Black-footed and Laysan Albatrosses

PlumaDevariationand hybridizationin
Black-footedand LaysanAlbatrosses
Tristan McKee
P.O. Box631
Ferndale,
California
95536
(eraall:
bertmckee•yahoo.com)
PeterPyle
4990Shoreline
Highway
SUnson
Beach,
California
94970
(email:
ppyle@prbo.org)
INTRODUCTION
Black-footed
(Phoebastria
nigripes)
andLaysan
(P.immutabilis)
Albatrosses
nest
sideby sidein denseislandcolonies.
Theirbreeding
populations
centerin the
northwestern
Hawaiian
Islands,
withsmaller
colonies
scattered
across
thesubtropicalNorthPacific.
Bothspecies
visitnutrient-rich
waters
offthewestcoast
ofNorth
America
throughout
theyeartoforage.
Black-footeds
concentrate
incoastal
waters
fromnorthern
California
tosouthern
Alaska,
whileLaysans
frequent
moreoffshore
andnortherly
waters
in thisregion.
Bkders
onpelagic
tripsofftheWestCoast
often
encounter
significant
numbers
ofoneorbothofthese
species,
andsearching
for
other,
rareralbatrosses
among
themhasproven
tobeaworthwhile
pursuit
inrecen!
years
(Stallcup
andTerrill1996,
Cole2000).
Albatrosses
identified
asBlack-looted
x Laysan
hybridshavebeenseenand
studied
on Midway
Atollandothernorthwestern
Hawaiian
Islands
since
thelate
1800s(Rothschild1900,Fisher1948,1972).In addition,considerable
variationin
appearance
is foundwithinbothspecies,
indMduals
withstrikingly
aberrant
plumage
andsoftpartcolors
occasionally
being
encountered
(Fisher
1972,
Whittow
1993a).MidwayAtollhostsapproximately
two-thirds
of the world's
breeding A presumedhybridLaysanx Black-looted
Albatross
tendsa chickat Midway
Laysan
Albatrosses
(Fig.1) andone-third
of theworld's
breeding
Black-footedAtoll,14 February2000. Photograph
by PeterPyle.
Albatrosses.
These
populations
have
provided
uswithmany
opportunities
tostudy
ALBATROSS
andphotograph
presumed
hybrids
andunusual
individuals.
In thispaper,
wedis- BLACK-FOOTED
cuss
variation
in theplumages
of bothspedes
andtheappearances
of aberrant Worldwide,
theBlack-looted
Albatross
istheless
common
ofthetwospecies,
with
indMduals
andprobable
hybrids,
aswellasthepotential
pitfalls
toidentificationpopulation
estimates
ranging
from200,000
to300,000
individuals
(Whittow1993a,
thatsuch
birdsmaypose.
Ourobservations
arebased
ona collective
21months
on Cousins
& Cooper
2000).Adults
arriveatcolonies
in lateOc!ober,
fledging
takes
Midway
from1997to2000,in addition
tothestudy
ofthousands
of Black-footedplace
inlateJune
andJuly,
andadults
haveanincomplete
tocomplete
moltduring
andhundreds
ofLaysan
Albatrosses
atseaoffCalifornia.
April(non-breeding
individuals)
orJuly(breeders)
through
October.
Thisspecies
islargely
darkbrownatallages,
withwhiteshafts
totheouterprimaries.
Juveniles
have
whitish
bases
tothefeathers
encircling
thebillandtothose
feathers
in a crescentimmediately
undertheeye.Theresulting
paleareas
areobscured
atfledging,
resulting
in wholly
darkplumage
(Fig.2) butquickly
become
visible
withwear.
Fledglings
usually
show
well-developed
whiteareas
onthefacebythetimethey
reach
NorthAmerica
inlatesummer.
Wehaveseen
oneortwobreeding
adults
that
lacked
theeyecrescent
andshowed
limitedwhitearound
thebill,butthese
features
areobvious
onthevastmajority
of individuals
afterfledging.
Feather
edges
onthe
headbecome
veryfrayed
andbleached
onbirds
ofalllaterages
inthesummer,
and
thewhiteareacanencompass
mostoftheheadonsome
birdsinthisstate(Fig.3).
Adults
withheavily
bleached
heads
fromApriltoAugust
likelyrepresent
breeding
individuals
thathavespent
significant
timeatsubtropical
latitudes,
whereas
those
showing
less
bleaching
probably
areprebreeders
(ages
2-10ormoreyears)
orbirds
thatskipped
breeding
thatyearandremained
attemperate
or subarctic
latitudes,
thusbeing
exposed
toless
intense
sunlight.
Feather
edges
throughout
theneckand
underparts
alsobecome
bleached
andfrayed,
andonmanybirds
theedges
contrast
distinctly
withdarkfeather
bases
andcreate
ascalloped
lookoftanonbrown(see
Miller 1940).
Figure
1. Midway
Atollhostssignificant
portions
ofthebreeding
populations
of
bothBlack-looted
andLaysan
Albatrosses.
