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Translocation of an endangered insect species, the field cricket (Gryllus campestris Linnaeus, 1758) in northern Germany

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Relocations of species have become a tool widely used in nature conservation, but insects have rarely been considered as targets. Here, we present a translocation project of the field cricket (Gryllus campestris L. 1758), which is a threatened species at the northern edge of its range. Only ten populations were left in Lower Saxony (Germany), illustrating the need for urgent conservation measures. After 10 years of monitoring and management of an isolated population, 213 nymphs were captured and released at another nature reserve in summer 2001. The size of the new population increased significantly from 27 singing males in spring 2002 to 335 singing males in spring 2005. The occupied area increased from 5.66 ha to 33.14 ha. Altogether, the translocation project was evaluated as successful, but the inland dune proved to be not as suitable for the species as initially expected. Our results indicate that translocations of highly reproductive insect species are promising, as long as the release locality contains sufficiently large areas of suitable habitat and a high number of wild juveniles from a closely located and large source population are released in a climatically favorable period. Management and restoration of habitats, as well as continuous monitoring are of crucial importance for the success of the translocation project. Moreover, the importance of a high quality of cooperation between conservationists, authorities, foresters, farmers, financiers and scientists cannot be overstated.
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Abstract Relocations of species have become a tool widely used in nature
conservation, but insects have rarely been considered as targets. Here, we present a
translocation project of the field cricket (Gryllus campestris L. 1758), which is a
threatened species at the northern edge of its range. Only ten populations were left
in Lower Saxony (Germany), illustrating the need for urgent conservation measures.
After 10 years of monitoring and management of an isolated population, 213
nymphs were captured and released at another nature reserve in summer 2001. The
size of the new population increased significantly from 27 singing males in spring
2002 to 335 singing males in spring 2005. The occupied area increased from 5.66 ha
to 33.14 ha. Altogether, the translocation project was evaluated as successful, but the
inland dune proved to be not as suitable for the species as initially expected. Our
results indicate that translocations of highly reproductive insect species are prom-
ising, as long as the release locality contains sufficiently large areas of suitable
habitat and a high number of wild juveniles from a closely located and large source
population are released in a climatically favorable period. Management and resto-
ration of habitats, as well as continuous monitoring are of crucial importance for the
success of the translocation project. Moreover, the importance of a high quality of
cooperation between conservationists, authorities, foresters, farmers, financiers and
scientists cannot be overstated.
Keywords Heathland ÆInsect conservation ÆOrthoptera ÆRe-introduction Æ
Relocation ÆRestoration
A. Hochkirch (&)ÆK. A. Witzenberger
Department Biology/Chemistry, Division of Ecology, University of Osnabru
¨ck, Barbarastr. 11,
Osnabru
¨ck D-49076, Germany
e-mail: hochkirch@biologie.uni-osnabrueck.de
A. Teerling ÆF. Niemeyer
BUND Diepholzer Moorniederung, Langer Berg 15, Wagenfeld D-49419, Germany
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Biodivers Conserv (2007) 16:3597–3607
DOI 10.1007/s10531-006-9123-9
ORIGINAL PAPER
Translocation of an endangered insect species, the field
cricket (Gryllus campestris Linnaeus, 1758) in northern
Germany
Axel Hochkirch ÆKathrin A. Witzenberger Æ
Anje Teerling ÆFriedhelm Niemeyer
Received: 3 February 2006 / Accepted: 29 August 2006 / Published online: 27 October 2006
ÓSpringer Science+Business Media B.V. 2006
Introduction
Animal relocations have become a widely used tool in conservation management.
However, most re-introduction projects so far have focused on large vertebrates,
such as birds and mammals (Sarrazin and Barbault 1996; Fischer and Lindenmayer
2000). In spite of the fact that invertebrates constitute a substantial proportion of the
species richness and biomass, and play a significant role in ecosystem functioning,
they rarely have been considered as relocation targets and are even often discounted
in conservation management as a whole. Thus, invertebrates need to receive much
more attention in nature conservation (Pyle et al. 1981; Dunn 2005). Relocation
projects of highly reproductive invertebrates are much more promising than those of
large vertebrates due to their small body size, the low costs, and the small spatial
requirements (Pearce-Kelly et al. 1998). The few documented cases of invertebrate
relocations mainly deal with Lepidoptera species (Rawson 1961; Dempster et al.
