Internship March-June 2013.
“Territorial study of the distribution of the Woodlark (Lullula
arborea) and the Skylark (Alauda arvensis) in The Hoge Veluwe National
Park. Is there a connection to the recreational infrastructure?”
Zikopoulou Anastasia & Pagkakis Georgios
1.1 The Species………………………………………………………………………5
1.1.1 Woodlark (Lullula arborea)………………………………………………….5
1.1.2 Skylark (Alauda arvensis)……………………………………………………9
1.2 The study area…………………………………………………………………..12
1.2.1 In general……………………………………………………………………12
1.3 Infrastructure and disturbances…………………………………………………15
1.3.1 The importance of Carrying Capacity………………………………………18
1.3.2 The crucial importance of noise…………………………………………….19
1.3.3 The relation of non-limited access – disturbances………………………….20
2. MATERIALS AND METHODS………………………………………………….21
2.1 Data collection…………………………………………………………………..21
2.2 Data analysis……………………………………………………………………22
4. DISCUSSION – CONCLUSIONS………………………………………………..29
We would firstly like to express a big thank you to Mr. Rovekamp, for he was
of great help to us, although his working obligations were more than a few! He was
kind enough to support us and better us during this period of our lives!
Also, we would like to thank Mr. Leidekker, for giving us the chance of an
abroad Internship, and for being really hospitable and kind.
For having to cooperate with these two gentlemen we feel really thankful!
A big thank you also to S.E. Baron van Voorst tot Voorst, director of the
Also, a big thank you to Mrs. Sanders for her willingness to be of any help,
but also all the game-wardens for their cooperation, especially Mr. Wensink!
Our gratitude goes finally to all staff members of “The Hoge Veluwe National
Park”. And to our friends Margret and Pim!
Doing our internship in “The Hoge Veluwe” National Park was a real
pleasure!! Thank you for that!
Nature-based tourism is one of the most rapidly developing areas in the
service industry, but many activities and infrastructure related to tourism are
channeled into disturbance-sensitive natural and cultural environments of their near
Since both human development and human recreational use of nature are
likely to increase in the near future, the need to understand how wildlife responds to
human activities is becoming increasingly important (Jokimäki et al. 2007).
As for the current report, the research took place in ‘The Hoge Veluwe
National Park’ located in the Netherlands. Two different bird species were studied:
the Woodlark (Lullula arborea) and the Skylark (Alauda arvensis), because of their
significance as a Natura 2000 specie -the first one- and Red Listed according to
Habitat Directive –the second one-. Our main aim was to connect this years’ field data
–as concerns the number of territories-, to older archival data, being familiar with the
occurring territorial changes and, finally, make a connection to the recreational
infrastructure of the Park.
Birds are a passage for scientific study of nature. They can be easily identified
and studied as they distribute almost all over the Earth, found in forests, deserts,
mountains, meadows and over all oceans. Actually, in the words of Jokimäki et al.:
“Birds have been found suitable and good indicators of environmental changes. Birds
are known to be sensitive to many kinds of environmental disturbances and they can
be used for environmental monitoring” (2007). Some of the reasons as for their
importance (http://www.birdsinbackyards.net/birds/Birds-Indicators-Sustainability) are
They are at the top of the food-chain and are therefore vulnerable to
They have representatives that depend on the full range of animal diet.
They are easy to see and observe.
And are already relatively well-known, providing a good baseline against
which change can easily be monitored.
They present amazing behavior and play an important role for the ecosystems
supporting life. Their changing population, their absence or presence provide data on
the environmental "health" of an ecosystem, (and) therefore they are an excellent
indicator of environmental quality of their/a habitat.
Our main goal during the four month period (March-June) we were to spend
abroad was getting to know and understand the relationship between recreational
infrastructure of ‘De Hoge Veluwe National Park’ and bird behavior (Lullula arborea
& Alauda arvensis) concerning mostly territories. That for being achieved demanded
field visits (getting familiar first with our natural surroundings and then co-work with
them), literature reading (about the Park, our species, disturbances etc.), studying of
older territorial data (Excel charts and maps of how the territories have been changing
by the passing of years) and finally having an open mind in order to make
As for the research’s hypothesis: according to the literature and the common
thought –which has been formed by observations and personal experience- there are
two hypotheses to be tested:
1) A change in birds’ territories is expected, as many studies have highlighted the
negative impact human disturbance may have on wildlife.
2) A not so significant twist of territories is expected, because species tend to
evolve and not get distracted by every single disturbance. As long as a new
and continuous or a big scale disturbance does not occur (e.g.: a construction
of a road/path through their habitat, a removal of habitat), the birds do not get
affected. Even more they tend to get used to it.
1.1 The Species.
During the present study, two bird species were studied; the Woodlark
(Lullula arborea) and the Skylark (Alauda arvensis).
The Woodlark belongs in the Natura 2000 bird’s network (Bird directive
2009). It is identified as a species of Conservation Concern. The Natura 2000 network
operates in a European level always on account of historical declines concerning
population size and range (Langston et al. 2007).
“Alauda arvensis populations in most western European countries are now
under great pressure. Since the 1970s, declines of over 50% have been reported in
several countries, such as the UK, The Netherlands, France and Sweden. As a result
of these declines the Skylark has been put on Red Lists in several countries” (Kragten
et al. 2007). The Skylark is considered to be almost extinct from the Netherlands, as it
has declined by 96% since 1960 (Sovon, 2012 cited in Kuiper et al. 2013), and the
Hoge Veluwe National Park is one of the last regions in the country where it can be
1.1.1 Woodlark (Lullula arborea).
The Woodlark (Lullula arborea) is a ground-nesting passerine with an
unfavorable conservation status in Europe (Birdlife International 2004), due to a
widespread decline in population size and range.
