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Habitat selection of the Eurasian woodcock in winter in relation to earthworms availability


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The Eurasian woodcock (Scolopax rusticola) is a game species experiencing high hunting pressure, long-term modifications of its habitats, and with questions regarding its current conservation status. Winter is a season of highest concentration of birds and hunting pressure but woodcock precise habitat requirements are poorly known. It is crucial to assess threats and to develop sustainable management options for the conservation of woodcock populations. During three consecutive winters, we monitored 65 individual woodcocks fitted with radio-tags in Brittany, France. Habitat selection was analysed using GIS and compositional analysis, in relation to vegetation types, soil variables (humus types) and the abundance of their main prey (earthworms). Woodcocks used different habitats diurnally and nocturnally, generally preferring areas with high earthworm biomass. Diurnal habitat selection in forests was associated with humus type (preference for mulls, rich in earthworms) and dense shrub strata (better protection). Hedges with a high density of trees and shrub were also important habitat. At night, grazed meadows were the preferred habitat, containing five times higher biomass of earthworms compared to cultivated fields. Sustainable management of populations requires protection and management of habitats that incorporates food and cover. Forestry practices should preserve rich humus types and coppices by choosing tree species that ameliorate the soil and soil tilling. Changes in landscapes and intensive agricultural practices are current threats to woodcock populations: destruction of hedges, decrease of permanent grazed meadows, impoverishment of soils fauna biomasses from ploughing and chemical applications. However, woodcocks may benefit from the recent development of set-asides, grass field-borders and simplified farm practices (no-tillage and direct sowing).
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Habitat selection of the Eurasian woodcock in winter in
relation to earthworms availability
Olivier Duriez
, Yves Ferrand
, Franc¸oise Binet
, Eve Corda
Franc¸ois Gossmann
, Herve
Laboratoire dÕEcologie, UMR 7625, ba
ˆtiment A, 7e
´me e
´tage, case 237, 7 quai St Bernard, Universite
´Paris 6, 75005 Paris, France
Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, Station de Chize
Beauvoir-sur-Niort, 79360 Villiers-en-Bois, France
Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, 5 rue de St-Thibaut,
BP 20 St-Benoist, 78612 Le-Perray-en-Yvelines cedex, France
CNRS – Universite
´de Rennes I, UMR 6553, Ecobio 263 avenue du Ge
´ral Leclerc, Campus de Beaulieu, Ba
ˆt 14B, CS 74205,
35042 Rennes Cedex, France
Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, 53 rue Russeil, 44000 Nantes, France
CNRS – Centre dÕEtudes Biologiques de Chize
´, UPR 1934, BP 14, 79360 Beauvoir-sur-Niort, France
Received 27 February 2004; received in revised form 20 July 2004; accepted 5 August 2004
The Eurasian woodcock (Scolopax rusticola) is a game species experiencing high hunting pressure, long-term modifications of its
habitats, and with questions regarding its current conservation status. Winter is a season of highest concentration of birds and hunt-
ing pressure but woodcock precise habitat requirements are poorly known. It is crucial to assess threats and to develop sustainable
management options for the conservation of woodcock populations. During three consecutive winters, we monitored 65 individual
woodcocks fitted with radio-tags in Brittany, France. Habitat selection was analysed using GIS and compositional analysis, in rela-
tion to vegetation types, soil variables (humus types) and the abundance of their main prey (earthworms). Woodcocks used different
habitats diurnally and nocturnally, generally preferring areas with high earthworm biomass. Diurnal habitat selection in forests was
associated with humus type (preference for mulls, rich in earthworms) and dense shrub strata (better protection). Hedges with a high
density of trees and shrub were also important habitat. At night, grazed meadows were the preferred habitat, containing five times
higher biomass of earthworms compared to cultivated fields. Sustainable management of populations requires protection and man-
agement of habitats that incorporates food and cover. Forestry practices should preserve rich humus types and coppices by choosing
tree species that ameliorate the soil and soil tilling. Changes in landscapes and intensive agricultural practices are current threats to
woodcock populations: destruction of hedges, decrease of permanent grazed meadows, impoverishment of soils fauna biomasses
from ploughing and chemical applications. However, woodcocks may benefit from the recent development of set-asides, grass
field-borders and simplified farm practices (no-tillage and direct sowing).
2004 Elsevier Ltd. All rights reserved.
Keywords: Compositional analysis; Lumbricidae; Habitat changes; Scolopax rusticola; Sustainable management
1. Introduction
In Europe, many wildlife populations associated with
traditionally farmed landscapes declined with changes in
agricultural policies and farming practices (Pain and
0006-3207/$ - see front matter 2004 Elsevier Ltd. All rights reserved.
Corresponding authors. Tel.: +33 5 65 60 77 40
Fax: +33 1 30 46 60 99.
E-mail addresses: (O. Duriez), y.ferrand@ (Y. Ferrand).
Biological Conservation 122 (2005) 479–490
Pienkowski, 1997; Aebischer et al., 2000). These large
scale spatial changes in human land use reduces biodi-
versity (Robinson and Sutherland, 2002). For example,
the changes in agricultural practices caused little bus-
tards (Tetrax tetrax) and skylarks (Alauda arvensis)to
decline drastically in most areas of Europe (Chamber-
lain et al., 1999; Wolff et al., 2001). Similarly, the Eura-
sian Woodcock (Scolopax rusticola L.) is likely to suffer
from agricultural and forestry changes, especially in
winter, when it uses habitats that are declining in Eur-
ope, especially its nocturnal habitats.
Woodcocks are mostly migratory birds, breeding in
Northern and Eastern Europe and wintering in large
numbers in western France (Fadat, 1991). Their conser-
vation status is poorly known on breeding grounds.
They are atypical among waders, being solitary, living
inland, and nocturnal in winter (Piersma et al., 1996).
Woodcocks are specialist predators of soil macrofauna:
in winter, earthworms constitute about 85% of wood-
cocksÕdiurnal energy intake and probably even more
at night; the rest being arthropods (insect: larvae and
imagoes; myriapods) and slugs (Granval, 1987). In win-
ter, woodcocks use three types of habitats: woodlands
and hedges during the day and fields and meadows at
night (Cramp and Simmons, 1983; Hirons and Bick-
ford-Smith, 1983; Wilson, 1983; Gossmann et al.,
1988; Granval and Bouche
´, 1993). Although wooded
areas are increasing overall in the European Union, it
is mostly in the form of conifer plantations (Colombet
et al., 1996; Sondag, 2003). The disappearance of hedges
is more dramatic. In France, 60% of hedges (740,000
km) was destroyed between 1966 and 1996 (Schmutz
et al., 1996), and the trend is similar in the rest of the
European Union (Pain and Pienkowski, 1997; Robinson
and Sutherland, 2002). The situation for meadows and
wet grasslands is similar because most of these habitats
have been converted to crop fields since the late 1950s
(Pain and Pienkowski, 1997; Wakeham-Dawson and
Smith, 2000). Between 1975 and 1995, 12% of the natu-
ral meadows and pastures disappeared from nine Euro-
pean countries (Poiret, 2003). The decrease in grazing
cattle and the wider use of nitrogen fertilisers enables
less fertile land to be farmed, allowing farmers to con-
vert these old meadows into arable fields or woodlands
(Potter, 1997; Vickery et al., 2001).
In addition to habitat changes, woodcocks are hunted
in most European countries. Hunting occurs mostly in
winter, when populations are concentrated. French
hunters kill 30–40% of the total harvest in Europe
(about 1,200,000 woodcocks) and the interest for wood-
cock hunting has recently increased (Ferrand and Goss-
mann, 2000). Currently, there is no clear trend in
woodcock populations but the very low survival rates
calculated from the French ringing data base is a con-
cern (Tavecchia et al., 2002). These threats lead conser-
vationists to give the Eurasian woodcock a ‘‘vulnerable’’
status in winter (Tucker and Heath, 1994; Heath et al.,
2000) although it was recently revised to ‘‘stable’’ (Wet-
lands International, 2002), following a recommendation
of European management plan (Office National de la
Chasse, 1998).
