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Abstract – The Black Woodpecker has a wide northern Palearctic range, but in much of western Europe it has a highly fragmented dis-
tribution. As these isolated populations are vulnerable to land cover change, a better understanding of the factors driving their presence
is needed in the perspective of conservation. To shed light on the habitat preferences of the Black Woodpecker in the southern part of its
range, we carried out a research in a large protected area, the Cilento and Vallo di Diano National Park (the first investigation on this spe-
cies anywhere in southern Italy). We used a playback technique to detect occurrence of Black Woodpeckers, as well as sympatric wood-
pecker species, and recorded environmental characteristics that might explain the bird’s occurrence, such as tree species and stand age.
The “extent of occurrence” of the Black Woodpecker was calculated, and its habitat preferences investigated. Occurrence of the species
was clearly dependent on beech dominance, in contrast with the other woodpecker species, with an estimated total population for Nation-
al Park 18.56 (± 6.19) pairs in beech-dominated woods. Habitat preferences were narrower compared to northern European populations,
highlighting the dependence of this species on beech forests in southern Europe. Since beech forests in the Mediterranean region are pre-
dicted to recede due to climate change, our findings highlight the vulnerability of southern Black Woodpecker populations.
Key-words: beech, climate relict, extent of occurrence, Picidae.
1 Environmetrics Lab, Dipartimento di Bioscienze and Territorio (DiBT), Università del Molise - 86090 Pesche (IS), Italy
2 ARDEA, Associazione per la Ricerca, la Divulgazione e l’Educazione Ambientale - Via Ventilabro 6, 80126 Napoli,
Italy
3 Department of Biology, Colorado State University - Fort Collins CO 80523, USA
DaviDe De Rosa1,2, WalteR s. anDRiuzzi3, MiRko Di FebbRaRo1
Breeding habitat selection of the Black Woodpecker
Dryocopus martius L. in Mediterranean forests
INTRODUCTION
Due to their ecological importance and high sensitiv-
ity to disturbance that affects other components of avi-
fauna, woodpeckers have been identified as a particular-
ly important conservation target (Drever & Martin 2010,
Mikusiński et al. 2001). Woodpeckers are good indicators
of forest biodiversity as their presence is representative of
the condition of the forest and its overall environmental
health (Angelstam 1990, Mikusiński 1997). The consid-
erable reduction of deadwood not only at the stand but at
the landscape level is considered to be one of the principal
causes of biodiversity loss in managed forest ecosystems
worldwide. The presence of woodpecker assemblages and
their association with standing deadwood for both nesting
and foraging is used to emphasize the importance of the
entire range of snag degradation stages for maintenance of
key ecological processes in habitat remnants of managed
landscapes (Drapeau et al. 2009).
One of the most widely distributed woodpecker spe-
cies is the Black Woodpecker Dryocopus martius L.,
whose global range extends from Europe through the taiga
forest belt into Asia, with a core area between 62° and 69°
N (Winkler et al. 1995). Black Woodpecker usually uti-
lizes tall and large trunks of many coniferous and broad-
leaved trees forming extensive unbroken forests (Glutz &
Bauer 1980, Cramp 1985). Habitat use is possibly related
to its peculiar food requirements, especially carpenter ants
(Formicidae) (Cuisin 1988, Ceugniet 1989, Pechacek &
Krisvtin 1993, Rolstad & Rolstad 2000).
In Europe it ranges from the Arctic Circle region to
southern Italy, using a wide variety of tree species for
feeding and nesting (Angelstam 1990). In contrast with
this overall wide distribution, however, populations in
the southern part of the range, including the Iberian, Ital-
ian and Balkan peninsulas, are often small and fragment-
ed (Brichetti & Fracasso 2007, Aierbe et al. 2014). Ani-
mal populations at range margins are especially vulnerable
to environmental modification, e.g. due to climate change,
and may differ from core populations in ecological prefer-
ences and therefore conservation requirements (Hampe &
Petit 2005). This is exemplified by the contrast between
Avocetta 40: 63-69 (2016)
© 2016 CISO - Centro Italiano Studi Ornitologici
De Rosa et al.
64
the large Black Woodpecker population in northern Italy,
with an estimate of 1,300-3,700 breeding pairs mainly lo-
cated in forested Alpine and sub-Alpine regions, and the
small fragmented populations in the southern Apennines
(Nardelli et al. 2015).
