First Verifiable Records of the Thick-Billed from the United States

First verifiable records of the Figure 2. Thick-billed Vireo, Hypoluxo 1., Florida. Note that the face, wing and bill are muchlike the typicalindi- vidual pictured in Figure 1, and that the underpartscouM hardly be termed "uniform" or "yellow." The grayer- lookingeye of this individual is not unusual. Photograph/ DuncanS. Everedand Lyla R. Messick. Figure 1. TypicalThick-billed Vireo from northern Bahamas,Abaco. Note yellow lores contrasting with whiter broken eye-ring, prominent white wingbars offsetting blackish greater coverts, fairly uniform upperparts, and dirty white, slightly yellowish underparts with some olive tones on the breast. This individual's bill is darker than somebut still doesn'tappear black. Photo- graph/DuncanS. Everedand Lyla R. Messick. Figure 4. Molting Thick-billed Vireo, Cape Florida, Florida. This individual has a similar face and wingpattern to the bird in Figure I but has somewhatyellower underparts. Note the non-blackbill. Photograph/GeorgeF. Wagner. Figure 5. Anothervitro' of the Thick-billed Vireo at Cape Florida, Florida, showing the incomplete tail and very fine feather- ing below. At this angle, the throat appears more olive and the underparts Figure3. Thesame individual as in Figure2. Note more buffy. Again, note the prominent white edges to the tertials and the non-black bill. Photo- fairly uniform olive upperparts(tf. Figure 1). graph/George F. Wagner. Hypoluxo 1., Florida. Photograph/Duncan S. Evered and Lyla R. Messick. 372 AmericanBirds, Fall 1990 Thick-billed Vireo from the United States P. William Smith, Duncan Stuart Evered, Lyla R. Messick,and Mary C. Wheeler longerand thicker.The bird was in ac- overallappearance, but had a complete discoveredthe first of apparently tive molt. The brownish-olive tail was tail. Each individual seemedto keep NthreeSEPTEMBER Thick-billed9,1989, Vireos WHEELER (Vireo abouthalf grown, with a markedgrad- mainly to its own area about 100-200 crassirostris), that eventually were uation in feather length from the metersfrom the next, but occasionally closely observed,photographed, and shorterouter rectrices to the longer two or all three interacted. Both adult tape-recordedover a periodof several central ones. The upperpartsseemed and immatureWhite-eyed Vireos were weeksat Bill BaggsCape Florida State fresh and were basicallyolive, blend- also presentin the same vicinity but RecreationArea, Key Biscayne,Dade ing almostimperceptably from a more were not observed interacting with County,Florida (25ø40'N, 80ø 09'W). grayish-oliveshade on the head to a the Thick-billed Vireos. To Smith or On March 10, 1990, a singingThick- more greenish-olivetone on the back. Wheeler's knowledge, no one saw billedVireo was found by HowdrdP. The tertials were edged in white and more than one individual at the same Langridgeon Hypoluxo Island, Lan- seemedto form stripeson the upper- time after September17. On Septem- tana, Palm Beach County, Florida parts,parallel to the longitudinalaxis ber 19, GeorgeF. Wagnertook a long (26ø35'N, 80ø03'W). Captured that of the body. The greater and median seriesof flashphotographs of oneindi- day, measured,and photographedin wing coverts had broad white tips, vidual. By September30, no short- the hand by Evered and Messick, it forming two conspicuouswingbars. tailed individualswere being seen,and was subsequentlyseen by numerous The iriseswere brown. Distinct,bright it wasimpossible to distinguishany in- observersthrough April 1, 1990 (H.P. yellow loresextended from the baseof dividual with certainty.One studiedby Langridgepers. comm.). We believe the bill to the areaabove the eyes.Di- Smith on that date seemed to have that the level of documentation now rectlyabove each eye was a small,dark completed its body molt; it seemed available for these records, coupled gap in an otherwiseoff-white eye-ring more uniformly colored below than with more informationabout the spe- extendingbehind and below eacheye; any individualseen two weeksearlier roes' appearance,resolves the long- the portionof the eye-ringbehind the The color shadeof the underpartsthen standinguncertainty surrounding the dark gap was slightlyflared. A dusky wasmainly very pale dingyyellow, al- Thick-billed Vireo's status in the line stretchedfrom the bill to the eye most white, with some areasof olive, UrntedStates. Previously, it wasknown immediatelybeneath the yellow lores. mainly on the breast.Although neither from five publishedsight records. The underpartsappeared to be in heavy Smith nor Wheeler definitelyobserved Wheeler first observed what she be- molt and varied in shadingdepending a Thick-billed Vireo at Cape Florida lieved was a Thick-billed Vireo at uponfactors such as the angleof obser- after the end of September, reports CapeFlorida on September9, 1989, in vationor the amountof directsunlight. continuedoccasionally throu•gh the dense shrubs about 100 meters from The basiccolor was a dingy pale yel- autumn,until at least October26 ( H P. theocean. It respondedvery