Spotted Crake habitat use 117
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 115–134
and radio-tracked to provide information on
finer-scale habitat use of specific individuals.
Methods
Study area
Lille Vildmose was probably historically one
of western Europe’s largest lowland raised
mire systems, which developed from a
shallow brackish lagoon created behind a
series of low islands, sand banks and shoals
off the east coast of Jutland, south of the
opening to the Limfjord. Although attempts
were made to drain areas and dig peat locally
from the 1760s onwards, it was not until
1937 that the deep accumulation of peat
(> 5 m in places) attracted extensive
drainage schemes to create new land for
agriculture. In the period leading up to the
Second World War, 200 km of drainage
ditches were dug and the peat began to be
dug as a source of fuel for the cement works
in Aalborg, although in recent times, peat
has been extracted only for horticultural
purposes. Peat cutting across most of the
area ceased in 2011, but only after some 35
km
2
of the original 55 km
2
of raised mire
vegetation had been removed. The relic
raised mire vegetation constitutes some 50%
of this habitat remaining across Denmark,
so attempts were made to safeguard the
hydrological integrity of the intact mire
vegetation, with the longer-term objective
of restoring the cut-over areas back to
wetlands and ultimately to raised mire
habitat again. This major project to restore
the areas severely damaged by peat cutting
and agriculture is a collaboration involving
the Aage V. Jensen Fund, the Municipality of
Aalborg, and the Danish Nature Agency,
supported by EU LIFE+ Nature funding
(Nature Agency 2011). The project area
covers some 76 km
2
and includes
restoration of lakes and wetlands as well as
safeguarding some of the existing intact
mire and wetland habitats. The restoration
project was initiated in September 2011 and
will continue until at least the end of 2016.
Our study area comprised only
c.
16 km
2
of the northern section of the restoration
project area, which was the sector most
affected by previous peat cutting activities.
The extent of the study area mapped for
singing crakes is illustrated in Fig. 1, where
the hydrological boundaries formed by
peripheral ditching are shown to the north
and west, while the eastern and southern
borders are defined by the Hegnsvej,
Møllesøvej and Vildmosevej roads. The
post-extraction restoration landscape can
best be described in terms of the discrete
habitat units, which are also defined within
the site by the network of asphalt and gravel
roads, fencing and ditching as shown in
Fig. 1.
Mapping territorial singing birds
Surveys of singing Spotted Crakes were
carried out from 22:00 h onwards along the
roads of the study area during generally still
nights from mid-April until late July 2013, in
overcast or cloudless conditions, when
individuals could be detected over distances
of up to 2 km (Taylor & van Perlo 1998).
The estimated positions of singing
territorial birds were transferred onto aerial
photographs by triangulation based on the
crude observed angles of the sound.
Because there were relatively few singing
birds, their home ranges limited and the