Northern Italian population appears in expansion and
in the last twenty years there has been a progressive colo-
nization of hilly areas and, in some cases, planitial, by this
species, once relegated to the mountain forests (Nardelli et
al. 2015), whereas poor information is known about south-
ern population.
Reasons for this might go beyond climatic factors, as
for instance only occasional records have been reported
from the Abruzzo, Latio and Molise National Park, despite
the abundance of suitable old beech Fagus sylvatica for-
est habitat. A long history of hunting may explain why the
Black Woodpecker is largely absent today from much of
peninsular Italy (P. Harris in Gorman 2011). Small size of
suitable forest fragments is also an important limiting fac-
tor for this species, as shown in the Iberian Peninsula (Gar-
mendia et al. 2006).
In order to improve our understanding of Black Wood-
pecker habitat requirements in southern Europe, we inves-
tigated its presence and habitat in a large protected area in
southern Italy using the playback technique. The specific
objectives of our study were: a) to test the relationship be-
tween the species occurrence and forest structure charac-
teristics, b) to determine its extent of occurrence (EOO).
MATERIALS AND METHODS
Study area
The study area, “Parco Nazionale del Cilento, Vallo di Di-
ano e Alburni”, henceforth referred to as the Cilento Na-
tional Park, is one of the largest protected areas in south-
ern Europe, it extends from sea level to 1899 m a.s.l. of
Cervati mountains and is of outstanding ecological inter-
est due to its diverse range of habitats and the high bio-
diversity it supports (La Valva & Carrabba 1999, Per-
siani et al. 2010, Ravera & Brunialti 2012, Romano et
al. 2010). Established in 1991, it covers an area of about
180,000 hectares encompassing a wide range of vegeta-
tion types. About 1,800 plant species were surveyed in the
park, among which Yew Taxus baccata, Holly Ilex aqui-
folium and an Italian endemism, the Neapolitan Alder Al-
nus cordata. The inland area is covered by deciduous hard-
wood forests, with a mix of Turkey Oak Quercus cerris,
Downy Oak Quercus pubescens, Maples Acer spp., Horn-
beam O strya spp., Manna Ash Fraxinus ornus and Chest-
nut Castanea sativa up to about 1000 m above sea level.
Beyond this elevation, beech F. sylvatica dominates, usu-
ally preceded by a band of Neapolitan Alder.
Woodpecker survey
For this study, the park was divided into 2.5 × 2.5 km
grid plots using ArcGIS. Although a Black Woodpeck-
er’s home range may vary in size, depending on the re-
gion, plot size was based on an average of the minimum
home range sizes known for Europe (western Italian Alps:
3 km2, Bocca & Rolando 2003; Sweden: 5 km2, Tjernberg
et al. 1993; Norway: 1 km2, Rolstad et al. 2000; Denmark:
1.30 km2, Johansen 1989; Hungary: 2 km2, Gorman 2011).
A first selection of 104 grid plots was made, on the criteri-
on that each plot had to be at least 50% covered by wood-
land. All woodland types in the park were included, as the
Black Woodpecker is known to occur in many forest types
(Angelstam & Mikunsinski 1994). Subsequently, 34 plots
were randomly selected and investigated (Fig. 1).
The plots were surveyed one time between February
and March 2012, as courtship in the Black Woodpecker
can start anytime from February (Cramp 1985). The play-
back technique (Falls 1992, Douglas and Mennill 2010)
was used to record the number of individuals of the Black
Woodpecker. Sounds used for play-back were taken from
Roché (2008). An initial play-back was followed by five
minutes of silence in order to detect any response; the op-
eration was then repeated once. The procedure was used
for other Woodpecker species in this order: Leiopicus me-
dius, Dryobates minor, Dendrocopos major, Picus viridis.
Although the sampling period may not have been optimal
for these species, European woodpeckers are essentially
non-migratory and sedentary birds (Gorman 2011), and so
we opportunistically also detected their presence.
Since our main target species is highly territorial, the
location of breeding territories was used as a census proxy,
i.e. a targeted census (Svenssons 1979, Bibby et al. 1992).
We investigated the effect of the different forest variables
on Black Woodpecker during the breeding season. There-
fore, the conclusions that may be drawn from our data are
relevant to the territories used for breeding and not neces-
sarily to the habitats exploited during other seasons; how-
ever all woodpeckers are predominantly sedentary, espe-
cially the fragmented population (Gorman 2011).
