Spotted Crake habitat use 119
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 115–134
distances between individuals relatively
large, there was no ambiguity in assigning
singing birds to specific territories, the
centres of which are shown in Fig. 1.
Capture and marking of birds
Successful attempts were made to lure
singing birds with playback of the male’s
advertising song, the short sharp ascending
whistle repeated once a second, often for
prolonged periods (the “whiplash” song;
Cramp & Simmons 1980) on 29, 30 and 31
May 2013 in three different parts of the
study area. Chicken wire fence lines were
established, linking two walk-in funnel traps,
with lengths of “wader” mist netting strung
immediately above to catch flying birds
in the vicinity. A CD player was left
broadcasting crake song over one of the
traps. We succeeded in catching individual
Figure 1
. Map of Lille Vildmose, northern Jutland, Denmark, showing roads (dotted white lines, with
their names, from which observations were made during the mapping of singing Spotted Crakes) and
major habitat divisions (marked in yellow and detailed in the text). Points indicate the centres of territories
occupied by singing crakes heard at least twice during summer 2013, of which digits indicate captured
individuals (in Territory 3 a male and a female were caught and radio-tagged) and letters indicate other
individuals. The numbered sections refer to the following habitat types present in each: 1) Open water and
encroaching Common Reed
Phragmites australis;
2) Restored raised mire vegetation; 3) Flooded linear peat
extraction pits, mainly water <2 m deep separated by peat ridge banks, colonised to a greater or lesser
extent by
Phragmites
and Reedmace
Typha latifolia
; 4) Wet willow carr (Grey Willow
Salix cinerea
with some
Bay Willow
S. pentandra
); 5) Flat shallow wet acidic sedge meadow with invading
Phragmites
beds and
Salix
scrub; 6) Linear peat extraction pits, not flooded, often dominated by Common Cotton Grass
Eriophorum
angustifolium
or Purple Moor Grass
Molinia caerulea
in the base of the cuttings (dependent on water level)
and subject to
Salix
scrub invasion; 7) Levelled and fertilised acidic damp grassland intensively managed
for summer cattle grazing and local hay production; 8) Levelled wet peat extraction area with high water
tables, supporting a matrix of dry and wet acidic grassland, standing water bodies,
Phragmites
and
Typha
;
9) Levelled dry peat extraction area with some minor ridging dominated by acidic wet grassland with Soft
Rush
Juncus effusus
; 10) Levelled wet peat extraction area with high water tables subject to cattle grazing, a
complex matrix of shallow pools and bare substrate, with extensive areas of open acidic wet grassland,
Juncus effusus
,
Phragmites
and pockets of invasive
Salix
scrub; 11) Levelled peat converted to arable
agriculture; 12) Lillesø lake and surrounding
Phragmites
beds and
Salix
carr.
birds in the traps (2), in the mist net (1) and
with a hand net when caught in the beam of
a torch (1). University of Copenhagen
Zoological Museum metal rings were fitted
to each of the crakes and standard
measurements taken of total skull length,
tarsus, flattened and straightened wing and
body mass. Biotrack Pip Ag392 radios (1.38
g, 20 cm antennae,
c
. 8 week battery life)
attached to gauze pads were glued with
cyanoacrylate to the middle of the back. A
small area of large and inner down feathers
were clipped from the upper part of the
attachment area to ensure effective adhesion
across different levels of the plumage,
whilst still ensuring subsequent shedding
of the radio during body moult. Tags
transmitted at 150.871–151.185 MHz and
were tracked using a Staba XR-100 receiver
and three-element Yagi directional antenna
