126 Spotted Crake habitat use
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 115–134
vegetation was conversely significantly
higher in areas not used by crakes in the
management area containing Territory 3,
probably because the driest
Salix
thicket that
characterised the very tallest vegetation in
this area was not used by crakes. Given the
great variability in the nature and structure
of the vegetation in these three very
different management units, we suggest
that little biological significance can be
attached to these results. Due to extremely
high variance, we found no differences in
the area of open water, bare mud and
dead vegetation in areas used and not
used by crakes in any of the management
units (Mann-Whitney U tests: n.s. in each
case).
Small-scale differences in habitat use –
vegetation analysis
DCA provided a useful ordination of the
quadrats samples for the three management
areas (Fig. 6) and the relative ordination
of the species recorded illustrates plant
associations in the different quadrats (Fig. 7).
Most of the vegetation fell into readily
identifiable community types, with all of the
quadrats from the management area north of
the railway falling in a discrete cluster with
low values on the second axis (Fig. 6) where
Figure 4.
Relationship between mean vegetation height (
h
, in cm above water/substrate surface)
measured in 5 random positions in 1m × 1m vegetation quadrats against the mean water depth (
d
)
measured in 10 random positions in each of the three management units at Lille Vildmose, associated
with the territories of radio-tagged Spotted Crakes. Significant fitted regression models have the
formulae Territory 1
h
= –0.065
d
2
+ 3.516
d
+50.482,
r
= 0.64,
F
2,35
= 11.3,
P
< 0.001; Territory 2
h
= 4.784
d
+39.727,
r
= 0.82,
F
1,50
= 102.8,
P
< 0.001; Territory 3
h
= 6.862
d
+69.031,
r
= 0.52,
F
1,51
= 18.5,
P
< 0.001.
0
50
100
150
200
250
0 10 20 30 40 50 60 70
Mean vegetation height (cm)
Mean depth of water above soil surface (cm)
Territory 2
Territory 1
Territory 3
