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Avian 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.

To better understand how Cape porcupines are able to successfully occupy many agricultural lands, we studied their digestive parameters and energy assimilation when fed three economically important agricultural crops (potatoes [Solanum tuberosum], sweet potatoes [Ipomoea batatas] and butternut [Juglans cinerea]). Daily food intake, daily gross energy intake, daily faecal energy loss, daily energy assimilated, daily water intake and apparent assimilation efficiency were calculated for each porcupine and for each diet trial. Cape porcupines maintained body mass on all three experimental diets and energy intake ranged from 3 002.36 kJ kg−1 d−1 (potato) to 4 499.00 kJ kg−1 d−1 (sweet potato). The moisture content in each experimental diet was relatively high (>60%) and preformed water intake of winter acclimated Cape porcupines ranged from 60 ml kg−1 d−1 (potato) to 100 ml kg−1 d−1 (sweet potato). Assimilation efficiencies were high (>85%) on all three diets. Cape porcupines ingested c. 1.5–2.7 kg of each crop daily, translating to potentially large economic impacts on farmers. Knowledge and understanding of Cape porcupine food intake and dietary requirements give insight to their potential impact on commercial crops. This may aid in developing management and conservation strategies needed to manage this human–wildlife conflict. [ABSTRACT FROM AUTHOR]

There is a paucity of studies investigating the digestive efficiencies of avian frugivores fed fibrous (also referred to as woolly) aril pulp. We fed whole Strelitzia nicolai seeds with arils to captive Red-winged Starlings ( Onychognathus morio) to determine daily food and energy intake, digestive transit time and assimilation efficiency. Strelitzia nicolai arils were found to contain a remarkably high lipid content (66.78 %), with a correspondingly low water (7.61 %) and protein (5.79 %) content. Birds generally ate only the aril of S. nicolai seeds, but if they swallowed the seeds whole then they either defecated or regurgitated the seeds without the aril. Red-winged Starlings were found to have fast digestive transit times (approx. 24 min) and very high apparent assimilation efficiencies (approx. 96 %) of the aril of S. nicolai seeds. [ABSTRACT FROM AUTHOR]