Bulletin of The British Ornithologists' Club 1991 111:139-140
40027604

TAXONOMIC STATUS OF THE SWORD-BILLED HUMMINGBIRD ENSIFERA-ENSIFERA-CAERULESCENS

G R Graves
G.R.Graves
139
Bull.
B.O.C.
1991
111(3)
Taxonomic
status
of
the
Sword-billed
Hummingbird
Ensifera
ensifera
caerulescens
by
Gary
R.
Graves
Received
24
November
1990
Ensifera
ensifera
caerulescens
(Lowe,
1939)
was
described
from
an
unique
specimen
in
the
Royal
Albert
Memorial
Museum,
Exeter.
According
to
Lowe
(1939:
73)
the
new
taxon
is
distinguished
by
"its
smaller
dimen-
sions
and
by
having
the
sides
of
the
neck
and
band
across
the
chest,
when
held
to
the
light,
bright
metallic
blue".
Walters
(1986)
was
apparently
the
first
since
Lowe
to
critically
examine
the
type.
He
confirmed
Lowe's
diagnosis
and
concluded
that
caerulescens
may
be
a
valid
taxon
and
that
there
was
no
reason
to
suppose
that
the
colour
was
due
to
an
aberration.
As
part
of
a
comprehensive
review
of
Sword-billed
Hummingbird
sys-
tematics
I
examined
the
type
of
E.
ensifera
caerulescens.
Here
I
present
evidence
that
casts
doubt
on
its
taxonomic
validity.
The
specimen
is
a
taxidermy
mount
with
head
and
bill
tilted
upwards
to
the
left;
the
left
side
of
the
neck
and
upper
breast
are
slightly
concealed
from
view.
The
plumage
is
faded,
especially
the
throat
and
breast.
When
male
specimens
of
nominate
E.
ensifera
are
viewed
head-on
in
direct
light,
the
lower
throat
is
bordered
posteriorly
from
shoulder
to
shoulder
by
a
brilliant
green
pectoral
band.
In
caerulescens,
the
colour
of
the
pectoral
band
is
bluish-green
(changing
with
the
angle
of
inspection)
on
the
exposed
right
side,
becoming
slightly
greener
on
the
concealed
left
side.
The
feathers
that
reflect
the
bluest
light
when
viewed
head-on
are
violet
or
bluish-violet
in
indirect
light.
These
are
asymmetrically
distributed;
about
twice
as
many
violet
feathers
occur
to
the
right
of
the
ventral
mid-
line
as
to
the
left.
When
viewed
under
a
7-30
x
stereo
microscope
the
bases
of
violet
feathers
that
are
concealed
by
overlapping
feathers
are
green
as
in
nominate
E.
ensifera.
In
other
words,
only
portions
of
the
pectoral
feathers
that
are
exposed
to
light
are
violet.
The
asymmetric
distribution
of
blue
or
violet
feathers
strongly
suggests
that
the
distinguishing
character
of
caerulescens
is
an
artifact,
possibly
the
result
of
exposure
to
light.
The
occurrence
of
unfaded
feather
bases
in
the
affected
area
corroborates
that
possibility.
In
sum,
the
evi-
dence
indicates
that
the
distinguishing
character
of
E.
e.
caerulescens
Lowe,
1939
is
due
to
postmortem
change.
It
should
thus
be
placed
in
the
synonymy
of
Ensifera
ensifera
(Boissoneau,
1839).
Acknowledgements
I
am
grateful
to
Kelvin
Boot,
Curator
of
the
Royal
Albert
Museum,
for
lending
the
type
of
E.
e.
caerulescens
and
to
the
United
States
Department
of
State
for
safely
transporting
it
to
Washington.
I
thank
Richard
Banks
for
commenting
on
the
manuscript
and
Banks,
Ralph
Browning,
and
Richard
Zusi
for
examining
the
specimen.
References:
Lowe,
W.
P.
1939.
The
bird
collections
in
the
Royal
Albert
Memorial
Museum,
Exeter.
Ibis
(14)3:65-75.