In this proposal, management plans must be prepared
for sustainable use and conservation of woodcock popu-
lations in winter, as well as the establishment of hunting-
free reserves. Designing sound management schemes
requires improved knowledge of wintering ecology and
behaviour of this species. The first step is to understand
mechanisms that determine habitat selection in winter.
Are woodcocks more constrained by the declines of pas-
tures, hedges, or by the changes in the forestry practices?
How does resource availability influence habitat selec-
tion? Previous studies of habitat selection used pointing
dogs, bag statistics (Imbert, 1988), or habitats pros-
pected during ringing (Ferrand and Gossmann, 1988;
Granval and Bouche
´, 1993) and were biased by the
behaviours of the dog, the hunter, or the ringer. Radio-
telemetry can provide more rigorous and detailed data
on winter habitat selection by woodcock, avoiding
human biases (Kenward, 2001). Only three pilot studies,
based on three radio-tracked individuals in Ireland (Wil-
son, 1983), five and eight individuals in Cornwall (Hirons
and Bickford-Smith, 1983; Hoodless, 1994) had focused
on winter habitat selection in the Eurasian woodcock.
In this paper, we examine diurnal and nocturnal hab-
itat selection in winter, with a large sample of radio-
tagged woodcocks. We first investigated habitat selec-
tion in a relatively undisturbed landscape, offering a
large proportion of traditional habitats, with limited
hunting pressure because of the hunting-free reserve sta-
tus of the main forest complex. Humus type indicates
how organic matter (leaf litter) is decomposed and
mixed to the mineral fraction of the soil by soil fauna
(Frontier and Pichod-Viale, 1993) and therefore gives
information about the soil fauna present at each loca-
tion. Because soil characteristics are probably important
to understanding woodcock habitat selection, we also
investigated the influence of humus types and earth-
worms availability on habitat selection by woodcocks.
2. Methods
2.1. Study site
We collected data from December to April, during
three consecutive winters (1999–2000, 2000–2001 and
2001–2002, hereafter 2000, 2001 and 2002 winters,
respectively). The study was conducted in the Beffou for-
est (48300N, 328 0W) and the surrounding bocage, lo-
cated in Brittany, the main wintering region for
woodcocks in France (Fadat, 1991). The study area
was c. 1800 ha. The topography was composed of small
480 O. Duriez et al. / Biological Conservation 122 (2005) 479–490
hills and valleys (altitude range: 160–322 m). The bocage
was composed of small woods and fields (<1 ha) en-
closed by old woody hedges. Woodcock hunting has
been prohibited in the Beffou forest since 1995 but is al-
lowed in the surrounding woods and hedges. Winter cli-
mate in Brittany is oceanic: rainy and windy with mild
temperatures (mean 5 C).
2.2. Capture methods and radio-tracking
We captured woodcocks at night with a spotlight and
a landing net, as they fed in fields surrounding the forest
(Gossmann et al., 1988). We captured 37 woodcocks in
2000 (21 adults and 16 yearlings), 48 in 2001 (15 adults
and 33 yearlings) and 34 in 2002 (10 adults and 24 year-
lings). Birds were aged (adult or yearling) using wing
feather characteristics and moult status (Clausager,
1973). Each bird was fitted with a radio-transmitter
(TW3, Biotrack
, UK), weighting 7, 9 or 12 g (2–4%
of body mass) according to the battery size and presence
of activity tiltswitch (Duriez et al., 2004). In winter 2000,
radio-tags were secured on the back with a Teflon rib-
bon two-loop backpack harness (Kenward, 2001). Be-
cause seven woodcocks in 2000 were found dead of
starvation after the bill caught in the upper loop of the
harness, in winters 2001 and 2002, radio-tags were glued
on the back and secured with a single-loop wire harness,
passing around the belly and behind the wings (McAu-
ley et al., 1993). These seven birds were not included
in the rest of analyses.
Each bird was located 2–3 times per week during the
day and 2–3 times per week at night in winter 2000, until
departure, and 4–5 times per week in the following win-
ters. During the day, we approached woodcocks by cir-
cling to 10 m or less. Woodcocks did not leave diurnal
sites during the day or only moved by walking (usually
<100 m, personal observation). At night, woodcocks
were also approached by circling and located to the
nearest 50 m because they were more likely to fly, espe-
cially during clear moonlight nights. However the type
of field was determined each time. During seven nights
in 2001, we monitored 23 birds at 2-h interval. 80% of
birds stayed the entire night in the field chosen at the
beginning of the night and 89% within a radius of 150
m. Subsequently we located birds once per night.
2.3. Analysis of radio-telemetry data
We recorded each location on a habitat map using a
Geographic Information System (GIS; ArcView
ESRI, Redlands, California, USA). This map was digi-
tised from an aerial photograph taken in 1992 (scale
1/10,000, source: Institut Ge
´ographique National). For
all analyses, we compared birds with similar numbers
of locations. The number of locations varied according
to the date of capture of the bird (December to mid Jan-
uary) and the date of end of monitoring (death or migra-
tion starting in the last decade of February). We only
used birds with at least 7 precise diurnal/nocturnal loca-
tions (limit fixed on a natural break in the data set) dur-
ing the study period which was limited to January and
February (excluding December with scarce locations,
and the pre-migratory period in March). Therefore, we
used a total of 2834 locations concerning 65 woodcocks
over the three years: 22 birds in 2000 (15 adults and 7
yearlings), 22 in 2001 (8 adults and 14 yearlings) and
21 in 2002 (7 adults and 14 yearlings). During the entire
study period, we only had 3 days of frost in January
2000 and 4 days in February 2001. Because several con-
secutive days of freezing ground changed the behaviour
and habitat selection of woodcocks (Hirons and Bick-
ford-Smith, 1983; Wilson, 1983), we excluded from the
analyses the data obtained during the days of frost be-
cause accurate analysis of habitat selection was not
2.4. Habitat selection analysis
We analysed habitat selection using compositional
analysis (Aitchison, 1986; Aebischer et al., 1993) where
the sample size was the number of tagged individuals
and radiolocations served to subsample each individ-
ualÕs habitat use. Since we restricted the period of study
in two months in order to limit the differences in loca-
tions between individuals, we did not weighed the com-
positional analysis by the number (or the square-root) of
radiolocations. In compositional analysis, the propor-
tions of habitats used by each individual were compared
to the proportions of habitats available. Analysis of
habitat selection on the basis of home ranges was not
appropriate in the case of the woodcock, because birds
made flights between diurnal and nocturnal habitats.
Hence ‘‘used’’ habitats associated with radiolocations
were compared with the habitats available in the study
area. ‘‘Available’’ habitats were calculated differently
according to the type of habitat (see below). Composi-
tional analysis is sensitive to the number of habitats
tested and Aebischer et al. (1993) suggest minimising
the number of different habitats. Thus we analysed first
with all detailed habitats and second with pooled habi-
tats by grouping habitats similar in structure. Composi-
tional analysis allowed a comparison of habitat selection
according to individual characteristics (age) and sea-
sonal effects (year of study) using MANOVAs.
2.4.1. Woodlands
The ‘‘woodland’’ habitat included the Beffou forest
(612 ha) and surrounding woodlands (c. 130 ha). The
amount of available habitat of each type was calculated
from the GIS map (Table 1). The stands in the Beffou
forest was diverse and contained nine habitat types
(Table 1). Deciduous stands (plantations, coppices and
O. Duriez et al. / Biological Conservation 122 (2005) 479–490 481
timbers) mostly contained Beech (Fagus sylvatica)and
Oak (Quercus robur and Q. sessiliflora), and some Ash
(Fraxinus excelsior). Coniferous stands (plantations
and timbers) were mostly Sitka spruce (Picea sitchensis),
Common silver fir (Abies alba), and Grant fir (A. gran-
dis). ÔPine timbersÕcontained Scots pine (Pinus sylvestris)
and Maritime pine (Pinus pinaster). In all habitats types,
the shrub strata contained Yew (Taxus baccata), Holly
(Ilex aquifolium), and Hazel (Corylus avelana). ÔWet for-
estsÕwere characterised by Willows (Salix sp.), Alders
(Alnus glutinosa) and Poplars (Populus sp.) and by the
presence of typical wetland plants (Greater tussock
sedges Carex paniculata and Common rushes Juncus
conglomeratus). For the pooled analysis, we kept six
habitat types. We kept Ôdeciduous timbersÕ,Ômixed tim-
bersÕand Ôwet forestsÕ, but other categories were pooled
as follows: Ôpine timbersÕwith Ôconiferous timbersÕ,Ôde-
ciduous plantationsÕwith Ôconiferous plantationsÕand
ÔcoppicesÕwith Ôcoppices-with-standardÕ.
