Nectar Characteristics and food selection by hummingbirds

Haisworth, F. Reed; Wolf, Larry L.

doi:10.1007/bf00368847

Cited by 173 publications

(102 citation statements)

References 34 publications

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“…Hummingbirds are known for strong preferences with respect to sugars, favouring concentrated solutions [39], particularly sucrose-dominant nectar [39,40], while avoiding high fructose concentrations [37]. Therefore, given the contrasting effects of bacteria and yeasts on sucrose (figure 3c), glucose (figure 3d) and fructose (figure 3e), changes in sugar composition may underlie the microbial effects we observed on pollination.…”

Section: (A) Possible Mechanismsmentioning

confidence: 92%

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

2013

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Mutualistic interactions are often subject to exploitation by species that are not directly involved in the mutualism. Understanding which organisms act as such 'third-party' species and how they do so is a major challenge in the current study of mutualistic interactions. Here, we show that even species that appear ecologically similar can have contrasting effects as third-party species. We experimentally compared the effects of nectar-inhabiting bacteria and yeasts on the strength of a mutualism between a hummingbird-pollinated shrub, Mimulus aurantiacus, and its pollinators. We found that the common bacterium Gluconobacter sp., but not the common yeast Metschnikowia reukaufii, reduced pollination success, seed set and nectar consumption by pollinators, thereby weakening the plant-pollinator mutualism. We also found that the bacteria reduced nectar pH and total sugar concentration more greatly than the yeasts did and that the bacteria decreased glucose concentration and increased fructose concentration whereas the yeasts affected neither. These distinct changes to nectar chemistry may underlie the microbes' contrasting effects on the mutualism. Our results suggest that it is necessary to understand the determinants of microbial species composition in nectar and their differential modification of floral rewards to explain the mutual benefits that plants and pollinators gain from each other.

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Section: (A) Possible Mechanismsmentioning

confidence: 92%

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

2013

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“…Taste preferences and digestive limitations, such as differences in the time required to process or assimilate sugars, are affected by diet concentration, so that neither composition nor concentration can be considered independently. Bird-dispersed fruits resemble the nectars of passerine-pollinated (Percival 1965;Skead 1967;Hainsworth and Wolf 1972a, b;Hainsworth 1973Hainsworth , 1974Baker 1975;Gill and Wolf 1975a, b;Stiles 1975;Wolf 1975;Hainsworth and Wolf 1976;Wolf et al 1976;Cruden and Toledo 1977;Hainsworth 1977;Bolten and Feinsinger 1978;Bond and Brown 1979;Brown and Kodric-Brown 1979;Waser 1979;Pyke 1980;Corbet and Willmer 1981;Frost and Frost 1981;Pyke and Waser 1981;Baker and Baker 1982a, b;Feinsinger et al 1982;Paton 1982;Collins 1983;Cruden et al 1983;Heyneman 1983;Wiens et al 1983;Freeman et al 1984;Gottsberger et al 1984;Lammers and Freeman 1986;Buys 1987;Craig and Stewart 1988;Elisens and Freeman 1988;Moncur and Boland 1989;Arizmendi and Ornelas 1990;Freeman et al 1991;Stiles and Freeman 1993;van Wyk et al 1993;Johnson and Bond 1994;K...…”

Section: Sugarsmentioning

confidence: 99%

Nectar as food for birds: the physiological consequences of drinking dilute sugar solutions

2003

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Abstract. Nectarivory has evolved many times in birds: although best known in hummingbirds, sunbirds and honeyeaters, it also occurs on an opportunistic basis in a varied assortment of birds. We present a phylogenetic analysis of the distribution of nectarivory in birds. Specialised avian nectarivores are generally small, with an energetic lifestyle and high metabolic rates. Their high degree of dependence on nectar as a food source has led to convergence in morphological, physiological and behavioural adaptations. We examine the constituents of nectar which are most important to bird consumers, and how the birds deal with them in terms of physiology and behaviour. There are still unanswered questions: for example, the dichotomy between sucrose-rich nectars in hummingbirdpollinated plants and predominantly hexose-rich nectars in sunbird-pollinated plants appears to have little to do with bird physiologies and may rather reflect patterns of nectar secretion.

