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TARBOTON,W. R. 1978. Hunting and the energybud- WALTER,H. 1983. The raptor actigram: a general get of the Black-shoulderedKite. Condor 80:88- alphanumeric notation for raptor field data. Rap- 91. tor Res. 17:l-8. WAIAN,L. B., AND R. C. STENDALL.1970. The White- WARNER,J. S., AND R. L. RUDD. 1974. Hunting by tailed Kite in California with observationsof the the White-tailed Kite (Elunus leucurus).Condor Santa Barbara population. Calif. Fish Game 56: 76~226-230. 188-198.

The Condor89:911-913 0 The CooperOrnithological Society 1987

SEXUALLY MOSAIC PLUMAGE IN A FEMALE AMERICAN KESTREL’

JIMMIER. PARRISH Department of Zoology, 159 WID3, Brigham Young University,Provo, UT 84602 JOANNSTODDARD 4059 Diana Way, Salt Lake City, UT 84117

CLAYTON M. WHITE Department of Zoology, 161 WIDB, Brigham Young University,Provo, UT 84602

Key words: American Kestrel;Falco sparverius;bi- on the inner vane, near the margin, and immediately lateralgynandromorphism;plumage mosaic: endocrine proximal to a broad, subterminal black band. Rectrix abnormality. 5R is virtually identical in color pattern to rectrix 4R. Rectrix 6R is incompletely barred in black on either The plumage of the American Kestrel (F&o sparve- side of the vane with the inner vane more heavily rius) is well recognized to be dichromic between the barred, but the proximal black bars do not meet at the sexes(Meams 1892, Bent 1938, Bond 1943, Friedman rachis. Rectrix 6R terminates in a broad, black band, 1950, Parkes 1955, Cade 1982). On 24 July 1986, a proximal to a rust colored tip. Rectrices 1R to 5R are female American Kestrel was found along a roadside tipped in an ivory/whitish color, typical of males. Rec- in Salt Lake City, Utah, apparently having collided trices 6R, 6L, and 2L to 5L are tipped in a pale rust with an automobile. The right wing was missing, and color, typical of females. Rectrix 1L is tipped in an the bird was emaciatedand generallyin poor condition. ivory/whitish color similar to rectrix 1R. The bird was euthanizedand upon examination showed In general, rectrices 3R, 4R, and 5R are virtually both male and female plumage characteristics(Fig. 1). without female characteristics,with the exception of The breastplumage color pattern was characteristically the incomplete barring on the outer vane margin of female except for the lower left abdominal region (Fig. rectrix 3R. The length of the rectrices does not vary la), where dark brown/black spotting similar to male abnormally, but the vane of rectrices 2R to 5R is ap- breast plumage pattern was present. proximately 2 mm wider than rectrices2L to 5L. None The rectriceswere most aberrant (Figs. la, b, c), and of the tips of the rectricesshow signsof wear (Fig. lc). hereafter are numbered 1 (outermost) through 6 (cen- Basedon crown plumagecharacteristics (Parkes 1955) tral). Rectrix 1 right (1 R) is characteristicof a typical the kestrel was consideredto be a hatch-year bird. female, except the subterminal, black band is consid- The gonadswere paired, not an uncommon condi- erablywider (Fig. lc). Rectrix 2R is incompletelybarred tion that has been found in 30 to 50% of females of with black on the outer vane decreasingproximally to the genusFalco (seeWhite 1969). The left gonad mea- form tiny black spots on the margin. The inner vane sured 1.50 x 1.OO mm and the right measured0.66 x containsonly two partial black bars immediately prox- 0.66 mm. The right gonad was somewhat lighter in imal to a broad, subterminal black band. Rectrix 3R color and smootherin texture than the left, and neither is incompletely barred with black on the outer vane was enlargednor contained enlarged follicles. Results decreasingproximally to form tiny spots as in rectrix of a histological examination of the gonads proved 2R. The inner vane contains only a small black spot inconclusive in determining whether testicular tissue immediately proximal to a broad, subterminal black was present.Visually, both gonadsappeared to be ova- band, typical of males. Rectrix 4R contains no barring ries. on either side of the vane. One small, black spot occurs The occurrenceof sexuallymosaic plumageis some- what difficult to explain, since a variety of systems control secondarysex characteristicsin birds. One case ofgynandromorphism hasbeen reported for the Amer- ’ ’ Received 5 November 1986. Final acceptance 8 ican Kestrel (Brodkorb 1935), and generally refers to April 1987. individuals visually one-half male and one-half female 912 SHORT COMMUNICATIONS