1976; Duffey 1977; Va
¨isanen et al. 1994; Witkowski et al. 1997), but some examples
of Orthoptera relocations have also been published (Pearce-Kelly et al. 1998;
Sherley 1998; Berggren 2005).
Four different types of relocations are commonly distinguished (IUCN 1998):
Re-introductions (attempts to establish a species within its historical range), trans-
locations (attempts to establish new populations within the range), supplementations
(addition of individuals of different genotype to an existing population), and
conservation introductions (attempts to establish a species outside its natural range,
but in an appropriate habitat). The aim of translocation projects is usually to reduce
the risk of extinction for an endangered species by creating more self-sustaining
populations (Sherley 1998). Fragmentation of habitats and loss of (sub-)populations
have been recognized as main threats for many species (Primack 2002). The artificial
establishment of new populations is, therefore, a consistent method for enhancing
the survival probability of a species. However, only 26% of the relocation trials
analyzed in a recent review have been classified as successful (Fischer and
Lindenmayer 2000). There is a strong need for more thorough management of
relocation experiments, with careful background research, choice of suitable release
sites and release stocks, as well as monitoring before and after the relocation (IUCN
1998; Fischer and Lindenmayer 2000). Here we present the results of a translocation
experiment of the field cricket (Gryllus campestris L. 1758) in northern Germany.
We evaluate the success of the translocation project by using a strong criterion
(significant increase in population size) as indicator of the success.
Methods
The study object
The field cricket (Gryllus campestris) is a rather well-known insect. It is a compara-
tively large cricket species (17–26 mm), characterized by a shiny black body
coloration (Marshall and Haes 1990). The species mainly inhabits dry grasslands, and
is restricted to heathlands and oligotrophic grasslands at the northern edge of its
range (Kleukers et al. 1997), where it typically lives in burrows of approximately
30 cm depth (Regen 1906). The reproductive season of the univoltine species lasts
from May until the end of June. Nymphs hatch in mid July and overwinter during
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3598 Biodivers Conserv (2007) 16:3597–3607
their tenth or eleventh instar (Ko
¨hler and Reinhardt 1992). The final moult takes
place at the end of April or at the beginning of May. While males are territorial and
defend their burrows fiercely, females are vagrant and are attracted by singing males.
They lay their eggs in bare ground either close to a burrow or into the burrow. The
first instars can be found under bark or wooden pieces, but they also use old burrows
of adults. Populations of G. campestris are known to undergo extreme fluctuations
and are strongly affected by weather conditions (Remmert 1992).
The field cricket is a threatened species at the northern edge of its range, such as
the UK (Pearce-Kelly et al. 1998), Germany (Ingrisch and Ko
¨hler 1997), the
Netherlands (Kleukers et al. 1997), Denmark (http://redlist.dmu.dk, 2006) or
Switzerland (Thorens and Nadig 1997). In Lower Saxony it is listed as Critically
Endangered (Grein 2005), with only ten populations left (Grein 2000). The main
reason for its decline is believed to be habitat loss. Due to its well-known song, the
field cricket is a comparatively popular insect species. It probably represents one of
the scarce examples of ‘‘non-butterfly insects’’, which are suitable as flagship species.
For this reason, the species has been selected as Insect of the Year 2003 by the
‘‘Kuratorium Insekt des Jahres’’ of the German Entomological Institute
(Eberswalde) and the Federal Biological Research Center for Agriculture and
Forestry (Braunschweig) in Germany. In Lower Saxony, only one isolated popula-
tion remained west of the river Weser, at the eastern edge of the nature reserve
‘‘Neusta
¨dter Moor’’. This population has been monitored and managed intensely
during the last 15 years by the non-governmental organization BUND (‘‘Bund fu
¨r
Umwelt und Naturschutz Deutschland’’ or ‘‘Friends of the Earth - Germany’’).
From 1991 to 2001, the population increased from 32 to 949 singing males
(Hochkirch 1996; Teerling and Hochkirch 2002). In order to reduce the extinction
risk further, a translocation project was started in 2001, intending to establish a
second self-sustaining population in a nearby nature reserve (‘‘Renzeler Moor’’).