Presumed
hybrids
andaberrant
individuals
arefoundregularly
inthesedensecolonies.
Photograph
byPeterPyle.
VOLUME
56
(2002),
NUM.ER
2
Whiteleathering
develops
ontherump,uppertail
coverts,
lowerbelly,
vent,and
undertail
coverts,
anditsextent
hasbeenlinked
toageandsex(Streets
1877,
Bourne
1982,Pyleunpubl.
data),oldmales
beingwhitest.
Birdsshowing
areas
of white
131
Figure2. Juvenile
Black-tooted
Albatross
nearfledging.
Paleareasare
alreadydeveloping
ontheface,beforeallthedownis lost.MidwayAtoll,
June1999. Photograph
by PeterPyle.
Figure3. Anexceptionally
wornandbleached
adultBlack-tooted
Albatross.
Thebillis nearthe paleextremeforthe species.Photographed
in Monterey
Bay,offSantaCruz,California,
15 October
2000.Photograph
byMichael
Donahue.
Figure4. A striking
leucistic
Black-tooted
Albatross
in Monterey
Bay,
California,
18 September
1988.Thebillshapeeliminates
Southern
GiantPetrelandLaysan
Albatross;
the birdalsoshowsa shadowof the Black-tooted'sfacialpattern.Photograph
by SergeLaFrance.
Figure5. A leucistic
Black-tooted
Albatross
onTernIsland,Hawaii,January
1993. Bocumented
detailsof the wingandtail patternindicatethatthisis
thesameindividual
as presented
in Figure4, photographed
severalyears
earlier.Photographs
fromU.S. FishandWildlife
Servicefiles.
132
Figure6. Leucism
oftenappearsin patches,
as inthisBlack-tooted
with
whiteouterprimaries
anda whitestripacrossthe belly;notealsothe pale
splotching
onlhefeet.Thefacialpatternistypicalofadults.Midway
Atoll,
23 June2000.Photograph
by PeterPyle.
NORTH
AMERICAN
BIRDS
Black-looted
and Laysan
Albatrosses
elsewhere
onthebodyduetoleucism
areveryrarebuthave
beenphotographed
in
several
locations
(e.•, Figs.
4, 5,and6).In extreme
cases,
suchasthemostly
white
birdinFigures
4 and5,thiscancreate
anappearance
reminiscent
ofalight-morph
Southern
Giant-Petrel
(MacroheRes
giganteus).
Thedistinctive
bill structure
of
MacroheRes
withexternal
nasal
tubes
atoptheculmen,
consistently
distinguishes
thisgenus
fromallalbatrosses
(Harrison
1983).Roberson
(1980)mentioned
white
in therectrices
andlightdusky-yellow
feetonsome
birds.Wehaveseenpalecolorationin theseareas
onlyon obviously
leudstic
Black-footeds,
soit doesnot
appearto be age-related.
Similarly,
paleunderwings
applyonlyto presumed
hybrids
andleucistic
birdsin ourexperience.
SuchbirdswerenotedbyStallcup
(1976),
whofeltthatit wasage-related,
andbyRoberson
(1980),
whoconsidered
it
a feature
of aberrant
birdsorhybrids.
Theappearance
of indistinct
paleareas
can
alsobecreated
bytheexposure
offeather
bases
ofbirdsinheavy
moltinearlysummeen
TheBlack-footed's
billisblackish,
usually
witha pinkish
tingeofvarying
intensityatthebase.
Thiscoloriswelldeveloped
insome
individuals
ofbothsexes,
makingthebillappear
fairlybrightpinkwitha blackish
ordarkgraynail(Fig.3),espe- Figure7. JuvenileLaysanAlbatross,
showingwhiteauriculars;
adultbillcolor
cially
inbrightsunlight.
Pink-billed
birdsmaycause
confusion
withjuvenile
Short- beginsto developnearfledging.MidwayAtoll,June1999.Photograph
by
tailed
Albatross
(P..albatrus),
whichhasa considerably
larger
bill.ThebillofShort- PeterPyle.
tailed
isdarkatfledging
(H.Hasegawa,
pers.
comm.
toPyle),
buteventually
itdevelopsa brightpinkbaseandpalebluetip.Thetimingof thischange
isunknown.
Largelydark,pink-billedbirdsphotographed
off Californiain Octoberto
December
have
beenregarded
asjuveniles
(e.g.,Stallcup
andTerrill1996,
N.A.B.52:
203),butthese
birdsshowworn,retained
feathers,
suggesting
thatthesecond
prebasic
molthastakenplace.Pink-billed
birdsphotographed
in Oregon
in March
(N..A.B.
55:506)andCalifornia
inlanuary(McKee
andErickson,
in press)
mayin
factbejuveniles,
butageing
criteria
inthisspedes
arestillundeaen
Short-tailed
Albatrosses
slowly
acquire
anextensively
whiteadultplumage
(cf.
