VOLUME 57 (2003) - PDF document

VOLUME 57 (2003) € NUMBER 1 lines appear to circle behind the eye and con-the pinkish, red or maroon facial skin readilydistinguishes these birds as White-faceds. The five birds with intermediate charactersfrom a bird very closely resembling an adultGlossy Ibis to one appearing as an off-toneThree birds depicting clearly intermediatecharacters are those in Figures 4-7. Thesebirds may be subadults in their first-alternateplumage. Bird A (Figs. 4…5) has a brown tobrownish-red eye. The bare facial skin hasThe line forming the upper border to thewhile that forming the lower border containsfacial lines. There is some white featheringBird B (Fig. 6) also has characteristics ofclearly red areas. The facial skinbelow, are white (suggestive ofmeet behind the eye (as in Bird Aabove). There are also some whiteThe eye of Bird C (Fig. 7) isbrown with areas of red. The bareoration with patches of gray. Thelines bordering the facial skin arewhiter and blue-white areas. TheThe adult hybrid in Figures 8…9(Bird D) looks most like a GlossyIbis. However, it has severalclearly red areas in the eye. Thefacial skin is largely a plum-purpletone approaching, but essentiallyduller than, the maroon tones on the bare-skin areas of the White-faced Ibis in Figure 3.The lines forming the borders of the facialskin are pale blue and appear very much likesomewhat. The eyelid is dark. There is whiteBird E (Fig. 10) may be a hybrid or possi-bly a variant White-faced in retarded first-on the anterior portions of thehead shows a few white streaksthat may be remnants of first-basicplumage. The facial skin is largelyplum-gray, with a few brighterareas of plum coloration charac-The lines forming the borders ofthe facial skin are a pale plum orpale maroon (the intermediatelower. The eyelid is plum posteri-orly, matching the lower border-line, but gray anteriorly. The eyeis brown but, upon close inspec-reddish-brown, possibly a condition ofretarded juvenile color.Three of the five intermediates show com-binations of red in eyes (of White-faceds) andGlossies); in a fourth, the facial lines arewhitish. The most diagnostic feature sharedby these hybrids is the presence of the plum-and/or toning to its pale borderlines. Webelieve all four of these are hybrids. The plumtone in the eye-lines of bird E is consistentwith tones in the other birds. This wouldsuggest hybrid status for this bird as well. Palmer (1962) suggested, from the occur-rences of breeding records, that the GlossyIbis spread to America from the Old World incussed this historical spread into Atlantic andGulf coastal areas of the United States. FromWhite-faced Ibises were geographically iso-lated for some time, allowing reproductiverecent increase in extralimital records ofGlossy Ibis into the western reaches of theshowing an especially pronounced increaserecent increase in Glossy Ibis sightings for thesouthern Great Plains. A bird found by JoLoyd and Pat Seibert and photographed bySteve Metz in Tulsa County, Oklahoma in1992). The next to appear were in the springof 1999, when at least three were noted in theSouthern Great Plains Region of Nebraska,In 2000, Arterburn discovered several adult .Typical adult Glossy Ibis in breeding condition at Salt PlainsN.W.R.,Oklahoma 6 July 2002.The dark brown eye and blue-blackfacial skin with borders,above and below,of bluish-white lines arecharacteristic of breeding birds.Photograph by James W.Arterburn..Adult White-faced Ibis in breeding condition at SaltPlains N.W.R.5 July 2002.White feathers surround the facialskin and red eye.The facial skin appears pinkish-red.Notethe pale eyelid.Photograph by James W.Arterburn..Another adult White-faced Ibis in breeding condition at SaltPlains N.W.R.7 June 2002.Note the bright red eye and rich maroonfacial skin of this bird.Photograph by James W.Arterburn.HYBRIDIZATION BETWEEN GLOSSY AND WHITE-FACED IBISES 138 during the breeding season.White-faced Ibis breeds very locally atscattered localities in the Great Plains andMountain West (Ryder and Manry 1994).Cheyenne Bottoms Wildlife ManagementArea and Quivira National Wildlife Refuge inwith one recently documented nesting colonyin Meade County, Kansas during 1998 (Flow-Concomitant with the increasing extralim-southward expansion in breeding of thewas first noted breeding on Ralston Island,Salt Plains National Wildlife Refuge, north-were observed annually during summer onthis island since 1992 (Shepperd 1996). Dur-colonies were observed in Kingfisher andBeaver Counties of northwestern Oklahoma(Arterburn, pers. obs.) and as far south asTillman County in southwestern Oklahomaibises has not been observed in sev-eral Gulf Coast colonies where both occurson 1977). In Texas, Glossy Ibisdown Island in Matagorda Bay(pers. comm.) and Brush Free-man. In surveying ibis coloniesduring 2002 on Matagorda Bayislands, Hockey found approxi-mately23 Glossy Ibises on nestsIbis and other herons and egrets.studied ibises in the Texas coastalareas and found only one sus-pected intermediate, a birddepicted in his recent identifica-Alfalfa County birds.reported to date in theently on the Texascoast? With isolatingrarely occur. However,with little knowledge on courtshipbut speculation can be offered.Many waterfowl are geneticallydetailed and stereotyped displaysand very discrete male plumagesenon induced by the relative rarityhybridization between birdcourtship displays and extendedscarcity. In Gulf coastal colonieswhere both species nest, hybridshave not been found (or recog-there, making it easier to find atively, hybrids may be present butrare relative to the total populations, makingGulf coastal colonies needs more study(Ryder and Manry 1994, Patton and Lasleybroadly or one of occasional local occurrencedepends presumably in large measure on theeffectiveness of current isolating mecha-nisms. Given that hybrids have been rare todate even when looked for, isolating mecha-nisms between these species may be effective.Wewould, thus, predict frequencies ofhybridization similar to those for waterfowl,occurring only occasionally where vagrantsin breeding condition encounter localizedbreeding populations of the regionallyexpected species. .Hybrid(possibly subadult) near Salt PlainsN.W.R Oklahoma 30 May 2002.Notice the brown to brownish-redeye;facial skin that has pink,plum-purple,and gray patchesand pale blue-line borders;and white feathers above the loralstripe and near the gape.Photographs by James W.Arterburn..Hybrid(possibly subadult) near Salt Plains N.W.R6 June 2002.The eye is mostly red,and the facial skin has pink,plum-purple,and gray coloration.The lines forming the borders of the facial skin arewhite,the upper line thickening;the pale eyelid makes them appearto connect behind the eye.Also note white feathers above the loralstripe and near the gape.Photograph by James W.Arterburn..Hybrid(possibly subadult) at Salt Plains N.W.R6 July 2002.The eye is brown with patches of red,and the facial skinhas plum-purple and gray coloration.The lines forming the borders ofthe facial skin are mostly plum-purple,with some areas of blue-white(upper) and white (lower),the upper line thickening.Note theeyelids of this bird are dark.Photograph by James W.Arterburn.NORTH AMERICAN BIRDSHYBRIDIZATION BETWEEN GLOSSY AND WHITE-FACED IBISES