Humus types depend on many factors: biotic (vegeta-
tion, soil fauna, macrofauna) and abiotic (nature of geo-
logic substrate, slope, hydrology). Consequently, humus
could change in short distances (within 10 m) and were
very difficult to map. Thus, ‘‘available’’ humus variables
were the proportions of each type of humus in a system-
atic sampling based on a 200 ·200 m grid covering the
entire forest and extended to several surrounding woods
(182 sampling points). Three types of humus were deter-
mined following Jabiol et al. (1995) (mors, characterised
by the accumulation of litter resulting from acid sub-
strate and scarcity of earthworms; mulls, characterised
by only a thin litter layer resulting from an active and
abundant soil fauna; and moders in the intermediate sit-
uation) and their proportions are given in Table 2.
Because shrub cover is probably an important param-
eter to provide cover for woodcocks during the day, the
proportion of shrub cover was estimated with a 10-m
tape (decametre) and the presence/absence of a shrub
was noted every 0.5 m. We calculated the % shrub cover
for each site as the ratio of the number of points with
shrubs to the total number of points (20). Shrub cover
was estimated from 82 sites randomly chosen from the
182 sites used for the humus availability survey, and
on 176 sites used by woodcocks (74 in 2000 and 102 in
Table 2
Proportions of the humus types in woodlands and hedges types in the
study area in Brittany, France
Habitat type Code Number of points %
Mor 24 13.2
Moder 61 33.5
Mull 97 53.3
Wooded with strip WS 30 33.7
Wooded without strip W 27 30.3
Shrub with strip SS 13 14.6
Shrub without strip S 10 11.2
Relictual R 9 10.1
The proportions of each type were considered as the same in the three
years. Humus types were estimated from a systematic sampling of 182
sites and hedges were estimated from a random sampling of 89 sites
(see text).
Table 1
Description of the habitat types in the study area, comprising the Beffou forest and the surrounding woods and fields in Brittany, France
Habitat Code Area (ha) %Description
Deciduous plantations DP 191 25.2 2–4 m, 10–15 years, Abundant shrub and grass strata
Coniferous plantations CP 21 2.8 2–4 m, 10–15 years, Abundant shrub and grass strata
Coppices COP 60 7.9 5–10 m, 15–30 years, Abundant shrub and grass strata
Coppices-with-standard CWS 55 7.3 15–30 m, 30–60 years, Abundant shrub and grass strata
Deciduous timber DT 165 21.8 15–30 m, 40–120 years, Shrub and grass strata limited or absent
Mixed timber MT 71 9.3 15–30 m, 40–120 years, Shrub and grass strata limited or absent
Pine timber PT 14 1.8 15–30 m, 40–120 years, Shrub and grass strata limited or absent
Coniferous timber CT 148 19.6 15–30 m, 40–120 years, Shrub and grass strata limited or absent
Wet forest WF 32 4.2 Various height, age and shrub strata, aquatic plants, saturated soil
Total woods 756 100
Seed plots SP 135 13.0 Grass or winter wheat, vegetation 5–10 cm, bare soil
Stubbles ST 176 17.0 Corn or wheat (or mustard), bare soil
Young grazed meadows YGM 47 4.5 <3 years, Sowing furrows still visible, regular structure, vegetation <15 cm
Dry grazed meadows DGM 441 42.5 3–10 years, Sowing furrows not visible, irregular structure, vegetation <15 cm
Wet grazed meadows WGM 58 5.5 Permanent, vegetation <15 cm, aquatic plants, saturated soil
Un-grazed meadows UM 178 17.5 No trace of grazing, vegetation >15 cm, dry or saturated soil
Total fields 1035 100
Total study zone 1791
The area (in hectares) and % (in italics) of each habitat are given as means for each of the three years of study.
482 O. Duriez et al. / Biological Conservation 122 (2005) 479–490
2.4.2. Hedges
Because it was impossible to map the characteristics
of every hedge in the study zone (more than 200 km
of hedges), we randomly sampled 89 50-m sections of
hedges to determine the availability of each type of
hedge. Differences in computation of habitat availability
between forest habitats and hedges (area vs. proportion)
precluded any combination of the two habitats in the
same analysis. Hedges were constituted by trees and
shrubs growing on an embankment. Hedge had four
vegetation strata: (1) the tree strata (7–20 m), mostly
beeches and oaks; (2) the shrub strata (1–7 m), mostly
Hazels, Gorse (Ulex europaeus), Broom (Cytisus scopa-
rius); (3) the grass strata (<1 m); (4) an edge strata (lat-
eral strip), which was the lateral extension of the hedge
into the meadow (not on the embankment, 0.3–3 m
wide) and contained mostly brambles, brackens, grass
and branches and sometimes shrubs. For the pooled
analysis, hedges were divided into three types: Ôwooded
hedgesÕwith tree, shrub and grass strata; Ôshrub hedgesÕ
with shrub and grass strata; and Ôrelictual hedgesÕwith
only the grass strata (Table 2). For the detailed analysis,
we also analysed the presence/absence of the lateral
shrub strip and we kept five types of hedges: Ôwooded
with stripÕ,Ôwooded without stripÕ,Ôshrub with stripÕ,
Ôshrub without stripÕand ÔrelictualÕ(always without
strip) (Table 2).
2.4.3. Fields
Nocturnal ÔfieldÕhabitat included c. 1200 land par-
cels. We calculated area of each type of available habitat
from the GIS (Table 1). Meadows represented 70% of
the fields and were divided in three types: young mead-
ows, old dry meadows, and permanent wet meadows. A
meadow was characterised as ÔgrazedÕif it showed actual
or recent grazing with cow dungs, footprints and short
vegetation. Tall grass identified Ôun-grazed meadowsÕ,
which included meadows that had not been grazed for
the six previous months, meadows for mowing and old
wet set-asides. Other fields included Ôseed plotsÕ(wheat
and grass) and ÔstubblesÕ(corn and wheat). For the de-
tailed analysis, the six habitats were: Ôyoung grazed
meadowsÕ,Ôdry grazed meadowsÕ,Ôwet grazed meadowsÕ,
Ôun-grazed meadowsÕ,ÔstubblesÕand Ôseed plotsÕ. For the
pooled analysis, four habitats were kept: Ôgrazed mead-
owsÕ(young, dry and wet), Ôun-grazed meadowsÕ,Ôstub-
blesÕand Ôseed plotsÕ.
2.5. Earthworm sampling
We sampled earthworms using the standardised
method described by Bouche
´and Gardner (1984) and
´and Aliaga (1986). This method is a combina-
tion of two complementary extraction techniques: a
chemical extraction by 0.4% formalin application to ex-
pel active earthworms from the deep soil to the soil sur-
face, and a physical extraction by hand-sorting soil cores
(30 ·30 ·10 cm) to collect additional earthworms that
did not respond to the chemical extraction. Earthworm
sampling was performed in both diurnal and nocturnal
sites used by woodcocks (i.e., woodlands and fields)
from January to March 2001 and 2002. To select a plot
for earthworm sampling, we flushed a radio-tagged
woodcock (which usually returned to the same site on
the following day), in early morning (around 09:00) in
diurnal sites and at dark (around 20:00) in nocturnal
sites. We avoided samplings during freezing weather,
in very wet soils (no effect of formalin application), in
young wheat or grass seed plots (to prevent trampling
on crops) and in un-grazed meadows (not used by
Because earthworm populations are highly aggre-
gated in patches (Poier and Richter, 1992; Rossi et al.,
1997), earthworm formalin extraction was done on an
area of 6 1-m
plots (3 1-m
spaced 10 m apart in a tri-
angle at the woodcock place and 3 other 1-m
plots in a
place randomly chosen 50 m apart) to take into consid-
eration the variability of the horizontal distribution of
earthworms biomass. Then, within each of the 6 plots,
2 soil cores (30 ·30 ·10 cm) were dug and hand-sorted.