Although there are no former records of field crickets available for this nature
reserve, it consists of many seemingly ideal but unoccupied habitats for field crickets
and was thought to enable them to spread further. However, it is separated from the
source population by a distance of 3.5 km, with the river ‘‘Große Aue’’ and wet
grasslands acting as effective barriers for these flightless insects.
The study area
The two study sites are located in the central part of the natural region ‘‘Diepholzer
Moorniederung’’, an area between the towns Hannover, Bremen and Osnabru
¨ck
(Lower Saxony, Germany). The region is characterized by large peat bogs, wetlands
and dry alluvial sand ridges. These dry areas are naturally oligotrophic and were
heavily overgrazed from the middle ages to the 19th century. During this period,
heathlands, dunes and oligotrophic grasslands spread over northern Germany
(Webb 1998). After the invention of artificial fertilizers and massive changes in land
use, only small fragments of heathland have been left (Bakker and Berendse 1999).
All peat bogs are strongly degraded, either by cultivation, peat cutting or dehy-
dration. At the beginning of the 1970s, regional conservationists started a conser-
vation project in order to save the remaining peat bog fauna, which has been
continued by the BUND since 1983. With increasing experience the field of activities
spread to other types of habitat, such as wet grasslands, dunes and heathlands, which
surround the peat bog areas.
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Biodivers Conserv (2007) 16:3597–3607 3599
The nature reserves in the ‘‘Neusta
¨dter Moor’’ include the peat bog, as well as
adjacent heathlands and wet grasslands at the western edge. The main part of the
source population occurs east of these reserves, but it has spread into them during
the last decade (Teerling and Hochkirch 2002). We chose two release sites on a
former inland dune system in the northwestern part of the nature reserve ‘‘Renzeler
Moor’’ (established in 1970). This area was used as farmland and pine forest during
the past decades and transformed into meso- to oligotrophic grasslands at the
beginning of the 1990s. Both reserves are maintained by extensive sheep grazing,
which is also known to be advantageous for field crickets (Schmidt 1998).
The translocation procedure
From 1990 to 2001, the population at the Neusta
¨dter Moor was intensely monitored
and managed, leading to an approximately 30-fold increase in population size. In
2001 the population size was sufficiently large to start the translocation procedure,
which was oriented towards a previous re-introduction project for the field cricket in
England (Pearce-Kelly et al. 1998). The release sites at the Renzeler Moor were
inspected by the authors and an additional expert (G. Grein) and there was general
agreement that they represent suitable habitats for the field cricket. However, a
detailed habitat analysis was not performed. Two localities were chosen as release
sites: a meso- to oligotrophic pasture, which was managed by sheep grazing since
1992 and a restored inland dune, which was formerly forested with pines and
deforested in the winter of 1990/91. The great habitat-diversity of the surrounding
terrain was expected to allow further dispersal to suitable sites during the following
years. Since the success of translocations can be increased by using wild animals as a
source, releasing a large number of individuals and removing any detrimental factors
(Fischer and Lindenmayer 2000), we followed these recommendations. In contrast to
the breeding program presented by Pearce-Kelly et al. (1998), only wild nymphs
were released during the translocation. Although the source population could be
genetically rather invariable due to a bottleneck in 1991 (32 singing males), it was
chosen to gain nymphs only from this well-monitored area, which is also the closest
population to the release area. In order to increase the genetic diversity as far as
possible, nymphs were collected from different subpopulations at the Neusta
¨dter
Moor. The populations of both release and source area were monitored during the
following years.
A total of 213 nymphs (instar 7–8) were collected on 4 days in July 2001. They
were stored in boxes with swards of grass and heather to enable the nymphs to find
shelter beneath them during the transportation. Fish food was supplied until they
were released on 31 July 2001. Approximately half of the individuals (113 speci-
mens) were introduced directly on the inland dune, the other half (100 specimens)
on the pasture. Individuals from all subpopulations were released at each site to
increase the genetic variability. During the first days pieces of bark where placed on
the ground as shelter.