Roberson
1980,
Erickson
andHamilton
2001).Paleareas
ontheupperwing
coverts
canbeamong
thefirstsigns
ofthistransition
inShort-tailed,
butit should
benoted
that the innermostgreatercoverts,tertials,and humeralson Black-looted
Albatrosses
havepalerinnerwebs.
Whenworn,thispatchof feathers
cancontrast
withtheremainder
of theupperwing,
creating
an appearance
similarto Shorttailed.
LegandfootcolorofBlack-looted
usually
isblackish
ordarkgray.
Wehave
foundseveral
individuals
withirregular
palesplotching
onthelegsandfeet(e.g.,
Fig6; these
birdsoftenshowieucistic
plumage
aswell),butin no casewasthis
extensive
enough
toresemble
theentirely
pinkfeetofjuvenile
Short-taileds.
Figure8 A Laysan
withratherpaleunderwings,
showing
narrowblack
margins.MidwayAtoll,May1999. Photograph
by Tristar/McKee.
LAYSANALBATROSS
Although
abouttentimesmorenumerous
thantheBlack-looted
Albatross,
witha
worldpopulation
estimated
at 2.5 millionbirds(Whittow1993b),the Laysan
Albatross
isnotencountered
asfrequently
dosetotheNorthAmerican
continent.
Laysans
alsoarrive
atbreeding
colonies
inNovember,
fledge
young
inJulyandearly
August,
andhaveanannualincomplete
to complete
moltfromAprilto October.
Thisspecies
wasnamedimmutabilis,
meaning
unchangeable,
because
ofitslackof
obviously
different
innnature
andadultplumages
(Jobling
1991).Whileit istrue
thatage-related
variation
is subtle,
thisspecies
nonetheless
shows
a considerable
amount of individual variation.
Laysans
atfledging
arewhitethroughout
theheadandunderparts,
witha small
blackpatch
surrounding
theeye(Fig.7).Theylackthegraywashacross
theauricularsof adultbirds(Fig.8). Theexacttimeatwhichgrayin thefacedevelops
is
unknown.
Procellariiformes
typically
donotmoltbetween
fiedging
andthesecond
prebasic
molt(see
Howell
andCotben
2000)during
thefollowing
breeding
season,
sograyauriculars
arenot likelyacquired
beforethen. Our observations
off
California
confirm
thatjuveniles
canremain
white-faced
atleastuntilDecembeen
Thegraywash
normally
isquiteevident,
though
variable,
bythetimebirdsreturn
tocolonies,
manyofwhicharethreetofouryears
old(bands
examined).
Ageing
is
notalways
straightforward
atsea,
because
thegray
wash
ofadults
canbedifficult
to Figure9. A Laysantowardthe darkendof the spectrum,
withblackareas
discern
inbright
sunlight.
Itsextent
alsoisreduced
bywear,
andsome
birds
takeon mergingonthe underwings.
MidwayAtoll,February
2000. Photograph
by
afacial
pattern
likethatofthejuvenile
bylatesummer,just
before
theprebasic
molt. Tristan McKee.
Theheavily
wornmantle
feathers
ofthese
birdsreadily
distinguish
themfromfresh
VOLUME
56
(2OO2),
NUMBER
2
133
Figure10.A leucistic
Laysan
Albatross,
nearfledging
at MidwayAtoll25
June1999.Oneortwomostlywhitechicksarefoundalmosteveryyearon
Midway.Photograph
byPeterPyle.
juveniles.
All ageshavea darkbrownback,upperwings,
andrearices
andshow
whiteshafts
totheouterprimaries.
Thebillisdarkgrayish
onyoung
chicks,
buta
dullpinkbase
andbluish-gray
nailbegintodevelop
before
fledging.
Theunderwing
pattern
ofthisspecies
usually
isdistinctive,
butthereissubstantialvariation
in theamount
of blackversus
white(National
Geographic
Society
1999,Sibley
2000).Preliminary
observation
of known-age
birdsonMidwayhas
indicated
thatunderwing
variation
isnotstrongly
related
toage,
butmorestudy
is
needed
toconfirm
this.Black
ispresent
ontheleading
edge
oftheunderwing,
the
flightfeathers,
theprimary
coverts,
andusually
inatriangular
patch
onthehumerals.Nearthepalest
extreme
forbirdsthatotherwise
appear
normal(butcf.leucisticbirds),
theblack
borders
areverynarrow
andthehumeral
patch
limitedtoa few
blackish
streaks
oragrayish
shadow.
Thehumeral
patch
isabsent
orinvisible
inthe
fieldonafewbirds,
whichappeared
torepresent
less
than0.01%oftheoverall
populationat Midway.They couldcreateconfusion
with the ShyAlbatross
(Thalassarche
cauta)
complex
(Cole2000),butsize,
structure,
andbillshape
differences
areeasily
visible
andshould
beusedto confirm
anyShyAlbatross
in the
North Pacific.
