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Ageing "brown" Merlins

posted by Jerry Liguori at
on Friday, June 15, 2012 

The discussion of how to tell adult female from juvenile Merlins has come up several times in the past few months. There is variation in juvenile and adult plumage and great variation and overlap in race. Often it is impossible to tell adult female from juvenile Prairie Merlin (and the same for black Merlin). However, typical adult female and juvenile Taiga Merlins can be told apart.

 Check out these typical birds, juvenile on the left, adult female center and right (right bird - photo by Pete Gustas, "click" to enlarge). The juvenile is pale with brown streaks and a brown head. The adult female is buffer underneath with broader, "blobby" streaks, and a slate-colored head. The topside is also slate-gray compared to the browner juvenile. Notice the retained juvenile inner secondaries and upperwing coverts on the topside, that are browner in color.

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Blogger Tim Avery said...

I have enough trouble putting an exact type on some Merlins--let alone ageing them! Thanks as always for your great information Jerry!

June 19, 2012 at 8:05 AM  
Anonymous Derek Lyon said...

I'm with Tim, but out my way I rarely know that I'm seeing another type. Can ageing be done in the field visually, or do you need to inspect photos? With 7x or 8x binoculars and the speed of Merlin, I rarely get the chance to see enough details in the field to sex Merlin let alone age them. Great info though, I'll be putting it to use this fall hawkwatch season.

June 19, 2012 at 2:07 PM  
Anonymous Jerry Liguori said...

Hi guys

Thanks for the comments...you need good looks in the field to tell young ones from females. The best way is if you see the slaty upper side and head vs. the browner jugs. Otherwise it can be very difficult. But, if you know the underside and upper side differences, you cam start to look for them. Also, if it is molting flight feathers in fall, it is not a juvenile!


June 19, 2012 at 8:54 PM  

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