“It’s rather small, brown and short-tailed. Often perches exposed in trees,
bushes or on wires, though spends most of the time on ground. Tail tipped white,
adding to the short impression when seen against the bright sky. Sides of tail not
white (as on Skylark) but pale brown, and trailing edge of wing on adult not light.
When perched, note characteristic light-dark-light pattern near bend of wing; also
broad buffish-white supercilia reaching far back (almost joining on hindneck). Song
mostly delivered in drifting song-flight high up (100-150m), often at very first light,
or even beneath stars on pitch-dark night. Song is one of the most attractive,
consisting of pleasant and ‘sweet but melancholy’ notes in series, opening hesitantly,
accelerating, often falling in pitch and gaining in loudness.” (Svenson 2009).
Woodlarks are partial migrants (Wernham et al. 2002 cited in Langston et al.
2007), insectivorous and nest on the ground, preferring areas of extremely short
vegetation or bare ground on well-drained soil with very sparse cover of bushes and
trees. These conditions are frequently provided in young conifer plantations and
heathland (Langston et al. 2007).
The main factor influencing the long-term suitability of heathland for
Woodlarks is the control of scrub development and the maintenance of mosaics of
short vegetation and bare ground (Sitters et al. 1996). As Bowden, cited in Mallord et
al. 2007, has also said: “The Woodlark is a specie of open habitats having in general a
very patchy distribution within heathlands. Most heathland is thus not suitable
While tall vegetation provides them their nesting habitat, moving around more
freely on bare ground seems as an option also. As for foraging, the Woodlarks can
either pick invertebrates from the surface or by gleaning prey from taller vegetation.
So, it seems that vegetation structure is more important than species composition
(Mallord et al. 2007).
Woodlarks tend to breed in clearfelled and re-planted stands with trees up to 9
years old, but most are found on stands less than 6 years old or areas of permanent
open space (Wright 2006).
In continuance, Woodlarks are multi-brooded, making many repeated nesting
attempts following nest failure and up to two further broods following successful
fledging of an earlier brood (Mallord et al. 2008 cited in Wright et al. 2009). Another
attribute of the Woodlarks is that, they are more likely to colonize areas already
occupied by other Woodlarks, which slows the pace of range expansion (Langston et
Image 1.1: Woodlark.
Factors causing population declines - The case study of the Woodlark.
Long-term and substantial loss, degradation and fragmentation of lowland
heathland habitats have been some of the major factors associated with the dramatic
population declines of bird species (Langston et al. 2007). And in the case of the
woodlark, they must be considered carefully as well.
Having to complete our research though in ‘The Hoge Veluwe National Park’
we must add to the above the importance of the low levels concerning soil diversity.
And just as a reminder, biodiversity and soil are strongly linked, soil is considered to
be the medium for a large variety of organisms and interacts closely with the wider
biosphere; conversely, biological activity is a primary factor in the physical and
chemical formation of soils (Bardgett 2005). But the reforestation during the many
years of the Parks existence is again of great consideration.
To set Britain though also as an example, changes in habitat have been
responsible for some of the major changes in Woodlark numbers since the 1950s.
Quite subtle changes in vegetation structure can again in many cases render sites as
unsuitable (Sitters et al. 1996).
Climate change and variations in weather have also though been suggested as
possible factors. As it’s been noted by Wright et al.: “climatic conditions, the
prevailing weather patterns in an area over a long period, are a key factor affecting
many ecological processes and climate change will alter many species population
Hard winters in particular, do have a limiting effect on Woodlark populations.
Hard winters though do not affect all regional populations in the same way (Sitters et
Vegetation succession, mainly as a result of reduction in grazing, can also
provide a significant role as to the decline of the Woodlark. Varied grazing
procedures tend to maintain Woodlark habitat on much heathland and is increasingly
being used as a conservation management tool (Sitters et al. 1996). Vegetation
cutting is less likely to create, nor to maintain, such tightly compacted swards with
bare soil patches.
Clearly, a reduction in breeding output may have conservation implications,
but to assess how serious these are one must understand the population consequences
of any reduction (Gill, Norris & Sutherland 2001b cited in Mallord et al. 2007). From
a conservation viewpoint it must be reminded that as noted: “the impact at the
population level is of paramount importance” (Mallord et al. 2007).
In The Netherlands, the Woodlarks can be found mostly on agricultural lands
(mostly during winter) and protected areas. In the following chart, we can see their
population during the last twenty years. In general, the numbers are ranging from 200
to 250, with some fluctuations through the years. Also, in Image 1.2, we can see their
distribution in The Netherlands.
Chart 1.1: Woodlarks in The Netherlands (number of plots=631, source:SOVON).
Image 1.2: Woodlark populations in The Netherlands (source: SOVON).
1.1.2 Skylark (Alauda arvensis).
“Greyish-brown, streaked above and on breast; breast buff, belly white.
Streaking of breast ends rather abruptly above unmarked belly. Males can erect blunt
crest on crown. Often seen on fields and along roadsides; when approached, it first
squats, then ‘catapults’ up, retreating short distance low over ground with fluttering
wings and landing with half-spread, lowered tail, the brown bird showing thin, diffuse
(brownish-white) trailing edge to wing and white sides of tail. Sings at times (often at
dawn) from perch but usually in typical song-flight, climbing higher and higher on
fluttering wings, and eventually stays at one spot at 50-100(150)m, difficult to detect.
