GENERAL
Observations
on Feather
Color
NOTES
Variation
in a Presumed
Common
Flicker
Inter-
grade. --The occurrenceof somered flight feathersin individualsof the yellow-shafted
race of the CommonFlicker (Colapresa. auratus),within the easternpart of its range,has
beenan enigma. Test (1969) discountedthe idea that the presenceof red featherswas the
resultof the transferof C. a. cafergenomeinto the C. a. auratusgenome,but was unableto
put forth an alternativehypothesis.Short (1965) statedthat althoughit cannotbe proven,
1976
I
H
6H
1977
1978
FIGURE1. The incidenceof red flight feathers(denotedby shading)in a presumedCommon Flicker intergradefor 3 consecutive
years: 1976, 1977, and 1978. Featherswith
the same letter are molted at the same time based on the molt scheme of Test (1945).
403
404]
General
Notes
J.Field
Ornithol.
Autumn
1985
the presenceof red flight feathers in eastern C. a. auratuspopulationsis probably due to
introgressionwith the western C. a. caferpopulation. Both Test (1969) and Short (1965)
usedonly museumspecimens
or specimenscollectedfor the purposeof studyingintrogression. We had the unique opportunity to study the incidenceand variation of red flight
feathersin a wild C. a. auratusflicker over three seasons,a phenomenonthat has not been
documented.
On 14 February 1976 a male C. a. auratusflicker with somered flight featherswas
trapped and bandedat the University of Wisconsin-MilwaukeeField Station, Ozaukee
County, Wisconsin(Ingold 1976). The bird was subsequentlyretrapped15 January 1977,
26 February 1977, and 28 February 1978. Data on flight feather color were taken on all
recapturedatesexcept 15 January 1977.
On the three dateswhen plumagewas examined,the only traceof C. a. caferplumage
charactersoccurredin the flight feathers.The incidenceand variation in red flight feathers
are outlinedin Figure 1. A secondindividual showingred flight featherswas bandedby
Ingold 29 April 1978 in Brookfield,WaukeshaCounty, Wisconsin.This bird was a female
and showedonly C. a. auratuscharactersexceptin the flight feathersof which primaries 5
and 6, secondaries6 and 8, and rectrices 2, 3, and 4 were red. In both birds the incidence
of red featherswas symmetrical.
The red and yellow colorsthat occur in feathers of flickers are due to carotenoid
pigmentsthat are not primary gene productsbut "asemanticmolecules,"that must be
obtained from the diet (Zuckerlandl and Pauling 1965). The ingestedcarotenoidsare
modified by enzymesto different productswhich are then depositedin the feathers (Test
1942). Carotenoidpigmentshavebeenstudiedin a varietyof avianspecies(tanagers,Brush
1967, 1970; flamingos,Fox 1962a; Scarlet Ibis, Eudocimusruber, Fox 1962b; Roseate
Spoonbill,Ajaia ajaja, Fox 1962c;flickers,Test 1942), but the siteand the geneticsof the
enzymesystemis unknown(A. H. Brush,pers.comm.,Rawles 1960).
If we assumethat diet alone cannotproducethe red pigment (Test 1969), there must
be a geneor set of genespresentto producesomeenzymaticinteractionwith the diet. The
importanceof our data lies in the fact that the red featherswere not the same in each of
the 3 years.It is important alsoto note that feathersthat normally are moltedand regrow
at the sametime (Test 1945) showeddifferent patterns of pigmentation(Fig. 1). Many
alternativescan be proposedto explain the variation in flight feather pigmentation,such
as: (1) the genesturn on and off during the molt processand influenceall growingflight
feathers,but are imperfectin timing; (2) the genesare always"on" but exert their action
only on certain flight feathers;(3) the geneis under hormonalcontrolwith fluctuationsin
hormonelevels;(4) theremay be variationin carotenoidprecursoruptakeor in the transport
mechanism.Although our limited data set doesnot allow us to supportany of the above
alternatives,we believethat it points out a variation that has not been documentedand
which may be of importanceto further researchin the area of the geneticsand physiology
of avian feather pigmentation.
We would like to thank Drs. A. H. Brush, W. Moore, and S. I. Guttman for reading
variousdrafts of the manuscript.This is Publication#64 of the University of WisconsinMilwaukee
Field
Station.
LITERATURE
B•,USH,A. H.
CITED
1967. Pigmentationin the ScarletTanager, Pirangaolivacea.Condor 69:
549-559.
ß 1970. Pigmentsin hybrid, variant and melanictanagers(birds). Comp. Biochem.
Physiol. 36:785-793.
Fox, D. L. 1962a. Metabolic fractionation,storageand display of carotenoidpigments
by flamingos.Comp. Biochem.Physiol.6:1-40.
