HFCheung

I have been writing on Black Kite id.  Here are my observations on how to age Black Kites in HK.  Is this true?  I think the Black Kite group or some experts may be able to tell me more about this.  Thanks.

1. Adults have plainer body (no whitish streaks on neck and body).  Completely mature bird have whitish forehead and throat, and paler iris.  See the photo in the following link.  
http://www.hkbws.org.hk/BBS/view ... &extra=page%3D2

2. Juveniles have whitish streaks on neck and body, see the following photo which is clearly a juvenile.
http://www.hkbws.org.hk/BBS/view ... &extra=page%3D1

3. Immature (at least 1st summer birds) still have white streaks on neck.

4. Subadults have pale fringes to coverts and scapulars more obvious than adults.

HF Cheung

ajohn

One comment I would have is that immature and subadult are not very useful terms. Both basically just refer to a bird that is too young to be in adult plumage, but are not specific to any other age class. I think you are using these to indicate 2nd or 3rd calendar year, in which case you would need to be clearer.

I thought that young kites in their first summer (i.e. about 1 year old) moulted into a plumage similar to adults, and that 2nd/3rd year birds were indistinguishable from adults on plumage (possibly still on moult contrast?), so personally I would be cautious about ageing kites beyond separation of juvenile/1st winter(/1st summer?) and adult.

John

HFCheung

I think many young birds start to breed before they have full adult plumage.  I believe they are called sub-adults.  Immatures are those that have not started breeding.  Is that right?
The problem with "2nd year" or "3rd year" is that they are hard to pinpoint.  Immature is a bit blur but I think quite useful.

How about subspecies?  Anyone doubt that the HK birds are subspecies "lineatus"?  It does not seem to fit the description on Handbook of the Birds of the World.

[ Last edited by HFCheung at 2/08/2014 20:41 ]

AjaA

A juvenile is a bird in its first plumage. An adult is a bird with a plumage which is not changing in subsequent moults (at least not much). Useful definitions for immature and subadult plumages are that an immature is a non-adult bird and a subadult is a bird which is neither juvenile nor adult (there are others - for example an immature bird is still not capable of reproducing).  

Young Black Kites in autumn are very patterned. the Underparts are strongly streaked pale buff and the covert have pale tips. The whole plumage is uniformly fresh. They are quite different looking from adults.

By the first spring, the birds have become worn and also rather bleached and are more difficult to tell from adults because much of the juvenile patterning has been lost. The plumage is still uniform, but not fresh any more. Additional characters
helping in ageing are the secondaries which are barred almost to the tip (adults have a wide black terminal band) and darkish eyes (more reddish in adults).

During the first spring the young birds start to moult and the moult is completed in autumn (in autumn you can some times identify three age classes: juveniles plus second year birds and adults, if you can see which feathers are not yet moulted and tell if they are juvenile or adult). After the moult is complete the plumage is adult-like, but still not fully mature. Exact ageing is probably not possible. This is based on ageing Black kites of the European nominate (sub)species, lineatus is somewhat
different.

The type locality of lineatus is "China" so Hong Kong birds very probably should be called by that name independent of how the different (sub)species of Black Kites are split or lumped.