Changes in nectar concentration: how quickly do whitebellied sunbirds (Cinnyris talatala) adjust feeding patterns and food intake?

Köhler, Angela; Verburgt, Luke; Fleming, Patricia A.; Nicolson, Susan W.

doi:10.1007/s00360-008-0269-5

Cited by 13 publications

(18 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results are similar to those obtained for some other nectarivores such as sunbirds (e.g. Lotz and Nicolson, 1999;Köhler et al, 2008) and hummingbirds (e.g. López-Calleja et al, 1997).…”

Section: Discussionsupporting

confidence: 90%

Digestive efficiency of Knysna and purple-crested turacos fed varying concentrations of equicaloric and equimolar artificial fruit

Wilson

Downs

2011

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYAvian frugivores have been somewhat poorly studied with regards to the effects that different fruit sugar types and concentrations have on their digestive efficiencies. Therefore, two relatively large South African frugivores, the Knysna turaco (Tauraco corythaix) and the purple-crested turaco (Gallirex porphyreolophus), were fed artificial fruit that contained equicaloric and equimolar concentrations of different sugars, to determine their daily food and energy intake, digestive efficiencies and digestive transit times. The artificial fruit contained 6.6, 12.4 or 22%, or 0.42, 0.83 or 1.66moll -1 sucrose or glucose. Food intake of both turaco species increased with decreasing sugar concentration and molarity, irrespective of sugar type, suggesting compensatory mechanisms for energy requirements. Apparent assimilation efficiencies of both turaco species ranged from 61.4-90.0% and 60.2-92.4% for equicaloric and equimolar artificial fruit diets, respectively. Digestive transit times for both turaco species were slowed with an increase in sugar concentration and molarity, irrespective of sugar type. Consequently these two frugivores appear to be tolerant of sugar type and would be expected to select fruits based on energy yields. Future studies of the composition of indigenous forest fruit sugars may give insight into food preferences of the turaco species and their role as potential seed dispersers of fruiting tree species.

show abstract

Section: Discussionsupporting

confidence: 90%

Digestive efficiency of Knysna and purple-crested turacos fed varying concentrations of equicaloric and equimolar artificial fruit

Wilson

Downs

2011

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…When energy demands increase, birds also have to ingest more food. Our sunbirds compensated for a decrease in nectar concentration or T a by increasing the number of feeding events, confirming our earlier finding that food intake is mainly adjusted via feeding frequency (Köhler, Verburgt & Nicolson 2006; Köhler et al. 2008).…”

Section: Discussionsupporting

confidence: 90%

Energy management on a nectar diet: can sunbirds meet the challenges of low temperature and dilute food?

et al. 2010

View full text Add to dashboard Cite

Summary1. Animals commonly experience variation in both food quality and metabolic requirements, and must regulate their food intake to maintain energy balance. 2. We exposed captive whitebellied (Cinnyris talatala) and amethyst (Chalcomitra amethystina) sunbirds (Nectariniidae) to different nectar sugar concentrations (0AE25, 0AE5 and 1 M sucrose), i.e. food qualities, and ambient temperatures (5, 15 and 25°C), i.e. energy requirements, to examine the effects on food intake, feeding patterns and body mass of the birds. 3. Both species compensated for decreased dietary sugar concentration by increasing food intake. While whitebellied sunbirds showed a constant sugar intake over the range of diet concentrations, amethyst sunbirds ingested less sugar on 0AE25 M than on 0AE5 M sucrose. During acute short-term exposure to 5°C, birds increased food and thus sugar intake on all diet concentrations by almost 27%, compared to the similar intake at 15 and 25°C. Despite increased food consumption, all birds lost more body mass at 5 and 15°C than at 25°C. 4. Adjustment of food intake in both species took place via changes in feeding frequency, with the duration of feeding events unchanged. 5. Apparent sugar assimilation in whitebellied sunbirds was >99%, irrespective of diet concentration and temperature. A chemical reactor model of digestive capacity based on measurements of intestinal hydrolytic capacity mostly underestimated the maximal food intake of whitebellied sunbirds in the cold, but predicted higher maximal intake for amethyst sunbirds than observed on most diet concentrations. 6. We conclude that physiological constraints impose upper limits on compensatory feeding in sunbirds. These constraints are mainly digestive at low temperature and osmoregulatory on dilute diets, while the combination of both stresses leads to additional metabolic costs. 7. The moderate mass loss of both species when exposed to these energy challenges suggests that behavioural changes and ⁄ or hypothermia may be used to reduce energy expenditure.

show abstract

“…Short-term adjustment of food intake in this species occurs through changes in feeding frequency rather than feeding duration (23). Whitebellied sunbirds rapidly detect changes in nectar sucrose concentration and adjust their feeding frequency within a few minutes of a concentration change (22). Pair-wise tests of the concentration preferences of whitebellied sunbirds show that they prefer the higher concentration up to 1 mol/l for both sucrose and equicaloric hexose solutions, while they generally tend to prefer the lower concentration above 1 mol/l (24).…”

Section: Discussionmentioning

confidence: 98%

Dilute bird nectars: viscosity constrains food intake by licking in a sunbird

Köhler

Leseigneur

Verburgt

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Floral nectars of bird-pollinated plants are relatively dilute. One hypothesis proposed to explain this concerns the difficulty for birds of drinking nectar of high viscosity. We examined the effects of viscosity, separately from those of sugar concentration, on feeding by captive whitebellied sunbirds (Cinnyris talatala). Viscosities of artificial nectar (sucrose solutions ranging in concentration from 0.25 to 1.5 mol/l) were altered with Tylose, an inert polysaccharide. Food consumption was measured over 3 h, and lick frequency and duration were recorded using photodetection devices on feeding apertures too small for the bill but large enough for the extended tongue. Volumetric intake rates (ml/s) were inversely proportional to nectar viscosity, and were similar over the range of sucrose concentrations when viscosity was held constant. Sucrose intake rates (mg/s) remained the same on pure sucrose solutions, but they decreased with increasing viscosity at a constant sucrose concentration. Lick frequencies and tongue loads were reduced at high viscosities, and lick duration increased, which confirms that sunbirds take longer to ingest viscous solutions. Licking behavior was remarkably similar in birds feeding on different sucrose concentrations if viscosity was held constant. Nectar ingestion rate is determined by viscosity; however, total food intake is mainly modulated by sugar concentration. Similar effects of food viscosity have been observed in insects that suck nectar.

show abstract

Changes in nectar concentration: how quickly do whitebellied sunbirds (Cinnyris talatala) adjust feeding patterns and food intake?

Cited by 13 publications

References 40 publications

Digestive efficiency of Knysna and purple-crested turacos fed varying concentrations of equicaloric and equimolar artificial fruit

Digestive efficiency of Knysna and purple-crested turacos fed varying concentrations of equicaloric and equimolar artificial fruit

Energy management on a nectar diet: can sunbirds meet the challenges of low temperature and dilute food?

Dilute bird nectars: viscosity constrains food intake by licking in a sunbird

Contact Info

Product

Resources

About