Because some earthworms perform nocturnal migra-
tion and emerge from the soil at night (Lee, 1985), earth-
worm biomass available to woodcocks should be higher
at night than during the day. Hence, we slightly modi-
fied the sampling procedure for nocturnal habitats to
investigate about the earthworm biomass available to
woodcocks in the first 10 cm of soil, at night in fields.
After flushing a radio-tagged bird, we placed 6 1-m
plots similarly as for daytime sampling in forest. One
soil core (30 ·30 ·10 cm) was dug in each of the 6 plots
to measure the biomass of earthworms present in the
first 10 cm of soil. This soil core was kept in a trash
bag for future hand sorting in the following afternoon.
In the following morning, we moved the plots 1 m away
and performed the chemical extraction with formalin to
calibrate on the standard procedure of Bouche
´and Ali-
aga (1986). The nocturnal sampling procedure and cal-
culations are fully described in Duriez (2003).
For the two extractions (formalin and hand-sorting),
the earthworms collected were preserved in 4% formalin
prior to identification in the following months. All indi-
viduals were identified to species, counted and weighed
to the nearest 0.01 g (fresh mass). For each sampling
place, the earthworm biomass value was the mean of
the 6 square plots and was expressed as kg (fresh weight
worm) per hectare. We sampled a total of 38 sites in
fields and 43 sites in woodlands.
2.6. Statistical analyses
Means were reported ±1 standard deviation (SD) and
were compared with StudentÕst-tests or General linear
O. Duriez et al. / Biological Conservation 122 (2005) 479–490 483
models (GLM) with TuckeyÕs post-hoc tests, using SPSS
10.0 software (SPSS, 1999). To avoid pseudo-replication
(Hurlbert, 1984), we used General Linear Mixed Models
(GLMM) with individual as a random variable to give
the same weight to every individual, whatever the num-
ber of recordings (Littel et al., 1991). Normality of the
variables was assessed with the Kolmogorov–Smirnov
tests. We wrote a program for compositional analysis
for SPSS. As advised by Aebischer et al. (1993), a rand-
omisation test based on pairwise permutations was per-
formed to obtain an accurate p-value in compositional
3. Results
3.1. Earthworm biomass
In fields, earthworms were more abundant and heav-
ier than in woodlands (number of individuals: 283 ± 199
,n= 43 samplings in forest vs. 737 ± 390
,n= 38 samplings in fields, t
P< 0.001; mass per individual worm: 0.085 ± 0.176 g,
n= 12,464 worms in forest vs. 0.397 ± 0.616 g,
n= 28,765 worms in fields; t
=78.87, P< 0.001).
Therefore, earthworm biomass was about 12 times high-
er in nocturnal field habitats than in diurnal woodland
habitats (Fig. 1;Table 3). In diurnal woodlands, the
earthworm biomass was four times higher in wet forest
and coppices, and to a lesser extent in recent plantations
than in the older stands (timbers) (Fig. 1;Table 3).
Among the humus types, earthworm biomass tended
to be higher in mulls than in moders and mors, although
it was not significant (Fig. 1;Table 3). In forest, earth-
worm sampling was slightly influenced by the month,
but not by the year nor the air temperature (Table 3).
There was no difference in earthworm biomass and its
spatial distribution between the three types of meadows
(young, dry and wet), but stubbles had 4–5 times less
earthworm biomass than meadows (Fig. 1;Table 3).
Earthworm sampling tended to be affected by air tem-
perature, but not by the month or the year (Table 3).
3.2. Diurnal habitat selection in woodlands and hedges
We used 59 of the 65 woodcocks in the analysis of
habitat selection in forest because the remaining 6 birds
spent most of their time in hedges and were located less
than 7 times in forest. Using the detailed classification
based on nine wood stands, habitat selection index k
was not highly significant (P= 0.037, Table 4). The
pooled classification of six forest stands showed prefer-
ences (P< 0.001). Plantations and coppices were the
most preferred habitats by woodcocks and timbers were
the least preferred. When considering soil humus types,
mulls were preferred to moders and mors (Table 4).
For forest stands as well as soil humus, there was no ef-
fect of year or age of woodcocks on their habitat selec-
tion (all P> 0.1). Mulls were present in 78% of
plantations, 70% of coppices and 50% of wet forests
(Fig. 2). Coniferous stands showed the highest propor-
tion of mors (30%), but they still contained similar high
proportion of mulls (30%).
Plantations, coppices and wet forests had more shrub
cover than older forest stands (Fig. 3; ANOVA
= 0.34, F
= 27.26, P< 0.001), and were richer in
earthworms. Percent shrub cover was higher in the 175
sites used by woodcocks compared to the 82 random
sites from systematic sampling (75.6 ± 27.2% vs.
57.7 ± 36.3%, respectively; GLMM on 44 individuals:
= 1040.11, P= 0.021).
Hedges were less frequented than woodlands: only
nine individuals that were located more than seven times
in hedges were analysed. In the detailed analysis, wooded
and shrub hedges with lateral shrub strip were preferred
over the other types (Table 4). The pooled analysis
showed that wooded hedges were preferred to shrub
woodland habitat and humus types
plant cop DT MT CT WF Mor Moder Mull mean
mean earthworm biomass (kg/ha)
forest stands
forest humus
Mean forest
field types
mean earthworm biomass (kg/ha)
field types
Mean fields
Fig. 1. Earthworm biomasses (mean ± standard error SE in kg/ha) for
each diurnal (top) and nocturnal (bottom) habitat type used by
woodcocks (see Table 1 for labels). Numbers on the top of bars are the
number of sites sampled.
484 O. Duriez et al. / Biological Conservation 122 (2005) 479–490
Table 3
Factors influencing mean earthworm biomasses in different habitats (fields and forests) and at different levels (stands or humus types)
Analysis R
Factor Ftest df PInterpretation
Woods/fields 0.71 Habitat 175.51 1.73 <0.001 Fields > woods
Air temperature 3.10 1.73 0.084 Increase with temperature
Month 1.73 2.73 0.185
Year 0.09 1.73 0.767
Woods stands 0.33 Stand type 3.09 5.31 0.022 Cop = WF = plant > CF = DT > MT
Month 2.81 2.31 0.076 March > February > January
Year 0.31 1.31 0.580
Air temperature 0.10 1.31 0.921
Woods humus 0.28 Mull type 2.20 2.34 0.126 Mull > moder > mor
Month 1.79 2.34 0.182
Air temperature 0.60 1.34 0.444
Year 0.05 1.34 0.945
Fields 0.62 Field type 10.01 3.29 <0.001 Meadows > stubbles
Air temperature 4.08 1.29 0.053 Increase with temperature
Year 0.83 1.29 0.369
Month 0.47 2.29 0.628
Results are from GLM and the differences among groups were tested with TuckeyÕs post-hoc tests.
Table 4
Results of compositional analysis on habitat selection in wintering woodcocks
Analysis Group nWilkÕskPHabitat ranking
Woods stands Detailed 59 0.736 0.037 DP COP > CP > WF > PT > CWS > DT > CT > MT
Pooled 59 0.606 <0.001 Plantation coppice WF > coniferous timber > DT > MT
Woods humus Detailed 59 0.531 <0.001 Mull moder mor
Hedges Detailed 9 0.067 0.004 WS SS>W>S>R
Pooled 9 0.002 <0.001 Wooded shrub > R
Fields Detailed 63 0.273 <0.001 DGM ST > WGM > YGM UM > SP
Pooled 63 0.290 <0.001 Grazed meadows ST UM > SP
Diurnal habitat selection was analysed in woodlands (two levels: stands and humus) and in hedges, while nocturnal habitat selection was analysed in
fields. Habitats were ranked from the most preferred to the least preferred. A significant preference between two habitats was indicated by ‘‘’’ while
a non significant difference was indicated by ‘‘>’’ (Aebischer et al., 1993). The codes used for ranking of habitats are given in Tables 1 and 2.Pvalues
were given by randomisation.
