. The Canadian field-naturalist. 2000 Notes 701. Figure 1. Contents of food bolus from pre-fledged Common Loon. Left: crayfish; centre: dragonfly nymphs (below) whirlygig beetle elytra (above) and two round structures (on top); right: perch. in Hull. Its measurements were: weight — 1562 g, total length — 605 mm, wingspan — 995 mm, tarsus — 76 mm, bill length (tip to end of feathers) — 55 mm; it was thus smaller and lighter than 2-3 month old young measured by Mclntyre (1975). The bulge in the neck was a food bolus in the esophagus comprised of: 15 Yellow Perch (Perca flavescens) plus 6 other p
. The Canadian field-naturalist. 2000 Notes 701. Figure 1. Contents of food bolus from pre-fledged Common Loon. Left: crayfish; centre: dragonfly nymphs (below) whirlygig beetle elytra (above) and two round structures (on top); right: perch. in Hull. Its measurements were: weight — 1562 g, total length — 605 mm, wingspan — 995 mm, tarsus — 76 mm, bill length (tip to end of feathers) — 55 mm; it was thus smaller and lighter than 2-3 month old young measured by Mclntyre (1975). The bulge in the neck was a food bolus in the esophagus comprised of: 15 Yellow Perch (Perca flavescens) plus 6 other possible ones (the longest, from snout to tail fork was 95 mm, and the only other 3 measurable ones were 73 mm, 56 mm, and 55 mm long); 46 dragonfly larvae (45 Somatochlora cingulata (length range: 19-26 mm), and one Aeschna sp. at too early an instar to identi- fy); 6 Cambarus robustus crayfish; 4 Dineutus sp. whirligig beetles (Family: Gyrinidae), at least one D. nigrior, the other 3 probably the same species, or possibly D. assimilis (the 4 measurable elytra (hardened front wings) were all 8 mm long); 2 white round structures, possibly consumed for digestive purposes. Necropsy Results Necropsy examination by DC showed that, on gross examination, the only significant abnormality was dilation of the esophagus to a diameter of approximately 4 cm. The mucosal surface of the esophagus was covered in plaques of fibrin. The remainder of the digestive tract was normal in appearance, apart from small amounts of abnormally dark intestinal content. No lead was present in the proventriculus or giz- zard, and testing of liver and kidney did not detect any evidence of lead. Samples of heart, lung, liver, kidney, adrenal gland, esophagus, proventriculus and gizzard were fixed in 10% formalin and processed routinely for histology. Histologic examination con- firmed the presence of extensive plaques of fibrin, mixed with cellular debris and bacteria coating an ulcerated mucosal surf
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