December 2023 – vol. 116, issue 12, pp 727–728 In Corso et al. (2014), the pattern and coloration of the underside of the outer primaries was described as one of the most important features in differentiating Slender-billed Curlews Numenius tenuirostris from Eurasian Curlews Numenius arquata. However, the authors noted that this feature was not always clear-cut, with some Eurasian Curlews showing a pattern on the outer prim... This article is only available to registered users.To read more, please log in or purchase a subscription.