FIGURE 1. (a) Ventral view of female American Kestrel showingdark, masculinizedflank featherson the left side and masculinized rectriceson the right side; (b) dorsal view; (c) close-up dorsal view of rectricesshown in Figures la and 1b. SHORT COMMUNICATIONS 913 and possessingovary and testis (Campbell and Lack permanent. Cade (1982) questioned why sexual di- 1985). When sex-linked differences in plumage exist, chromatism appearsin the juvenile plumage of Amer- they will externally reflect the place of gonads, with ican Kestrels and not in congenerics.Hormonal ma- one side displaying male plumage characteristicsand nipulation experimentsmay help to identify the effects the other female (Witschi 1961). Most described gy- of epigeneticfactors on sexual dichromatism, as well nanders appear male on the right side and female on as on the unique evolutionary phenomena of mascu- the left (Kumerloeve 1954). Bilateral gynandromorph- linization and feminization of plumage pattern cur- ism usuallyoccurs when both an ovary and a testisare rently taking place in some congeners. presentbut may resultwhen an ovary and an ovotestis, R. A. Heckman conducted the histological exami- or a mixed, undifferentiated gonad, are present (P. A. nation of the gonads. D. M. Bird, P. A. Buckley, R. Buckley, pers. comm.). Since incomplete masculini- Bowman, Jan Dyck, and an unidentified reviewer pro- zation occurred on both sides of the female reported vided helpful comments on the manuscript. The spec- on herein, however, the bird cannot be considered a imen (No. 825 1) is currently in the bird collection of gynandromorph in the strictest sense. the Monte L. Bean Life SciencesMuseum, Brigham Buckley(1982) reported on a wide range of plumage Young University, Provo, Utah 84602. variation resulting from both genetic and epigenetic factors. Sexualdifference in phenotype is often the re- LITERATURE CITED sult of a precisebalance between medullary (male) and cortical (female) hormonal components of the gonads BENT, A. C. 1938. Life histories of North American of fowl and lower orders of birds. However, this bal- birds of prey. Part 2. U.S. Nat. Mus. Bull. 170. ance can be too easily disturbed or shifted during de- BOND, R. M. 1943. Variation in western Sparrow velopment. Thus, a plausible explanation for sexually Hawks. Condor 45:168-185. mosaic plumage is that the condition resulted from BRODKORB,P. 1935. A Sparrow Hawk gynandro- some abnormality in the endocrine system of the bird, morph. Auk 52: 183-l 84. as any imbalance of this systemcan produce profound BUCKLEY,P. A. 1982. Avian genetics,p. 21-110. In plumage changes. Huxley and Bond (1934) demon- M. L. Petrak led.], Diseases of cage and aviary strated that cock-feathering in the hen Ring-necked birds. 2nd ed. Lea-and Febiger, Philadelphia, PA. Pheasant (Phasiunuscolchicus) resulted from phasic CADE. T. J. 1982. The falcons of the world. Com- imbalance of endocrine function. Masculinization of stock/Cornell Univ. Press, Ithaca, NY. females suggestsan evolutionary trend in some di- CAMPBELL,B., ANDE. LACK(EDS.). 1985. A dictionary morphisms which were short-lived and mediated by of birds., D._ 180-l 84. 472-474. Buteo Books. Ver- hormonal secretions during the breeding cycle, sug- million, South Dakota. gestingendocrine control of plumagecharacteristics is FRIEDMAN, H. 1950. The birds of North and Middle advanced during ontogeny (Murton and Westwood America. Part XI. U.S. Nat. Mus. Bull. 50. 1977). Androgenshave a function in adult female birds HUXLEY, J. S., AND C. J. BOND. 1934. A caseof gynan- and generally influence secondary sexual characteris- dromorphic plumage in a pheasant re-examined tics (Murton and Westwood 1977). Increasedandrogen in the light of Lillie’s hypothesis of hormone levelsassociated with paired or undifferentiatedgonads threshold. J. Genet. 29:5 l-59. could accountfor both male and female plumagebeing KUMERLOEVE, H. 1954. On gynandromorphism in expressedin a mosaic fashion rather than bilaterally. birds. Emu 5417l-72. In related congenersthe male Mauritius Kestrel (F. MEARNS, E. A. 1892. A study of the Sparrow Hawk punctatus)plumage pattern has become feminized while (SubgenusTinnunculus) of America, with especial the female SeychellesKestrel (F. arueu) plumage pat- referenceto the continental species(F&o sparve- tern has become masculinized (Cade 1982). The ge- rius Linn.). Auk 9~252-270. netic factors controlling plumage pattern differences MURTON, R. K., AND N. J. WESTWOOD. 1977. Avian may simply be labile in most kestrel stocksand could breeding cycles.Oxford Univ. Press, Oxford. accountfor our finding, as well as for the extreme vari- PARKES,K. C. 1955. Notes on the molts and plum- ability in tail and head plumage patterns of the Amer- ages of the Sparrow Hawk. Wilson Bull. 67:194- ican Kestrel. 199. It is unfortunate that the described bird met with WHITE, C. M. 1969. Functional gonads in Peregrines. sucha fatal set of circumstances.If it had not been so Wilson Bull. 8 1:339-340. critically injured, perhaps monitoring of subsequent WITSCHI, E. 1961. Sex and secondary sexual char- feather growth and hormonal manipulation in vivo acters, p. 115-168. In A. J. Marshall [ed.], Biology could have helped identify what causedthe expression and comparative physiology in birds. Vol. 2. Ac- of sexually mosaic plumage, and if the condition was ademic Press, New York.