Toward
thedarker
sideoftheunderwing
spectrum,
theblack
areas
merge,
sometimestotheextent
thatwhiteislimitedtotheoutersecondary
coverts
(Fig.9, cf.
Fig.20).A fewindividuals
showno whiteontheunderwing,
witheithera gray
shadow
ofthelatterpattern
orentirdydarkunderwings.
It isnotknownwhether
these
areatthedarkextreme
forthespecies
orif thisisstrictly
theresult
ofintrogression
withtheBlack-footed
Albatross
(seebdow).Theamount
ofdarkonthe
rumpisalsovariable
andoftenloosely
mirrors
thatoftheunderwing.
Thedarkest
birdshavea darkrumpwithonlya thinU-shaped
whiteareaontheuppertail
coverts,
contrasting
withthedarktail,whilethepalest
show
a straight
lineofcontrast,
evenwiththetrailing
edge
ofthewings,
between
thedarkbackandanentirelywhiterump.Mostbirdsfallbetween
these
twoextremes,
showing
apatchy
dark
areaextending
intothecenter
ofanextensively
whiterump(Fig.20).Laysans
show
a variable
amount
ofdarksmudging
around
thethighs,
whichisdiscussed
bdow.
Asin Black-footeds,
leucism
andotherplumage
aberrancy
isoccasionally
noted
In Laysans.
Oneor twomostly
whitechicks
(e.g.,Fig.10)arefoundonMidway
almost
every
year,
andsomehavebeenfollowed
tofledging,
butnonehavebeen
knownto returnasadults.These
birdsagaincouldcause
confusion
withgiantpetrels
untilbillstructure
isnoted.Billstructure
alsoisanimportant
feature
for
determining
which
ofthePhoebastria
isinvolved
whendealing
withleucistic
birds:
Figure11. Laysan
Albatross
chicksshowing
a scalyor barredpatternto the
withexperience,
theshorter,
thicker
billofBlack-footed
isdistinguishable
inthefidd
upperparts,
anotherregularoccurrence
in largecolonies.
Thebirdontheleft
fromtherelatively
slimmer
billofLaysan,
whichshows
a moreconcave
culmen
(cf.
wasphotographed
at MidwayAtoll,21 May1997,thebirdat right30 May
Figs.
6 and13).Figures
11,12,and13illustrate
some
of theotherwaysleucism
1993.Photograph
byPeterPyle(left)andfromU.S.FishandWildlife
Service and/or
othertypes
ofplumage
aberrancy
canbemanifested
inthisspecies.
A varifiles(right).
ablean•ount
ofgrayorwhitish
inthemantle
feathers,
ofteninauniform
pattern,
is
themostcommonly
encountered
example.
Thiscaninvolve
ascaly
pattern
ofcontrasting
feather
edges,
various
internal
bars,or darkanchor-shaped
markings
on
pale-based
feathers.
Fisher
(1972)described
suchbirds,
andwehavefounda small
number
regularly
onMidway.
Such
plumages
maybecaused
byschizochroism
(the
lackofapigment
throughout)
ordilution
(reduction
inquantity
ofapigment),
but
thespecific
cause
is difficultto determine
withoutprecise
genetic
information
(Buckley
1969;
E A.Buckley,
pets.comm.).
Indistinct
white
bars
ondarkfeathers
areparticularly
common
inchicks
(Fig.! 1)
andmaybe
exaggerated
growth
bars
resulting
frommetabolic
changes
during
feathergrowth
(see
Michener
andMichener
1938).
Theadultin Figure
12takes
grayin
themantle
totheextreme.
Several
aberrant
Laysans
onMidway
havereturned
to
specific
areas
yearafteryear,
retaining
thesame
patterns
ofabnormal
pigmentation
through
repeated
molts.
Theunusual
coloration
of thebirdin Figure13isevident
in boththeplumage
andthesoftpartxThebillisexceptionally
brightpink,thegraywash
islacking
on
theface,
andtheupperparts
show
a considerable
amount
ofwhite.
Thisbirdsuper-
resembles
a near-adult
Short-tailed
Albatross
in coloration,
butsizeand
Figure
12.Aberrant
Laysan
Albatross.
Suchbirdscanshowa palegrayshadow ficially
features
identify
it readily.
of thetypicalLaysan
underwing
patternof darkmargins
andhumerals.
Midway structural
Atoll,April1993.Photograph
fromU.S.FishandWildlife
Service
files.
134
NORTH
AMERICAN
BIRDS
Black-footed
andLaysanAlbatrosses
HYBRIDS
In 1997-2000,
we observed
up to 20 different
presumed
first-generation
(F])
hybrids
onMidway.
Although
nohybridbetween
these
species
hasyetbeenconfirmedgenetically
or throughparentage,
presumed
hybrids
are intermediate
between
Black-looted
andLaysan
inplumage,
soft-part,
behavioral,
andvocal
characters
(Fisher
1972),
andtheywouldbedifficult
toexplain
asresulting
fromvariationin eitherparental
species.
