Bulletin of The British Ornithologists' Club 2010 130(4):286-301
47499910

A new taxon of Collared Petrel Pterodroma brevipes from the Banks Islands, Vanuatu

Vincent Bretagnolle, Hadoram Shirihai
Vincent
Bretagnolle
&
Hadoram
Shirihai
298
Bull.
B.O.C.
2010
130(4)
(i)
Biometrically,
P.
b.
magnificens
is
smaller
(especially
culmen,
tarsus
and
wing)
than
other
P.
brevipes
populations,
(ii)
Its
plumage
is
unique
within
the
P.
brevipes
complex
in
being
monomorphic,
and
40%
darker
than
any
dark
morph
of
P.
brevipes.
(iii)
It
apparently
breeds
in
the
austral
summer
(but
see
above),
unlike
all
other
P.
brevipes
populations
known
to
date.
Without
comparative
molecular
analysis
and
playback
experiments
between
P.
b.
magnificens
and
other
P.
brevipes
populations,
it
is
impossible
to
exclude
either
of
Helbig
et
al/s
(2002)
categories
4.1
(full
species)
or
category
4.2
(allospecies).
We
conservatively
rank
P.
b.
magnificens
as
a
subspecies
of
P.
brevipes
pending
acoustic
or
molecular
studies
of
the
entire
P.
brevipes
/
lencoptera
complex
to
be
completed.
Although
the
subspecies
rank
appears,
to
some
extent,
to
be
falling
out
of
'favour'
in
avian
taxonomy,
we
favour
such
a
conservative
designation
in
this
case.
We
also
emphasise
that
our
recent
molecular
work
on
several
petrel
complexes
(Gangloff
et
al.
submitted,
in
prep.)
have
revealed
considerable
problems
in
using
only
cytochrome-^
gene
(cyt-fc)
markers,
especially
to
establish
species
limits.
Even
using
the
Cytochrome
Oxydase
1
gene
(COl)
in
addition
to
cyt-b
divergence
does
not
solve
the
problem
of
designating
taxonomic
ranks.
In
fact,
we
consider
it
highly
advisable
to
combine
molecular
work
with
rigorous
playback-response
experiments,
and
analyses
of
morphologv
and
behavioural
ecology.
Such
integrative
work
is
now
in
progress
for
the
entire
lencoptera
/
brevipes
complex,
which
should
help
to
resolve
the
taxonomic
rank
of
magnificens.
However,
such
work
is
likely
to
take
several
years
and
while
in
progress
we
consider
it
important
recognise
magnificens,
at
least
subspecifically.
Conservation.
During
our
relatively
short
expedition
in
December
2009
we
found
P.
b.
magnificens
to
be
not
rare
off
the
Banks.
It
is
far
more
frequently
encountered
than
Vanuatu
Petrel,
and
is
perhaps
the
second-most
numerous
petrel
after
Puffimis
pacificus,
being
at
least
as
common
as
Audubon's
Shearwater
P.
(Iherminieri)
gunax
(see
Appendix
2).
Nevertheless,
Vanua
Lava
is
the
most
populated
island
in
the
Banks
and
we
suspect
that
feral
pigs,
cats
Felis
catus
and
introduced
rats
Rattus
spp.
could
be
significant
threats
to
a
small-sized
petrel
such
as
P.
b.
magnificens.
On
Mt.
Suretamatai,
we
found
no
evidence
of
any
alien
mammals,
but
pigs
occur
only
a
few
km
from
the
volcano.
No
rats
were
trapped,
though
a
single
night
trap
was
realised
in
December
2009.
Islanders
suggested
that
local
communities
heavily
exploited
petrels
and
especially
shearwaters
on
the
Banks
for
many
generations
until
the
19th
century,
but
in
recent
years
they
have
apparently
only
been
infrequently
harvested
at
most
(Totterman
2009).
Harvesting
of
Collared
Petrels
is
especially
well
known
from
Fiji
(Watling
1986)
and
apparently
still
occurs
on
Tanna
(www.positiveearth.org/vanbirds/),
but
it
remains
to
be
seen
if
this
practice
still
affects
P.
b.
magnificens
on
the
Banks.
Totterman
(2009)
found
evidence
at
the
summit
of
Mt.
Suretamatai
of
predation
on
Vanuatu
Petrels,
perhaps
by
Peregrine
Falcons
Falco
peregrinus,
w
hich
species
has
been
recorded
hunting
Gould's
and
Collared
Petrels
around
or
near
colonies
in
Fiji
and
Australia,
respectively
(Watling
1986,
Marchant
&
Higgins
1990).
We
found
several
Swamp
Harriers
Circus
approximans
on
the
slopes
of
the
volcano,
which
species
could
also
be
a
predator
of
petrels.
Vanua
Lava
volcano
is
still
partially
active,
and
a
serious
eruption
would
be
devastating
for
its
breeding
petrels,
as
could
be
a
major
tropical
cyclone
in
November-March,
when
both
Vanuatu
Petrel
and
P.
b.
magnificens
are
breeding.
According
to
BirdLife
International,
Collared
Petrel
is
currently
listed
as
Near
Threatened
because
it
is
assumed
to
have
a
small
and
declining
population,
with
very
small