Brown Falcon at Lower Coldstream

To: Birding Aus <>
Subject: Brown Falcon at Lower Coldstream
From: Paul McDonald <>
Date: Mon, 5 Aug 2013 09:58:04 +1000
Dear David et al,

Great to see people talking about Brown Falcon plumages again, but 
disappointing that David didn't mention an alternate viewpoint. We've debated 
this on Birding-Aus previously, so no point going through the details again 
that are available in the archives (e.g., and other 
messages from both viewpoints in that thread).

The synopsis is that HANZAB concluded morphs existed in 1993, in 2003 (Emu 
103:21-28) I described plumage in marked birds in Werribee, southern Victoria 
and concluded that age/sex differences in that area closely resembled many of 
the characteristics of the described morphs. Further, plumages of individual 
birds also apparently moved between morphs over time. My conclusion from that 
was that much of the variation in plumage is thus driven by age changes 
throughout an individual's life, with strong patterns associated with each sex.

The fact that this is one area only is irrelevant, the HANZAB text itself 
acknowledges that more work is needed to understand these plumages, and by 
demonstrating changes inconsistent with morphs in one area, these data justify 
re-examination with new data patterns in other areas. This is particularly 
important as there are so many intermediate birds between morphs, as HANZAB 
also points out, that further cloud the validity of discrete, non-overlapping 
morphs. My opinion is that all of this variation is more parsimoniously 
explained by linear variation potentially driven by something like age, with 
separate patterns for each sex, than discrete morphs with presumably aberrant 
individuals between them.

David James disagrees, which is fine, but to ignore the above finding and set 
HANZAB results in stone is not how we'll finally get to understand the species. 
What we need is detailed information on changes in plumage from individuals of 
known age (i.e., more detail than simply  adult, as changes clearly happen 
after first adult plumage in at least some birds) across the different regions 
of their range. Some banders, rehab folk and therefore birders may well be in a 
position to start collecting some of this data, which would be very useful, 
particularly in problematic areas away from SE Australia. I maintain that until 
this is done, the below picture of three morphs alone is not complete and does 
not explain all of the observed variation in the field.

Happy to answer further questions off list as this is a well worn debate that 
sorely needs new data to progress.


Dr Paul G. McDonald


Senior Lecturer and Convenor
Zoology, School of Environmental and Rural Science
University of New England
Armidale NSW 2351

Ph: +612 6773 3317  Fax: +612 6773 3814

Google Scholar:
University of New England: CRICOS 00003G

On 04/08/2013, at 8:21, David James wrote:

Hi Greg and Nikolas,

Brown Falcon plumages are very complicated, but they do have actual morphs. The 
morphs change with age (i.e they have phases within morphs). What's more, the 
morphs also vary geographically and there are slight difference between the 
sexes in adult plumage.

there are three morphs, brown, black and rufous. The downy young of all morphs 
are the same. The juveniles are similar (brown above and on the thighs and 
flanks with buff centre of breast and underparts) but the rufous morph has 
broader rufous fringes (scaling) to the upperparts and the dark morph has very 
little buff below.  In adult plumages of the brown morph the buff becomes cream 
and the upperparts become slightly duller and mottled; the rufous morph gets 
rufous upperparts and cream underparts, while the dark morph resembles a Black 
Falcon.  In this way the juveniles are intermediate between the rufous morph 
and dark morph, and the former get paler with age while the latter get darker 
and the brown morphs don't change so much..

Brown morph predominates in the SE (and is the only morph in Tassie), rufous 
morph predominates in the interior and west, dark morph is most common in the 
tropics but is comparatively rare (generally, the more humidity, the darker the 
plumage, but with exceptions). The distributions are difficult to determine 
precisely because there is lots of variation and lots of birds intermediate 
between rufous and brown morphs,, Also, the changes with age and differences 
between sexes make it even more confusing.

However, the rufous morph probably does not breed on the east coast, so the 
bird Greg saw likely was from inland, but not necessarily from very far inland.

Also, in the most arid central deserts there is a very pale version of the 
rufous morph that is quite similar to Nankeen Kestrel females, and could be 
named the kestrel morph.  In HANZAB, I didn't accept any subspecies in 
Australia, but previously 5 were recognised. Birds in the SW (all rufous morph, 
I think) are slightly smaller than those elsewhere, so you colud separate them 
as subspecies occidentalis.

There are more details in HANZAB.

David James

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