Asalsoreported
byFisher(1972),all presumed
hybrids
weobserved
wereinteracting
withLaysan
Albatrosses,
manybeingfound
among
thepureLaysan
populations
inthecentral
portions
oftheislands.
Wehave
witnessed
maleBlack-looted
Albatrosses
involved
in "rapes"
(Fisher1971)of
female
Laysans,
and,contra
Fisher
( 1948,1972),
webelieve
thathybrids
between
the
twospecies
aremostlikelyproducts
of these
extra-pair
copulatory
events
rather
thanofnaturally
occurring
mixedpairs,
something
wehaveseen
noevidence
ofon
Midway.
Thiswouldexplain
whyhybrids
seemed
to beimprinted
uponLaysan
ratherthanBlack-looted
Albatrosses:
theywerelikelyraised
bya pairof Laysans,
themaleunwittingly
notthefather.
Wehaveseenoccasional
attempts
atinterspecificcourtship
dancing,
butthese
rarely
lasted
morethana fewseconds
(seealso
Whittow1993b).
It should
benoted,
however,
thatFisher
(1971)examined
Laysans
afterintraspecific
extra-pair
copulatinn
andfoundnophysical
evidence
ofsuccessfidcopulation.
Because
oftheintermediate
nature
oftheirdisplays,
mostattempts
ofhybrids
at
courtship
withLaysans
appear
unsuccessful.
Weobserved
twopresumed
hybrids
incubating
eggs
andraising
chicks
withLaysan
mates
during
the1999-2000
season
(frontispiece);
hybrids
havebeenobserved
oneggs
onseveral
otheroccasions.
The
chicks
fromthesepairings
appeared
to havethickerbillsanddarkerfirst-basic
plumage
thanLaysan
chicks
fromadjacent
nests.Bloodfromhybrids
andthese
apparent
F2 (second-generation)
back-crosses
hasbeentakenbyU.S. Fishand
Wildlifebiologists
forDNAsampling
(N. Hoffman,
pers.comm.).If confirmed,
thiswouldrepresent
thefirstdocumented
record
ofa hybrid
albatross
successfully
breeding
(cf.Whittow1993b),
although
ourobservations
ofsuspected
back-crosses(seebelow)
indicate
thatthisprobably
hasoccurred
before.
Actual
parentage
is
difficult
toconfirm
inthefieldbecause"adoption"
ofvarious
objects,
indudlng
displaced
eggs
andyoung
chicks,
iscommon
in these
dense
colonies.
Mostpresumed
FI hybrids
arequitedistinctive,
withstrong
graytones
setting
themapartfrombothspecies
(Figs.14,15,16,17).Structural
andbehavioral
fea- Figure13. ThisLaysanshowsreducedpigmentin boththe plumageandsoft
resemblance
to a subadultShort-tailed
Albatross
tures,
softpartcolors,
courtship
displays,
andvocalizations
arevariably
intermedi- parts;notethe superficial
MidwayAtoll,8 February
2000.Photograph
byPeterPyle.
ate.Thehead
andneck
aregrayonmostbirds,
varying
froma palepearlgraytoa
dark,smoky-brown
color.
Whiteareas
around
thebillandundertheeyeareoften
moreextensive
anddiffused
attheedges
thanonfresh
Black-footeds,
giving
theface
a frosty
appearance.
Thegraywash
ontheneckcangivewaytowhiteonthebreast
or continuedownontothelowerbreast,
sides,
andflanks.Theundertaft
coverts
and
lowerflanks
oftenshow
somedarkgray,
evenonpalehybrids.
A largewhitearea
remains
onthebelly,
usually
moreextensive
thanonBlack-footeds.
Thegrayish
headandunderpart
colorof evenmostdarkhybrids,
suchasthe
birdinFigure
16,isdistinguishable
fromthedarkbrownofBlack-foote&
Figure
19
shows
theonlyhybrid-like
birdwehaveonrecord
in whichthedistinction
from
Black-looted
wasunclear.Withoutbehavioralinformation,thisbird'sidentification
mustbeleftunresolved.
Thelinebetween
palehybrids
andLaysans
isless
dear.We
haveencountered
asmallnumber
ofadults
thatappear
tobeintermediate
between
hybrids
andtypical
Laysans.
Individuals
suchastheonedepicted
in Figure18,
which
showed
extensive
darksmudging
ontheflanks,
averyl•aint
graywash
onthe
head,
andverydarkunderwings,
maybeF2back-crosses.
In 2000,wewereableto
follow
oneofthechicks
attended
byanadulthybrid
anda pureLaysan
through
to
fledging,
andit resembled
thebirdin Figure18 in itsextent
ofextralimital
darkness.
On theotherhand,suchbirdscouldrepresent
anomalous
plumages
or
extremes
in variation
amongpurebirdsorhybrids.
Wehaveobserved
similar
indi-
viduals
withmoreextensively
darkbellies
orslightly
darker
heads
thanthisbird,so
thereisnoclear
lineseparating
"typical"
grayhybrids
frompalerindividuals.
