Sturnus unicolor vs. Sturnus vulgaris (1 Viewer)

Hello again! These pictures were taken last winter in Guadalajara (Central Spain). I believe they are all Sturnus unicolor, but the bird in picture 1 includes spots just like Sturnus vulgaris does. Why does this happen? How can I distinguish these two types of bird?

I'd say 1 is vulgaris due to spotting on the head which unicolur shouldn't have.

I'd say numero uno is also a Spotless Starling in that it's wings, and particularly undertailcoverts, are far too dark for Common Starling.

I found a pretty good match in this handheld unicolor:

https://www.google.dk/search?q=spot...ECAsQAQ&biw=1024&bih=672#imgrc=Okv5Bul10nj5QM

Peter

Both are spotless starlings, Sturnus unicolor.
Bird 1 (annexed picture on the left) has undergone post-breeding/post-juvenile moult, and the new feathers show the characteristic white tips - winter plumage. Those white tips will be lost by abbrasion/wear, and by spring the bird shall look spotless (such as bird 2 - annexed picture on the right).

HLousa said:

Both are spotless starlings, Sturnus unicolor.
Bird 1 (annexed picture on the left) has undergone post-breeding/post-juvenile moult, and the new feathers show the characteristic white tips - winter plumage. Those white tips will be lost by abbrasion/wear, and by spring the bird shall look spotless (such as bird 2 - annexed picture on the right).

Click to expand...

You explain moult but not how to differentiate, 'Collins' states that 'usually', Spotless doesn't have spotting on the head as the first bird does.

P.Sunesen said:

I'd say numero uno is also a Spotless Starling in that it's wings, and particularly undertailcoverts, are far too dark for Common Starling.

I found a pretty good match in this handheld unicolor:

https://www.google.dk/search?q=spot...ECAsQAQ&biw=1024&bih=672#imgrc=Okv5Bul10nj5QM

Peter

Click to expand...

That's just a link to a gallery Peter.

http://http://blascozumeta.com/wp-content/uploads/aves-aragon/passeriformes/417.sturnusunicolor.pdf

All the birds in the link above (except those in p. 2, similar species) are hand-held spotless starlings, and there are some with spots in the head (1st winter birds, as mentioned above, mainly females) I'm aware the link is in Spanish, anyway it has been mentioned some times as a valuable ID source at this same forum.

HLousa said:

Both are spotless starlings, Sturnus unicolor.
Bird 1 (annexed picture on the left) has undergone post-breeding/post-juvenile moult, and the new feathers show the characteristic white tips - winter plumage. Those white tips will be lost by abbrasion/wear, and by spring the bird shall look spotless (such as bird 2 - annexed picture on the right).

Click to expand...

andyadcock said:

You explain moult but not how to differentiate, 'Collins' states that 'usually', Spotless doesn't have spotting on the head as the first bird does.

I'm going to disagree and stick with vulgaris for one.

Click to expand...

True, that my explanation was not too detailed.
So I'm going to rely on my personal experience and some bibliography to support my ID, mostly for bird 1, since bird 2 ID doesn't pose much doubt.
S. unicolor, have a duller iridescence when compared with S. vulgaris (Blasco-Zumeta & Heinze 2018, Svensson et al. 2009, Shirihai & Svensson 2018). Bird 1 is rather duller.
S. unicolor, in winter plumage, have smaller/duller white tips of feathers when compared with S. vulgaris (Blasco-Zumeta & Heinze 2018). Bird 1 has smaller spots relatively to the size I would expect to see on S. vulgaris.
S. unicolor, lacks (or have very thin) paler fringes of wing flight feathers/ and some coverts; by contrast, S. vulgaris show broader buff fringes in these feathers (Blasco-Zumeta & Heinze 2018, Svensson et al. 2009). Bird 1 fits S. unicolor description for this feature.

Shirihai & Svensson (2018) refer bill shape/size, leg colour and hackle size also as features used to differentiate between these too species. These are hard to assess in picture 1. Blasco-Zumeta & Heinze (2018) also mention wing formula which I think we can agree it's useless in this picture 1.

Two links which I think are helpful:
http://blascozumeta.com/wp-content/uploads/aragon-birds/passeriformes/416.starling-svulgaris.pdf
http://blascozumeta.com/wp-content/...seriformes/417.spotlessstarling-sunicolor.pdf


Also I'd like to ask if SLopezM could state the date of the pictures.

Ref:
Blasco-Zumeta, J.F., Heinze, G.-M., 2018. Identification Atlas of Aragon’s Birds. URL http://blascozumeta.com/atlas-de-aves/ (accessed 12.7.18).
Shirihai, H., Svensson, L., 2018. Handbook of Western Palearctic Birds: Passerines.
Svensson, L., Mullarney, K., Zetterström, D., 2009. Collins bird guide, Second edition.

Thank you everyone for your help! The pictures were taken during the first week of February 2018.