Many studies of nutrient allocation to egg production in birds use stable isotope ratios of egg yolk to identify the origin of nutrients. Dry egg yolk contains >50% lipids, which are known to be depleted in ¹³C. Currently, researchers remove lipids from egg yolk using a chemical lipid-extraction procedure before analyzing the isotopic composition of protein in egg yolk. We examined the effects of chemical lipid extraction on δ¹³C, δ¹⁵N, and δ³⁴S of avian egg yolk and explored the utility of an arithmetic lipid correction model to adjust whole yolk δ¹³C for lipid content. We analyzed the dried yolk of 15 captive Spectacled Eider (Somateria fischeri) and 20 wild King Eider (S. spectabilis) eggs, both as whole yolk and after lipid extraction with a 2:1 chloroform:methanol solution. We found that chemical lipid extraction leads to an increase of (mean ± SD) 3.3 ± 1.1‰ in δ¹³C, 1.1 ± 0.5‰ in δ¹⁵N, and 2.3 ± 1.1‰ in δ³⁴S. Arithmetic lipid correction provided accurate values for lipid-extracted δ¹³C in captive Spectacled Eiders fed on a homogeneous high-quality diet. However, arithmetic lipid correction was unreliable for wild King Eiders, likely because of their differential incorporation of macronutrients from isotopically distinct environments during migration. For that reason, we caution against applying arithmetic lipid correction to the whole yolk δ¹³C of migratory birds, because these methods assume that all egg macronutrients are derived from the same dietary sources.