| dna hybridization evidence for the principal lineages of hummingbirds (aves:trochilidae). | the spectacular evolutionary radiation of hummingbirds (trochilidae) has served as a model system for many biological studies. to begin to provide a historical context for these investigations, we generated a complete matrix of dna hybridization distances among 26 hummingbirds and an outgroup swift (chaetura pelagica) to determine the principal hummingbird lineages. fitch topologies estimated from symmetrized delta tmh-c values and subjected to various validation methods (bootstrapping, weighted ... | 1997 | 9066799 |
| neural song control system of hummingbirds: comparison to swifts, vocal learning (songbirds) and nonlearning (suboscines) passerines, and vocal learning (budgerigars) and nonlearning (dove, owl, gull, quail, chicken) nonpasserines. | males of certain hummingbird species such as anna's hummingbirds (calypte anna) learn their song during postnatal development. here we report that male anna's hummingbirds and male amazilia hummingbirds (amazilia amazilia), two singing hummingbird species, possess forebrain areas that are similar in morphological appearance, location, and connectivity to the song control areas ra (nucleus robustus archistriatalis), hvc (nucleus hyperstriatalis ventrale, pars caudale, or higher vocal center), and ... | 2000 | 10982462 |
| effect of floral orifice width and shape on hummingbird-flower interactions. | nectar guides are common among insect-pollinated plants, yet are thought to be rare or absent among hummingbird-pollinated plants. we hypothesize that the lower lips and trumpet-shaped orifices of many hummingbird flowers act as nectar guides to direct hummingbirds to the flowers' nectar and orient the birds for pollination. to test this hypothesis we conducted laboratory experiments using flowers of monarda didyma (bee balm) and m. fistulosa (wild bergamot), which have orifice widths of about 4 ... | 1996 | 28307448 |
| limits to flight energetics of hummingbirds hovering in hypodense and hypoxic gas mixtures. | hovering hummingbirds offer a model locomotor system for which analyses of both metabolism and flight mechanics are experimentally tractable. because hummingbirds exhibit the highest mass-specific metabolic rates among vertebrates, maximum performance of hovering flight represents the upper limit of aerobic locomotion in vertebrates. this study evaluates the potential constraints of flight mechanics and oxygen availability on maximum flight performance. hummingbird flight performance was manipul ... | 1996 | 8896366 |
| hummingbird hovering performance in hyperoxic heliox: effects of body mass and sex. | owing to their small size and hovering locomotion, hummingbirds are the most aerobically active vertebrate endotherms. can hyperoxia enhance the flight performance of this highly oxygen-dependent group? hovering performance of ruby-throated hummingbirds (archilochus colubris) was manipulated non-invasively using hyperoxic but hypodense gas mixtures of sea-level air combined with heliox containing 35% o2. this manipulation sheds light on the interplay among metabolic power input, mechanical power ... | 1996 | 9110957 |
| transient hovering performance of hummingbirds under conditions of maximal loading. | maximal load-lifting capacities of six ruby-throated hummingbirds (archilochus colubris) were determined under conditions of burst performance. mechanical power output under maximal loading was then compared with maximal hovering performance in hypodense gas mixtures of normodense air and heliox. the maximal load lifted was similar at air temperatures of 5 and 25 degrees c, and averaged 80% of body mass. the duration of load-lifting was brief, of the order of 1 s, and was probably sustained via ... | 1997 | 9100364 |
| hyperglycemia in hummingbirds and its consequences for hemoglobin glycation. | we measured levels of glucose and glycated hemoglobin in the blood of three of the world's smallest nectarivorous birds, the anna's (calypte anna), costa's (calypte costae), and ruby-throated hummingbirds (archilochus colubris). plasma glucose levels of hummingbirds that were fasted overnight (17 mm) were higher than those in any mammal and are among the highest ever measured in a fasting vertebrate. glucose levels in hummingbirds just after feeding were extreme, rising as high as 42 mm. the sur ... | 1998 | 9787825 |