We
hybrid
witha contrasting
grayheadandbreastand
havealsoseen
birdsthatareslightly
palerandmoreLaysan-like
thanthebirdin Figure14.Thisisa "classic"
whiteunderparts.
Thisbirdsharedincubation
dutieswitha Laysan
Figure18,making
thedarkextreme
in "pure"
Laysans
difficult
to pinpoint.
The extensively
Albatross
in December
1999at Midway.Photograph
byJenniferW.
Schramrn.
VOLUME
56
(zoOz),
NUMBER
2
135
amount
of darksmudging
onthethighs,
flanks,
andundertail
coverts
of Laysan
showsa considerable
amountof variation.UnlikeWhittow(1993b),wehavefound
noevidence,
based
onexamination
ofknown-age
birds,
thatthissmudging
ismore
extensive
onjuveniles
thanadults.
Thereappears
to bea continuous
gradation
or
overlap
between
typical
Laysans
andsuspected
back-crosses
inbothflankcolor
and
underwing
pattern
(Fig.20),andtheincreased
pigmentation
ofmostnotably
dark
individuals
isevident
inbothareas.
Birds
retaining
thepurewhitehead,
belly,
and
upperflanks
andsomepattern
ontheunderwing
probably
fallwithintherange
of
variation
ofpureLaysans,
butthose
showing
moreextensive
darkness
aredifficult
tocategorize.
Hybrids
alsopresent
apotential
source
ofconfusion
withotheralbatross
species.
George
Watson
(inWahl1970)discussed
theidentification
ofthese
birdsincom-
Figure15. Presumed
hybridstypicallyassociate
withLaysanAlbatrosses.
Thisbirdshowsa fairlyevengraywashthrough
theheadandunderparts.
MidwayAtoll,March1999. Photograph
by Tristan
McKee.
parison
withanimmature
Short-tailed
Albatross
photographed
offWashington,
dtingwhitefeathers
ontheunderwings
andthedarker
billandfeetofhybrids
(see
alsoRoberson
1980).OlderShort-taileds
develop
paleunderwings,
butlikeBlacklooted,
theyalways
lackthedistinctive
graycastofhybrids.
Sizeandstructural
featuresarealsodiagnostic.
Although
Wahllaterexpressed
doubts
abouttheidentity
oftheWashington
bird(Helm1980,
Roberson
1986),
wefeelthattheplumage
patternandstructural
features
visible
inthephotograph
strongly
support
hisoriginal
conclusion.
Ontheotherhand,
weconcur
thatthephotograph
published
inHelm
(1980),originally
identified
asa Short-tailed
butlaterasa Black-footed
or Blackfooted
x Laysan
hybrid
(Roberson
1986),
isawornBlack-footed.
Thisbird's
neck,
Figure18.Thisbirdshowsa veryfaintgraywashto theheadandextensive
darksmudging
ontheflanks;
it maybeanF2 backcross.
Determining
the
darkextremefor pureLaysansis problematic.
MidwayAtoll,April1999.
Figure16. Although
thispresumed
hybridis at the darkextreme,the grayish Photograph
by Tristan
McKee.
castto the headstilldistinguishes
it fromBlack-footed.
MidwayAtoll,March
2000. Photograph
by Tristan
McKee.
Figure17.A muchpalerpresumed
hybrid,
showing
a pearl-gray
washonthe
headandbreast.MidwayAtoll,March2000.Photograph
by Tristan
McKee.
136
Figure19.Unidentified
albatross
onLaysan
Island,
February
1995.Thisbird
superficially
resembles
othersuspected
hybrids,
buttheheadandneckare
brownish,
closerin colorto Black-footed.
Thebluishbilltip,palefeet,and
extentofwhiteonthebellyareunusual
inourexperience
forBlack-footed
but
mightappearona leucistic
bird.Notealsothelackofgrayintheauriculars,
normally
present
inadultLaysans
andpresumed
hybrids.
Photograph
from
U.S. Fish and WildlifeService files.
NORTH
AMERICAN
BIRDb
Black-footed
andLaysanAlbatrosses
Figure
20. Underwing
andrumppatterns
ofLaysan
Albatrosses
andpresumed
hybridsLaysans
thatareapparently
"pure"canshowanyoftheseunderwing
patterns,
although
(1)isextremely
rareand(4)maysuggest
intregression
withBlack-footed
insomecases.Mostpresumed
F•hybrids
showpatterns
similar
to(3)and(4)orevendarker.Allthreerumppatterns
arecommon
in Laysan,
whilehybrids
tendto beclosest
to (C). Sketch
byTristan
McKee.
species.
ThetailsofBlack-browed
andGray-headed
aregrayish
when
breast,
andupperbellyareconsiderably
darker
thananyhybrid
wehaveencoun- Phoebastria
andHiggins1990),whilehybrids
share
thedarkbrowntailsof
tered,
andthebillcolor,
headpattern,
andextent
ofwhiteonthelowerunderparts fresh(Marchant
Black-looted
andLaysan.