Habitat evaluation
In each plot a set of environmental variables was meas-
ured, including forest characteristics and elevation. For-
est type was identified based on the tree species assem-
blage as one the following: Beech, Chestnut, Holm Oak-
Alder, deciduous oaks, deciduous oaks and beech, mixed-
oak, and mixed-Mediterranean forest. Stand maturity was
Black Woodpecker in Mediterranean forests
65
classified on a discrete scale from 1 to 3, from recent (< 15
years) coppice to mature stands. Likewise, beech density
and presence of dead trees were classified from 1 (no liv-
ing beech trees and no dead trees detected, respectively)
to 3 (beech-dominated, i.e. virtually only beech as arbo-
real species, and over 10 dead trees per km2 respectively).
Analysis
Occurrence, habitat use and population size of the Black
Woodpecker and other co-occurring Picidae were inves-
tigated in a subset of 34 plots randomly selected from the
initial set of 104 grids. To highlight potential differences
in plot use among the five woodpecker species surveyed,
we performed Principal Component Analysis (PCA) on
species presence/absence data (five species) using plots as
sites. A generalised linear model (GLM) with a binomial
distribution of errors and a clog-log link function was used
to model the probability of recording a Black Woodpeck-
er in relationship to beech tree density, presence of dead
trees and woodland age. Each of the explanatory variables
was dropped in turn and subjected to an analysis of devi-
ance using Chi-square tests to assess its significance. Val-
ues were considered significant at a 5% probability level,
and variance explained by the model was calculated as the
ratio of the difference between null and residual deviance
to null deviance (Zuur et al. 2009). GLM estimates are pre-
sented as means ± standard errors.
Based on our field data, we used kernel estimation to
evaluate the EOO of the Black Woodpecker in Cilento.
This technique was chosen because it is one of the best
known in statistics (Börger et al. 2006) and is the main
choice for modern studies of animal-habitat relationships
(Marzluff et al. 2004). We adopted the fixed kernel method
for bivariate data as recommended by Seaman & Powell
(1996). Regarding the choice of the bandwidth, a parame-
ter showing a very strong effect on kernel estimation (Sea-
man & Powell 1996, Burgman & Fox 2003, Börger et al.
2006), as it regulates its smoothing, we followed the ‘rule
of thumb’ proposed by Scott (1992):
- hopt = 1.06An-1/5 where hopt = optimal bandwidth;
- n = sample size;
- A = min (standard deviation, interquartile range/1.34).
Following the recommendation of Börger et al. (2006)
to adopt a utilization distribution isopleth between 90%
and 50% (the range in which kernel estimators perform
better), we chose a 50% isopleth to calculate the external
range boundaries. Statistical analyses and kernel estima-
tions were performed in R 2.15.3 (R Development Core
Team, 2012; maptools and Genkern packages).
In addition we estimated density of Black Wood-
pecker in beech-dominated woodland dividing the num-
ber of birds by the explored area and assuming the every
birds contacted represented a pair (see Douglas & Men-
nill 2010). Based on the total number of plots identified as
beech-dominated, pairs were estimated to occur across all
beech forests in the Cilento National Park.
Figure 1. Study area in Cilento National Park, Southern Italy. Red squares are the parcels established at the beginning of the study, with
numbers marking those selected for the field survey.
De Rosa et al.
66
RESULTS
Black Woodpeckers were recorded in 10 out of 34 plots.
In nine of these only one individual was found, and only
in one two distinct males were recorded. Most individu-
als were found in beech-dominated plots, with only three
found in mixed-oak forest. PCA suggests that the Black
Woodpecker shows markedly different habitat preferences
from the other four species in the study area (Fig. 2). The
first two axes together account for 63% of the variation in
the woodpecker assemblage. The first axis was positively
correlated with beech density (Spearman’s r = 0.34, p =
0.05), while neither the first nor the second axis were sig-
nificantly correlated with stand age or the presence of dead
trees (r < 0.1, p > 0.1) According to the GLM, the prob-
ability of recording a Black Woodpecker was significantly
related to increasing beech dominance (p < 0.01), increas-
ing from 8.9 ± 6.5% in areas without living F. sylvatica,
to 56.2 ± 13.51% in areas with complete F. sylvatica cov-
er (Fig. 3), whereas it was influenced by neither stand age
(from 27.3 ± 21.9% in young coppice to 29.5 ± 7.9% in
mature stands, p = 0.7), nor presence of dead trees (from
33.3 ± 10.2% in absence of dead trees to 23.1 ± 11.7% with
over 10 dead trees per km2, p = 0.7). The final model with
beech dominance explained 20.4 % of the total variance in
Black Woodpecker occurrence, and its residual variance
was 32.16 on 31 degrees of freedom (ratio = 1.04), there-
fore indicating no over dispersion.