At the end of song-flight descends while singing, but in the final stage falls to ground
with folded wings. Sings from late winter until midsummer, from first light to
evening. Song is an incessant outpour of rolling, chirruping and whistling notes at fast
pace and for periods lasting 3-15 min., some notes repeating and varied, and with a
few imitations woven in.” (Svenson 2009).
The skylark (Alauda arvensis) nests between April and August, successful
pairs may raise up to four broods in one breeding season. The nest is always on the
ground, and is usually very well concealed within vegetation. Young birds leave the
nest when eight to ten days old, but remain dependant on their parents for a further
one to two weeks. The male usually performs his song flights throughout the breeding
During winter time, skylarks move away from upland areas, and tend to create
large flocks on lowland farmlands, often in conjunction with other species such as
meadow pipits. Stubble fields provide the most important winter food source but set-
aside can be useful, particularly if cereal stubbles are short in supply.
The skylark's breeding range covers all of Europe and the temperate zone of
Asia as far east as Japan and the Kamchatka peninsula. Breeding birds are mainly
resident in the UK, although numbers are swelled in winter by visitors from the
Skylarks mainly utilise open habitats, such as saltmarshes and coastal grazing
lands, arable farmlands and rough grazing in the uplands. The majority of foraging is
carried out in short vegetation.
The skylark is classified as Least Concern (LC) on the IUCN Red List. Listed
under the EC Birds Directive.
Image 1.3: Skylark.
Factors causing population declines - The case study of the Skylark.
Destruction and fragmentation of natural habitat, extensive changes in
landscape structure and the intensification of agricultural practices are key factors in
the decline of many bird species. The skylark lost half its number after it underwent a
decade of rapid decline from the mid-1970s onwards and since then has continued to
decline albeit at a reduced rate (Rahman et al., 2012).
The major period of skylark decline began with fundamental changes in
agriculture, through simplification of crop rotations, increased use of chemical
pesticides, a shift from spring to autumn sown cereals, and intensive grassland
management, all of which made skylark populations vulnerable due to the lack of
suitable arable and grassland habitat and food resources (Rahman et al., 2012).
Nowadays trend of more intensive farming methods is thought to be one of the
main causes of decline for the Alauda arvensis. Increasing use of agri-chemicals has
also reduced the invertebrate populations on which the birds depend for food in the
breeding season (http://www.arkive.org/skylark/alauda-arvensis/).
In The Netherlands, Skylarks can be also found on agricultural lands and
reserved areas. In the following chart, we can see their population during the last
twenty years. Their declining population is notable, and the main reason is the
intensification of farming. The last decade, the numbers seem to be stabilized,
although obviously declined. Also, in Image 1.4, we can see their distribution in The
Chart 1.2: Skylarks in The Netherlands (number of plots=2.017, source:SOVON).
Image 1.4: Skylark populations in The Netherlands (source: SOVON).
1.2 The Study Area.
1.2.1 In general.
The study area for the specific Inventory was “The Hoge Veluwe National
Park”, in The Netherlands, a cultural heritage formed early in the twentieth century by
the married couple Anton and Helene Kröller-Müller. It is the largest actively
managed conservation area in private hands in the Netherlands. The Park covers 5,400
hectares of woodland, heathland, peat bogs and drift sand and is entirely fenced off. It
enjoys a wide variety of plants and animals and provides habitats to extremely rare
Red List species. The current landscape is highly fragmented. There are three
entrances: Hoenderloo on the north-east side, Otterlo on the west side and
Schaarsbergen in the south. The Hoge Veluwe National Park is as we noted above a
privately-owned land, but also an economical independent Foundation. The Park and
its continued existence more or less depend on paying visitors.
The undulating landscape was formed during the Ice Age. In the Middle Ages
it was a densely wooded area, until large-scale logging for ship-building cleared the
area of its vegetation. So the sandy surface soil was blown away causing sand drifts.
The wind-battered scot pines with their crooked shapes grew from wild seedlings and
gave the area its very own character. In 1935, The Hoge Veluwe National Park
Foundation was created and the area became the second National Park of the country
(The Hoge Veluwe - Nature and Art, 2005).
The areas of the park where the two species could be found were selected
according to literature and after discussion with the ecologist concerning Park matters,
Mr. Chris Rovekamp (see also the following map).
The areas in particular were:
When the Kröller-Müller husband and wife team still lived in the area, the
drifting sands were more extensive than today. Due to expansion of woodland, the
effect of the wind decreased and algae and mosses started to cover the drifting sands
areas. Gradually, the landscape that was such a key feature of the Veluwe began to
change, threatening to sound death knell for dozens of rare plant and animal species
that are dependent on drifting sands. In 2001, the National Park's board decided that it
was essential to restore this landscape. Roughly 90 hectares of coniferous woodland
was felled and 40 hectares of topsoil removed, once again exposing the underlying
drifting sands to the elements (The Hoge Veluwe - Nature and Art, 2005).
The Park has coniferous woodland, deciduous woodland and mixed woodland,
where coniferous and broad-leaved trees grow side by side. It also has a very unusual
Juniper wood. There are also other landscapes besides woodland, such as wet and dry
heathland, drifting sands and grasslands. In total counts: 3,200 hectares of woodland,
2,100 hectares of heathland and 60 hectares of drifting sands. It is interesting to note
that each environment has its own plant types. Rare plants found in the area are:
marsh gentian, bog asphodel and bog or wild rosemary (The Hoge Veluwe - Nature
and Art, 2005).