| maximal horizontal flight performance of hummingbirds: effects of body mass and molt. | hovering and fast forward flapping represent two strenuous types of flight that differ in aerodynamic power requirement. maximal capabilities of ruby-throated hummingbirds (archilochus colubris) in hovering and forward flight were compared under varying body mass and wing area. the capability to hover in low-density gas mixtures was adversely affected by body mass, whereas the capability to fly in a wind tunnel did not show any adverse mass effect. molting birds that lost primary flight feathers ... | 2013 | 10068617 |
| hovering performance of hummingbirds in hyperoxic gas mixtures. | hummingbirds evolved during a period of decline in atmospheric oxygen concentration and currently encounter varying levels of oxygen availability along their elevational distribution. we tested the hypothesis that inspiration of hyperoxic gas increases hummingbird hovering performance when birds are simultaneously challenged aerodynamically. we measured the maximum duration of hovering flight while simultaneously monitoring the rate of oxygen consumption of ruby-throated hummingbirds (archilochu ... | 2001 | 11441043 |
| high levels of docosahexaenoic acid (22:6n-3)-containing phospholipids in high-frequency contraction muscles of hummingbirds and rattlesnakes. | phospholipids containing docosahexaenoic acid (22:6n-3) have been proposed to be required as conformational cofactors for the functional assembly of membrane proteins such as rhodopsin, ion pumps and the various complexes of the mitochondrial electron transport chain (infante, 1987, mol. cell. biochem. 74, 111-116; infante and huszagh, 2000, febs lett. 468, 1-5). this hypothesis predicts that high-frequency contraction muscles, which are endowed with a high content of sarcoplasmic reticulum ca(2 ... | 2001 | 11567891 |
| hummingbird hovering energetics during moult of primary flight feathers. | how does a hovering hummingbird compensate for the loss of flight feathers during moult when the mechanism of lift force generation by flapping wings is impaired? the flight performance of five individual ruby-throated hummingbirds with moulting primary flight feathers and reduced wing area was compared with that before their moult. hummingbirds were flown in reduced air densities using normoxic heliox so that a range of flight energetics was displayed. the rate of moulting and the extent of win ... | 1997 | 9192500 |
| adipose energy stores, physical work, and the metabolic syndrome: lessons from hummingbirds. | hummingbirds and other nectar-feeding, migratory birds possess unusual adaptive traits that offer important lessons concerning obesity, diabetes and the metabolic syndrome. hummingbirds consume a high sugar diet and have fasting glucose levels that would be severely hyperglycemic in humans, yet these nectar-fed birds recover most glucose that is filtered into the urine. hummingbirds accumulate over 40% body fat shortly before migrations in the spring and autumn. despite hyperglycemia and seasona ... | 2005 | 16351726 |
| nectar reward and advertisement in hummingbird-pollinated silene virginica (caryophyllaceae). | we tested for an association between nectar and various floral traits and investigated their roles as primary and secondary pollinator attractants in hummingbird-pollinated silene virginica. our goal was to gain insight into the mechanisms of pollinator-mediated selection that underlies floral trait divergence within the genus. in a field population of s. virginica, we measured five floral and eight vegetative traits and quantified nectar volume, nectar sugar concentration, and total sugar rewar ... | 2006 | 21642126 |
| multiyear study of multivariate linear and nonlinear phenotypic selection on floral traits of hummingbird-pollinated silene virginica. | pollination syndromes suggest that convergent evolution of floral traits and trait combinations reflects similar selection pressures. accordingly, a pattern of selection on floral traits is expected to be consistent with increasing the attraction and pollen transfer of the important pollinator. we measured individual variation in six floral traits and yearly and lifetime total plant seed and fruit production of 758 plants across nine years of study in natural populations of ruby-throated humming ... | 2010 | 19663992 |
| experimental floral and inflorescence trait manipulations affect pollinator preference and function in a hummingbird-pollinated plant. | controversy is ongoing regarding the importance of pollinator-mediated selection as a source of observed patterns of floral diversity. although increasing evidence exists of pollinator-mediated selection acting on female reproductive success, there is still limited understanding of pollinator-mediated selection on floral traits via male reproductive success. here we quantify potential selection by the ruby-throated hummingbird, archilochus colubris, on four floral traits of hermaphroditic silene ... | 2011 | 21613116 |