Black Woodpecker density in beech-dominated wood-
land was estimated at 0.09 (± 0.03) pairs per km2. Based
on the total number of plots identified as beech-dominat-
ed, 18.56 ± 6.19 pairs were estimated to occur across all
beech forests in the Cilento National Park. According to
the EOO, the species is mainly distributed in the northern
part of the Cilento Park, especially in proximity to the Al-
burni and Cervati mountains (Fig. 4).
Figure 3. Probability of observation of the Black Woodpecker
Dryocopus martius in Cilento National Park as related to beech
Fagus sylvatica density. The shading represents the 95% confi-
dence region around the mean estimate (solid line).
Figure 2. Principal component analysis based on presence of five woodpecker species in the study area. Black dots represent the sampled
parcels (n = 34). Parcels where the same bird numbers were recorded overlap. Arrows refer to the species, with the following abbrevia-
tions: B = Black Woodpecker Dryocopus martius; GS = Great Spotted Woodpecker Dendrocopos major; MS = Middle Spotted Wood-
pecker Leiopicus medius; LS = Lesser Spotted Woodpecker Dryobates minor; G = European Green Woodpecker Picus viridis. The ei-
genvalues for the first, second, and third axes are, respectively, 0.355, 0.266 and 0.170.
1
0
-1
100
75
50
25
0
-1
0 50 100
PCA axis 1 (R2 = 0.36)
% Living beech tree cover
PCA axis 2 (R2 = 0.27)
% Probability occurrence D. martius
0 1
Black Woodpecker in Mediterranean forests
67
DISCUSSION
In our study sites, the Black Woodpecker used plots domi-
nated by F. sylvatica, as the probability of recording an in-
dividual was significantly higher with increasing beech tree
density. Conversely, woodland age did not influence its oc-
currence. This may well be partly due to the presence of
very old trees in old non-productive snow deposits used in
the past. Indeed, these could be perfect breeding sites also
in young forests, where it is easier for woodpeckers to find
ants (Mikusinski 1997). Species presence clearly corre-
sponded to the Alburni and Cervati mountains (Fig 4), like-
ly to be the only two locations in the national park where
suitable large trees in which to excavate nest holes can be
found. One caveat is that non-detection may not necessar-
ily indicate true absence as assumed in our analysis.
Our results indicate that the Black Woodpecker has
different habitat preferences at our study site when com-
pared to more northerly sites across Europe, where broad-
er tree species choices have been recorded (Angelstam &
Mikunsinski 1994). This is in line with studies in the Ital-
ian Alps which recorded a different habitat choice as com-
pared with the Pyrenees and other parts of Europe (Bocca
et al. 2007). Therefore, the Black Woodpecker’s habitat
choice appears to be context-dependent. This implies that
local data should be preferred for woodland management
aiming to address this species’ conservation, as opposed to
data from other populations.
The Black Woodpecker appears to be a specialist re-
garding habitat choice, with a strong selectivity for beech-
dominated stands. Such habitat use differed from that of
the other co-occurring species of Picidae (Fig. 1). This dif-
ference is probably due to the breeding ecology of Black
Woodpecker with respect to other woodpecker species:
only in beech forest it may find large enough trees in which
to excavate cavities, as the other forest types are over-ex-
ploited and offer few suitable trees for nesting.
Although overall Italian population of Black Wood-
pecker appears to be increasing in numbers and expanding
geographically, as indicated by recent observations in the
Foreste Casentinesi National Park (Ceccarelli et al. 2003)
and in the Aspromonte National Park (G. Martino, pers.
comm.), occurrence in the Apennines remains scarce (Boi-
tani et al. 2002). Our data led to an estimation of fewer
than 20 pairs inhabiting beech woodland in the Cilento Na-
tional Park. This indicates that even in the second largest
protected area in Italy this glacial relict species has a very
small population size, suggesting that its survival in south-
Figure 4. Extent of occurrence of the Black Woodpecker in Cilento National Park study area.