Monitoring of the field crickets
The population size of G. campestris in the Neusta
¨dter Moor and Renzeler Moor
was estimated by counting the number of singing males on each occupied site. The
characteristic calling song of the field cricket is well suited for monitoring, since it
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3600 Biodivers Conserv (2007) 16:3597–3607
can be heard up to 100 m, allowing a fast and comprehensive survey (Detzel 1998).
Females and non-singing males were ignored, to allow comparability of the data
between different years. Since not all males sing simultaneously, the data have to be
regarded as minimum values. The study sites were checked on dry, warm and
windless days during the main calling phase (from May to June). Densely populated
sites were mapped preferably during the highest activity in the late afternoon or in
the evening. All records were transferred to a map and analyzed with ArcView GIS
3.2. This method has been applied since 1990 in the study area (Hochkirch 1996;
Teerling and Hochkirch 2002).
Statistical analysis
We computed a linear regression model for population growth for the whole
population as well as for three different habitat types (pasture, dune, peat bog) and
tested for a positive increase in population size. All data were log-transformed prior
to statistical treatment to comply with the model assumptions. The tests were carried
out in ‘‘R 2.1.1’’ (R Development Core Team, 2004).
Results
In total, 27 singing males were recorded in the Renzeler Moor in the spring of 2002
(Fig. 1). Assuming a balanced sex ratio, this corresponds to a survival rate of 25.4%.
Considering that G. campestris is known to have a high mortality during the winter
(Remmert 1992), the survival rate was surprisingly high. This led to the decision, not
to supplement cricket nymphs in 2002. In the following year, 42 stridulating males
were counted and the population had spread also spatially compared with 2002
(Fig. 1). Most of the males were found between the dune and a degraded part or the
bog. After the unusual hot summer of 2003 (Ciais et al. 2005) the population
increased up to 107 stridulating males in spring 2004. The majority of individuals
(70%) were recorded on the pasture, whereas only 7% inhabited the inland dune
(Fig. 2). In 2005, the population had grown immensely, reaching 335 stridulating
males. Again the majority of crickets (77%) inhabited pastures and bog sites
surrounding the inland dune (Fig. 2). Some initial subpopulations colonized sites
approximately 250 m outside the nature reserve, such as adjacent fields and mead-
ows. The occupied area increased from 5.66 ha in 2002 to 33.14 ha in 2005 (Fig. 1).
The overall population growth was significantly positive (linear regression model,
df =2,t= 7.55, p= 0.017, R2= 0.9661) and so was the increase of the occupied area
(linear regression model, df =2, t= 4.53, p= 0.046, R2= 0.911). However, after
analyzing the data for the three habitats (dune, bog, pasture) separately, the sub-
population growth on the dune was not significant (linear regression model, df =2,
t= 0.910, p= 0.459, R2= 0.293), while the subpopulations increased significantly on
the pasture (linear regression model, df =2,t= 8.695, p= 0.013, R2= 0.974) and in
the bog (linear regression model, df =2,t= 10.39, p= 0.009, R2= 0.982).
Discussion
Four years after the translocation of cricket nymphs, we evaluated the project as
successful. The population persisted and increased significantly, indicating a high
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quality of the release area as habitat for Gryllus campestris. However, despite of these
overall results, the suitability of single sites (or habitat types) differed from our
expectations. While the population size increased strongly on the pasture and
degraded peat bog, the inland dune turned out to be much less suited than expected
(Fig. 2). A possible reason for this might be found in inappropriate conditions for
digging burrows (Ko
¨hler and Reinhardt 1992), due to either the dense cover of mosses
and plant litter or the soil structure of the dune. As initially intended, the increase in
population size also caused a considerable dispersal of the field cricket into adjacent
areas. Some of these habitats, such as peat bog sites or arable fields, might not be
Fig. 1 Dynamics of the new population of Gryllus campestris in the Renzeler Moor from 2002 to
2005 (black dots: singing males). The crossed squares represent the two release localities, the
southern of which was located on the inland dune, the northern on a pasture. Peat bog sites (striped)
are mainly situated southeast of the inland dune. The bold line marks the border of the reserve. Sites
north of the reserve consist mainly of conventional farmland
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suitable as persistent habitats, but they may serve as stepping stones for future
expansion. In the source area (Neusta
¨dter Moor), degraded peat bog has been
colonized permanently during the last decade, allowing dispersal to remote heath-
lands. Continuous monitoring of the source population showed that the loss of 213
nymphs had no negative consequences. In 2005, the source population reached a new
maximum of 1945 singing males (unpublished data). We consider ten factors as crucial
for the success of the translocation method, which can be grouped into three major
classes: ecological factors, translocation procedure, scientific and administrative
support.