quickly to low from the bill to the vent. However, Langridgein litt.). On October 18, at a "pish" and approachedto less than it varied in intensity and appearance the same site, Robert Odear (pers two metersat heightsunder three me- from whitish to buffy, with areas of comm.) watched as a vireo, which he ters. It moved methodically,seemed duskyolive, particularlyon the throat had identified as a Thick-billed,was quite curious,and remainedin close and breast.The vireo did not sing,but capturedby a passingraptor. viewing distancefor about ten min- did scold vigorously.The scold was Figure 1 showsa bird photographed utes. On September13, Wheeler and distinctively harsh and resembled a by Evered and Messickon Abaco,Ba- VirginiaEdens studied the sameor an- series of low, protractedpishes. On hamas, about 300 kilometers east of otherThick-billed Vireo in thisvicinity September 14, Smith and Walter Florida. This is a typical Thick-billed for nearly an hour. As before, it re- George,both familiar with the Thick- Vireo of the northern Bahamas,big- spondcdquickly to a pish, was ex- billed Vireo in the northern Bahamas, billed and bulky-looking, with a tremely tame, and foraged in dense confirmed the identification. mainly grayish to horn-colored (not shrubsand nearby fig trees(Ficus sp.) On September16, in the samegen- truly black) bill, a prominent broken at heightsfrom 0.5 to 6 meters,eating eral area, Smith and numerous other whitish eye-ring contrastingwith yel- fruit and insects,including at least one observers saw three Thick-billed Vir- lower lores,prominent white wingbars large wooly caterpillar.The bird ap- eos together.The secondindividual, contrastingwith blackishwing coverts, peared somewhatsimilar in size and also in obvious molt, possessed a mostlyolive upperpartsand yellowish- appearanceto an immature White- longerbut still incompletelygrown tail white underparts,with some buffy- eyed Vireo (Vireo griseus),but it ap- andappeared less olive on the throat olive tones on the sides of the breast pearedmore robustand bull-headed; and breastcompared to the first, while Somenorthern individuals appear dull •ts bill, brownish in color, seemed the third individual was similar in yellow or even buffy below, but the Volume44, Number3 373 Table1 MEASUREMENTS (mm) OF THICK-BILLED AND WHITE-EYED VIREOS the distinctive plumage features of adults and might appear more like N Mean Min. Max. S.D. Thick-billed Vireos in the field. How- Thick-billed Vireo. Hypoluxo I., EL 3/10/90 1 ever, T. Lloyd-Evans,who hashandled Wing length{natural choffi) 59 Tail length(to longestfeather) 48 many molting young White-eyed Bill length(fromanterior point of nostril) 8.5 Vireos at the Manomet Bird Observa- Bill depth(at anteriorpoint of nostril) 4.6 tory, Massachusetts,indicates (pets. Bill width(at anteriorpoint of nostril) 4.2 comm.) that the only reliablemeans of Bill sizeindex (bill lengthx depthx width) 164.2 distinguishingjuveniles from adultsby Weight(g, light fat evident1 14.4 late summeris by their brownisheye Live Thick-billed Vireos, Abaco, Bahamas colorand incomplete skull ossification. Wing length 63 60.5 54 65 2.26 Indeed, Smith was unable to find a Tail length 63 51.2 47 54 1.89 White-eyed Vireo specimen of any Bi.11length 7 8.49 8.[ 8-8 0.29 age,either at the USNM or in the Uni- Bill depth 7 4.51 -4.3 427 0.14 versity of Miami ResearchCollection Bill width 7 4,39 4•0 4.6 0.21 (UMRC), that closely resembledthe Bill size index 7 167.76 158.4 180.1 6.74 vireosat Cape Florida. Weight(g, lightfat or less) 61 13.24 11.9 15.6 0.73 The Thick-billed Vireo on Hypoluxo White-eyedVireos from southFlorida UMRC Island (Figs. 2, 3) had measurements Winglength 20 59.2 55 63 1.73 consistentwith data collected by Ev- Tail length 20 48.2 45 53 1.85 ered and Messick on Abaco, Bahamas, Bill length 20 7.29 6:7 8.2 0.37 for that species(Table 1). On the other Bill depth 20 4.06 3z8 4.4 0.17 Bill width 20 3.76 3.2 '412 0.21 hand, its bill size was inconsistent with BillsiZe'index 20 111.27 93.1 133.6 10.18 bills of White-eyed Vireos from south- Weight(g, fromtag) 13 11.24 8•3 13.0 1.34 ern Florida in the UMRC. Because there was overlapbetween the species in most individual measurements All measurementsby D. S. Evered (Table 1), we computed an index to representthe overallbill size(s)of each deeperyellow individuals(which also these birds in having lemon-yellow fully measuredbird by multiplying its have yellower eye-rings and greener flanks, a grayish white throat and bill length by width by depth. This upperparts)depicted in popular field breast,a white belly, and suffusedyel- statisticeasily discriminatedall fully guides (National GeographicSociety low spectacles. They also typically measuredWhite-eyed Vireos (S<134), 1983, Bond 1985) are foundlargely in have rather green backsand contrast- including those collected in southern the southernBahamas (Buden 1985). ing gray necks, but this character Florida and the Keys in summer,from The birdsat CapeFlorida (Figs.

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