20 km
1050
Black Woodpecker occurrences
Cilento National Park
Black Woodpecker EOO
De Rosa et al.
68
ern Italy may be precarious (Calvario et al. 2011, Peronace
et al. 2012). The fact that it almost only occurred in beech
woodland may be especially critical, since this habitat is
predicted to decrease dramatically in the coming decades
due to ongoing climate change (Innangi et al. 2015).
Such a small local population might be a consequence
of the current management of beech woodland in the Ci-
lento National Park, which may need to be modified if
conservation of rare beech woodland species, such as the
Black Woodpecker, is of the overriding consideration.
More studies in the other areas of southern Europe where
the Black Woodpecker occurs are required to understand
the links between its demographic status and forest man-
agement. An important contribution may come from stud-
ies on juvenile dispersals and adult movements using tele-
metric techniques (Rostald et al. 1998, Bocca et al. 2007).
These data could be linked to the spatial expansion of
Woodpecker species in the last decades of the 20th cen-
tury in Mediterranean Europe, which seems to be closely
related to forest maturation, following large-scale decline
in traditional uses (Gil-Tena et al. 2013). Notably, howev-
er, our findings show that Black Woodpecker occurrence
in Cilento National Park is linked to the presence of beech
but not to stand age.
To our knowledge, no other studies on the density of
this species have been carried out in other areas of south-
ern Italy. Indeed, ours is a first attempt to quantify the hith-
erto unknown population size of the Black Woodpecker
in this important region near the margin of its range. We
suggest that Black Woodpeckers may be more widespread
in southern Italy than is currently believed, although the
absence of environmental corridors connecting to larger,
more stable populations in continental Europe make south-
ern populations particularly vulnerable to climate change
and land use change.
In conclusion, although the Black Woodpecker is ex-
panding in continental Europe (Vos et al. 2008), isolat-
ed populations in the southern part of the range, such as
southern Italy, are to be considered endangered, with a
lack of data on context-specific ecological requirements
hindering their conservation. In addition, considering the
Black Woodpecker as an indicator species, like those spe-
cies whose ecological requirements guarantee the exist-
ence of particular environmental conditions (Campbell &
Lack 1985) would also help to protect a wide range of ani-
mal species that share its habitat, including important wild
pollinators, rare Coleoptera and bats.
Acknowledgments – The authors would like to thank Andrea
Senese, Alfredo Galietti, Rosario Balestrieri and Valerio Giovan-
ni Russo for invaluable field work assistance, and Laura De Risio
(Servizio Conservazione Natura, Parco Nazionale del Cilento e
Vallo di Diano) for authorising field work and the CTA of Vallo
della Lucania. We are also grateful to Egidio Fulco and Giuseppe
Martino for information on the Black Woodpecker populations of
Basilicata and Calabria, and to Ivan Maggini, Barry McMahon
and Mark Walters for constructive comments that improved the
manuscript. Two anonymous referees contributed to improve ear-
lier version of the manuscript.
REFERENCES
Aierbe T., Beñaran H., Fernández-García J.M., Gracianteparaluc-
eta A., Hurtado R., Olano M. & Ugarte J., 2014. Distribution
and abundance of the Black Woodpecker (Dryocopus mar-
tius) in a recently colonized area in SW Europe. Woodpeck-
ers in a changing world’ International Conference.
Angelstam P. 1990. Factors determining the composition and per-
sistence of local woodpecker assemblages in taiga forest in
Sweden - a case for landscape ecological studies. Pp. 147-164
in: Carlson A. & Aulén G. (eds) Report 17, Uppsala.
Angelstam P. & Mikusiński G.,1994. Woodpecker assemblages in
natural and managed boreal and hemiboreal forest a review.
Ann. Zool. Fenn. 31: 157-172.
Bibby C.J., Collar N.J., Crosby M.J., Heath M.F., Imboden C.,
Johnson T.H., Long A.J., Stattersfield A.J. & Thirgood S.J.,
1992. Putting Biodiversity on the Map: Priority Areas for
Global Conservation. International Council for Bird Conser-
vation, Cambridge, UK.
