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TOPIC: Comparative Images to help identify key species differences

Comparative Images to help identify key species differences 7 months 2 weeks ago #1425

  • Mark Lethlean
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Hi All, I'm not sure how easy it would be to achieve but I was wondering if some of the better photographers who are also good birders might be interested in submitting images that focus on the key differences between some of those difficult species. Classical examples would be between Brown Goshawk and Collared Sparrowhawk; Leaden, Satin, and Broad-billed Flycatcher or the really difficult trifecta of Lewin's, Yellow-spotted and Graceful Honeyeaters. The problem with just putting them on the forum without moderation is that we may spread misinformation and the discussion may just add to the confusion.
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Comparative Images to help identify key species differences 7 months 2 weeks ago #1426

  • Catherine Noone
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That would be very useful to those of us struggling with identification. Perhaps it could be presented one "problem" at a time. My vote is to start with Brown Goshawk and Collared Sparrowhawk! I have lots of images of "Brown Goshawk or Collared Sparrowhawk". I understand identification may be difficult or impossible from a single image of a particular bird. I wonder how reliable "tail shape" is for identification. I have images of perched birds but I can't decide whether the tail tip look "rounded" or "square-tipped" as illustrated in my guide book. I am not even sure if tail shape is only relevant when looking at a bird in flight. Attached are two shots. First is of a perched bird taken at the You Yangs, Victoria. The second is a bird that has just taken flight, taken at Woodlands Historic Park, Victoria.
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Comparative Images to help identify key species differences 7 months 2 weeks ago #1427

  • Mark Lethlean
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Hi Catherine, so there is a forum topic that allows you to submits images for possible ID. It would be better however if we had a couple of good comparative images for the Collared Sparrowhawk and the Brown Goshawk that highlighted those key features you've mentioned- the position of the 1st knuckle, the brow and the square vs rounded tail.I know all these detail are in the books but sometimes actual images may make the comparisons easier.
So here is an attempt to compare and distinguish the features that are obvious and not so obvious in the 3 spp of Honeyeaters I photographed at Kingfisher Park this year.They can be an ID nightmare and I am sure there maybe plenty of people that may challenge my assessment. Kingfisher Park supply a great comprehensive sheet of notes to help us newbies to the area. So when comparing these 3 images.....
Lewins Honeyeater;- has a definite crescent ear spot, the area b/n the ear spot and eye is a grey wash and different from the colour of the crown and the gape forms a straight line with the pale yellow feathers beneath the eye. Iris blue/grey
Yellow-spotted Honeyeater;- has rounded ear spot, the area between the ear spot and eye is olive like crown, and the yellow gape and and feathers beneath eye are the same yellow colour and form a single line with a slight bulge. Iris brown
Graceful Honeyeater;- has rounded ear spot, the area between the ear spot and eye is olive like crown, and the yellow gape is obvious while the yellow feathers beneath the eye are poorly defined and do not form a definite line. Iris blue/gey. The bill is generally longer and finer with obvious down curvature cf the other 2 spp.
Of course in addition a good birder will know the differences in calls and behaviours. Gracefuls are extremely active when cf the other 2 spp.
So hopefully something like this might help people heading to the wet tropics ( or just make it even more confusing) Maybe someone more capable than me could tackle those dam raptors
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Comparative Images to help identify key species differences 7 months 2 weeks ago #1428

  • Glenn Pure
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Good analysis of the three honeyeaters Mark. I struggled with Yellow-spotted versus Graceful when in Cape York and Cairns area last year. I find iris colour is a good separator for Lewin's. Graceful Honeyeaters are a little smaller than the other two as well. Great to record sound in the field to so calls can be compared when you get home (I wish I'd done this) as call is a good separator particularly Yellow-spotted versus Graceful.

As for Collared Sparrowhawk v Brown Goshawk, the former is smaller as well with minimal overlap in size with the larger Brown Goshawk. Size isn't easy to determine in the field but there is a method for difficult cases like this where there is a photo opportunity and especially a profile shot: Take careful note of the focus distance on your lens after photographing the bird - hopefully there is a scale on your lens to show this. Then either make a careful note or better, switch the lens to manual focus then set up an object of know size at exactly the same focus distance. In the field, do this by walking back and forth until the object of know size is in sharp focus without touching the focus ring (this is why you switch to manual focus so that doesn't change). Take a photo of the object. When you get home, measure the known object (eg, a tripod or piece of camera gear) and compare this to the size of the bird in the frame. You should be able to make an accurate estimate of the bird's length.

More generally, BLP is planning to set up a bird ID gallery but it is dependent on our very limited time resources so there is no firm schedule for this task. I'm sure this gallery will be a great help with ID questions like this.
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Comparative Images to help identify key species differences 7 months 2 weeks ago #1429

  • Bruce Terrill
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Great idea Guys, and I'm glad to hear that it is under consideration for future inclusion.
I'm a little sorry that I'm of no use to the Forum when it comes to computer work, it came along after me and I never bothered to catch up.
There's an idea for my epitaph, "He never bothered to catch up." hahaha hehehe. It's mine, leave it alone!!
Bruce

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