Wornbirdsofbothgenera
havesimilarly
dark,brownish
appear
tobewithintherange
ofvariation
ofBlack-footed.
Atfirstglance,
hybrids
mayrecall
gray-headed
forths
oftheShyAlbatross
com- tails. Good viewsof a combination of thesefeaturesshouldallow the identification
allbirds.Observers
arestrongly
encouraged
to photographically
docuplex,
buttheirunderwing
patterns,
aswellassize
andstructure,
should
prevent
con- of nearly
albatrosses
appearing
offNorthAmerica,
including
suspectfusion.
Morecritically,
manypresumed
hybrids
showa superficial
resemblance
to mentany"gray-headed"
tinmature
Black-browed
(Thalassarche
mdanophr?s)
andGray-headed
(T.chrysos-edBlack-looted
x Laysan
hybrids,
which
toourknowledge
have
notyetbeen
docuroma)
Albatrosses.
Theunderwing
pattern
ofsome
hybrids
maintains
arecogniza-mented near the continent.
being
large
andgenerally
easy
toidentify,
albatrosses
show
complex
agebleresemblance
tothe"average"
Laysan
pattern,
butothers
retainonlyanindistinct Despite
andgeographic
variation
intheirplumages.
Thiscancause
confusion,
espepalestripontheunderwing
coverts
(e.g.,
seeFig.2in Fisher
1972),
appearing
near- related
whenencountered
intheir,butnotour,element:
roughseas.
It does
nothelp
ly identical
todarkimmature
Black-browed
andGray-headed
Albatrosses
in this cially
stablespecies,
the Black-footed
andLaysan
respect.
Theheadpattern
ofhybrids
canbea close
match
forthese
species
aswell, thattwo of the moregenetically
showextensive
individual
variation,
whichisfurthercomplicated
by
although
thetwosouthern
species
aremorelikelyto retaina darkpartialcollar, Albatrosses,
hybridization.
Wehopethispaper
willstimulate
others
tocontinue
todocwhilehybrids
usually
showsome
suggestion
of theBlack-footed's
fadalpattern. apparent
variation
inalbatross
plumages
throughout
theseven
seas.
Thalassarche
species
differnoticeably
atseafromPhoebastria
intheirgreater
caudal umentandunderstand
projection,
thatis,longer
projection
ofbodyand
tailbehind
thetrailing
edge
ofthe
wings
(S.N. G.Howell,
pers.
comm.).
Thefeetoftheformer
donotextend
notice- Acknowledgments
special
thanks
tothepeople
ofMidway,
including
U.S.FishandWildlife
ablybeyond
thetailtip.ThefeetofNorthPacific
Phoebastria
project
wellbeyond Weextend
personnel
RobShailenberger,
KenNeithammer,
NanetteSeto,Nancy
thetailtipwhentheyareextended,
butthese
species
oftenflywiththefeettucked Service
andAaronGallagher,
aswellasBirgitWinningof the
intothecontour
feathers.
Another
important
feature
isrumpcolor,
whichispure Hoffman,KeithLarson,
Society,
whoall facilitated
ourpresence
andworkon theatoll.We are
whitein Black-browed
andGray-headed
(Morlan1985,Marchant
andHiggins Oceanic
toDebraShearwater,
whohasmadeit possible
forustospend
a consid1990).Onlythepalest
Laysans
show
thispattern,
andwehavenever
seen
a hybrid indebted
California
studying
albatrosses
on Shearwater
withouta noticeable
intrusionof darkontothe upperrump (cf. Fig.20). erableamountof timeoffshore
trips;shealsoprovided
valuable
photos
forusein thispaper.
Wethank
Considering
thatoldmaleBlack-footeds
canalso
bewhite-rumped,
however,
this Journeys
RichStallcup,
MichaelDonahue,
Jennifer
Schramm,
James
Aliberti,andthe
pattern
isnotinconceivable
onhybrids.
Hawaiian
Islands
National
WildlifeRefuge
forcontributing
useful
Otherpotentially
useful
features
toexamine
onconfusing
birdsareexact
billand Northwestern
andpermission
topublish
them,andwearemostgrateful
toCindy
tailcolors.
Veryyoung
Black-browed
andGray-headed
Albatrosses
initially
show photographs
forgranting
permission
forusto usethephotograph
of thelateSerge
blackish
bills,butbirdsofthisageareunlikely
tobeencountered
inNorthAmerica. LaFrance
KimballL Garrett,
Steve
N.G.Howell,HiroshiHasegawa,
andJoseph
Thebillof Black-browed
quickly
develops
a dullpinkish
castatthebase,
before LaFrance.
discussion
or information
relating
to
changing
toyellowish
orhornwitha darktip (S.N. G.Howell,
pets.comm.;
cf. Smithhaveaddedhelpfulandinteresting
species.