% of humus
54 22 35 15 46 10
Fig. 2. Proportions of humus types in the six types of woodland
habitats in the study area (black = mor, light grey = moder and dark
grey = mull). The proportions of humus are calculated on the
systematic sampling of 182 sites (the number of sites for each habitat
are given above the columns). Legend: PL = plantation; COP = cop-
pices; DT = deciduous timber; MT = mixed timber; CT = coniferous
timber; WF = wet forest.
% shrub cover
20 30 40 50 60 70 80 90 100
earthworm biomass (kg/ha)
Coppice Wet Forest
Deciduous timber
Mixed timber
Coniferous timber
Fig. 3. Relationship between the percentage of shrub cover and
earthworm biomass (means ± standard error SE) in six habitat types in
woodlands. Values of percentage of shrub cover represent means ± SE
of 82 random sites and 175 sites used by woodcocks.
O. Duriez et al. / Biological Conservation 122 (2005) 479–490 485
and relictual hedges (Table 4). Year and age effects could
not be tested because sample size was too small.
3.3. Nocturnal habitat selection in fields
For the nocturnal habitats analyses, 63 woodcocks
were used and 2 were removed because they almost
never frequented the fields. We did not consider habitat
selection on nights when birds stayed in woodlands, be-
cause they were always located in the same habitat used
the previous day. Nocturnal habitat selection was differ-
ent from random use (P< 0.001) and dry grazed mead-
ows were preferred, followed by stubbles and wet and
young grazed meadows (Table 4). Un-grazed meadows
and seed plots were avoided. When the three types of
grazed meadows were pooled, they were the most pre-
ferred habitats. There was no effect of year or age in
any of the analyses (all P> 0.3).
4. Discussion
4.1. Diurnal habitat selection
Among the various types of woodlands, outside frost
period, woodcocks preferred young forest stands as hab-
itats: plantations, followed by coppices and wet forests.
Woodcocks avoided older stands of timber. Plantations
and coppices were characterised by an important shrub
strata, because more light reached the ground, while the
shrub strata was scarce in timbers. The shrub strata pro-
vides overhead protection from raptors and increases
cover from terrestrial predators. Preference for young
habitats in winter was suspected from the hunting statis-
tics (Imbert, 1988; Fadat, 1995) and woodcocks moni-
tored by Wilson (1983) almost exclusively used young
(20–30 years old) planted coniferous woodlands. Amer-
ican woodcocks (Scolopax minor) also preferred shrub-
lands and young pine plantations in winter, but could
adapt to a variety of habitats (Krementz and Pendleton,
1994; Krementz and Jackson, 1999).
The compositional analysis showed that mulls humus
soils were preferred to moders and mors. Mulls, slightly
richer in earthworms, constituted the majority of humus
types in wet forests, coppices and plantations. Conifer-
ous timbers ranked fourth in habitat selection, although
they contained few earthworms. Contrary to standard
coniferous forest features, rich patches of earthworms
also existed in the coniferous timbers of the Beffou forest
where one third of soil types were mulls. The presence of
alkaline springs in coniferous stands induced these
patches of mull and hazel trees. Most of the woodcocks
frequenting timbers were in the vicinity of these patches
and avoided mor type humus. The habitat types with
highest earthworms density were also the richest in
shrub cover. Therefore, we conclude that, in winter,
woodcocks choose their habitat in woodlands on the ba-
sis of rich patches of food (e.g., mull humus) and on the
presence of an important shrub strata. However, it is not
possible with our dataset to tease apart the relative
importance of these features that are probably related
to prey accessibility and abundance, and to protection
from predators. Insect larvae biomass and availability
was not considered in this study. Although generally less
abundant in woodland, their occurrence in patches in
some sites that were relatively poor in earthworms might
explain their selection by woodcocks. However, another
study based on the same radio-tagged woodcocks
showed that these birds used different foraging strategies
depending on earthworm availability in their diurnal site
(Duriez et al., 2004). In a site rich in earthworms, they
could stay several day or weeks foraging only by day
and staying in woodlands at night. But in poorer diurnal
sites, they could not meet all their energetic require-
ments without going to fields at night (where there was
always sufficient food). This result suggests that earth-
worm abundance may drive woodcock habitat selection
and behaviour in winter while other invertebrates would
play a secondary role.
Wooded hedges were preferred to shrub or relictual
hedges. Moreover, hedges with a lateral strip were pre-
ferred to hedges without a strip. Because woodcocks
mostly use forests for breeding and wintering, their pref-
erence for the wider and denser hedges, which resembles
a miniature forest habitat, was expected. The shrub and
grass strata, as well as a lateral strip, providing condi-
tions for efficient camouflage, certainly play a role for
protection against predators. Moreover, the presence
of a lateral shrub strip could allow diurnal feeding
opportunities. All the hedges of the study area occur
on embankments. Our protocol to estimate earthworm
biomass was inadequate to sample the hedges, but earth-
worms likely were limited or scarce because of shallow
soil and the current dry soil conditions. In this context,
only the strip, extending the hedge on the field (usually a
meadow), likely provided food in high quantity.
4.2. Nocturnal habitat selection
Meadows (especially old dry grazed meadows) were
preferred by woodcocks over fields of stubble and seed
plots, as found in England and Ireland (Hirons and
Bickford-Smith, 1983; Wilson, 1983; Hoodless, 1994).
Because earthworm biomass (woodcockÕs main prey
item) was four to five times higher in meadows than in
the other cultivated fields, this choice probably reflected
food availability. Binet (1993) found a tenfold reduction
in earthworm biomass when going from a meadow to
corn plot in Brittany. In addition to earthworm abun-
dance, insect larvae was found to be an important com-
ponent of the diet and habitat selection of similar-sized
grassland waders (e.g., Golden plovers Pluvialis apricaria;
486 O. Duriez et al. / Biological Conservation 122 (2005) 479–490
Pearce-Higgins and Yalden, 2003). Although not sys-
tematically measured, insects larvae biomass was con-
siderably lower than earthworm biomass in our study
site. Because its diet is composed of more than 80% of
earthworms in winter (Granval, 1988), we believe that
if woodcock habitat selection is driven by prey availabil-
ity, it should be primarily towards earthworms.
Un-grazed meadows were avoided compared to the
three types of grazed meadows. Grazed meadows sup-
port more earthworms than hay-meadows (Nic¸aise,
1996), because cattle manure serves as food for most
earthworm species (Lee, 1985; James, 1992). Although
we did not sample earthworms in un-grazed meadows,
we did a qualitative visual inspection using a spade
and found numerous earthworms there. In addition to
probable but minor differences in earthworm abun-
dance, we believe that the avoidance of un-grazed mead-
ows is likely the result of the difference in vegetation
structure (tall grass compared to short grass in grazed
meadows). Ferrand and Gossmann (1995) hypothesised
that the short swards of grazed meadows enable easy
mobility of woodcocks and better detection of their
preys and predators. Indeed predation by mammals (feral
cats, foxes and mustelids) mostly happen at night in
fields (Duriez et al., 2005). Such selection of short-sward
grazed meadows were also found in similar-sized grass-
land waders like Lapwings Vanellus vanellus (Mason
and MacDonald, 1999) and Golden plovers (Milsom
et al., 1998; Whittingham et al., 2000; Pearce-Higgins
and Yalden, 2003), and also passerines (Perkins et al.,
Although grazed meadows were generally preferred,
stubbles ranked second. Stubbles were intensively used
by some individuals (5 birds used them >50% of their
time, and 2 birds >90%). Stubbles probably offered an
easier mobility and prey detection. Moreover, stubbles
following a first cereal crop, after several years in mead-
ows, may be rich in earthworms because of the high in-
put of organic matter in the soil (ploughed-under grass)
(Edwards and Lofty, 1977 in Lee, 1985). In 2000, a first-
year wheat stubble was used every night by 2–3 wood-
cocks. Although the sampling protocol was not applied
in 2000, the presence of hundreds of molehills in this
field indicates that this plot was probably rich in earth-
worms, because Moles (Talpa europaeus) are specialist
predators of earthworms (Granval and Aliaga, 1988).
Fields with molehills, used as an indicator of earthworm
abundance, were also significantly selected by Golden
plovers (Whittingham et al., 2000).