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“…The general lack of correspondence between bills and flowers has led some researchers to conclude that present-day interactions between hummingbirds and their food plants have arisen through diffuse coevolu- 3 E-mail: ejtemeles@amherst.edu tion at best (Feinsinger 1983, Cotton 1998. Similarly, field and laboratory experiments on a variety of hummingbird species have found that longer-billed birds can feed more quickly from longer artificial flowers than shorter-billed birds, whereas shorted-billed birds do not feed more quickly from shorter artificial flowers than longer-billed birds (Hainsworth 1973, Hainsworth and Wolf 1976, Montgomerie 1984, Temeles and Roberts 1993; a similar finding has been reported for other nectar-feeding animals, e.g., hawkmoths [Haber and Frankie 1989] and euglossine bees [Borrell 2005]). The finding that longer bills are equal or better than shorter bills raises the question of why some hummingbird species have short bills (Montgomerie 1984).…”

Section: Introductionmentioning

confidence: 99%

“…We used two measures of feeding performance: (1) maximum extraction depth of nectar from a flower, which is a measure of how deeply a bird can successfully feed from a flower (Montgomerie 1984, Temeles andRoberts 1993), and (2) handling time, a measure of the time it takes a bird to insert its bill, extract nectar, and withdraw its bill from a flower (Hainsworth 1973, Hainsworth and Wolf 1976, Temeles and Roberts 1993. Based on previous studies (Hainsworth 1973, Hainsworth and Wolf 1976, Montgomerie 1984, Temeles and Roberts 1993, Temeles 1996, we expected longer-billed birds within and between sexes to have greater maximum extraction depths and shorter handling times at the longest flowers relative to shorter-billed birds. The reason for the latter prediction is that at long flowers, a longer-billed bird should be able to insert its bill more deeply than a shorter-billed bird, which would reduce the distance between the bill tip and the nectar supply and thus the distance the tongue must be extended on each lick (Temeles 1996).…”

Section: Introductionmentioning

confidence: 99%

Effect of flower shape and size on foraging performance and trade‐offs in a tropical hummingbird

Temeles

Koulouris

Sander

et al. 2009

Ecology

100

116

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Abstract. Matches between the bills of hummingbirds and the flowers they visit have been interpreted as examples of coadaptation and feeding specialization. Observations of birds feeding at flowers longer or shorter than their bills combined with a lack of experimental evidence for foraging trade-offs, however, fail to support these interpretations. We addressed these inconsistencies by considering a seldom-studied dimension of hummingbird-flower relationships, the shape of bills and flowers, through experiments on the Purple-throated Carib, Eulampis jugularis, and its major food plant, Heliconia, in the eastern Caribbean. Bills of male E. jugularis are considerably shorter and straighter than bills of females. We examined foraging performances and trade-offs during visits to natural heliconias and 34 artificial flowers of differing length and curvature. Supporting predictions based on matches between bill and flower morphology, handling times of females were significantly shorter than those of males at the long, curved flowers of a green morph of H. bihai. Contrary to predictions, handling times of males were not significantly shorter than handling times of females at the short flowers of H. caribaea. At artificial flowers, maximum extraction depths of females were significantly longer than maximum extraction depths of males at all curved flowers, but not at straight flowers. Handling times of females were significantly shorter than handling times of males at the longest artificial flowers for all curvatures, whereas handling times of males were significantly shorter at short, straight, artificial flowers, but only while hover-feeding without a perch. Within each sex, handling times were inversely related to bill length at long flowers for all shapes. Taken together, these performance trade-offs suggest that the long, curved bills of females are adapted for feeding from long, curved flowers, whereas the short bills of males are adapted for hover-feeding from short, straighter flowers. In addition, the finding that differences in feeding performance occur at the extremes of floral phenotypes suggests that the evolution of bill morphology may be driven by a small subset of the flowers visited by a hummingbird species.

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Nectar Characteristics and food selection by hummingbirds

Cited by 173 publications

References 34 publications

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

Nectar as food for birds: the physiological consequences of drinking dilute sugar solutions

Effect of flower shape and size on foraging performance and trade‐offs in a tropical hummingbird

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