This forum is for asking questions and providing answers on bird identification. New and visiting birders are encouraged to ask and participate.
By rainbird
#87256
Here's a photo of two Scaup. I've been told that Lesser Scaup have a purple iridescence in the head, and Greater Scaup a green iridescence, but that that fieldmark is unreliable. So here we have birds with green and purple iridescence, yet they apear to me to be the same structurally. Are they different species or not?
They were part of a large mixed flock of scaup as well as wigeon, shovelers, bufflehead, pintail, gadwall, etc on the sewage lagoon across the river from Port Alberni on Vancouver Island.
https://flic.kr/p/EQCbNr
Sandy McRuer
Port Alberni, BC
By revs
#87258
For me, i always look at the shape of head when ID'ing.
In my experience Greater has a rounder head and Lesser has a more peaked head.

Image
Lesser

Image
I have this labeled as Lesser on Flickr but i do believe now that it is Greater.
By Rokman
#87271
On AVERAGE, head colour may be suggestive, but it is completely unreliable much of the time for this species pair. The colours are structural, not due to pigments, so they depend on angle and quality of light. On one sunny day at Iona, I was sorting through several hundred Lesser Scaup, trying to pick out a Greater. Every single one showed a purple head. I moved around to get about 90 degrees different angle, and every one then showed a green head. As Revs points out, the head shape is considerably more useful. Better still, if you can see the dark nail at the tip of the bill, that is diagnostic (narrow for Lesser, broader and spoon-shaped for Greater). Habitat (fresh for Lesser, salty for Greater) is very suggestive, not diagnostic - but IMHO more reliable than head colour.
Rokman has spoken.
By Robert
#87278
According to Audubon:
Greater Scaup very much like Lesser Scaup, but different head shape (more rounded, with highest point toward front of head), larger bill.
By Rokman
#87283
Re relative whiteness of sides: yes Greater tends to be paler, on average, but paleness difficult to judge on an individual bird, and also varies with age of bird. Revs photos do show paler Greater, but the quality of lighting in the two photos so different that not really comparable. Relative paleness is a trend, but not very useful when viewing a single bird.
Re size of bill: yes Greater is said to be larger, but can you see that in revs photos? Unless you have the bird in one hand and a calliper in the other hand, this is not a very usable field mark.
Again, the most reliable marks are shape of the head and the size/shape of the nail. In flight, the Greater has a longer pale wing-stripe - that is diagnostic.
One last hint: if you look at the vertical line that separates dark/light at the front side of the bird, on Greater that line tends to be convex towards the dark front, and on Lesser it tends to be convex towards the pale sides. This is an average tendency, often useful but not diagnostic. It works on revs top bird, is more neutral on the other one.
By mcrosbie
#87297
Another thought that occurred to me in the photo shown on Flickr, the two Scaups are together as a couple, suggesting that in all likelihood they are of the same species (is species the correct word?)

It is more likely that two birds alone together on the water like this are the same type.

Just a thought. I might be wrong.
By revs
#87302
mcrosbie wrote:Another thought that occurred to me in the photo shown on Flickr, the two Scaups are together as a couple, suggesting that in all likelihood they are of the same species (is species the correct word?)

It is more likely that two birds alone together on the water like this are the same type.

Just a thought. I might be wrong.
both heads are peaked so its a good bet that they are both Lesser.
By Rokman
#87303
Both are most definitely Lessers. The narrow black nail on the tip of the bill and the head peaked at rear are clearly evident. As mentioned before, you CANNOT depend on head colour - and this pair very nicely illustrates why.
By revs
#87304
Rokman wrote:Both are most definitely Lessers. The narrow black nail on the tip of the bill and the head peaked at rear are clearly evident. As mentioned before, you CANNOT depend on head colour - and this pair very nicely illustrates why.
Thanks for chiming in Roko, its good to have a veteran birder here willing to do that.
By rainbird
#87318
Rokman wrote:Both are most definitely Lessers. The narrow black nail on the tip of the bill and the head peaked at rear are clearly evident. As mentioned before, you CANNOT depend on head colour - and this pair very nicely illustrates why.
Which is precisely why I posted this.

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