The results of our study suggest that woodcock win-
tering in Brittany use meadow and stubble habitats,
probably in relation to prey availability, which is a com-
bination of sward height and prey abundance. However,
it was not feasible to sample variation in prey abun-
dance and sward height at a sufficiently fine resolution
to tease these components apart. Because of the large
wintering range of the woodcock (from Great-Britain
to the Mediterranean coasts), our study should not be
generalised too widely, although our conclusions on
the influence of the availability of its primary food item
should be fairly robust for such a specialised predator.
Understanding woodcocks wintering strategies will re-
quire additional studies in other parts of the winter
range, in similar environments, as well as in completely
different habitats, for example British moorlands, pine
forests in the French Landes, or Mediterranean
4.3. Implications for conservation management
In winter, woodcock populations use a mosaic of
habitats, including woodlands and fields. Currently,
the few woodcock reserves only prohibit hunting in
woodlands. A more effective reserve would not only lim-
it hunting, but should manage the different habitats
(diurnal and nocturnal) to provide sufficient food and
shelter. The mosaic of habitats (bocage features), once
common, is decreasing and/or changing today.
Although woodlands are now increasing in the Euro-
pean Union, the recent increase of deciduous plantings
follows three decades of massive introduction of conifer-
ous trees in native plain forests. In some parts of their
winter range, woodcocks are found in pine timbers be-
cause it is the only stand type available. Indeed the use
of such habitats by woodcocks seems to be primarily
constrained by the presence of mull soils (synonymous
of high earthworm activity) and dense shrub strata.
Granval and Muys (1992) reviewed that restoration of
degraded forest soils is possible. Some tree species
(e.g., ashes and alders) have an ameliorating effect on
earthworm biomasses (Muys et al., 1992). Moderate lim-
ing without tilling can ameliorate humus if earthworms
are still present (Granval and Muys, 1992). In uninhab-
ited humus (mor), earthworm introduction could be
tried (Huhta, 1979; Brun et al., 1987; Judas et al.,
1997). Because beeches and oaks have relatively acid lit-
ter that favours moder humus formation (Muys et al.,
1992), the plantations in the Beffou forest were limed
with natural mae
¨rl (Fornasier, personal communica-
tion), which probably enhanced earthworm activity
and abundance, resulting in mull type humus.
High earthworms biomass in a diurnal habitat is not
sufficient to attract woodcocks if there is no cover to
protect them. The shrub strata is naturally abundant
in the early stages of plantations but forestry practices
in France tend to suppress it after 20–30 years to man-
age for homogenous stands. The old practice of coppic-
es-with-standard, providing firewood, is often
abandoned. This practice was probably benefiting not
only to woodcocks but also to many other forest species
(mammals and birds) by providing cover and food re-
sources (Fuller and Peterken, 1995). The optimal forest
O. Duriez et al. / Biological Conservation 122 (2005) 479–490 487
habitat for a woodcock is a mosaic of stands of various
ages. Management favouring coppices and mull types
humus (ameliorating trees, liming) should be used. A
simple management technique would be to create
numerous small clearings, allowing the natural develop-
ment of shrub species (hazels, brambles), enhancing
earthworm population growth as well as other
The conservation of traditional bocage landscapes
with hedges and grazed meadows seems essential for
woodcocks. Agricultural changes are of major concern
for conservation of woodcock in winter and many bird
species in western Europe (Robinson and Sutherland,
2002). Considering the high food potentiality in mead-
ows for woodcocks, the loss of meadows in Europe is
of concern. Moreover, changes in farming techniques
could lead to damages to quality of meadows (Potter,
1997; Wakeham-Dawson and Smith, 2000; Vickery
et al., 2001). Unimproved pastures were preferred to im-
proved pastures by Lapwings and Curlews Numenius
arquata (Barnett et al., 2004). The spreading of manures
and mineral Nitrogen as fertilisers could benefit earth-
worms if done moderately (Cotton and Curry, 1980)
but heavy or high frequencies of applications reduce
invertebrate abundance (Zajonc, 1975; Gerard and
Hayes, 1979; Curry, 1998). In agrosystems dominated
by crops, pesticides also affect earthworms and insect
populations (reviewed in Edwards, 1998), which already
suffer from deep ploughing (Barnes and Ellis, 1979; Ed-
wards, 1983; Binet, 1993). The recent development of
simplified cultural techniques (no-tillage or minimum-
tillage and direct sowing) shows that it is possible to
yield abundant quality crops as under conventional
practices, resulting from auxiliary action of abundant
earthworms (Barnes and Ellis, 1979; House and Parme-
lee, 1985; Baker, 1998). These practices should be
encouraged to protect the soil fauna and their associated
predators. Set-asides, now imposed by the EU Common
Agricultural Policy, are attractive to many bird species
(Henderson and Evans, 2000) and would be attractive
to woodcocks if they are grazed or mowed in autumn,
because earthworm biomasses is higher there than in
crops (Bernard et al., 1998). In agricultural landscape
offering adverse soil conditions (heavy ploughing, low
organic matter content, acid pH), field margins may
serve as refuges for earthworms where they can spread
out into agricultural fields, thereby keeping up high
abundance and biodiversity (Lagerlo
¨f et al., 2002) that
favours their use by birds (Vickery et al., 2002).
This study was funded by the Office National de la
Chasse et de la Faune Sauvage. We are very grateful
to all the persons involved in the fieldwork: Y. Chaval,
J.-L. Chil, S. Descamps, C. Guyot, H. Jamin, J. Le Bi-
han, F. Leroy, J. Marie, J.-P. Richard and S. Alary.
G. Eon and V. Farcy determined more than 41,000
earthworms! Many thanks to S. Said, E. Bro, P. Gran-
val, D. Pinaud, H. Lorme
´e, J.-M. Boutin, D.G. Kre-
mentz, D.G. McAuley, J.D. Goss-Custard, C.-A. Bost,
D. Chamberlain and one anonyms refree for useful dis-
cussions and comments on the Manuscript. P. Landry
digitised the map on GIS. We are grateful for the logistic
facilities provided by the Conseil Ge
´ral des Co
dÕArmor’’, Jean-Claude Fornasier (Office National des
ˆts). Many thanks to all the farmers for allowing a
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... Environmental conditions influence the Woodcock's behavior, especially in the non-reproductive period (i.e., wintering period), when the distribution and abundance of its populations seem to be particularly affected by temperature and rainfall [27][28][29]. The Woodcock is sensitive to the thermal regime [27,29,30] and seasonal variations in soil moisture [31,32], as well as habitat features related to vegetation cover [33][34][35]. Landscape and forest habitats' heterogeneity can significantly affect Woodcock abundance since habitat requirements appear to vary with different stages of its annual life cycle [35]. ...
... Landscape and forest habitats' heterogeneity can significantly affect Woodcock abundance since habitat requirements appear to vary with different stages of its annual life cycle [35]. The Woodcock's distribution is also strongly conditioned by food availability [31,36]. It has a diet specialized in soil microfauna: arthropods, annelids (mainly worms), and slugs [36]. ...
... During the breeding season, the Woodcock selects habitat mosaics with specific characteristics such as deciduous forest habitats [46,47], mixed forest, or conifers [25,48,49]. During the wintering period, it shows less specific habitat requirements, selecting different habitats such as hedged forests during the day, for refuge, and meadows at night, for feeding [25,31,50], where it can find high invertebrate biomass, particularly annelids [26,51]. ...
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Migratory birds are particularly exposed to habitat changes in their breeding and nonbreeding grounds. Remote sensing technologies offer an excellent opportunity to monitor species’ habitats from space at unprecedented spatiotemporal scales. We analyzed if remotely sensed ecosystem functioning attributes (EFAs) adequately predict the spatiotemporal variation of the Woodcock’s (Scolopax rusticola) relative abundance in southwest Europe, during autumn migration and wintering periods. We used data gathered from Woodcock monitoring through citizen science (N = 355,654 hunting trips) between 2009 and 2018. We computed a comprehensive set of EFAs on a weekly basis from three MODIS satellite products: enhanced vegetation index (EVI), tasseled cap transformation (TCT), and land surface temperature (LST). We developed generalized linear mixed models to explore the predictive power of EFAs on Woodcock’s abundance during the non-breeding season. Results showed that Woodcock abundance is correlated with spatiotemporal dynamics in primary productivity (measured through the EVI), water cycle dynamics (wetness component of TCT), and surface energy balance (LST) in both periods. Our findings underline the potential of combining citizen science and remote sensing data to monitor migratory birds throughout their life cycles—an issue of critical importance to ensure adequate habitat management in the non-breeding areas.
