Abstract
Direct and dendrographic comparison of the profiles of abundant fatty acids in depot fat was unable to separate 10 avian species on a basis of their overall proportions but was able to distinguish broad dietary groups or those in a habitat with distinctive nutritional characteristics such as avian marine carnivores. In all species considered, including North Island brown kiwi (Apteryx mantelli), oleic (C18:1) and palmitic acids (C16:0) were most abundant. The relative proportions of linolenic (C18:3) acid were 4% or lower across all species, while the relative proportions of palmitoleic acid (C18:0) were less than 7% in nine of the avian species, with the exception being the insectivorous red-eyed vireo (Vireo olivaceous). The levels of linoleic acid (C18:2) were lower in avian marine carnivores than in avian herbivores, insectivores, and omnivores. Whilst the mean values of the individual fatty acids in fat from various avian species were separated by hierarchical cluster analysis, the wide range of values of each fatty acid precluded any correlation of clustering with any known variation in dietary items. Similarly, the wide range in fatty acid composition of kiwi fat rendered it unhelpful in determining the optimum composition of the captive diet.
Highlights
Fatty acids, the main constituent of most dietary lipids, are released from ingested fat molecules such as triacylglycerols during digestion but are not degraded before storage [1]
Evidence for this comes from demonstration that the fatty acid composition of the depot fat of pigs [7] and rats [8] is influenced by changes in dietary constituents
We investigate whether species can be separated on a basis of the relative proportions of the more common fatty acids or on a basis of their diet
Summary
The main constituent of most dietary lipids, are released from ingested fat molecules such as triacylglycerols during digestion but are not degraded before storage [1]. This relative resistance to degradation has led to the use of fatty acid analyses of fat depots to infer dietary intake Such inference would be of value in determining the natural diets of threatened or cryptic species such as wild North Island brown kiwi (Apteryx mantelli). The majority of studies, based largely on mammalian species, conclude that the method may provide a useful indicator of diet [1,2,3,4,5,6] Evidence for this comes from demonstration that the fatty acid composition of the depot fat of pigs [7] and rats [8] is influenced by changes in dietary constituents. The relative proportions of fatty acids in the depot fat of Adelie penguins (Pygoscelis adeliae) were reported to correspond to that of their normal diet [11]
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