics, such as connectance, specialization, nestedness and asymmetry. In cold environments of elfin forests, which are located at the top of the tropical montane forest zone, many plants are adapted for pollination by birds, making this an ideal system to study plant–pollinator networks. To build the network of interactions between birds and plants, we used direct field observations. We measured abundance of birds using mist-nets and flower abundance using transects, and phenology by scoring presence of birds and flowers over time. We compared the length of birds' bills to flower length to identify ''forbidden interactions''—those interactions that could not result in legitimate floral visits based on mis-match in morphology. Diglossa flowerpiercers, which are characterized as ''illegitimate'' flower visitors, were relatively abundant. We found that the elfin forest network was nested with phenology being the factor that best explained interaction frequencies and nestedness, providing support for biological constraints hypothesis. We did not find morphological constraints to be important in explaining observed interaction frequencies and network metrics. Other network metrics (connectance, evenness and asymmetry), however, were better predicted by abundance (neutral process) models. Flowerpiercers, which cut holes and access flowers at their base and, consequently, facilitate nectar access for other hummingbirds, explain why morphological mis-matches were relatively unimportant in this system. Future work should focus on how changes in abundance and phenology, likely results of climate change and habitat fragmentation, and the role of nectar robbers impact ecological and evolutionary dynamics of plant–pollinator (or flower-visitor) interactions.

Hummingbirds obtain most of their dietary calories
from floral nectar ingested during hovering flight. Despite
the importance of dietary sugar to hummingbird
metabolism, the turnover of newly ingested carbon in the
pool of actively metabolized substrates has not been
adequately characterized in hovering hummingbirds. By
combining respirometry with stable carbon isotope
analysis of respired breath, we show that in rufous
(Selasphorus rufus) and Anna’s (Calypte anna)
hummingbirds at high foraging frequencies, utilization of
newly ingested sugars increased over a period of
30–45·min until it accounted for virtually 100% of the fuel
oxidized. This newly ingested sugar disappears from the
actively metabolized pool of substrates over a similar time
course. These results demonstrate that turnover of carbon
in the pool of actively metabolized substrates is rapid;
carbon from ingested sucrose is available for oxidation for
30–45·min before being cleared. By monitoring expired
CO2 for the appearance and disappearance of the
signature characteristic of newly ingested sugar and then
calculating energy budgets using video recordings of
hummingbird activity, we estimated the proportion of
recently ingested sugar used to fuel ongoing metabolism as
well as the proportion devoted to energy storage.
Consistent differences between species in the percentage of
ingested cane sugar oxidized during the 2·h experimental
periods suggest that individuals of each species adopted
energy intake patterns appropriate to their needs. This
approach provides a means by which to examine the
partitioning of dietary carbon intake between energy
expenditure and storage using non-invasive, field compatible
techniques.

enfoques como el que aquí presentamos evidencian que la conservación de la biodiversidad de cualquier sitio puede promoverse eficientemente a través de especies bandera. La protección y manejo sostenible de los bosques de la Sierra Madre Oriental beneficiará no solamente a la Cotorra serrana oriental, sino a otras especies importantes con la que comparte el hábitat como el Oso negro (Ursus americanus), el Águila real (Aquila chrysaetos), el Búho manchado (Strix occidentalis), el Noa (Agave victoria-reginae) y el Pino enano (Pinus culminicola), entre otros.

Ecological communities that experience stable climate conditions have been speculated to preserve more specialized interspecific associations and have higher proportions of smaller ranged species (SRS). Thus, areas with dispropor-tionally large numbers of SRS are expected to coincide geographically with a high degree of community-level ecological specialization, but this suggestion remains poorly supported with empirical evidence. Here, we analysed data for hummingbird resource specialization, range size, contemporary climate, and Late Quaternary climate stability for 46 hummingbird –plant mutualistic networks distributed across the Americas, representing 130 hum-mingbird species (ca 40% of all hummingbird species). We demonstrate a positive relationship between the proportion of SRS of hummingbirds and community-level specialization, i.e. the division of the floral niche among coexisting hummingbird species. This relationship remained strong even when accounting for climate, furthermore , the effect of SRS on specialization was far stronger than the effect of specialization on SRS, suggesting that climate largely influences specialization through species' range-size dynamics. Irrespective of the exact mechanism involved, our results indicate that communities consisting of higher proportions of SRS may be vulnerable to disturbance not only because of their small geographical ranges, but also because of their high degree of specialization.