... The transmitters were programmed to record one GPS location per day, which was timed a few minutes after midnight to maximize the probability of proper satellite data communication, assuming that the birds would be feeding in open fields at those times (Duriez et al. 2005a). According to factory default settings, the tags transmitted the localization data to a central database via the Argos satellite system after every third successful fix. ...
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Eurasian Woodcock (Scolopax rusticola) plays a special role in the cultural heritage of most nations in Europe. In the last decade, ringing revealed the main migratory patterns of some well studied and intensively harvested Woodcock populations wintering in Western and Southern Europe. The same study sites and populations were in focus when the recently revolutionized satellite tracking technologies allowed the study of individual migrations. In contribution to these efforts, we present here the pre-nuptial migration data of Woodcocks captured and tagged with GPS-Argos transmitters in Central Europe, in 2020. Woodcocks migrated from the tagging site in Hungary to Ukraine, European Russia and Central Siberia by an average of 2,678 km (range 677–5,002 km). The duration of the migration ranged between 1–52 days, the overall migration speed was 382 km/day, the absolute maximum distance covered in a day was 866 km. The individual number of stopovers varied during the migration from 0 to 5. The average time spent at each stopover site was 5.6 days. Within the stopover sites, the daily displacements ranged between 11–3,329 m. The Carpathian Basin may be more important in the wintering of Woodcocks than previously assumed, as tagged birds stayed significantly longer compared to any later en route migratory stopover. In accordance with the results of previous DNA analysis, identified breeding grounds of tagged individuals represented a large part of the distribution area.
... Other potential causes may be agriculture intensification (nest destruction due to increased frequencies of agricultural activities e.g. mowing), low food availability (because of use of artificial fertilizers and pesticides; Duriez et al., 2005;Hulscher & Verhulst, 2003), human disturbance and climate change (van de Pol et al., ...
... Other potential causes may be agriculture intensification (nest destruction due to increased frequencies of agricultural activities e.g. mowing, low food availability because of use of artificial fertilizers and pesticides; Hulscher & Verhulst, 2003;Duriez et al., 2005), human disturbance and climate change ( Van de Pol et al., 2014). ...
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Aim In many species, density‐dependent effects on reproduction are an important driver of population dynamics. However, it is rarely considered that the direction of density dependence is expected to vary over space and time depending on anti‐predator behaviour and predator community. Aggregation may allow for effective group mobbing against avian nest predators while aggregation may also attract mammalian predators, causing negative density dependence. We aim to quantify spatial variation in the effect of conspecific breeding density on nest survival in a mobbing bird species (Eurasian oystercatcher; Haematopus ostralegus) and identify whether this variation in density dependence can be explained by the predator community. Location Country‐wide (The Netherlands). Methods We integrated reproductive data with breeding territory maps of Eurasian oystercatchers and occupancy maps of avian and mammalian predator species across the Netherlands for a 10‐year period. Results Spatial variation in the composition of the predator community explained the effects of neighbour density, showing decreasing nest survival when both conspecific density and mammalian dominance increased. Also, heterospecific density (from breeding godwits and lapwing) has an additional effect on the oystercatcher nest survival. Strikingly, this pattern did not extend to mammal‐free island populations. Main conclusions Our study provides evidence that both the strength and sign of density dependence can vary spatially within species, implying that it is dangerous to generalize results from a single local population to large‐scale management implications and modelling exercises. The study also suggests that conservation actions that aim to attract breeding birds should be prioritized in areas with fewer mammalian predators, but this idea requires further testing on island populations.
Diffuse pollution of the environment by pesticides has become a major soil threat to non-target organisms, such as earthworms for which declines have been reported. However some endogeic species are still abundant and persist in intensively cultivated fields, suggesting they become tolerant to long-term anthropogenic pressure. We thus considered the working hypothesis that populations of Aporrectodea caliginosa earthworms from conventionally managed fields developed a tolerance to pesticides compared with those from organically managed fields. To investigate this hypothesis, we studied earthworm populations of the same genetic lineage from soils that were either lowly or highly contaminated by pesticides to detect any constitutive expression of differentially expressed molecular pathways between these populations. Earthworm populations were then experimentally exposed to a fungicide—epoxiconazole—in the laboratory to identify different molecular responses when newly exposed to a pesticide. State-of-the-art omics technology (RNA sequencing) and bioinformatics were used to characterize molecular mechanisms of tolerance in a non-targeted way. Additional physiological traits (respirometry, growth, bioaccumulation) were monitored to assess tolerance at higher levels of biological organization. In the present study, we generated the de novo assembly transcriptome of A. caliginosa consisting of 64,556 contigs with N50 = 2862 pb. In total, 43,569 Gene Ontology terms were identified for 21,593 annotated sequences under the three main ontologies (biological processes, cellular components and molecular functions). Overall, we revealed that two same lineage populations of A. caliginosa earthworms, inhabiting similar pedo-climatic environment, have distinct gene expression pathways after they long-lived in differently managed agricultural soils with a contrasted pesticide exposure history for more than 22 years. The main difference was observed regarding metabolism, with upregulated pathways linked to proteolytic activities and the mitochondrial respiratory chain in the highly exposed population. This study improves our understanding of the long-term impact of chronic exposure of soil engineers to pesticide residues.
Many bird species typical to farmland have declined in numbers in recent decades. Some farmland bird species occur outside farmland in other open man-made habitats, such as forest clear-cuts. Given that in Sweden the total area of clear-cuts (5–6 %) almost equals that of farmland (8 %), clear-cuts have the potential to be an important habitat for some farmland birds. We investigated how bird community composition and species abundance on Swedish clear-cuts varied with geographical region, clear-cut characteristics and the surrounding landscape, with special focus on farmland species. Based on short visits in 2017–2019, we surveyed the occurrence of birds on 300 representative clear-cuts in Sweden, including six regions and 1300 km of latitude. We counted 1170 birds of 66 different species, including 10 out of 15 bird species in existing farmland bird indicators. Both bird community composition and species abundance varied with clear-cut size, age, vegetation height, region and proportion of nearby farmland, depending on species’ ecology. All six farmland species being proportionally common on clear-cuts are, when in farmland, dependent on residual habitats such as pastures and field borders with bushes and trees. In contrast, a third of the dedicated farmland species were scarce in clear-cuts, probably avoiding them because of predator-related avoidance of forest edges and/or a lack of suitable nest sites or food resources. To determine the full importance of forest clear-cuts for farmland species, and potentially make them more favourable for farmland birds, more studies are needed on the reproductive success on clear-cuts and which site features make them suitable habitat. This study did not determine the consequences of clear-cuts for forest birds across the forest cycle, consequences which needs to be balanced against any gains for farmland birds.
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Based on the results of dietary surveys of the Woodcock ( Scolopax rusticola L.) in 11 countries (Great Britain, Scotland, France, Italy, Croatia, Germany, Hungary, Poland, Ukraine, Russia, and Romania), 63 taxa (42 animal and 21 plant) were detected in Woodcock gizzard contents, of which the predominant dietary components were of animal origin. The composition of the dietary components varies only within a narrow spectrum, adapting to seasonal changes in the insect fauna and the supply of the area. Earthworms ( Lumbricus spp.) represent the dominant proportion, also with larvae of Dermaptera, Myriapoda, Coleoptera taxa, and Diplopoda and Araneidae species being present in significant numbers. The mass fraction of plant components (mainly weed seeds) is low, with occasional occurrence of vegetative plant parts. The narrow species range of animal taxa recorded and the low proportion of plant dietary components clearly indicate that the Woodcock is a specialist species, and the availability of a few major dietary component taxa groups are a limiting factor in case of the Woodcock. Therefore, it is a major determinant of the diurnal, seasonal and annual movement patterns.
