---------- Forwarded message ---------- From: <[email protected]> Date: Sat, Apr 11, 2009 at 10:15 AM Subject: Re: [cobirds] Unidentified Hawk - Larimer County To: [email protected]
Leucism, aka hypomelanism, aka partial abinism, etc., is found in virtually all avian species. Among the raptors the Red-tailed Hawk is well known to display varying degrees of leucism. The lack of pigmentation is often symmetrical. May occur because of the embryologic failure of melanocytes to migrate to the feather follicles. The melanocytes are capable of making pigment, but some of them just don't arrive at the proper destination. I have seen 2 leucistic RT Hawks. One was almost entirely white. I don't think this has anything to do with a molt. Pigment is added to the feather as it erupts, rather than afterwards. Once a white feather, then white it will stay until shed. Likely the replacement will look the same. In regard to the above, you must consider the source (me!), who relies totally on memory from from past reading on the subject, although I did write a paper on the leucistic grebe at Mono Lake, published ihn Western Birds (38:1, Mar 2007). Jeff Davis wrote an excellent article on pigment abnormalities in birds about 3 years ago for Birding magazine (ABA). Cheers, Len Any Thoughts on this? Has anyone else seen bright white perpendicular stripes on the top of Red Tailed hawk wings? Is this a common "between molts" coloring? Thanks! ------------------------------ Hurry! April 15th is almost here. File your Federal taxes *FREE* with TaxACT.<http://pr.atwola.com/promoclk/100126575x1221653545x1201423923/aol?redir=http:%2F%2Fwww.taxact.com%2F08tax.asp%3Fsc%3D084102950004%26p%3D82> -- Kathryn Mikesell Hornbein 1317 Devils Gulch Rd. Estes Park, CO 80517 970-577-1832 (home) --~--~---------~--~----~------------~-------~--~----~ Join us at the 2009 Convention in Alamosa: http://cfo-link.org/convention/index.php You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.as/group/cobirds?hl=en -~----------~----~----~----~------~----~------~--~---