1962b. Carotenoidsof the Scarlet Ibis. Comp. Biochem.Physiol. 5:31-43.
1962c. Carotenoidsof the RoseateSpoonbill. Comp. Biochem. Physiol. 6:305-
31(•.
INGOI•D,J. L. 1976. A hybrid Common Flicker wintering in southeasternWisconsin.
PassengerPigeon 38:88.
Vol.56,No.4
General
Notes
[405
R^WLES,M. E. 1960. The integumentarysystem.Pp. 189-240, in A. J. Marshall, ed.
Biologyand ComparativePhysiologyof Birds. AcademicPress,New York.
SHORT,L.L. 1965. Hybridization in the flickers(Colapres)of North America. Bull. Am.
Mus.
Nat.
Hist.
129:509-428.
TEST, F. H. ]942. The nature of the red, yellow and orangepigmentsin woodpeckers
of the genusColapres.
Univ. California Publ. Zool. 46:371-390.
1945. Molt in the flight feathersof flickers.Condor 47:65-72.
ß 1969. Relation of wing and tail color of the woodpeckersColaptesauratusand
C. caferto their food. Condor71:206-211.
ZUKERLANDL,
E., ANDL. PAULING. 1965. Moleculesas documentsof evolutionaryhistory.
J. Theoret. Biol. 8:357-366.
J^MESL. INGOLD,Departmentof Biology,OberlinCollege,Oberlin,OhioddO7d,and CH^RLES
M. WEISE,Departmentof Zoology,Universityof Wisconsin-Milwaukee,
Milwaukee,Wisconsin
53201. Received15 Jan. 1985; accepted29 June 1985.
Evidencefor ReproductiveMixing of LeastTern Populations.--The Atlanticrace
of the Least Tern (Sternaantillarumantillarum) breedsalong the coastalbeachesand bay
systemsof the Atlantic Ocean and Gulf of Mexico from Maine to southernTexas, while
the Interior Least Tern (S. a. athalassos)
breedsin the interior of the United Statesalong
the MississippiRiver, its major tributary drainages,and portionsof the Pecosand Rio
Grande rivers (American Ornithologists'Union 1957). Although variousphysicaldistinctions betweenthesepopulationswere suggestedby Burleigh and Lowery (1942), none of
thesedistinctionshas been statisticallyverified, and separationof the racesremains largely
basedon geographicseparationof breedingareas.
On 15 July 1984, RLB captured an adult Least Tern while it was incubatingat
Quivira National Wildlife Refuge (QNWR), Stafford Co., Kansas.The tern had been
bandedby BCT on 27 June 1980 as a juvenile (#801-53109) on a coastaloystershell
islandnear Port Lavaca, Calhoun Co., Texas, approximately1250 km S of QNWR. The
mate to this tern was also capturedon 15 July 1984 and had beenbanded(#1181-01019)
at QNWR as an adult by RLB on 21 June 1980. Both ternswere examinedand released
on the day of capture.Although no criteria have beenestablishedfor sexingLeast Terns,
we believethat behavioralobservationsof the pair, as well as measurementsof both birds,
suggested
the Texas bird was a female (Table 1). The nest that this pair was attending
containedtwo eggson 12 July. On 10 August 1984, a juvenile about 15-18 days old was
foundwithin 10 m of the nest site and was banded.This juvenile was likely producedby
the bandedpair as the nearestneighboringnest was 200 m south.
These observationsdemonstratethat genetic mixing is occurring naturally between
membersof theseadjacentpopulations.The magnitudeof suchmixing cannotbe estimated
from this singleevent,but the low probabilityof a band recovery/returnfor this species
(ca. 0.5%) suggests
that it couldbe a reasonablyprevalentphenomenon.
The migratory pathwaysand winter distributionof these populationsare unknown
and this observationsuggestsat least minimal contactduring some period outside the
breedingseason.The belief that the Texas tern was a female is consistentwith findingsin
manyotherspecies(Boyd 1962, Greenwood1980, Leningtonand Mace 1975, Wilcox 1959)
in that the female has a greater tendencyto dispersefrom the natal area. Massey (1974)
and Wolk (1974) have suggested
that the elaboratecourtshipbehaviorand vocalizationsof
the Least Tern are associated
with the vicinity of the breedingareasand would not suggest
pairing on the wintering groundsor during migration.
Site tenacityof the Least Tern is only 50-55% at QNWR (Boyd, unpubl. data),
whereas populationson the west coastexperience90-95% site tenacity (Atwood, pets.
comm.).Both Atwood, with Least Terns, and Austin (1951) with CommonTerns, suggest
that the birds tend to dispersemore from lessstablenestingsites.Nesting habitat of the
Least Tern is subjectto substantialdisturbancesin both Kansasand Texas.