An investigation of causes of disease among wild and captive New Zealand falcons (Falco novaeseelandiae), Australasian harriers (Circus approximans) and moreporks (Ninox novaseelandiae) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University, Turitea, Palmerston North, New Zealand
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Date
2014
DOI
Open Access Location
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Massey University
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The Author
Abstract
Infectious
disease
can
play
a
role
in
the
population
dynamics
of
wildlife
species.
The
introduction
of
exotic
birds
and
mammals
into
New
Zealand
has
led
to
the
introduction
of
novel
diseases
into
the
New
Zealand
avifauna
such
as
avian
malaria
and
toxoplasmosis.
However
the
role
of
disease
in
New
Zealand’s
raptor
population
has
not
been
widely
reported.
This
study
aims
at
investigating
the
presence
and
prevalence
of
disease
among
wild
and
captive
New
Zealand
falcons
(Falco
novaeseelandiae),
Australasian
harrier
(Circus
approximans)
and
moreporks
(Ninox
novaeseelandiae).
A
retrospective
study
of
post-‐mortem
databases
(the
Huia
database
and
the
Massey
University
post-‐mortem
database)
undertaken
to
determine
the
major
causes
of
mortality
in
New
Zealand’s
raptors
between
1990
and
2014
revealed
that
trauma
and
infectious
agents
were
the
most
frequently
encountered
causes
of
death
in
these
birds.
However,
except
for
a
single
case
report
of
serratospiculosis
in
a
New
Zealand
falcon
observed
by
Green
et
al
in
2006,
no
other
infectious
agents
have
been
reported
among
the
country’s
raptors
to
date
in
the
peer
reviewed
literature.
During
the
review
of
post-‐mortem
records,
organisms
like
Mycobacterium
avium,
Serratospiculum
sp,
Sarcocystis
spp,
Trichomonas
galllinae
and
several
unidentified
helminths
were
identified
as
contributing
or
definite
causes
of
mortality
in
all
three
species
of
raptors.
But
neither
Plasmodium
spp
nor
Toxoplasma
gondii
infections
have
been
demonstrated
in
these
birds
so
far.
Therefore,
a
separate
study
was
designed
to
determine
the
presence
of
these
pathogens
in
New
Zealand
falcon,
Australasian
harrier
and
morepork
tissues,
using
established
molecular
techniques.
Molecular
analysis
of
archived
New
Zealand
raptor
tissues
confirmed
the
presence
of
both
Plasmodium
spp
(10/117;
8.5%)
and
T.
gondii
(9/117;
7.7%)
in
all
three
species
of
raptors.
Plasmodium
strains
identified
were
P.
elongatum
GRW6,
P.
sp
AFTRU5,
and
P.
relictum
GRW4
and
SGS1.
Surprisingly,
two
Australasian
harriers
and
one
morepork
tested
for
the
presence
of
both
Plasmodium
spp
and
T.
gondii
as
concomitant
infections.
However,
it
is
unknown
whether
any
of
the
positive
tested
birds
suffered
from
clinical
infections,
since
post-‐mortem
records
had
no
record
of
clinical
signs
of
disease
associated
with
either
infections
in
these
birds.
Once
the
presence
of
the
aforementioned
pathogens
among
New
Zealand
raptors
was
established,
an
attempt
was
made
to
investigate
their
presence
among
live
raptor
populations
as
well.
Blood
samples
were
collected
from
raptors
being
admitted
to
Wildbase
Hospital,
Massey
University,
Palmerston
North
and
Wingspan-‐
Birds
of
Prey
Research
Centre,
Rotorua.
Molecular
analysis
of
these
samples
by
PCR
did
not
reveal
the
presence
of
Plasmodium
spp
in
any
of
the
ii
tested
birds,
but
one
New
Zealand
falcon,
Australasian
harrier
and
morepork
each
tested
positive
for
the
presence
of
T.
gondii.
Interestingly,
none
of
the
positive
birds
showed
any
signs
of
clinical
illness
that
may
be
associated
with
toxoplasmosis
in
raptors.
We
also
analysed
faecal
samples
and
throat
swabs
from
these
birds
to
determine
the
presence
of
pathogens
like
Caryospora
spp,
Serratospiculum
spp,
Salmonella
spp
and
T.
gallinae,
since
many
of
these
organisms
have
been
detected
in
New
Zealand
and
are
also
found
affecting
raptors
in
other
parts
of
the
world.
However,
apart
from
eggs
resembling
Capillaria
spp,
none
of
the
other
pathogens
listed
above
were
identified.
My
study
has
some
limitations
such
as
a
small
sample
size
and
a
geographic
bias
in
terms
of
birds
being
submitted
to
Massey
University,
Palmerston
North
for
post-‐mortem
analysis.
But
this
research
may
be
regarded
as
the
first
report
of
Plasmodium
spp
and
T.
gondii
infections
among
New
Zealand’s
three
well-‐known
raptor
species
and
further
research
is
required
to
determine
the
prevalence
of
these
pathogens
among
the
country’s
total
raptor
population,
pathogenicity
of
the
organisms
towards
them
and
the
role
of
these
birds
in
the
epidemiology
of
these
diseases
within
New
Zealand
Description
Keywords
Raptors, New Zealand, Birds of prey, New Zealand falcon, Falco novaeseelandiae, Australasian harrier, Swamp harrier, New Zealand, Circus approximans, Morepork, Ninox novaseelandiae, Bird diseases, Plasmodium, Toxaplasma gondii