| neuromuscular control of hovering wingbeat kinematics in response to distinct flight challenges in the ruby-throated hummingbird, archilochus colubris. | while producing one of the highest sustained mass-specific power outputs of any vertebrate, hovering hummingbirds must also precisely modulate the activity of their primary flight muscles to vary wingbeat kinematics and modulate lift production. although recent studies have begun to explore how pectoralis (the primary downstroke muscle) neuromuscular activation and wingbeat kinematics are linked in hummingbirds, it is unclear whether different species modulate these features in similar ways, or ... | 2013 | 23948477 |
| glucose transporter expression in an avian nectarivore: the ruby-throated hummingbird (archilochus colubris). | glucose transporter (glut) proteins play a key role in the transport of monosaccharides across cellular membranes, and thus, blood sugar regulation and tissue metabolism. patterns of glut expression, including the insulin-responsive glut4, have been well characterized in mammals. however, relatively little is known about patterns of glut expression in birds with existing data limited to the granivorous or herbivorous chicken, duck and sparrow. the smallest avian taxa, hummingbirds, exhibit some ... | 2013 | 24155916 |
| resource defense and monopolization in a marked population of ruby-throated hummingbirds (archilochus colubris). | resource defense behavior is often explained by the spatial and temporal distribution of resources. however, factors such as competition, habitat complexity, and individual space use may also affect the capacity of individuals to defend and monopolize resources. yet, studies frequently focus on one or two factors, overlooking the complexity found in natural settings. here, we addressed defense and monopolization of nectar feeders in a population of free-ranging ruby-throated hummingbirds marked ... | 2014 | 24683460 |
| three-dimensional flow and lift characteristics of a hovering ruby-throated hummingbird. | a three-dimensional computational fluid dynamics simulation is performed for a ruby-throated hummingbird (archilochus colubris) in hovering flight. realistic wing kinematics are adopted in the numerical model by reconstructing the wing motion from high-speed imaging data of the bird. lift history and the three-dimensional flow pattern around the wing in full stroke cycles are captured in the simulation. significant asymmetry is observed for lift production within a stroke cycle. in particular, t ... | 2014 | 25008082 |
| bird-window collisions in the summer breeding season. | birds that reside in urban settings face numerous human-related threats to survival, including mortality from bird-window collisions (bwcs). our current understanding of this issue has largely been driven by data collected during spring and fall migration, and patterns of collision mortality during the summer breeding season remain relatively unexplored. we assessed bwcs during four breeding seasons (2009-2012) at a site in northwestern illinois, usa, by comparing the abundance, richness, migrat ... | 2014 | 25024923 |
| hummingbird flight stability and control in freestream turbulent winds. | airflow conditions close to the earth's surface are often complex, posing challenges to flight stability and control for volant taxa. relatively little is known about how well flying animals can contend with complex, adverse air flows, or about the flight control mechanisms used by animals to mitigate wind disturbances. several recent studies have examined flight in the unsteady von kármán vortex streets that form behind cylinders, generating flow disturbances that are predictable in space and t ... | 2015 | 25767146 |
| weekend bias in citizen science data reporting: implications for phenology studies. | studies of bird phenology can help elucidate the effects of climate change on wildlife species but observations over broad spatial scales are difficult without a network of observers. recently, networks of citizen volunteers have begun to report first arrival dates for many migratory species. potential benefits are substantial (e.g., understanding ecological processes at broad spatial and temporal scales) if known biases of citizen data reporting are identified and addressed. one potential sourc ... | 2013 | 23104424 |