Specifically speaking, the dominant vegetation types in the Study Plots are:
Otterlose Zand, Pampelse Zand and Oud-Reemster Zand: The landscape
in these plots consists of inland dunes with open Corynephorus and Agrostis
grasslands. These are open formations that can be found on inland dunes with
dry siliceous soils; they are species-poor and with a strong representation of
annuals. They include formations of unstable Germano-Baltic fluvio-glacial
inland sands with Corynephorus canescens, Carex arenaria, Spergula
morisonii, Teesdalia nudicaulis and carpets of fruticose lichens (Cladonia,
Cetraria) and other grasslands of more stabilized Germano-Baltic fluvio-
glacial inland dune systems with Agrostis spp. and Corynephorus canescens or
other acidophilous grasses. Also, in these plots, dry sand heaths with Calluna
and Genista can be found. The dunes are formed of quartzic sands originating
in redeposited and reworked glacial drift and outwash. They are highly
siliceous in the Netherlands. The dune systems, particularly the large ones,
harbour a unique ensemble of interacting communities and harbour many
specialized and localized organisms. They have considerably regressed and the
remaining examples are fragile and often threatened. Vegetation is dominated
by heaths with Calluna vulgaris, Genista anglica and Genista pilosa. In some
areas of open dry heath and drifting sands, heath star moss (Campylopus
introflexus) can be found in the form of a dense, centimeters-thick layer of
moss (Interpretation Manual of European Union Habitats, 2007).
Oud-Reemster Veld: The landscape here tends to change. Dry heaths, with
mesophile or xerophile heaths on siliceous and podsolic soils, are dominant
with the most representative plants to be Calluna vulgaris and perennial
Nardus grasslands (Interpretation Manual of European Union Habitats, 2007).
Heathland ecosystems are very dynamic and complex systems of great
ecological and aesthetic value. Nowadays, the function of heath is not mainly
important for agricultural reasons: the wealth and diversity of scenery and flora and
fauna of heaths is appreciated by scientists and naturalists, walkers, tourists and
sportsmen, giving heaths a more “aesthetic” function (Vermeulen 2009).
The wildlife population consists of (more or less) 200 Red deer, 150 Roe deer,
50 Wild Boars and 200 Mouflons (Corsican sheep). Also foxes, badgers and pine
martens contribute in Parks’ biodiversity.
In the Hoge Veluwe numerous species of insects and an impressive wealth of
butterflies have been found, with more than twenty species being endangered or
vulnerable. The Park also counts a significant number of reptiles (like sand lizards,
viviparous lizards, blindworm, grass snake, smooth snake and the poisonous adder),
as long as nine species of amphibians, among them the common toad, back-striped
toad, brown frog and heather frog.
As for the bird life, nine Natura 2000 bird species can be found in the Park:
the Eurasian Wryneck (Jynx torquilla), the European Honey Buzzard (Pernis
apivorus), the Red-backed Shrike (Lanius collurio), the Tawny Pipit (Anthus
campestris), the African Stonechat (Saxicola torquatus), the Northern Wheatear
(Oenanthe oenanthe), the Woodlark (Lullula arborea), the Black
Woodpecker (Dryocopus martius) and the Eurasian Nightjar (Caprimulgus
europaeus). Also, from 2007 efforts have been made to reintroduce Black Grouse
(Tetrao tetrix) which has become extinct here; work on the recreation of a suitable
biotope has been in progress for thirty years (The Hoge Veluwe - Nature and Art,
1.3 Infrastructure and disturbances.
The expansion of tourism into pristine areas is known by today to have
negative impacts on nature (occasionally). Human recreational activities are often
considered potential threats to biodiversity by restricting animal access to resources
that otherwise would be exploited (Gill 2007 cited in Jokimäki et al. 2007).
Conservationists have long been concerned about the effects of human
disturbance on wildlife (Beale and Monaghan 2004). Among the numerous reported
effects, it has been suggested that disturbance can prevent successful breeding, scare
animals away from preferred feeding areas and even have a direct effect on mortality
rates (Beale and Monaghan 2004).
As for the way nonconsumptive outdoor recreationists seem to affect wildlife,
one can pinpoint the unintentional (e.g., wildlife viewing, hiking) and intentional
(i.e., harassment) disturbance (Knight and Cole 1991 cited in Miller and Knight
But also disturbance by recreational activities can have major impacts on flora
and fauna at individual, population and community level in the short and long term. It
can have direct impacts such as causing ‘flight’ or modifying behavior (foraging
and reproduction) and indirect impacts such as habitat change and the introduction of
pests, pathogens and weeds (Marzano and Dandy 2012 citing Knight and Cole 1995).
Disturbance by recreationists can also result in behavioral changes (Miller and
Knight 1998). For birds in particular, species displacement or even more nest
abandonment is probable (Knight and Gutzwiller 1995 cited in Miller and Knight
1998). Species sensitive to disturbance may show avoidance or occur in reduced
abundance in areas where human activity is common (Van der Zande and Vos 1994
cited in Miller and Knight 1998).
Habitat modification is also to affect bird species; it can modify vigor,
productivity, or even survival of individuals. Several authors actually indicate that,
generally, human presence and activities impact on large animals while smaller
animals are more affected by habitat modification or other indirect impacts such as
those associated with infrastructure (Marzano & Dandy 2012).
