| nectar intake of white-bellied sunbirds (cinnyris talatala): can meal size be inferred from feeding duration? | 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 white-bellied 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 b ... | 2008 | 18781840 |
| whitebellied sunbirds (nectarinia talatala, nectariniidae) do not prefer artificial nectar containing amino acids. | amino acids are the most abundant class of compounds in nectar after sugars. like its sugar concentration, the amino acid concentration of nectar has been linked to pollinator type, and it has been suggested that amino acid concentrations are high in the floral nectars of plant species pollinated by passerine birds compared to those pollinated by hummingbirds. we investigated the feeding response of whitebellied sunbirds (nectarinia talatala) to the inclusion of amino acids in artificial nectar ... | 2007 | 17541603 |
| short-term energy regulation of whitebellied sunbirds (nectarinia talatala): effects of food concentration on feeding frequency and duration. | avian nectarivores show compensatory feeding by adjusting their volumetric intake in response to variation in nectar concentration. this study used an infrared photo-detection system to investigate the short-term feeding patterns of whitebellied sunbirds (nectarinia talatala) consuming three different sucrose concentrations (10, 20 and 30% w/w). sunbirds increased their feeding frequency on the most dilute diet, but there was no change in feeding duration. thus, the increase in total time spent ... | 2006 | 16857871 |
| dietary intake effects on arginine vasotocin and aldosterone in cloacal fluid of whitebellied sunbirds (nectarinia talatala). | the main objective of this study was to determine whether or not the renal outputs of the osmoregulatory hormones arginine vasotocin (avt) and aldosterone (aldo) reflect the osmotic status of whitebellied sunbirds (nectarinia talatala). the birds were fed a range of sucrose concentrations (from 0.07 to 2.5 mol/l, with osmolalities of 70 to approximately 5,800 mosm/kg), and adjusted their intakes so that they drank large volumes of dilute diets and small volumes of concentrated diets. renal fluid ... | 2004 | 15369833 |
| osmoregulatory response to acute diet change in an avian nectarivore: rapid rehydration following water shortage. | nectarivores may be required to switch between water conservation and water excretion as rapidly as they change food plants in nature. we examined the rehydration response in whitebellied sunbirds (nectarinia talatala) that had been fed a concentrated sucrose diet (2.5 mol/l) for 2 days and then were switched to a diet 10 x less concentrated (0.25 mol/l) on the morning of the third day. we measured water gain as well as cloacal fluid (cf) volume hourly over 12 h, and analysed cf osmolality and c ... | 2004 | 15313486 |
| circadian rhythm of water balance and aldosterone excretion in the whitebellied sunbird nectarinia talatala. | nectarivorous whitebellied sunbirds, nectarinia talatala, demonstrate distinct circadian patterns in osmoregulatory parameters. we recorded intake of a 1 mol/l sucrose solution which enabled calculation of total water gain, and collected cloacal fluid for measurements of volume, osmolality and aldosterone concentration. these variables were assessed hourly over 12 h of photophase, and averaged over the 12-h scotophase period. overnight, when sunbirds were in negative water balance, aldosterone c ... | 2004 | 14997332 |
| osmoregulation in an avian nectarivore, the whitebellied sunbird nectarinia talatala: response to extremes of diet concentration. | water intake of nectarivores is intrinsically linked to nectar concentration. osmoregulation in whitebellied sunbirds nectarinia talatala (body mass 9.3+/-0.1 g, mean +/- s.d., n=7), was examined by feeding them sucrose solutions, equivalent to extreme diet concentrations (0.07-2.5 mol l(-1) sucrose; 2-65% w/w), with and without supplementary drinking water. total water gain was 33-515% of body mass daily. cloacal fluid (cf) volume increased with diet dilution from 0.4% to 309% of body mass whil ... | 2003 | 12728006 |