Hummingbirds are nectar-feeding birds that pollinate plants in the Americas. This is a mutualistic relationship where hummingbirds feed on nectar while transporting pollen among flowers, thus aiding plant reproduction. This relationship has received a lot of attention and many studies have been published. In order to provide a more accurate estimate of the number and identity of plant species visited by hummingbirds, we compiled a data set of published surveys of plant-hummingbird interactions. A total of 111 papers, 43 academic theses, and 11 books were reviewed. A total of 1339 plant species belonging to 108 families and 294 hummingbird species were included in the interaction matrix. The matrix was analyzed using hierarchical clusters, grouping by plant families and phylogenetic groups in hummingbirds. Clear groups were formed indicating geographical relationships and preferences.

In most vertebrates, uptake and oxidation of
circulating sugars by locomotor muscles rises with increasing
exercise intensity. However, uptake rate by muscle plateaus
at moderate aerobic exercise intensities and intracellular
fuels dominate at oxygen consumption rates of 50 %
of maximum or more. Further, uptake and oxidation of circulating
fructose by muscle is negligible. In contrast, hummingbirds
and nectar bats are capable of fueling expensive
hovering flight exclusively, or nearly completely, with
dietary sugar. In addition, hummingbirds and nectar bats
appear capable of fueling hovering flight completely with
fructose. Three crucial steps are believed to be rate limiting
to muscle uptake of circulating glucose or fructose in
vertebrates: (1) delivery to muscle; (2) transport into muscle
through glucose transporter proteins (GLUTs); and (3)
phosphorylation of glucose by hexokinase (HK) within the
muscle. In this review, we summarize what is known about
the functional upregulation of exogenous sugar flux at each
of these steps in hummingbirds and nectar bats. High cardiac
output, capillary density, and blood sugar levels in hummingbirds and bats enhance sugar delivery to muscles
(step 1). Hummingbird and nectar bat flight muscle
fibers have relatively small cross-sectional areas and thus
relatively high surface areas across which transport can
occur (step 2). Maximum HK activities in each species are
enough for carbohydrate flux through glycolysis to satisfy
100 % of hovering oxidative demand (step 3). However,
qualitative patterns of GLUT expression in the muscle (step
2) raise more questions than they answer regarding sugar
transport in hummingbirds and suggest major differences
in the regulation of sugar flux compared to nectar bats.
Behavioral and physiological similarities among hummingbirds,
nectar bats, and other vertebrates suggest enhanced
capacities for exogenous fuel use during exercise may be
more wide spread than previously appreciated. Further,
how the capacity for uptake and phosphorylation of circulating
fructose is enhanced remains a tantalizing unknown.

Based on the floral visits and palynological analyzes, we characterized the hummingbird-
plant interaction in three tropical dry forest remnants (BsT) located in the municipality
of Chimichagua (Cesar, Colombia). We used mist nets to capture hummingbirds and
binoculars for observations. The flowering time and number of flowers produced by
the plants visited by hummingbirds, as well as data on the quantity and quality of
nectar were recorded. The sampling period (five months) covered climate variability
in the study area. Two species of hummingbirds, Lepidopyga goudoti and Phaethornis
anthophilus, visited 31 plant species. Arrabidaea cf. corallina, which is present in
the three forests patches, was the most important resource (IVIR = 0.14840) followed
by Aphelandra pulcherrima (IVIR = 0.05356) and Pogonopus speciosus (IVIR =
0.02773). Another important species with low value was Cochlospermum vitifolium.
According to the analysis of pollen loads, the most important resource was Pogonopus
speciosus (IVIR = 0.29643), followed by Aphelandra pulcherrima (IVIR = 0.09286)
and Hemistylus cf. odontophylla (IVIR = 0.03294). In the overall analysis for the three
sites, the most important resources for hummingbirds were Pogonopus speciosus (IVIR
= 0.06207), Aphelandra pulcherrima (IVIR = 0.06021) and Cochlospermum vitifolium
(IVIR = 0.01095). Lepidopyga goudoti used 22 plant species while P. anthophilus
used only seven. The flowers visited by hummingbirds were mostly tubular with
bright contrasting colors, such as red, purple, and violet, and their sizes and lengths
matched the hummingbirds’ bill. Hummingbirds also visited white and yellow flowers,
such as Cochlospermum vitifolium, Sterculia apetala, and Ceiba pentandra, which
are listed as species adapted to pollination by insects. In the analysis of the pollen
loads of L. goudoti we found pollen from all plant species that appeared as important
resources according to the intensity of use whereas Phaethornis anthophilus used
only six species.

