You mean this one?

Sorry for being inspecific! I mean the one flying just above the adult Black-headed Gull (also flying).
/Daniel

Quote:

引用第226楼qing627于2010-03-22 21:52发表的  :
Sorry for being inspecific! I mean the one flying just above the adult Black-headed Gull (also flying).
/Daniel

and below a 1-win Common Gull.

I feel a bit shamed of myself ~

one of these two?

Yes Vivian, the upper one looks like a Slaty-backed Gull (2nd winter) to me, although I have never seen one. The lower is the Common Gull mcaribou is referring to. From this angle the wings look really broad, which I reckon is the reason I first took it for a larger gull...
Vivian, please don't feel bad - it's just birds, nothing really important!   
And your contribution with all your pictures is very much appreciated, I have learned a lot from lookig at them! Thanks!
/Daniel

Daniel,
Thanks for your kind words.
I wish I could remember the names~

I found this bird with other Dusky Thrushs several days ago in the park.
Is it  a female Dark-throated Thrush?

Bird names are indeed difficult to remember sometimes, especially in many different languages!...
This thrush is a Naumann's Thrush. The strong black marking(s) on the side of throat points out it's a 2nd year bird. A Dark-throated Thrush would be much cleaner (almost white) on the belly, in sharp contrast to throat/upper breast. Undertail coverts in Dark-throated Thrush is white, but always marked in Naumann's. Back of Dark-throated is much greyer than Dusky/Naumann's, but of course that can be difficult to see from this angle (or from beneath if sitting up in a tree).
/Daniel

Vivian, nice shot of the Naumann's. I have a question for Daniel and the other experts. In older books, the Naumann's thrush and the dusky thrush are treated as a single species, also called the dusky thrush. Let's assume that the "super dusky" has indeed split (or is in the process of splitting) into two species. Why is the super dusky speciating? What's the evolutionary reason? Studying dusky and Naumann's thrushes, I can't see much of a difference in their behavior. One reason for the split may be that long ago the populations of the old "super dusky" species were isolated, perhaps during an ice age. While isolated, reddish and brownish birds became predominant in the isolated groups. Eventually, the ranges of the reddish and brownish races or species overlapped again. Is there another theory?

Craig, The scenario you're describing is a classic explanation of how a species splits into two. The reason why different birds (in this case reddish and brownish) begin to dominate in a population is most often unknown, and it can perhaps be just a coincidence, but most probably it's favourable and gives a higher fitness under the specific circumstances under which the population thrives. Apparently Naumann's and Dusky Thrush breed in different habitat (and regions), but as hybrids are often seen there must still be overlap.
Birds can also speciate without isolation. Let's say that, for some reason it's more favourable to be reddish in the southern part of a species range. Then, as the reddish birds have higher fitness and get more young, there will eventually be more and more reddish birds. If the mix with brownish birds is limited two different populations can appear in the end. However, this kind od speciation usually only result in subspecies, so in general the isolation factor is very important for new species to evolve.
I find Naumann's Thrush much more often in more open habitats (away from trees) than Dusky, and much more often single birds (Dusky in flocks). If this is a real difference in behaviour I don't know. The latter circumstance could, for example, be due to the fact that less Naumann's winter in the Shanghai region, but considering I've hardly ever seen a single Dusky Thrush it might be a true behavioral difference...
/Daniel

Thanks Daniel and Craig.
I feel that in the Century Park the number of Naumann's thrushs are less than  the dusky
thrushs.

Daniel, great explanation. I've seen lone dusky thrushes at Gongqing Park.

If ying216 gets more familiar with gulls,I'll be benefited:)
At the same time I was at the other side of the harbor and I didn't see any Slaty-backed or Common Gull.
Slaty-backed is a rare winter visitor--last winter in Rudong I saw one,and one or two in Lianyungang.
In this pic,it shows thick bill,pot belly,wide tail band,contrasting underwing coverts/flight feathers.Is there any pic showing its mantle?
while in the Common,its tiny bill rules out large gulls.
Gull watching is really challenging so pls dont feel ashamed or exhausted.Keep watching!

I believe you Craig, but are you sure there were no other Dusky Thrushes in the close neighbourhood?!...
What I meant was that Dusky Thrsuhes don't seem to like to stand out ALL alone, if there are others around, while Naumann's don't seem to worry that much. Sometimes, of course, they don't have a choice, for example the Dusky ones turning up as vagrants in Europe (several records in Finland, but none in Sweden).
/Daniel

Daniel, you may remember my dusky thrushes; the photos are earlier in this thread. For three days straight there was a single individual all alone in the big field near the rocket. The Naumann's whose photos I posted a few days ago were a trio. My two observations aren't enough to draw any conclusions, of course.

So perhaps it mostly has to do with the availability of company...
But it would be interesting to know if Naumann's more often appear in open landscapes, which I get the impression of.
/Daniel

It would seem to me that if long isolation produced red and brown coloring in the Naumann's and dusky, then long isolation could also produce a slightly different "coloring" of behavior. Know what I mean?

MC:
This one seems to be the same of line 228

This one might be the same one.

It's back~

I see what you mean Craig.
I think the first of these last three pics looks fine for a 2nd winter Slaty-backed. Check the "string of pearls" in the moulted inner primaries, colour of back, tail band and bill.
The other one looks more like a 1st winter mongolicus.
/Daniel

242 is a good photo of Slaty-backed!
Today I saw another in Rudong Saltworks