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Index of Subjects Hi Everyone, Ian McLaren wrote: "So the question remains, why don't cormorants scope? They can set the dive reflex readily enough, as Nancy indicates. Am I missing something?" I originally thought the answer to this question might be as simple as cormorants see underwater much better than other birds so don't need to scope from above the waterline. I'd read somewhere that their green eye colour allowed them to see better in low light conditions. However, I came across the following 2007 paper by Craig R. White, Norman Day, Patrick J. Butler, Graham R. Martin titled "Vision and Foraging in Cormorants: More like Herons than Hawks?" In the paper they describe how they measured the vision of Great Cormorants and found it unexpectedly poor, about the equivalent of human vision underwater, and inferior to avian aerial predators. Their conclusion however may hold, at least in part, the answer to the above question: "Their efficient hunting involves the use of specialised foraging techniques which employ brief short-distance pursuit and/or rapid neck extension to capture prey that is visually detected or flushed only at short range." The authors also note that cormorants show "... the highest known foraging yield for a marine predator...". In the Birds of North America account, Jeremy J. Hatch and D. V. Weseloh note that there are a number of special adaptations of the eye of the cormorant which suggest that they have effective underwater vision but the authors conclude that: "Double-crested Cormorants commonly catch bottom-dwelling fish in turbid water where visibility is very low, so tactile sensitivity may be important for both locating and capturing prey" The simple answer appears to be that cormorants don't need to scope having evolved a hunting technique without its use which is extremely effective. All the best, Lance Lance Laviolette Glen Robertson, Ontario
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