Birds may also habituate to predictable disturbances such as walking, driving
or camping in consistent locations. This may reduce the recreation disturbance, but it
can also be detrimental if habituated birds later approach humans and are persecuted.
The potential influence of disturbance increases with its frequency and intensity
To set another example though, an increase in visitor use of a park in the
Netherlands was correlated with reductions in songbird density (Van der Zande and
Vos 1984 cited in Marzluff 1997).
Disturbance from recreation on wildlife depends on the recreationist and the
animals (Knight and Cole 1995 cited in Marzluff 1997). The predictability, frequency,
magnitude, timing, and location of recreation are important to songbirds.
It seems that developing an understanding of how recreational activities affect
wildlife becomes necessary.
In “The Hoge Veluwe”, the recreational infrastructure that is to act as a
possible disturbance, refers to:
Roads through the park (the local road, other metalled/unmetalled
roads, cycle paths and foot paths).
A camping site.
The “Kröller-Müller” Museum, the “Bezoekerscentrum”, a restaurant,
the “Jachthuis St.Hubertus” and the Service building (Dienstgebouw).
And memorials and observation posts.
Image 1.4: Map of “The Hoge Veluwe National Park”, where infrastructure activities
can be noticed.
Image 1.5: Legend.
1.3.1 The importance of Carrying Capacity.
Recreation carrying capacity is an important concept in park and protected
area management for estimation of optimum recreation use (Sayan and Atik 2011).
Carrying capacity refers to the amount and type of use that can be
accommodated in parks and related areas without unacceptable impacts to park
resources and/or the quality of the visitor experience (Manning 2001, cited in Sayan
and Atik 2011). The World Tourism Organization defined the carrying capacity as:
"The maximum number of people that may visit a tourist destination at the same time,
without causing destruction of the physical, economic and socio-cultural environment
and an unacceptable decrease in the quality of visitors' satisfaction" (Anonymous
1997, cited in Sayan and Atik 2011).
Overuse of a National Park may disturb fragile soils, vegetation, and wildlife,
and may cause unacceptable crowding and visitor conflicts. The capability of the
resource base and the recreation setting to provide for recreational use raises the
concept of carrying capacity (Pigram and Jenkins 1999 cited in Sayan and Atik 2011).
According to Coccossis and Mexa (2004, cited in Sayan and Atik 2011),
carrying capacity considerations revolve around three basic components:
physical-ecological (the maximum level or threshold limit of
recreational use, that can be accommodated by an area or an
ecosystem, before an unacceptable or irreversible decline in natural
and cultural values occurs)
socio-cultural (the maximum level of recreational use, above which
there is a decline in the quality of the recreation experience)
and political-economic (the impacts of tourism and recreation on the
local economic structure, activities, etc. including competition with
To sum up, the capacity of a park varies depending upon the place, season,
time, user behavior, facility design, patterns and levels of management, and the
dynamic character of the environmental elements.
1.3.2 The crucial importance of noise.
Anthropogenic noise and acoustic masking habitat destruction and
fragmentation also are of great importance to species extinctions (Barber et al. 2009).
It can be surely expressed, that many current threats to ecological integrity and
biodiversity transcend political and land management boundaries.
Noise though knows no boundaries! Noise management should be taken
seriously as an emergent issue for protected lands, and a potential opportunity to
improve the resilience of these areas to climate change and other forces less
susceptible to immediate remediation.
As for animal responses and always in relevance to the words of Barber et al.,
they do probably depend upon the intensity of perceived threats rather than on the
intensity of noise (2009). But one cannot also forget the paramount role different
sources, but also frequencies of sounds add to the whole of the situation.
An acoustical environment is not a collection of private conversations between
signaler and receiver but an interconnected landscape of information networks and
adventitious sounds (Barber et al. 2009). As an extensive study conducted actually in
the Netherlands, showed, 26 of 43 (60%) woodland bird species tended to be reduced
in number near roads (Barber et al. 2009).
1.3.3 The relation of non-limited access - disturbances.
On sites with open access, areas with suitable habitat are less likely to be
occupied by breeding birds at higher levels of disturbance (Barber et al. 2009). As
noted in the case of the Langston et al. research (2007):
Within sites open to public access, birds only settled to breed in areas
with low numbers of visitors. Heavily disturbed areas were used only
for foraging, although the habitat was suitable for both foraging and
The probability of suitable habitat being colonized was reduced to below 50%
at around eight disturbance events per hour. However, there was no effect of
disturbance on nest survival, and productivity was actually higher on more disturbed
heaths due to strong density-dependence operating on various stages throughout the
breeding cycle, including influencing rates of local recruitment (Mallord 2005 cited in
Langston et al. 2007).
From all of the above, it is understood that visitor access should always be
considered as part of any management plan for heathland and forest sites.
As shown in another research concerning woodlark nest survival, it was not
affected by disturbance. Although woodlarks appeared tolerant to humans when
nesting, often placing their nests close to paths, the lack of an effect of disturbance on
breeding success was mainly a result of avoidance of nesting in areas with the highest
levels of disturbance (Mallord et al. 2007).
The response can be considered as a trade-off between use of a certain
resource (in this case a breeding territory) and the perceived predation risk posed by
humans (Gill, Sutherland & Watkinson 1996 cited in Mallord et al. 2007).