| competition between hummingbirds and bumble bees for nectar in flowers of impatiens biflora. | using removal experiments and concurrent measurement of resource levels, evidence was obtained for exploitation competition between ruby-throated hummingbirds and two bumble bee species (bombus fervidus and b. vagans) foraging for nectar on impatiens biflora.when all three species were active, flower visitors showed a complex pattern of resource partitioning involving both diel and spatial changes. hummingbirds foraged almost exclusively from the outermost exposed flowers on plants from which th ... | 1985 | 28310808 |
| nectar extraction by hummingbirds: response to different floral characters. | handling times of hummingbirds (amazilia rutila and cynanthus latirostris) visiting artificial flowers were a positive function of corolla length, nectar volume and nectar concentration. corolla angle had no consistent effects on handling times. a multiple regression model explained 83% of the variation in handling times for these two species. the model also closely fit independent data from another hummingbird, archilochus colubris, suggesting that it is general enough to apply to other medium- ... | 1984 | 28311018 |
| reproductive biology and nectar production of the mexican endemic psittacanthus auriculatus (loranthaceae), a hummingbird-pollinated mistletoe. | many mistletoe species produce 'bird'-pollinated flowers; however, the reproductive biology of the majority of these species has not been studied. psittacanthus auriculatus is a mexican endemic mistletoe, most common in open, dry mesquite grassland. knowledge of the reproductive biology of p. auriculatus is essential for understanding species formation and diversification of psittacanthus mistletoes, but it is currently poorly understood. thus, we studied floral biology and phenology, nectar pro ... | 2016 | 26154599 |
| permanent genetic resources added to molecular ecology resources database 1 august 2009-30 september 2009. | this article documents the addition of 238 microsatellite marker loci and 72 pairs of single nucleotide polymorphism (snp) sequencing primers to the molecular ecology resources database. loci were developed for the following species: adelges tsugae, artemisia tridentata, astroides calycularis, azorella selago, botryllus schlosseri, botrylloides violaceus, cardiocrinum cordatum var. glehnii, campylopterus curvipennis, colocasia esculenta, cynomys ludovicianus, cynomys leucurus, cynomys gunnisoni, ... | 2010 | 21565018 |
| a new dimension to hummingbird-flower relationships. | the close correspondence between the bills of hummingbirds and the lengths of the flowers they feed from has been interpreted as an example of coadaptation. observations of birds feeding at flowers longer and shorter than their bills, however, and the lack of experimental evidence for any feeding advantage to short bills, seem to contradict this interpretation. i address this problem by considering a little-studied dimension of floral morphology: corolla diameter. in laboratory experiments on fe ... | 1996 | 28307145 |
| what do foraging hummingbirds maximize? | hainsworth and wolf (1976) reported that under certain conditions hummingbirds made food choices which did not maximize their net rate of energy intake while foraging. they concluded that the birds were not foraging optimally. we show here that their birds probably maximized a different utility function, the net energy per unit volume consumed (nevc), which appears to be an optimal choice on a time scale longer than that of a foraging bout. our own experiments with archilochus colubris support t ... | 1984 | 28311211 |
| myosin heavy-chain isoforms in the flight and leg muscles of hummingbirds and zebra finches. | myosin heavy chain (mhc) isoform complement is intimately related to a muscle's contractile properties, yet relatively little is known about avian mhc isoforms or how they may vary with fiber type and/or the contractile properties of a muscle. the rapid shortening of muscles necessary to power flight at the high wingbeat frequencies of ruby-throated hummingbirds and zebra finches (25-60 hz), along with the varied morphology and use of the hummingbird hindlimb, provides a unique opportunity to un ... | 2014 | 24671242 |
