Transcript Threatened fauna of the Canterbury Region

Threatened fauna of the
Canterbury Region
Colin F J O’Donnell
Southern Regional Science Centre
Department of Conservation
PO Box 13049, Christchurch
Threatened
fauna
Terrestrial Birds
mammals
Critical
6
Endangered
1
6
Vulnerable
6
Serious
4
decline
Gradual
9
decline
Sparse
5
Range
1
restricted
Total
1
37
Reptiles Freshwater Invertebrates Total
fish
10
16
1
11
19
6
2
6
6
3
6
24
2
2
25
39
34
40
8
6
93
145
Proportion of national total in
Canterbury - fauna taxa
35
25
20
15
10
5
ra
te
s
ve
rte
b
es
hw
Fr
In
at
er
fis
h
til
es
s
Bi
rd
Re
p
am
m
al
s
0
Te
rr
es
tri
al
m
Percentage
30
Wetlands/lowland rivers
>90% drained
Canterbury Mudfish
•
Aquatic vegetation/
overgrown springs and
margins of wetlands
• Can cope with short
periods of drying – form
burrows
• Solitary
N
0
40 km
Lowland longjaw galaxias
Kakanui (Kauru River)
Hakataramea (1989)
Twizel area (e.g.
Fraser Stream)
N
0
20 km
Open braided
cobble/gravel river
Shallow riffle habitat
? Spawning
requirements
Threats
Badly designed culverts,
weirs, and dams
•
• Pollution and sedimentation
• Changes in water
levels/drainage
• Stock damage to margins
• Predation & competition
• Loss of habitat
• Reduced flows
• Overfishing
• Weed encroachment
Braided rivers
– Multiple channels
– Flow instability
– High gradients
– High levels of sediment supply and
movement
– Constant channel movements
– Seasonally rich food supplies
These processes provide outstanding
feeding and nesting habitat for
wetland birds & other fauna
an
t
W erb
es ur
tC y
N
el oas
so
n/ t
So M a
ut rl
hl
an
d
O
H
aw tag
ke o
s
G B ay
is
bo
W
r
el ne
lin
W gto
a
n
B a ng
y an
ui
of
Pl
e
Ta nty
ra
na
ki
C
hectares
Distribution of braided rivers
nationally
160000
140000
120000
163 rivers
100000
80000
60000
40000
20000
0
Number of wetland birds
from index counts on rivers
25,000
> 80 bird species
20,000
15,000
10,000
5,000
As
hb
ur
to
n
R
As
hl ive
r
ey
H
ur
R
un
iv
M
ui
ac er
R
ive ken
zie
rs
&
M
ou
O
pi
hi th
Ri
O
ve
ra
r
ri
R
R
iv
ak
er
a
R
ia
an
R
i
gi
ta ver
ta
Ri
W
ve
ai
W
a
r
ai
u
m
ak Riv
er
ar
iri
W
Ri
a
W
ita ver
ilb
ki
er
fo Riv
er
rc
e
R
iv
er
0
O’Donnell & Moore (1983), Robertson et al. (1984), Maloney (1999)
Trends in wrybill numbers
8000
7000
6000
5000
4000
3000
2000
1000
0
1965
1994
2001
Hay (1979), Davies (1997), Riegen & Dowding (2001)
c.1900
1979
2007
Trends in wrybill numbers
Edwards Stream –
Scree Skink habitat
Threats: weed encroachment
Proportions of major rivers with
weed encroachment
80
70
After Wilson (2001)
50
40
30
20
10
As
hb
ur
to
n
O
pi
hi
ey
As
hl
ta
an
gi
ta
ak
a
R
au
W
ai
ia
R
ai
m
ak
ar
iri
0
W
% weeds
60
Loss of water: Increased
demand for irrigation water
Loss of water:
Each species has a different requirement
Log mean flow
Relationship of mean flow (log) to tern numbers
3
2.5
2
1.5
1
0.5
0
y = 0.237Ln(x) + 0.2929
2
R = 0.3836
0
500
1000
tern numbers
1500
Predation by introduced mammals
The ‘moat’ effect – islands separated
from the mainland by large flows appear
to limit predation
What can be done?
Rules for habitat protection
Firewood
cutting rules
Legal
protection of
waterways
Adequate environmental
flows to sustain fauna
• Assured environmental flows and water
levels in rivers/wetlands/coastal lagoons
Protected areas networks
• Focus on lowlands where >90% loss
• For example: Protect a representative range of
rivers
– Braided rivers are not represented in our
reserve network (though the waters of some
are now protected with Conservation Orders)
• Most riverbeds are classed as “unoccupied
crown land” or are council/private land
Known fates*
Sustained predator control
10
9
8
7
6
5
4
3
2
1
0
Poison laid
80% dead within 2 days
1
3
5
7
9
11
13
15
Days since live trapping ended
17
19
Community conservation
initiatives: bat houses in South Canterbury
Species translocations: Quail Island
using wooden disc technique for beetles…
Recreation
management
Black-fronted tern chick
crushed by vehicle
Education
Conclusions:
Huge challenges
• Most threatened biodiversity does NOT
occur in reserves or on DOC land
• Need good inventories of what still remains
• Regional action plans (Canterbury
Biodiversity Strategy first step)
• Need to turn the strategy into action to halt
the loss