In addition, woodlarks tend to respond rapidly to the provision of new areas of
suitable habitat, in both forested areas and on heathlands. It should thus be possible to
create new areas of suitable habitat in order to mitigate for the effects of increased
disturbance. Woodlarks respond opportunistically and rapidly to the creation of new
habitat (Sitters et al. 1996).
2. MATERIALS AND METHODS.
2.1 Data collection.
The study was carried out from March to June 2013. The first month, and as
long as the winter was continuing, relevant literature was studied. The field visits
started on 19th
of April and ended on 28th
As referred above, the areas of the park where the two species could be found
were in particular:
In each one of these areas, 6 visits took place. All areas were visited at least
once a week, but no more than twice. Surveys were conducted between 08:00-13:00
and/or 18:00-21:00 hours, when bird activity is high. On every visit, date, time,
temperature and wind direction were noted. Each field was surveyed by walking
across the field in a way that ensured that the whole field was visible. The plots were
walked at a slow pace so all the birds detected could be located on the maps. Routes
and directions varied between visits so we ensured that there was no systematic
tendency for any particular part of the plot to be visited earlier or later in the day, on
Every individual was represented on the map by two letters, “La” for the
Woodlarks (Lullula arborea) and “Sl” for the Skylarks (Alauda arvensis). Symbols
were used to describe bird activities:
A flying Woodlark / Skylark in song.
Woodlark moving between two spots. The solid line
indicates that it was definitely the same bird.
Two flying Woodlarks in song at the same time. The dotted
line indicates that were definitely different birds.
La / Sl A Woodlark / Skylark in song. (Hearing record.)
A question mark “?” was used when a registration was unsure, so we were aware of
the fact of “double recording”.
2.2 Data analysis.
After all data were collected, they had to be transferred in one (total) map. For
this part, the Auto-Cluster method was used. Every field visit was saved in the project
“Veluwezoom” on http://avimap.org/avimap/avimap/invoer. After all data were
uploaded and saved, the Auto-Cluster created the territories and appeared them on
Based on literature and personal experience, some assumptions were made and
should be taken into consideration:
All birds mapped, were the singing ones.
Records were plotted as much accurate as possible.
The experience of the observers: although this was the first time to do an
inventory like this one, we had enough time to read related literature, explore
the park, listen to birds’ sounds and get familiar with these. Of course, since it
was the first time to apply this method, we may have some “double counting”
-especially on first visits- or may have missed some others.
The rules of “Territory Mapping Methods” were followed as much as possible.
The following charts are concerning the temperature and the number of
individuals detected in each one of the study plots.
At the Otterlose Zand we can see the number of individuals to be partly
relating to the temperature, as the temperature tends to rise, the number of individuals
detected also seems to be increasing, it’s a correlation that exists for both of the
Chart 3.1: Temperature and number of individuals for Otterlose Zand.
One can say that the results at the Pampelse Zand are similar. The number of
individuals detected follows the temperature-line; although, there is a delayed decline
of both species populations when temperature drops, still they seem to recover.
Obvious is also the change related to the Woodlark population when the temperature
rises. As for the Skylark population, we had our best (concerning numbers) counts,
during a late-morning field visit.
Chart 3.2: Temperature and number of individuals for Pampelse Zand.
On the other hand, at the Oud-Reemster Zand, our lowest count, for both
studied species, was detected on an afternoon visit. Continuing, the Skylark
population seems not to be relating to the time the visits took place. For example on
an early-morning visit, the number of individuals was found to be one of the lowest
detected. Their highest population seems though to be correlated to the increasing
Chart 3.3: Temperature and number of individuals for Oud-Reemster Zand.
At Oud-Reemster Veld Skylarks are dominant. The number of individuals is
obviously affected by the temperature.
Chart 3.4: Temperature and number of individuals for Oud-Reemster Veld.
Vegetation & Number of Individuals.
Being by now familiar with Otterlose Zand, the dominant vegetation types are:
pine forests, moss and some sandy areas. The Woodlarks were always spotted by the
boundaries of pine forests and open areas. The Skylarks on the other hand, were
always spotted on open and/or sandy areas, flying and ‘sitting’ on low vegetation and
rarely on top of pine trees. Woodlarks detected in total were more than the Skylarks.
As for Pampelse Zand, the vegetation is quite similar to the one in Otterlose
Zand. Hence, we expected to find more Woodlarks than Skylarks. If we check the
numbers of individuals, the hypothesis is correct.
In Oud-Reemster Zand, we can also view pine forests that (gradually) turned
into low vegetation and later into sandy dunes. Again, Woodlarks are again found by
the edges of the forest or on small tree groups in more open areas. Skylarks are
spotted on open and sandier areas and are likely to be found on the sandy dunes.
The Oud-Reemster Veld landscape is totally different from the ones noted
above. The field is a totally open area and the vegetation types that can be seen there
are heath lands and low vegetation. The Woodlarks are not present on this field and
the Skylarks have the highest number of individuals than in any other plot.
The final numbers for the territories of the two species, occurred from the
Auto-cluster method, are: 93 territories for the Woodlarks and 142 territories for the
Skylarks. These can be seen in the following maps.
One can assume that, the area that includes the Kröller-Muller Museum, but
also the Bezoegerscentrum is to be one of the more heavily disturbed parts of the park
concerning recreational infrastructure. So the territories for the Pampelse Zand would
be expected to be minimum. Our territorial data though shows us differently with a
satisfying number of territories.