| reproductive biology and nectar secretion dynamics of penstemon gentianoides (plantaginaceae): a perennial herb with a mixed pollination system? | in many plant species, pollination syndromes predict the most effective pollinator. however, other floral visitors may also offer effective pollination services and promote mixed pollination systems. several species of the species-rich penstemon (plantaginaceae) exhibit a suite of floral traits that suggest adaptation for pollination by both hymenopterans and hummingbirds. transitions from the ancestral hymenopteran pollination syndrome to more derived hummingbird pollination syndrome may be pro ... | 2017 | 28828248 |
| optic flow stabilizes flight in ruby-throated hummingbirds. | flying birds rely on visual cues for retinal image stabilization by negating rotation-induced optic flow, the motion of the visual panorama across the retina, through corrective eye and head movements. in combination with vestibular and proprioceptive feedback, birds may also use visual cues to stabilize their body during flight. here, we test whether artificially induced wide-field motion generated through projected visual patterns elicits maneuvers in body orientation and flight position, in a ... | 2016 | 27284072 |
| west nile virus prevalence in wild birds from mexico. | west nile virus (wnv) emerged in the americas with its introduction in 1999 and now is considered endemic across the continent. in 2002, wnv was detected in mexico, where its occurrence and mortality are considerably lower compared with the us. however, continuous national surveillance programs in mexico are nonexistent. birds are considered the primary hosts and primary geographic dispersers of this pathogen. a total of 200 cloacal and tracheal samples from wild migratory or resident birds were ... | 2019 | 30339087 |
| determination of neonicotinoids and butenolide residues in avian and insect pollinators and their ambient environment in western canada (2017, 2018). | to examine the spatial, and temporal variation and potential sources of pesticide concentrations, primarily neonicotinoid insecticides, in hummingbirds in western canada, we sampled their cloacal fluid from sites in british columbia and saskatchewan, canada in 2017-2018. at a sub-sample of those sites, we also measured pesticides in honey bee (apis mellifera) nectar, water, and sediment. we collected cloacal fluid from 5 species of hummingbirds (n = 26 sites) in british columbia (bc) and saskatc ... | 2020 | 32563110 |
| glucose transporter expression and regulation following a fast in the ruby-throated hummingbird, archilochus colubris. | hummingbirds, subsisting almost exclusively on nectar sugar, face extreme challenges to blood sugar regulation. the capacity for transmembrane sugar transport is mediated by the activity of facilitative glucose transporters (gluts) and their localisation to the plasma membrane (pm). in this study, we determined the relative protein abundance of glut1, glut2, glut3 and glut5 via immunoblot using custom-designed antibodies in whole-tissue homogenates and pm fractions of flight muscle, heart and li ... | 2020 | 32895327 |
| metabolic partitioning of sucrose and seasonal changes in fat turnover rate in ruby-throated hummingbirds (archilochus colubris). | hummingbirds fuel their high energy needs with the fructose and glucose in their nectar diets. these sugars are used both to fuel immediate energy needs and to build fat stores to fuel future fasting periods. fasting hummingbirds can deplete energy stores in only hours and need to be continuously replacing these stores while feeding and foraging. whether and how hummingbirds partition dietary fructose and glucose towards immediate oxidation versus fat storage is unknown. using a chronic stable i ... | 2020 | 31836652 |
| mobility of impatiens capensis flowers: effect on pollen deposition and hummingbird foraging. | flexible pedicels are characteristic of birdpollinated plants, yet have received little attention in studies of hummingbird-flower interactions. a major implication of flexible pedicels is that flowers may move during pollination. we examined whether such motion affected interactions between ruby-throated hummingbirds (archilochus colubris) and jewelweed (impatiens capensis) by increasing pollen deposition and by altering the effectiveness of nectar removal. for i. capensis, flower mobility enha ... | 1996 | 28307089 |
| field flight dynamics of hummingbirds during territory encroachment and defense. | hummingbirds are known to defend food resources such as nectar sources from encroachment by competitors (including conspecifics). these competitive intraspecific interactions provide an opportunity to quantify the biomechanics of hummingbird flight performance during ecologically relevant natural behavior. we recorded the three-dimensional flight trajectories of ruby-throated hummingbirds defending, being chased from and freely departing from a feeder. these trajectories allowed us to compare na ... | 2015 | 26039101 |
