Short‐term energy regulation in nectar‐feeding birds: the response of Whitebellied Sunbirds (<i>Nectarinia talatala</i>) to a midday fast

Nicolson, Susan W.; Hoffmann, Dorothee; Fleming, Patricia A.

doi:10.1111/j.1365-2435.2005.01042.x

Cited by 6 publications

(9 citation statements)

References 47 publications

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“…Do they also compensate for perturbations to nutrient supply? This question has been addressed by comparing afternoon intakes of captive birds subjected to an enforced 2 h midday fast with their intakes on a control day with uninterrupted feeding (Köhler et al 2011;Nicolson et al 2005). Fig.…”

Section: Compensation For Perturbations To Nutrient Supplymentioning

confidence: 99%

Regulation of nutrient intake in nectar-feeding birds: insights from the geometric framework

2012

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A nectar diet is simple in composition and easily digested, but may vary greatly in its proportions of sugar and water. Here we apply the geometric framework, a modelling approach for investigating how animals balance nutrient needs in multidimensional and dynamic nutritional environments, to captive whitebellied sunbirds (Cinnyris talatala). We address the question of how these small birds (~8 g) prioritize sugar and water intake, and how dietary salt content interacts with sugar and water intake. Sunbirds kept at 20˚C and provided with moderate to high sucrose concentrations (≥1 M), together with supplementary water, converge on an intake target of 2.79 g day -1 of sucrose and 7.72 g day -1 of water: equivalent to 0.85 M sucrose. When the birds are given more dilute sucrose concentrations, they defend their sugar intake by overingesting water, up to a ceiling of 47 g day -1 . Sugar intake thus gets priority over water intake, but the birds have a finite capacity to over-ingest water to gain the target level of sugar.Regulation appears to be less precise when birds are given a choice between two sucrose solutions than when they choose between a sugar solution and supplementary water. Intake targets vary in response to internal and external factors, and sunbirds increase their sugar intake in response to increased activity and cold, irrespective of nectar concentration. They also compensate for interruptions in foraging activity, whether overnight or during the day.Interactive effects became evident when sodium was included as a third nutrient: on very dilute nectar (≤0.1 M), where sunbirds lose body mass, the addition of sodium to the diet helps to achieve the carbohydrate intake target, while raising the ceiling on water intake. This analysis provides a new perspective on nectarivory, while adding to the comparative database on nutrient regulation and emphasising water as a nutrient.

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Section: Compensation For Perturbations To Nutrient Supplymentioning

confidence: 99%

Regulation of nutrient intake in nectar-feeding birds: insights from the geometric framework

2012

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“…In response to a midday fast (imposed by turning off the lights), rufous hummingbirds are apparently unable to adjust their intake rates and consequently end the day with energy deficits that necessitate the use of torpor (Tooze and Gass, 1985). By contrast, sunbirds and honeyeaters are able to increase their rate of feeding following the fast, implying greater plasticity in their rates of digestion and absorption of sugars (Köhler et al, 2011;Nicolson et al, 2005).…”

Section: How Do Nectarivorous Birds Deal With Fasting?mentioning

confidence: 99%

Drinking problems on a ‘simple’ diet: physiological convergence in nectar-feeding birds

Nicolson

Fleming

2014

Journal of Experimental Biology

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Regulation of energy and water are by necessity closely linked in avian nectarivores, because the easily available sugars in nectar are accompanied by an excess of water but few electrolytes. In general, there is convergence in morphology and physiology between three main lineages of avian nectarivores that have evolved on different continents -the hummingbirds, sunbirds and honeyeaters. These birds show similar dependence of sugar preferences on nectar concentration, high intestinal sucrase activity and rapid absorption of hexoses via mediated and paracellular routes. There are differences, however, in how these lineages deal with energy challenges, as well as processing the large volumes of preformed water ingested in nectar. While hummingbirds rely on varying renal water reabsorption, the passerine nectarivores modulate intestinal water absorption during water loading, thus reducing the impact on the kidneys. Hummingbirds do not generally cope with salt loading, and have renal morphology consistent with their ability to produce copious dilute urine; by contrast, as well as being able to deal with dilute diets, honeyeaters and sunbirds are more than capable of dealing with moderately high levels of added electrolytes. And finally, in response to energy challenge, hummingbirds readily resort to torpor, while the passerines show renal and digestive responses that allow them to deal with short-term fasts and rapidly restore energy balance without using torpor. In conclusion, sunbirds and honeyeaters demonstrate a degree of physiological plasticity in dealing with digestive and renal challenges of their nectar diet, while hummingbirds appear to be more constrained by this diet.

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“…For avian nectarivores, however, food intake is commonly determined only hourly or daily. Nectar intake has been measured by weighing the feeder (Nicolson and Fleming 2003;Nicolson et al 2005) or by reading changes in fluid meniscus levels in glass or plastic feeders, as done for honeyeaters (Collins and Clow 1978), sunbirds and sugarbirds (Jackson et al 1998), and hummingbirds (Ló pezCalleja and Bozinovic 2003). Feeding durations of nectar-feeding birds, however, have been recorded with a stopwatch (Collins and Clow 1978) or a video camera (Mitchell and Paton 1990).…”

Section: Introductionmentioning

confidence: 99%

Nectar Intake of White‐Bellied Sunbirds (Cinnyris talatala): Can Meal Size Be Inferred from Feeding Duration?

Köhler

Verburgt²,

Nicolson³

2008

Physiological and Biochemical Zoology

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A positive relationship between feeding duration and meal size of avian nectarivores has often been assumed in earlier studies. We investigated whether feeding duration can be used as a surrogate for the amount of sugar solution ingested by whitebellied sunbirds, Cinnyris (Nectarinia) talatala. Feeding durations of sunbirds consuming three sucrose concentrations (10%, 20%, and 40% w/w) were measured using an infrared photodetection system, and the amounts consumed were recorded simultaneously by weighing the feeder throughout the experiment. For all three diet concentrations, a positive relationship was found between the time spent feeding per 30 min and the mass consumed. Therefore, feeding duration is demonstrated to be an index of the amount ingested on a particular sugar concentration. The rate of ingestion, however, depended on the sugar concentration, with the highest rate at the lowest concentration of 10% and the lowest rate at the 40% concentration. Less total time was spent feeding on the 20% solution than on the 10% solution, but time increased on the 40% diet because of viscosity effects. There appeared to be a weak relationship between feeding patterns and sex, but this was not significant, probably because of interindividual variation.

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Short‐term energy regulation in nectar‐feeding birds: the response of Whitebellied Sunbirds (Nectarinia talatala) to a midday fast

Cited by 6 publications

References 47 publications

Regulation of nutrient intake in nectar-feeding birds: insights from the geometric framework

Regulation of nutrient intake in nectar-feeding birds: insights from the geometric framework

Drinking problems on a ‘simple’ diet: physiological convergence in nectar-feeding birds

Nectar Intake of White‐Bellied Sunbirds (Cinnyris talatala): Can Meal Size Be Inferred from Feeding Duration?

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