Ecological factors
Four ecological factors were probably of importance for the success. (1) The habitat
quality in the release area was rather high, due to an intense habitat restoration and
management since the end of the 1980s. Continuous management by sheep grazing
and mowing is needed to counteract the increased nitrogen deposition from the
atmosphere (Bakker and Berendse 1999). Although the dune was less suited for
G. campestris, deforestation and extensive sheep grazing supported the development
of large suitable habitats. The availability of high quality habitat is known to be the
major determinant for the success of relocation projects (Rawson 1961; Griffith et al.
1989; Wolf et al. 1996; Sarrazin and Legendre 2000). (2) The high habitat hetero-
geneity (grasslands, degraded peat bog, dune) in the release area supported the
success, as the field crickets were able to choose optimal sites and microhabitats.
Orthoptera are known to perform an active habitat choice (Whitman 1987).
Moreover, even less suited sites could be colonized in optimal years and serve as
stepping stones for future dispersal (Hochkirch 1996). (3) The weather conditions
were suitable for population growth from 2003 to 2005. This is probably of crucial
importance, since field crickets (as many insects) are highly dependent on favorable
weather at the northern edge of their range, which can influence the success of
translocation projects immensely (Pearce-Kelly et al. 1998). From 2002 to 2003, the
weather conditions were unfavorable (rainy), which is illustrated by a lower popu-
lation growth (Fig. 2). Apparently, the habitat quality of the pasture was even
Fig. 2 Comparison of the population development between the three main habitat types: grassland
(open circle), peat bog (closed square), dune (open triangle)
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suitable under these conditions, since the population persisted and increased slightly
in that year. (4) Gryllus campestris is a univoltine species, which is known to produce
high egg numbers leading to rapid population growth (Remmert 1992; Pearce-Kelly
et al. 1998). Demography is generally thought to be of high importance for popu-
lation survival (Lande 1988).
Translocation procedure
We distinguish four major parameters of the translocation procedure, which assured
the success. (1) Differently to the project of Pearce-Kelly et al. (1998) we had the
chance to gain specimens from a sufficiently large wild population. Relocation
projects using wild animals are generally more successful than those using captive
animals (Griffith et al. 1989; Fischer and Lindenmayer 2000). Moreover, transloca-
tion success of wild-caught animals correlates positively with the density and
increase of the source population (Griffith et al. 1989), which was also true for the
population at the Neusta
¨dter Moor. (2) As the source population was located close
to the release area, the translocated individuals were probably genetically adjusted
to the local conditions. The higher success of translocations using founder groups
from indigenous sources has been reported also from other taxa (Ebenhard 1995;
Sarrazin and Barbault 1996; Singer et al. 2000). (3) Another important factor could
be the use of nymphs for the translocation. Nymphs of Gryllus campestris are more
mobile than adults, since they do not show any territoriality. They do not start to dig
burrows before autumn (Detzel 1998). Results from population modeling suggest
that the use of juveniles in translocation projects is generally more efficient than
relocating adults (Robert et al. 2003). (4) We transferred a high number of indi-
viduals. It is noteworthy to mention that the relation between translocation success
and the number of animals released is asymptotic (Griffith et al. 1989). Pearce-Kelly
et al. (1998) introduced between 106 and 1200 nymphs of G. campestris, but the
survival depended more upon the habitat quality than on the number of released
insects. Although there is a minimum number of animals that should be released,
translocations have low chances of success without high habitat quality (Griffith
et al. 1989; Ebenhard 1995).
