Only in English News Support us Volunteer Species list Deviation Log Ringing numbers Yearly totals Abroad About us Volunteers 2019-2025 Volunteers 2015-2018 Recording area Norwegian list Accommodation Guiding Publications 2011-2025 1957-2010 Transport Contact Bird Obs Norway Videos Log in Search the site	What’s the best criteria to sex Great Grey Owls? Last spring a study was published in the peer-reviewed journal Ornis Norvegica. The article presents the results from a study of 83 dead Great Grey Owls from western and northern Finland found during the period 1962-2004. Although the traditional measurements to determine gender in many owls, including the Great Grey Owls, are wing length, tarsus, bill and body mass, this study shows that the most reliable way to sex them (95% of correct sex determination in this study) is the combination of forearm (radius and ulna) from elbow to wrist, second claw and wing length. Based on the 83 individuals measured on this study, females were on average 147 mm forearm, 26,4 mm second claw and 457 mm wing length. On the other hand, males were on average 138 mm forearm, 23,6 mm second claw and 437 mm wing length. Forearm measurements had far less overlap than wing length measurements. Forearm length has been used to determine sex in raptors before, such as Eagle Owl and Booted Eagle. One of the reasons why the forearm is significantly longer in females could be that females require heavier preys and therefore stronger bone structure in the wings rather than longer feathers (Mikkola & Tornberg 2014, 2015). You to read the whole article here: Morphometric sex determination of Great Grey Owls Strix nebulosa.	Ringing numbers Sorry, but we are outside of the spring and autum seasons. Detailed log Reportasje fra Lista FS i Aftenposten Seasonal deviation Two-barred Crossbill 1 -99% Eurasian Jay 7 -99% Tengmalm´s Owl 1 -98% Lapland Longspur 2 -97% Great Skua 9 -95% Common Stonechat 419 +1447% Long-tailed Tit 2893 +1186% Willow Tit 2857 +965% Common Redpoll 1124 +825% Common Quail 80 +691% View deviation of seasons Facebook Følg Følg Lista FS på facebook.com Siste 5 på siden   Looking for bird ringers for spring and/or autumn 2026   Report from spring 2025   Festivalgjester presenterer ny fuglebok   Lista Fuglefestival 2025   Report from autumn 2024
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