To make the above notice even more complicated and generalize it, from the
auto-clustering maps, one can clearly see that lot’s of the territories are to be found
really close to the paths (foot, cycle and road paths). That’s mainly because of the
renewing of the soil at were a path is carved, in other words the soil gains nutrients
that are helpful for the growth of microorganisms, that can contribute to the growing
of plants, and eventually the habituation of insects and so on, as in the circle of life.
We have to point out that, our species main food source varies from plant seeds to
different kind of insects that can abundantly found on them parts.
In a similar way, in the Oud-Reemsterveld Skylarks are abundant in numbers
due to food availability. Small agricultural plots can be found scattered within the
open heathland area and seem to be crucial for foraging, especially during winter
So one can understand that regardless of the recreational infrastructure in the
park, our two species seem to be focusing more on their food reliance and not about
perceiving passersby’s as potential threat. In general we could point that, safe resting-
breeding areas and availability of food can be considered as of great importance for
the survival of the Woodlark, but also the Skylark, but so do for many other species.
When comparing the auto-clustering maps above, with the images 1.2 and 1.4,
that a broader look of the species distribution in The Netherlands can be seen,
immediately one can understand the role of “The Hoge Veluwe” National Park
regarding a conservational level. Where the Woodlark, the Skylark and any other
species has the chance to a life more or less simulation wildlife.
4. DISCUSSION - CONCLUSIONS.
‘Disturbance’ can take myriad forms. What if though, a connection of that
complicated in meaning word and that of natural environment must be implemented!
The broad range of disturbance reflects not clearly of a direct relation between
recreational activities and impacts on wildlife.
As Knight and Cole (1995) cited in Marzano & Dandy (2012) have suggested,
and we on our own find to be true through our research, the features that influence an
impact of recreational use on environment are:
(1) The predictability of an activity and whether it is frequent enough to be
considered non-threatening and thus requiring little response;
In our case, having a military base on a close distance and the repeatability of
the shooting occurring there. If one was truly to consider the noise pollution because
of the specific place, then a great number of species should be scared off. Because
though of the predictability of the shooting time and it’s almost everyday occurrence,
the species (bird species at least for our part) seemed to be used to it. And of course
the species not witnessing any casualties from that experience do not respond and just
continue their routine.
In a similar way they must respond to the human presence. Considering that
the opening hours of the park are fixed, the visitors entering are doing so in relevance
with the hours. Furthermore, their routes are already specified – so as long as they
stick to the paths- the animals know which places they should avoid and when. Long
as a new and continuous or a big scale disturbance doesn’t occur (e.g.: a construction
of a road/path through their habitat, a removal/change of habitat), the birds do not
tend to be affected; on the contrary, they show an adoptive behavior.
In relevance to the above, as a large mammal e.g. Red deer might walk
through their territory, so can a human. For a moment that individual can be
considered as a potential predator (with a probable flee of the bird), but as long as
there’s no significant interaction between the two of them, then the return to its
original position is more than likely to happen.
(2) The frequency and magnitude of disturbance over and above thresholds
where the activity becomes detrimental to wildlife;
Being inside the boundaries of a National Park, the frequency, but also the
magnitude of disturbances should not be of great importance, because part of the
policy followed by a National Park is to preserve nature and not neglect it by any
means. And for doing so, disturbances tend to be minimized.
The visitors may divide in two groups:
In first group, belong they that have a superior perception of nature; they
respect the rules of circulation inside the park, the boundaries and
prohibitions. They are here to learn and admire nature, so they try not to create
any pressure concerning wildlife.
There is though a second group; visitors who are not keen on the idea of
nature and wildlife conservation. They might operate as a disturbance to
nature, intentionally or not, but the magnitude of the disturbance is (again) not
to be considered as of a great importance.
(3) The timing (e.g. recreational disturbance is known to be damaging to wildlife
during the breeding season but) can also have serious effects at other times such
as periods of feeding or resting;
Of course the breeding season is thought to be one the most important moment
in a ‘birds life’, but once again one must understand that a disturbance can be
‘neutralized’ and that’s because of how it’s been perceived by the bird. If for a long
time, there’s no negative feedback for the species, then there won’t be any distraction
because of the disturbance. Also, it is for smaller animals in comparison with bigger
game, that are more affected by habitat modification or other indirect impacts such as
those mostly associated with infrastructure.
Moreover, the hours that bird activity is on the peak – would be from dawn till
mid-morning and a couple of hours before dusk- do not match with the visiting hours.
The majority of the people visit the park from around 10:00 until 18:00, so they barely
interact with the birds.
It’s very wise to understand and always remember though, that even very low
levels of repetitive use can cause impact. Therefore, avoiding impact is not an
option unless all recreation use is curtailed. A scenario unlikely to happen, as that
would lead to the park’s disfunction.
In many situations, impact increases more as a result of new places being
disturbed than from the deterioration of places that have been disturbed for a long
time. (A good example for that, we think is the presence of an ice-cream/waffle truck
at the Gymnasium area. As is known, there is a parking lot at that area, in which
many visitors leave their cars and wonder around. Having a little canteen though,
would more likely add a certain amount of disturbance to the area, changing so to
speak the distribution of nearby species.)
To conclude, based on our observations we would like to point out that:
Visitors in general stick to the carved foot/cycle paths, with only few
exceptions going off them. We for sure know that in those cases, the
disturbance is of greatly to be considered. That’s why an extended study is
needed; unfortunately we on our own cannot jump into conclusions.