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11 spp. chapters In book: Atlas das Aves Invernantes e Migradoras 2012/2013 Hydrobates castro, Platalea leucorodia, Tachybaptus rufficollis, Falco columbarius, Gallinulla chloropus, Larus genei, Sterna sandvicensis, Sterna paradisaea, Stercorarius parasiticus, Alca torda, Cuculos canorus
Earthworms live in simple or complex communities with considerable variation in their ecology and behavior specialized to the soil systems which they occupy. Earthworms also possess dense patchworks of associations with individual species having relationships to groups of organisms such as microorganisms, other invertebrates, and vertebrates, with the activities of various earthworm species tending to be complementary. Earthworms have been grouped into various classification schemes meant to categorize them based on burrowing and feeding activities as well as vertical stratification within the soil. The three common categories used by Bouché’s cardinal system are often contended for want of further nuance to better categorize earthworm activities. Earthworm species numbers and diversity are also discussed herein as well as examples of new discoveries in earthworm diversity. The mechanisms and characteristics of earthworm dispersal, both active and passive, are discussed including the consequences and mechanisms behind invasive behavior and associated challenges. Earthworms are also the target of a diverse range of vertebrate predators as well as a swath of parasites and pathogens which are discussed in the chapter. Ecological and physiological energetics are also discussed in detail including consumption of energy by earthworms, allocation of energy to growth, reproduction and oxidative metabolism, and the loss of energy through egestion, excretion, and death. Finally, ecosystem energetics discusses the energy flow through earthworm populations in the wider context of various ecosystems and earthworms’ contribution to these systems.
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Mithilfe von Wildtierkameras wurde untersucht, ob und wie regelmäßig Waldschnepfen Scolopax rusticola Kurzumtriebsplantagen (KUP) in ihre Lebensraumnutzung einbeziehen und welche Funktion diese neuartigen Biomasse-Kulturen als Lebensraum für die Art erfüllen. Die Untersuchungen erfolgten in verschiedenen Jahreszeiten auf mehreren Flächen in den niedersächsischen Landkreisen Emsland und Heidekreis. Jahreszeitenübergreifend konnten auf allen untersuchten KUP Waldschnepfen nachgewiesen werden, in den verschiedenen Jahreszeiten wurde die Art ebenfalls auf den meisten untersuchten Flächen erfasst. Der geringe Anteil an Tagen bzw. Nächten mit Nachweisen der Art (1 bis max. 11 % der untersuchten Tage bzw. Nächte pro Fläche und Jahreszeit) deutet jedoch, unabhängig von der untersuchten Region und Jahreszeit, auf eine eher unregelmäßige Nutzung der Kulturen hin. Innerhalb der Plantagen konnten keine Unterschiede in der Nutzungshäufigkeit zwischen randnahen und zentralen Bereichen festgestellt werden. Hinweise, dass die untersuchten Flächen der Art zur Brut dienten, konnten nicht erbracht werden. Aufgrund deutlicher Unterschiede zu bevorzugten Bruthabitaten (ausgedehnte, strukturreiche, frische bis feuchte Laub- und Mischwälder) dürften KUP als Bruthabitat für die Waldschnepfe kaum eine Rolle spielen. Dennoch können die Kulturen zur Deckung und als Nahrungshabitat in unterschiedlichen Jahreszeiten durchaus bedeutsam sein. Insbesondere in ausgeräumten Agrarlandschaften mit einem geringen Anteil an Wäldern und anderen Gehölzstrukturen oder Nahrungshabitaten wie Grünländern und Brachen können sie das Habitatangebot erweitern und einen Baustein zur Förderung der Art darstellen, sofern sie dabei nicht wertvolle Brut- oder Nahrungshabitate ersetzen. Durch strukturbereichernde Maßnahmen innerhalb der Plantagen, beispielsweise durch ein Gehölzarten- und Umtriebsstadienmosaik oder die Integration von Lichtungen oder Bewirtschaftungsgassen, kann die Habitatqualität von KUP für Waldschnepfen zusätzlich erhöht werden. // Camera traps were used in order to investigate whether (and how frequently) short-rotation coppice (SRC) are incorporated into the habitat utilisation of the Eurasian Woodcock Scolopax rusticola. Surveys were carried out in different seasons on several study sites in the Districts of Emsland and Heidekreis in Lower Saxony, Northern Germany. Woodcocks were found across all surveyed SRC sites in at least one of the seasons under investigation. However, the relatively low proportion of days/nights with detections (1 % to max. 11 % of the days and nights respectively per site and season) indicates a rather sporadic utilisation of the woody crops by Woodcocks, regardless of the region and season studied. Within the plantations there were no differences in use frequency between areas close to the edge and central areas of the crop. There was no evidence that the study sites were used as breeding habitats by the species. Due to the considerable differences between them and preferred breeding habitats (large, structurally diverse, wet deciduous and mixed forests), SRC are unlikely to play a major role as breeding habitat for the Eurasian Woodcock. However, the woody crops can be important for cover and foraging in different seasons, particularly in cleared agricultural landscapes with a low proportion of woodland and other woody habitats (like hedges) or foraging habitats such as grasslands or set-asides. Under these conditions SRC can provide additional habitats and may therefore be a suitable measure to support the species, as long as they do not replace any other valuable breeding or foraging habitat. To further increase the habitat quality of SRC for Woodcocks, structure-enhancing measures can be implemented within the plantations, e.g. by establishing a mosaic of tree species and age classes or by integrating clearings and rides.
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PU 178 Regime alimentaire diurne de la becasse des bois (scolopax rusticola) en hivernage approche quantitative
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In the last 50 years, intensification of agricultural grassland management has led to over 97% of all grassland being 'improved' in the UK. Despite grassland being an important habitat for birds in Europe, both in terms of area and preference by several species of conservation concern, the impact of grassland intensification on both breeding and wintering birds is poorly understood. This study compared habitat characteristics and bird diversity, in winter, between improved and unimproved lowland grassland in England comprising 44 unimproved fields (350ha) and 59 improved fields (290ha) at 7 paired sites. Key habitat differences were found between grassland types. These included, on improved fields, a denser sward, less surface water, more dung flies and more fields with seeding grass. Species that are dependent on soil invertebrates (particularly earthworms) were found to be more numerous on unimproved grassland, whilst generalist insectivores such as corvids were much more numerous on improved grassland. Grassland improvement may have been one important factor behind the recent increases in numbers of some corvid species in the UK.
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In order to survive throughout the winter, birds have to solve an adaptive trade-off between the need to feed and predator avoidance. In the case of Woodcock, this trade-off is articulated around habitat selection. The risk of predation is higher in meadows used at night than in forests, but food biomass (earthworms) is ten times more abundant in meadows than in forests. Radio tracking highlighted two overwintering strategies. A third of Woodcocks remained in a unique site throughout the winter, while the rest visited several sites, alternatively or successively. The choice of strategy seems to depend on the foraging efficiency of each individual and their ability to escape predators. The use of meadows at night, which varies among individuals, provides another explanation to the starvation / predation trade-off. Most Woodcocks were active during the day (in forest) and at night (in meadows), but some of them were completely diurnal and stayed in the forest at night. The decision to use meadows at night seemed to be taken every evening, depending on foraging success of during the day in the forest. Following a successful feeding day, in a good patch of food, the individual would not take the risk to fly to meadows. As the patch started to get depleted, the individual need could not be satisfied and it was forced to fly to meadows at night (where there is always enough food) and/or change its diurnal site. Therefore, the trade-off between feeding and predation risk depends on the efficiency of the individual at finding a good foraging patch in the forest and to exploit it optimally during the day.
The decomposition of the produced plant mass which becomes again a source of plant nutrition represents an important part of the circulation of substances in ecosystem characteristics. Of the agrobio- coenoses it is the intervention of man just into this phase of the natural metabolism of the total system. Man harvests the crop and translocates it to another system so that no decomposition and natural renovation of soil fertility can occur here. Uptaken substances are then replaced mostly by mineral manures and these influence the life of soil organism providing a single phase of decomposition together with another chemical intervention. Although it is obious that the pre sent intensive agriculture depends, in the domain of nutrition and plant protection, first on chemical means we must focus our attention on the effects of agrotechniques on the living components of the soil which remain a natural renewer of its fertility.