+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Effects of nectar concentration on water balance, osmoregulation, and thermoregulation in a nectar-feeding sunbird

Effects of nectar concentration on water balance, osmoregulation, and thermoregulation in a nectar-feeding sunbird

American Zoologist 40(6): 1109

The water balance of nectar-feeding animals is inextricably linked to their energy balance. Because nectar secreted by bird-pollinated flowers can be dilute, birds can be forced to consume high volumes of water to satisfy their energy demands. I examined the consequences of feeding on dilute nectar for the African sunbird Nectarinia chalybea (Nectariniidae). Sunbirds ingested the same amount of sugar over a wide range of sugar concentrations by modulating volumetric intake. When feeding on 0.2 M sucrose, birds consumed four times their body mass in water daily. Most of this water was excreted, with a remarkably small loss of electrolytes. Evaporative water loss was twice as high in sunbirds fed 0.2 M sucrose than in those fed 1.2 M sucrose. I estimated that birds used 10% of their total daily energy intake to warm 0.2 M sucrose from 20degreeC to body temperature, in contrast to the negligible amount of energy used to warm 1.2 M sucrose. To compensate for the increasing costs of evaporative heat loss and food warming with decreasing food concentration, sunbirds maintained higher metabolic rates while feeding on lower nectar concentrations. I hypothesize that the thermal insulation of sunbirds feeding on dilute nectar is higher than that in birds feeding on more concentrated nectar, because the increase in metabolic rate that I observed accounts only partially for the estimated costs of evaporative heat loss and food warming.

Please choose payment method:

(PDF emailed within 1 workday: $29.90)

Accession: 034825215

Download citation: RISBibTeXText

Related references

Energy and water balance in the lesser double-collared sunbird (Nectarinia chalybea) feeding on different nectar concentrations. Journal of Comparative Physiology B Biochemical Systemic and Environmental Physiology 169(3): 200-206, 1999

Rates of nectar feeding in butterflies effects of sex size age and nectar concentration. Functional Ecology 2(3): 289-296, 1988

Osmoregulation in a nectar feeding insect the carpenter bee xylocopa capitata water excess and ion conservation. Physiological Entomology 15(4): 433-440, 1990

Osmoregulation in a nectar-feeding insect, the carpenter bee Xylocopa capitata: water excess and ion conservation. Physiological Entomology 15(4): 433-440, 2008

Nectar microbes can reduce secondary metabolites in nectar and alter effects on nectar consumption by pollinators. Ecology 97(6): 1410-1419, 2016

Energy intake and expenditures in a nectar-feeding sunbird. Ecology 56(1): 92-104, 1975

Metabolism, thermoregulation and evaporative water loss in two species of Australian nectar-feeding birds (family Meliphagidae). Comparative Biochemistry and Physiology A: 674: 629-635, 1980

Nectar concentration preferences and sugar intake in the white-bellied sunbird, Cinnyris talatala (Nectariniidae). Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 179(6): 673-679, 2009

Nectar passage and gut morphology in the malachite sunbird and the black-capped lory: implications for feeding in nectarivores. Ostrich 73(3-4): 138-142, 2002

Nectar productivity and sugar concentration of nectar of fruit trees and berry plants. Pchelovodstvo 34(5): 39-41, 1957

Honeybees prefer warmer nectar and less viscous nectar, regardless of sugar concentration. Proceedings. Biological Sciences 280(1767): 20131597, 2013

Nectar loads as fuel for collecting nectar and pollen in honeybees: adjustment by sugar concentration. Journal of Comparative Physiology. A Neuroethology Sensory Neural and Behavioral Physiology 202(6): 435-443, 2016

Preferences and tradeoffs in nectar temperature and nectar concentration in the Asian hive beeApis cerana. Behavioral Ecology and Sociobiology 68(1): 13-20, 2014

Morphological specialization influences nectar extraction efficiency of sympatric nectar-feeding bats. Journal of Experimental Biology 215(Pt 22): 3989-3996, 2012

Lack of evidence for the toxic nectar hypothesis: a plant alkaloid did not deter nectar feeding by Lepidoptera. Florida Entomologist 76(4): 556-566, 1993