Long-tailed Tit ageing on bare parts (1 Viewer)

[01101001]

I've just read that the eyering changes colour depending on age: according to an article by published on the Polish Society for the Protection of Birds website, it's pink for juveniles, red for immatures and yellow for adults (I might've misconstrued the ages for pink and red).*

The feature is not mentioned in Blasco Zumeta's paper, but it seems to be observed in the photographed birds (red for juvenile, yellow for adult, no immatures).

Bonus question No. 1: Speaking of Blasco Zumeta's guide, if a feature is visible in the photos but not spoken of in the text, is it still valid (i.e. can I assume the photos there are representative of a whole age group of a given bird at a given time of year)?

Bonus question No. 2: Has anyone written a paper about the identification of the various (and varied in appearance) subspecies of alpinus group LTTs from europaeus group LTTs just like there are many papers considering the differences and intergrades between the latter and caudatus?

EDIT: Bonus question No. 3: Where can I find caudatus LTT in ornitho-Regioportal?

*Raniuszek (2011) - OTOP Eyering colour better visible against all-white caudatus heads (but--surely--there must be a better explanation, so maybe a mistake or--which is also possible--I'm not reading it the right way)?

 

[Butty]

eyering changes colour depending on age

If memory serves, ringers were using this at least 50 years ago.

can I assume the photos there are representative of a whole age group of a given bird at a given time of year

I can't think of any reason at all to assume that.

. . . subspecies of . . .

Tried the Geographical Variation section in BWP?

 

[01101001]

How many age classes did they recognise based on eyering colour?

I assume BWP means Birds of the World (?) The Birds of the Western Palearctic

 

[Butty]

No idea - but it's presumably covered in Svensson's ringer's guide.
Cramp - Birds of the Western Palearctic. As someone who is heavily into detail, you should have this. And the Svensson guide if you haven't.

 

[01101001]

Bookmark added--thanks. I also saw the new edition by Helm Guides: Handbook of Western Palearctic Birds: Passerines (?)

 

[Butty]

Totally different thing.

 

[01101001]

Yes, sorry, not a new edition indeed. It looks encouraging, though.

 

[pompenguin]

I've just read that the eyering changes colour depending on age: according to an article by published on the Polish Society for the Protection of Birds website, it's pink for juveniles, red for immatures and yellow for adults (I might've misconstrued the ages for pink and red).*

The feature is not mentioned in Blasco Zumeta's paper, but it seems to be observed in the photographed birds (red for juvenile, yellow for adult, no immatures).

Bonus question No. 1: Speaking of Blasco Zumeta's guide, if a feature is visible in the photos but not spoken of in the text, is it still valid (i.e. can I assume the photos there are representative of a whole age group of a given bird at a given time of year)?

Bonus question No. 2: Has anyone written a paper about the identification of the various (and varied in appearance) subspecies of alpinus group LTTs from europaeus group LTTs just like there are many papers considering the differences and intergrades between the latter and caudatus?

EDIT: Bonus question No. 3: Where can I find caudatus LTT in ornitho-Regioportal?

*Raniuszek (2011) - OTOP Eyering colour better visible against all-white caudatus heads (but--surely--there must be a better explanation, so maybe a mistake or--which is also possible--I'm not reading it the right way)?

Using eye ring colour as an aging feature for long-tailed tits was discredited as long ago as 1983 (see the link to the Bird Study paper below)

https://www.tandfonline.com/doi/pdf/10.1080/00063658409476812

Neither Svennson or the English version of the Demongin ringing guide mention it. The Bird Study paper concludes that colour changes are due to the emotional state/stress levels of individuals rather than age and that the colour can change whilst the bird is in the hand. The BTO ringing software will not accept an entry of 1st year for a long-tailed tit after the post juvenile moult by which time adults and first years are indistinguishable either in the hand or in the field.

 

[01101001]

These results demonstrate that there is more to the eye-lid colour of Long-tailed Tits than a simple change accompanying development from juvenile to adult.

imply that the structure has a different significance, as an indicator of the bird's internal state.

I love the idea of Long-tailed Tits internally feeling forever young (I may be slightly misrepresenting the data here).

There's at least one more interesting bit:

Whatever the underlying causes of the colour change, there is no evidence at present to indicate what role, if any, eye-lid colour plays in mediating social interactions between Long-tailed Tits.

It is interesting to note that an unusually large number of species with communal social systems share a combination of morphological characteristics that includes colour-changes of bright red, yellow or orange bills, eyes, legs or wattles (see Hardy 1973, Brown 1978). Short-term changes of colour, such as that shown by Long-tailed Tits, have never been reported among communal species, however. They do occur in the African Harrier-hawk Polyboroides typus, in which a normally yellow bare facial area can 'blush' rapidly to deep pink (Smeenk and Smeenk-Enserink 1983).

Thanks a lot!