Bocca M. & Rolando A., 2003. The ecology of the Black Wood-
pecker in Mont Avic Natural Park (Italian Western Alps). P.
48 in: Pechacek P. & d’Oleire-Oltmanns W. (eds), 5th Int.
Woodpecker Symp.
Bocca M., Carisio L. & Rolando A. 2007. Habitat use, home rang-
es and census techniques in the Black Woodpecker (Dryoco-
pus martius) in the Alps. Ardea 95 (1): 17-29.
Boitani L., Corsi F., Falcucci A., Maiorano L., Marzetti I., Masi
M., Montemaggiori A., Ottaviani D., Reggiani G. & Rond-
inini C., 2002. Rete Ecologica Nazionale. Un approccio alla
conservazione dei vertebrati italiani. Università di Roma “La
Sapienza”, Dipartimento di Biologia Animale e dell’Uomo,
Ministero dell’Ambiente, Direzione per la Conservazione
della Natura, Istituto di Ecologia Applicata, Roma.
Börger L., Franconi N., De Michele G., Gantz A., Meschi F.,
Manica A., Lovari S. & Coulson T.I. M., 2006. Effects of
sampling regime on the mean and variance of home range
size estimates. J. Animal Ecol. 75 (6): 1393-1405.
Burgman M.A. & Fox J.C., 2003. Bias in species range estimates
from minimum convex polygons: implications for conserva-
tion and options for improved planning. Animal Conserv. 6
(1): 19-28.
Calvario E., Gustin M., Sarrocco S., Gallo-Orsi U., Bulgarini F. &
Fraticelli F., 2011. Nuova Lista Rossa degli uccelli nidificanti
in Italia. LIPU-WWF.
Ceccarelli P., Agostini N. & Milandri M., 2003. Presenza del Pic-
chio nero nelle Foreste Casentinesi: una nuova specie per la
check-list regionale. Asoer, Notizie, Bologna.
Cramp 1985. Handbook of the birds of Europe, the Middle East
and North Africa: the birds of the Western Palearctic. Vol.
IV Terns to woodpeckers. Oxford University Press, Oxford.
Douglas S.B. & Mennill D.J., 2010. A review of acoustic play-
back techniques for studying avian vocal duets. J. Field Orn.
81: 115-129.
Drapeau P., Nappi A., Imbeau L. & Saint-Germain M., 2009.
Standing deadwood for keystone bird species in the eastern
boreal forest: Managing for snag dynamics. Forestry Chroni-
cle 85: 227-234.
Black Woodpecker in Mediterranean forests
69
Drever M.C. & Martin K., 2010. Response of woodpeckers to
changes in forest health and harvest: implications for conser-
vation of avian biodiversity. Forest Ecol. Manage 259 (5):
958-966.
Falls J.B, 1992. Playback: a historical perspective. Playback and
studies of animal communication. Springer US, 11-33.
Garmendia A., Cárcamo S. & Schwendtner, O. 2006. Forest man-
agement considerations for conservation of black woodpeck-
er Dryocopus martius and white-backed woodpecker Den-
drocopos leucotos populations in Quinto Real (Spanish West-
ern Pyrenees). Pp. 339-355 in: Forest Diversity and Manage-
ment, Springer, Netherlands.
Gil-Tena A., Brotons L., Fortin M.J., Burel F. & Saura S., 2013.
Assessing the role of landscape connectivity in recent wood-
pecker range expansion in Mediterranean Europe: forest man-
agement implications. Eur. J. For. Res. 132 (1): 181-194.
Gorman G., 2011. Black Woodpecker. A monograph on Dryoco-
pus martius. Lynx ed., Barcelona.
Hampe A. & Petit R.J., 2005. Conserving biodiversity under cli-
mate change: the rear edge matters. Ecology Letters 8 (5):
461-467.
Innangi M., d’Alessandro F., Fioretto A. & Di Febbraro M., 2015.
Modeling distribution of Mediterranean beech forests and
soil carbon stock under climate change scenarios. Climate
Res. 66(1): 25-36.
Johansen B.T. 1989. Sortspættens Dryocopus martius be-
standsstørrelse, territoriestørrelse og yngleresultater i Tis-
vilde Hegn, Nordsjælland, 1977-1986. Dansk. Orn. Foren.
Tidsskr. 83: 113-118.