Steve
N. G.HowellandE A.Buckley
reviewed
drafts
ofthemanuPatteson
etal.1999).Duringthebriefperiod
whendullpinkisevident,
thebill these
andadded
manyhelpful
suggestions.
appears
verysimilarto that of presumed
Black-footed
x Laysan
hybrids. script
Developing
yellow
orhorncoloration
isindicative
ofBlack-browed,
butbeware
of
hybrids
illuminated
bylow-angle
sunlight,
which
canappear
tohave
yellow
tintsto Literaturecited
Albatross.
theirbills.Gray-headeds
develop
yellowish
orhorncoloration
alongtheculmen Bourne,W.R.E 1982.The colorof the tail covertsof the Black-footed
Sea Swallow31: 61.
andat thetip of themaxilla,
a patternthatis easily
distinguished
fromthatof
VOLUME
56
(2002),
NUMBER
2
137
Buckley,
P.A.1969.
Genetics.
Pp.23-43,
in:Diseases
inCage
andAviaryBirds,
ed.M.L.Petrak.LeaandFebiger,
Philadelphia.
Cole,LW.2000.A firstShyAlbatross,
Thalassarche
cauta,
Sibley,
D.2000.TheSibley
Guide
toBirds.
Alfred
A.Knopf,
NewYork.
Stallcup,
R.W.1976.
Pelagic
birdsofMonterey
Bay,
California.
Western
Birds
7:113-136.
Stallcup,
R.,andS.Terrill.
1996.
Albatrosses
andtheCordell
Bank.
Birding
28:106-110.
Streets,
T.H. 1877.
Contributions
tothenatural
history
oftheHawaiian
andFanning
islands
andLower
m California and a critical re-examinationof Northern
California.
Bulletin
oftheUnited
States
Natural
History
Museum
7:1-172.
Hemisphere
recordsof the formerDiomedea
cauta Wahl,
T.R.1970.
A Short-tailed
Albatross
record
fromWashington
State.
California
Birds
1:113-115
complex•
NorthAmerican
Birds
54:124-135.
Whittow,
C.1993a.
Black-looted
Albatross
(Diomedea
nigripes).
In:TheBirds
ofNorthAmerica,
No 65
Cousins,
K.,andJ.Cooper.
Thepopulation
biology
ofthe
(A. PooleandE Gill,eds.),Philadelphia
Academy
of NaturalSciences
andthe American
Black-footed
Albatross
in relation
to mortality
caused
Ornithologist's
Union,
Washington,
D.C.
by longline
fishing.
Western
Pacific
Regional
Fishery Whittow,
C.1993b.
Laysan
Albatross
(Diomedea
immutabilis).
In:TheBirds
ofNorth
America,
No.66(A
Management
Council,
1164Bishop
St.,Honolulu,
HI
Poole
andE Gill,eds.),
Philadelphia
Academy
ofNatural
Sciences
andtheAmerican
Ornithologist's
96813.120pp.
Erickson,
R•.• andR.A.Hamilton.
2001.Reportof the
California Bird Records Committee: 1998 Records.
Union,
Washington,
D.C.
z•
WesternBirds 32: 13-49.
Fisher,
H.I. 1948.Interbreeding
of Laysan
andBlackfootedalbatrosses.
Pacific
Science
2:132.
Fisher,
H.I. 1971.TheLaysan
Albatross:
itsincubation,
hatchingand associated
behaviors.
LivingBird10:
19-78.
F•sher,
H.I. 1972.Sympatry
of Laysan
andBlack-footed
Albatross.Auk 89:3 81-402.
Harrison,P. 1983.Seabirds,
An Identification
Guide.
Houghton
Mifflin,Boston.
Helm, R.C. 1980.A Short-tailed
Albatross
off California.
WesternBirds 11: 47-48.
Howell,
S.N.G.,
andC.Corben.
2000.A commentary
on
moltandplumage
terminology:
implications
fromthe
Western Gull. WesternBirds31: 50-56.
Jobling,
J•. 1991.A Dictionary
ofScientific
BirdNames.
Oxford
University
Press,
Oxford.
Marchant,S., and P.J.Higgins,co-ordinators.
1990.
Handbook
of Australian,
NewZealandandAntarctic
B•rds Volume 1: Ratitesto Ducks,Part A. Oxford
University
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Oxford.
McKee,T., andR. A. Erickson
In press.
Reportof the
Cahfornia Bird Records Committee: 2000 records.
WesternBirds33.
Mlchener,
H., andJ.R.Michener.
1938.Barsin flight
feathers. The Condor40:149-160.
Miller, L. 1940. Observationson the Black-footed
Albatross.The Condor42:229-238.
Morlan,J. 1985.Eighthreportof the California
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National
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1999.FieldGuide
totheBirds
ofNorthAmerica,
3rded.National
Geographic
Society,
Washington,
D.C.
Patteson,
J.B.,M. A.Patten,
andE.S.Brinkley.
TheBlackbrowed
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NorthAmerican
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138
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