Hummingbirds are known for their distinctive patterns of sexual dimorphism, with many species exhibiting sex-related differences in various ecologically-relevant traits, including sex-specific differences in bill shape. It is generally assumed that such patterns are consistent across all hummingbird lineages, yet many taxa remain understudied. In this study we examined patterns of sexual size and sexual shape dimorphism in bills of 32 of 35 species in the monophyletic Mellisugini lineage. We also compared patterns of bill size dimorphism in this group to other hummingbird lineages, using data from 219 hummingbird species. Overall, the presence and degree of sexual size dimorphism was similar across all hummingbird lineages, with the majority of Mellisugini species displaying female-biased sexual size dimorphism, patterns that remain unchanged when analyzed in a phylogenetic context. Surprisingly however, we found that sexual dimorphism in bill shape was nearly absent in the Mellisugini clade, with only 3 of the 32 species examined displaying bill shape dimorphism. Based on observations in other hummingbird lineages, the lack of sexual shape dimorphism in Mellisugini is particularly unusual. We hypothesize that the patterns of sexual size dimorphism observed here may be the consequence of differential selective forces that result from competition for ecological resources. We further propose that an influential mechanism underlying shape dimorphism is competition and niche segregation. Taken together, the evolutionary changes in patterns of sexual shape dimorphism observed in Mellisugini suggest that the evolutionary trends of sexual dimorphism in the Trochilidae are far more dynamic than was previously believed.

Many animal displays involve colorful ornamental traits that signal an individualʼs quality as a mate or rival. Brilliant iridescent ornaments are common, but little is currently known about their production cost and signaling value. One potential cost of colorful ornaments is the acquisition of limited dietary resources that may be involved, directly or indirectly, in their production. Protein, the primary component of bird feathers and of many nanostructural components of iridescent traits, is naturally restricted
in hummingbird diets (comprised mostly of sugars), suggesting that iridescent coloration may be especially challenging to produce in these animals. In this study, we experimentally investigated the effect of dietary protein availability during molt on iridescent color expression in male Annaʼs hummingbirds (Calypte anna). We fed captive birds either a 6% (high) or a 3% (low) protein diet and stimulated molt by plucking half the gorget and crown ornaments on each bird as well as the non-ornamental iridescent green tail feathers. We found that birds receiving more protein grew significantly more colorful crown feathers (higher red chroma and redder hue) than those fed the low-protein diet. Diet did not affect gorget coloration, but regrowth of feathers in captivity affected both gorget and crown coloration. Additionally, birds on the high-protein diet grew yellower (higher hue) green tail feathers than birds on the low-protein diet. These results indicate that iridescent ornamental feathers are sensitive to diet
quality. Further, because both ornamental and non-ornamental iridescent coloration were affected by conditions during their growth, iridescent color in these birds appears to be generally condition dependent.

Floral phenotype and pollination system of a plant may be influenced by the abiotic environment and the local pollinator assemblage. This was investigated in seven plant–hummingbird assemblages on the West Indian islands of Grenada, Dominica and Puerto Rico. We report all hummingbird and insect pollinators of 49 hummingbirdpollinated plant species, as well as six quantitative and semi-quantitative floral characters that determine visitor restriction, attraction and reward. Using nonmetric multidimensional scaling analysis, we show that hummingbirdpollinated plants in the West Indies separate in floral phenotypic space into two gradients—one associated with the abiotic environment and another with hummingbird size. Plants pollinated by large, long-billed hummingbirds had flowers with long corolla tube, large amounts of nectar and showy orange-red colouration. These attracted few or no insect species, whereas plants pollinated by small, shortbilled ummingbirds were frequently pollinated by insects, particularly lepidopterans. The separation of plants related to environmental factors showed that species in the wet and cold highlands produced large amounts of dilute nectar, possessed no or a weak odour, and were associated with few insects, particularly few hymenopterans, compared to plants in the dry and warm lowlands. The most specialised hummingbird-pollinated plants are found in the West Indian highlands where they are pollinated by mainly large, long-billed hummingbirds. At the other extreme, highly generalised plants growing in the dry and warm lowlands are pollinated by small, short-billed hummingbirds and numerous insect species. This illustrates that, even within the hummingbird-pollinated flora, pollination syndrome and the degree of specialisation may vary tremendously depending on pollinator morphology and environment.