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Post by paulos on Aug 24, 2016 8:20:29 GMT -8
Hi, I've recently been puzzling over the possibility of being able to distinguish female Sooty Grouse from Dusky Grouse by sight. The only specific information I've been able to find (for females) is that Sooty tends to be darker overall. In the Manning area and some other eastern and northern borders of our checklist area I have seen sightings for both. I came across four individual grouse on Sunday in Manning, and I'd like to ask for input on the pictures. I'm leaning Sooty here, though the lighting was a little funny for the photos because I take pictures through a binocular lense.  Sooty Grouse? by Paul Foth, on Flickr  Sooty Grouse? by Paul Foth, on Flickr  Sooty Grouse?4 by Paul Foth, on Flickr  Sooty Grouse? by Paul Foth, on Flickr |
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Post by murraybrown on Aug 24, 2016 10:39:49 GMT -8
Paul, I went through the same dilemma a few years back after the AOU/ABA made the decision to split the Blue Grouse into the two you mention.
Brian Stech, Thor Manson and I hiked for kilometers into the high country toward Three Brothers Mountain in Manning hoping to find a pure Dusky for me (they both already had one for B.C.) We finally found a very tame bird that I was sure met all the criteria for the one I wanted. The other guys weren't so sure!
Since then I have seen many of both and now believe that Manning is probably the worst spot to look for a pure bird of either species. Being a transition zone, you can find birds there that even in the same family group, will have characteristics of both species. I'm convinced that those birds are hybrids or intergrades and if you really want to be sure, head up to Princeton or somewhere east of the coast mountain range.
Having said all that, I still hear of birders finding what they claim is a pure Dusky and who knows, maybe they're right.
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Post by Randy on Aug 24, 2016 11:57:48 GMT -8
Tough dilemma! I for one am generally in favour of lumping rather than splitting for this exact reason!
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Post by paulos on Aug 24, 2016 15:34:05 GMT -8
Paul, I went through the same dilemma a few years back after the AOU/ABA made the decision to split the Blue Grouse into the two you mention. Brian Stech, Thor Manson and I hiked for kilometers into the high country toward Three Brothers Mountain in Manning hoping to find a pure Dusky for me (they both already had one for B.C.) We finally found a very tame bird that I was sure met all the criteria for the one I wanted. The other guys weren't so sure! Since then I have seen many of both and now believe that Manning is probably the worst spot to look for a pure bird of either species. Being a transition zone, you can find birds there that even in the same family group, will have characteristics of both species. I'm convinced that those birds are hybrids or intergrades and if you really want to be sure, head up to Princeton or somewhere east of the coast mountain range. Having said all that, I still hear of birders finding what they claim is a pure Dusky and who knows, maybe they're right. Yeah, my only sure encounter with a Dusky is hearing a male hoot in Osoyoos, which is well in range. I suppose I should leave Manning grouse as either way. You mentioned criteria you were looking for in a Dusky. Is there any criteria anyone could share? I don't know what to look for and I have not found field guides I have to be helpful. Range will of course be my first differentiator. |
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Post by Gord on Aug 24, 2016 16:18:50 GMT -8
Paul, I've not much to add that Randy and Murray has not already said.
Another element to add confusion at this time of year are the year's young birds that are getting adult colours. A good example is the last bird photographed that is a young male to my eye so pretty tough to say which one he is, or if possibly a hybrid which apparently is not uncommon.
I'm sort of the opinion that unless I can see something very obvious, like a male (that is singing/hooting as a bonus)I go for the Dusky/Sooty Grouse designation. I have since added that option to the eBird checklist for the eBird users among us.
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Post by murraybrown on Aug 25, 2016 12:21:08 GMT -8
Paul, as far as I know a female or immature could not reliably be identified as to species. The males though have at least four characteristics that apparently separate them.
1. The location of the band on the tail.
2. The colour of the inflatable air sac on the neck.
3. The number of calls that are made, ie: four hoots versus five.
4. The amount of pale feathering in the plumage as you made reference to.
I still think that range is the most reliable field mark though.
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