Brown Falcon at Lower Coldstream
By Birding-Aus, on August 2nd, 2013
Nikolas Haass kindly reminded me that the ‘morphs’ of the Brown Falcon are actually ’phases’, that is colour variants that change over time. The rufous ‘morph’ is actually an adult male plumage. It is interesting that I don’t recall ever seeing an adult male Brown Falcon in the Clarence Valley before. The bird that we saw yesterday isn’t necessarily an inland bird but I do suspect that Brown Falcons visit the north coast from inland areas, or from southern latitudes, during the winter months as numbers are greater then. Brown Falcons are uncommon locally during the breeding season. Regards Greg Dr Greg. P. Clancy Ecologist and Birding-wildlife Guide | PO Box 63 Coutts Crossing NSW 2460 | 02 6649 3153 | 0429 601 960 http://www.gregclancyecologistguide.com =============================== To unsubscribe from this mailing list, send the message: unsubscribe (in the body of the message, with no Subject line) to: birding-aus-request@vicnet.net.au http://birding-aus.org ===============================
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., http://bioacoustics.cse.unsw.edu.au/birding-aus/2011-10/msg00126.html 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. Cheers, Paul ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Dr Paul G. McDonald paul.mcdonald@une.edu.aupaul.mcdonald@une.edu.au> http://www.une.edu.au/ers/research/abel/ Senior Lecturer and Convenor Zoology, School of Environmental and Rural Science University of New England Armidale NSW 2351 Australia Ph: +612 6773 3317 Fax: +612 6773 3814 Google Scholar: http://tinyurl.com/scholar-google-pgm 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. Cheers, David James Sydney ============================== =============================== To unsubscribe from this mailing list, send the message: unsubscribe (in the body of the message, with no Subject line) http://birding-aus.org =============================== =============================== To unsubscribe from this mailing list, send the message: unsubscribe (in the body of the message, with no Subject line) http://birding-aus.org ===============================