La Valva V. & Carrabba M.C., 1999. Dalle lave del Vesuvio al-
le vette del Cilento: Aspetti floristici e vegetazionali dei due
Parchi Nazionali della Campania. Pp. 297-329 in: Lucarelli
F. (a cura di), La rete Mab nel Mediterraneo: Parchi Nazi-
onali del Cilento e Vallo di Diano e del Vesuvio. Studio Idea
Editrice.
Marzluff J., Millspaugh J., Hurvitz P. & Handcock M.A., 2004.
Relating resources to a probabilistic measure of space use:
forest fragments and Steller’s Jays. Ecology 85:1411-1427.
Meschini E. & Frugis S., 1993. Atlante degli uccelli nidificanti
in Italia. Istituto Nazionale Fauna Selvatica, Ozzano Emilia.
Mikusinski G., 1997. Winter foraging of the Black Woodpecker
Dryocopus martius in managed forests in south-central Swe-
den. Ornis fennica 74:161-166.
Mikusiński G., Gromadzki M. & Chylarecki P., 2001. Woodpeck-
ers as indicators of forest bird diversity. Conserv. Biol. 15(1):
208-217.
Peronace V., Cecere J.G., Gustin M. & Rondinini C., 2012. Lis-
ta Rossa 2011 degli Uccelli nidificanti in Italia. Avocetta 36:
11-58.
Persiani A.M., Audisio P., Lunghini D., Maggi O., Granito V.M.,
Biscaccianti A. B., Chiavetta U. & Marchetti M., 2010. Link-
ing taxonomical and functional biodiversity of saproxylic
fungi and beetles in broad-leaved forests in southern Italy
with varying management histories. Plant Biosystems 144:
250-261.
Pinheiro J., Bates D., DebRoy S. & Sarkar D., 2012. R Develop-
ment Core Team. nlme: Linear and nonlinear mixed effects
models, 2012. URL: http://CRAN. R-project. org/package=
nlme. R package version, 3-1.
Ravera S. & Brunialti G., 2012. Epiphytic lichens of a poorly ex-
plored National Park: Is the probabilistic sampling effective
to assess the occurrence of species of conservation concern?
Plant Biosystems, (ahead-of-print), 1-10.
Roché J.C., 2008. Bird Songs and Calls of Britain and Europe.
Rolstad J., Rolstad E. & Saeteren O., 2000. Black Woodpecker
nest sites: characteristics, selection and reproductive success.
J. Wildl. Manage. 64 (4): 1053-1066.
Rolstald J., Majewski P. & Rolstad E., 1998. Black Woodpecker
use of habitats and feeding substrates in a managed Scandina-
vian forest. J. Wildl. Manage. 62 (1): 11-23.
Romano A., Ventre N., De Riso L., Pignataro C. & Spilinga C.
2010. Amphibians of the “Cilento e Vallo di Diano” National
Park (Campania, Southern Italy): update check list, distribu-
tion and conservation notes. Acta Herpetologica 5: 233–244.
Scott D.W., 1992. Multivariate Density Estimation: Theory, Prac-
tice, and Visualization. Wiley, Hoboken, New Jersey, USA.
Seaman D.E. & Powell R.A., 1996. An evaluation of the accuracy
of kernel density estimators for home range analysis. Ecology
77 (7): 2075-2085.
Svensson S.E., 1979. Census efficiency and number of visits to
a study plot when estimating bird densities by the territory
mapping method. J. Appl. Ecol. 16: 61-68.
Tjernber M., Johnsson K. & Nilsson S. G., 1993. Density varia-
tion and breeding success of the Black Woodpecker Dryoco-
pus martius in relation to forest fragmentation. Ornis Fenn.
70: 155-162.
Vos C.C., Berry P., Opdam P., Baveco H., Nijhof B., O’Hanley J.
& Kuipers H., 2008. Adapting landscapes to climate change:
examples of climate proof ecosystem networks and priority
adaptation zones. J. Appl. Ecol. 45 (6): 1722-1731.
Winkler H., Christie D. & Nurney D., 1995. Woodpecker: a guide
to the woodpecker of the world. Houghton Mifflin, New
York.
Zuur A.F., Ieno, E.N. Walker, N.J. Saveliev A.A. & Smith G.M.,
2009. Mixed Effects Models and Extensions. Ecology with R.
Springer, New York, NY, USA
Associate Editor: Michelangelo Morganti
