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. 2016 Sep 27;113(39):10920-5.
doi: 10.1073/pnas.1603998113. Epub 2016 Sep 16.

Omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity

Cornelia W Twining  1 , J Thomas Brenna  2 , Peter Lawrence  2 , J Ryan Shipley  3 , Troy N Tollefson  4 , David W Winkler  3
Affiliations

Omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity

Cornelia W Twining et al. Proc Natl Acad Sci U S A. .

Erratum in

Abstract

Once-abundant aerial insectivores, such as the Tree Swallow (Tachycineta bicolor), have declined steadily in the past several decades, making it imperative to understand all aspects of their ecology. Aerial insectivores forage on a mixture of aquatic and terrestrial insects that differ in fatty acid composition, specifically long-chain omega-3 polyunsaturated fatty acid (LCPUFA) content. Aquatic insects contain high levels of both LCPUFA and their precursor omega-3 PUFA, alpha-linolenic acid (ALA), whereas terrestrial insects contain much lower levels of both. We manipulated both the quantity and quality of food for Tree Swallow chicks in a full factorial design. Diets were either high-LCPUFA or low in LCPUFA but high in ALA, allowing us to separate the effects of direct LCPUFA in diet from the ability of Tree Swallows to convert their precursor, ALA, into LCPUFA. We found that fatty acid composition was more important for Tree Swallow chick performance than food quantity. On high-LCPUFA diets, chicks grew faster, were in better condition, and had greater immunocompetence and lower basal metabolic rates compared with chicks on both low LCPUFA diets. Increasing the quantity of high-LCPUFA diets resulted in improvements to all metrics of performance while increasing the quantity of low-LCPUFA diets only resulted in greater immunocompetence and lower metabolic rates. Chicks preferentially retained LCPUFA in brain and muscle when both food quantity and LCPUFA were limited. Our work suggests that fatty acid composition is an important dimension of aerial insectivore nutritional ecology and reinforces the importance of high-quality aquatic habitat for these declining birds.

Keywords: aerial insectivores; nutritional ecology; omega-3 long-chain polyunsaturated fatty acids.

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Conflict of interest statement

T.N.T. is employed at Purina Mills, LLC, which manufactures the product tested. The authors declare no other conflicts of interest.

Figures

Fig. 1.
Fig. 1.
Reaction norms for (A) mass, (B) size-specific mass growth rate, (C) size-specific skeletal growth rate, (D) body condition, (E) immunocompetence, and (F) BMR. Treatment means and SE bars are shown. Black represents high-LCPUFA treatments, and gray represents low-LCPUFA treatments.
Fig. 2.
Fig. 2.
Chick mass over time. Treatment means and SE bars are shown. Black circles represent our Hh treatment, gray circles represent our Hl treatment, black triangles represent our Lh treatment, and gray triangles represent our Ll treatment.
Fig. 3.
Fig. 3.
Fatty acid composition results for (A) brain EPA, (B) brain DHA, (C) muscle EPA, and (D) muscle DHA. Treatment means and SE bars are shown. Black circles represent our Hh treatment, gray circles represent our Hl treatment, black triangles represent our Lh treatment, and gray triangles represent our Ll treatment.
See this image and copyright information in PMC

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