Wednesday, March 20, 2013

Mount Lorette Raptor Count Spring 2013

Introduction 2013 is the 22th consecutive year that a spring raptor count has been conducted at the Mount Lorette site. In 1992 an 8-day reconnaissance count established that Golden Eagles moved to the north in significant numbers through the Rocky Mountain Front Ranges. Most of the birds moved along the Fisher Range, crossing the Kananaskis Valley to Mount Lorette before continuing their migration to the northwest. A 48 day (393 hour) count at the site in the spring of 1993 yielded 4140 migrating Golden Eagles and the following year a 70 day (649 hour) count produced 4213 birds which remains the highest spring count ever for the species at Mount Lorette. Between 1994 and 2007 extensive spring counts averaging 82 days (897 hours) were conducted at the site with a maximum count in 2005 of 94 days (1238 hours). Despite the steady increase in observer effort during this period, the number of migrating Golden Eagles counted has steadily and significantly decreased since 1995. In 2006 RMERF conducted it first complete fall count at the Piitaistakis-South Livingstone site near the Crowsnest Pass in SW Alberta and in 2008-10 also conducted full spring counts there. During this period extensive comparative counts were made at Mount Lorette between March 1 and April 15 which is coincident with the height of the Golden Eagle migration and during which period over 90% of the population moves north. Observer effort from 2008-10 at Mount Lorette averaged 43 days (487 hours) with a maximum count of 46 days (519 hours) in 2010 when no days were lost to inclement weather. In 2011 the count period was extended by 1 week (March 1 to April 22) and we plan to observe during the same period this spring.

March 1 [Day 1] (Cliff Hansen, assisted by Joel Duncan) It was a pleasant day for the start of the season with the temperature rising to 7C from a low of 2C as the result of a strong Chinook wind that produced nimbistratus cloud in early afternoon which periodically obscured the ridges and brought light rain. These conditions were obviously not condusive to migration and the only migrant seen was a late subadult Bald Eagle. 10 hours (10) BAEA 1 (1) TOTAL 1 (1)

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