| wing-pitching mechanism of hovering ruby-throated hummingbirds. | in hovering flight, hummingbirds reverse the angle of attack of their wings through pitch reversal in order to generate aerodynamic lift during both downstroke and upstroke. in addition, the wings may pitch during translation to further enhance lift production. it is not yet clear whether these pitching motions are caused by the wing inertia or actuated through the musculoskeletal system. here we perform a computational analysis of the pitching dynamics by incorporating the realistic wing kinema ... | 2015 | 25599381 |
| the hummingbird's tongue: a self-assembling capillary syphon. | we present the results of a combined experimental and theoretical investigation of the dynamics of drinking in ruby-throated hummingbirds. in vivo observations reveal elastocapillary deformation of the hummingbird's tongue and capillary suction along its length. by developing a theoretical model for the hummingbird's drinking process, we investigate how the elastocapillarity affects the energy intake rate of the bird and how its open tongue geometry reduces resistance to nectar uptake. we note t ... | 2012 | 23075839 |
| low ambient temperature reduces the time for fuel switching in the ruby-throated hummingbird (archilochus colubris). | physiological adaptations that enhance flux through the sugar oxidation cascade permit hummingbirds to rapidly switch between burning lipids when fasted to burning ingested sugars when fed. hummingbirds may be able to exert control over the timing and extent of use of ingested sugars by varying digestive rates when under pressure to accumulate energy stores or acquire energy in response to heightened energy demands. we hypothesized that hummingbirds would modulate the timing of a switch to relia ... | 2019 | 31446070 |
| year-round monitoring reveals prevalence of fatal bird-window collisions at the virginia tech corporate research center. | collisions with glass are a serious threat to avian life and are estimated to kill hundreds of millions of birds per year in the united states. we monitored 22 buildings at the virginia tech corporate research center (vtcrc) in blacksburg, virginia, for collision fatalities from october 2013 through may 2015 and explored possible effects exerted by glass area and surrounding land cover on avian mortality. we documented 240 individuals representing 55 identifiable species that died due to collisi ... | 2018 | 29637021 |
| single-molecule, full-length transcript sequencing provides insight into the extreme metabolism of the ruby-throated hummingbird archilochus colubris. | hummingbirds oxidize ingested nectar sugars directly to fuel foraging but cannot sustain this fuel use during fasting periods, such as during the night or during long-distance migratory flights. instead, fasting hummingbirds switch to oxidizing stored lipids that are derived from ingested sugars. the hummingbird liver plays a key role in moderating energy homeostasis and this remarkable capacity for fuel switching. additionally, liver is the principle location of de novo lipogenesis, which can o ... | 2018 | 29618047 |
| temporal migration patterns between natal locations of ruby-throated hummingbirds (archilochus colubris) and their gulf coast stopover site. | autumn latitudinal migrations generally exhibit one of two different temporal migration patterns: type 1 where southern populations migrate south before northern populations, or type 2 where northern populations overtake southern populations en route. the ruby-throated hummingbird (archilochus colubris) is a species with an expansive breeding range, which allows opportunities to examine variation in the timing of migration. our objective was to determine a relationship between natal origin of ru ... | 2018 | 29340153 |
| evidence of high transport and phosphorylation capacity for both glucose and fructose in the ruby-throated hummingbird (archilochus colubris). | hummingbirds are able to fuel hovering flight entirely with recently ingested glucose or fructose. among vertebrates, several steps of sugar flux from circulation to skeletal muscle are potentially rate-limiting, including transport into muscle and subsequent phosphorylation. while capacities for glucose flux are substantial, capacities for fructose flux are comparatively low. the mechanisms underlying apparent high rates of glucose and fructose oxidation in hummingbird flight muscle remain uncl ... | 2018 | 29127075 |