Concerning the number of visitors, one has to have in mind that it fluctuates in
relevance to the time of year, but also from year to year. This means that, the
pressures added on areas close to all kind of paths, vary according to their use.
To bring this report to an end, and to answer the question of recreational
infrastructure having an impact on the distribution of the Woodlark, but also
the Skylark; we would have to say, no there isn’t a direct relation between the
two. The rest and safety can be important for the species, but it seems that
food is more of a significant factor for their survival. To that, we must lastly
consider the behavioural adaptability of species, which eventually contributes
to the acceptance of the human presence in order to improve their availability
For the coming years, a more complete research about the park’s recreation
related infrastructure should take place. As it isn’t just about knowing the numbers of
visitors that enter the park, but how do visitors make use of provided infrastructure
(which paths are more often in use, if they indeed diverge from the paths, if they ever
consider going into a resting area, etc.).
Furthermore, the Oud-Reemsterveld area should continue being specially
managed, and that’s because of its ability to host a large number of Skylarks in The
Barber Jesse R., Crooks Kevin R. & Fristrup Kurt M., (2009). “The costs of
chronic noise exposure for terrestrial organisms”. Trends in Ecology and
Evolution, vol. 25, issue 3, pp. 180-189.
Beale Colin M. & Monaghan Pat, (2004). “Human disturbance: people as
predation-free predators?”. Journal of Applied Ecology, vol. 44, pp. 335-343.
Bibby C. J., Burgess N. D., Hill D. A., (1992). “Bird Census Techniques”.
British Trust of Ornithology & Royal Society for the Protection of Birds.
Academic Press Limited.
European Commission Directorate-General for the Environment – Nature and
Biodiversity, 2007. Interpretation Manual of European Union Habitats.
Jokimäki Jukka, Jokimäki Marja-Liisa & Tuulentie Seija, (2007). “Bird
species as indicators of environmental changes at tourist destinations”. EU
LIFE Environent-project Arctic Centre, Arctic Centre Reports 50, University
Kragten Steven, Trimbos Krijn B., De Snoo Geert R., (2008). “Breeding
skylarks (Alauda arvensis) on organic and conventional arable farms in The
Netherlands”. Agriculture, Ecosystems and Environment, vol. 126, pp.163–
Kuiper M.W., Ottens H.J., Cenin L., Schaffers A.P., Van Ruijven J., Koks
B.J., Berendse F., De Snoo G.R., (2013). “Field margins as foraging habitat
for skylarks (Alauda arvensis) in the breeding season”. Agriculture,
Ecosystems and Environment, vol. 170, pp. 10-15.
Langston R. H. W., Wotton S. R., Conway G. J., Wright J., Mallord J. W.,
Currie F. A., Drewitt A. L., Grice P. V., Hoccom D. G. & Symes N., (2007).
“Nightjar Caprimulgus europaeus and Woodlark Lullula arborea – recovering
species in Britain?”. Ibis, vol. 149, pp. 250-260.
Marzano, M. & Dandy, N., (2012). “Recreational use of forests and
disturbance of wildlife – a literature review”. Forestry Commission Research
Report. Forestry Commission, Edinburgh. i–viii + 1–40 pp.
Marzluff John M., (1997). “Effects of Urbanization and Recreation on
songbirds”. Part of the literature review: Songbird Ecology in Southwestern
Ponderosa Pine Forests. [Online] Available at:
Miller Scott G. and Knight Richard, (1998). “Influence of recreational trails on
breeding bird communities”. Ecological Applications, vol. 8, pp. 162–169.
[Online] Available at: http://dx.doi.org/10.1890/1051-
Mallord John W., Dolman Paul M., Brown Andy F. & Sutherland William J.,
(2007). “Linking recreational disturbance to population size in a ground-
nesting passerine”. Journal of Applied Ecology, vol. 44, pp. 185-195.
Rahman M. L., Tarrant S., McCollin D. & Ollerton J., (2012). “Influence of
habitat quality, landscape structure and food resources on breeding skylark
(Alauda arvensis) territory distribution on restored landfill sites”. Landscape
and Urban Planning, vol. 105, pp. 281-287.
Sayan Mustafa Selcuk & Atik Meryem, (2011). “Recreation Carrying
Capacity Estimates for Protected Areas: A Study of Termessos National
Park”. Ekoloji, vol.78, pp. 66-74.
Sitters H.P., Fuller R.J., Hoblyn R.A., Wright M.T., Cowie N. & Bowden
C.G.R., (1996). “The Woodlark Lullula arborea in Britain: population, trends,
distribution and habitat occupancy”. Bird Study, vol 43, pp. 172-187.
Svensson, L. 2009. Collins Birds Guide, 2nd
edition. The most complete guide
to the birds of Britain and Europe. HarperCollins Publishers, London.
“The Hoge Veluwe - Nature and Art”. 2005 Stichting Het Nationale Park De
Hoge Veluwe. Waanders Publishers’ Zwolle.
Vermeulen M., (2009). Possibilities of hyperspectral remote sensing for
monitoring the structure and functioning of habitat types in heathland
ecosystems. MSc. Wageningen University and Research Centre.
Wright Lucy J., Hoblyn Ron A., Green Rhys E., Bowden Christopher G. R.,
Mallord John W., Sutherland WilliamJ. & Dolman Paul M., (2009).
“Importance of climatic and environmental change in the demography of a
multi-brooded passerine, the woodlark Lullula arborea”. Journal of Animal
Ecology, vol.78, pp. 1191-1202.