Scientific and administrative factors
Two factors within this class were of importance for the translocation project. (1)
Continuous monitoring of both source and release population has been performed
since 1990, allowing the assessment of the translocation method as well as the
influence of the removal of specimens from the source population. In many trans-
location projects, such intense monitoring measures are missing (Sarrazin and
Barbault 1996). Moreover, the experience of ten years of monitoring and manage-
ment facilitated the choice of suitable release sites. (2) The success of the translo-
cation project was also promoted by the excellent cooperation of the local and
regional administrations, foresters and farmers, financial supporters (see acknowl-
edgements), the executing organization (BUND) and the scientific consultants
(University of Osnabru
¨ck). There is a strong need for such a high quality of coop-
eration in nature conservation (Sarrazin and Barbault 1996).
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3604 Biodivers Conserv (2007) 16:3597–3607
Negative factors
Two factors could have had negative effects on the success of the translocation
process. (1) The transferred crickets were gained from only one population, which
passed through a genetic bottleneck at the beginning of the 1990s. It is rather likely
that the established population is genetically impoverished as has been shown for
other translocated populations (Stockwell et al. 1996). However, inbreeding need
not always cause inbreeding depression (Lande 1988; Hoelzel et al. 1993; Leberg
1993) and the consequences of genetics on survival or reproduction are difficult to
predict (Sarrazin and Legendre 2000). The strong population growth of the field
cricket indicates that currently the suggested loss of genetic diversity does not cause
any problems. Demography generally seems to be of higher importance for popu-
lation dynamics than population genetics (Lande 1988). Moreover, by transferring
specimens from a nearby locality, the risk of outbreeding depression is minimized
(Griffiths et al. 1996, Sarrazin and Barbault 1996). (2) There is another caveat, which
should receive a stronger consideration in future translocation projects. Based upon
the initial inspection of the release area, two sites (the dune and the pasture) were
regarded as suitable habitats for the field cricket. While the subpopulation on the
pasture increased continuously from 2002 to 2005, the subpopulation on the dune
decreased during the first three years (Fig. 2). The increase of the dune subpopu-
lation in 2005 might be caused by continuous immigration from the surrounding
sites. The success of the whole project was determined by the high performance of
the pasture and the surrounding bog sites. Had only the dune been chosen as a
release site, the project might have been less successful. Therefore, detailed habitat
analyses should be performed prior to relocation projects (Holloway et al. 2003).
Acknowledgements We are grateful to Till Eggers for statistical advice. We would also like to
thank Anselm Kratochwil for his constant support and encouragement throughout this project. The
Division of Ecology at the University of Osnabru
¨ck provided research facilities. Till Eggers, Julia
Gro
¨ning, Elisabeth Witzenberger and Anselm Kratochwil provided valuable comments on a
previous version of the manuscript. The local and regional administrations (Land of Lower Saxony,
district government Hannover, NLO
¨, NLWKN, Landkreis Diepholz) enabled us to carry out the
translocation and all associated surveys. Additionally our thanks go to the Forstamt Binnen and the
Sheep farm Grimberg, who supported and carried out habitat management measures. We owe great
thanks to our financial supporters (Land of Lower Saxony, Bingo Lotto, Deutsche Umwelthilfe,
Stiftung Naturschutz im Landkreis Diepholz, Arbeitsamt Nienburg, BUND, University of
Osnabru
¨ck).
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... This is especially true for those insect species which reproduce at high rates but which may be prone to population fluctuations. To maximise the chance of success of translocations involving such species, the release locality should contain a sufficiently large area of suitable habitat and the project should involve a large founder population released during a climatically favourable period (Hochkirch et al. 2007). Even with apparently suitable habitat, it is crucial to determine the current climate suitability of introduction sites as this can impact on the likelihood of introduction success. ...
... Populations at the rear (low altitude or latitude) edge of a range may respond rather differently to conservation measures compared to those at the front of the range (Hampe & Petit 2005). To ensure maximum likelihood of success, therefore, it has been suggested that insect releases should ordinarily comprise individuals from a donor population that is located as close as possible to the release site (Hochkirch et al. 2007). However, this may not account for releases as part of an AC process. ...
Technical Report
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Background Climate change is a major threat to global biodiversity. Changes in the location of suitable climatic conditions may drive species range-shifting, as species attempt to track suitable climate through space. However, land use change and associated habitat fragmentation, as well as inherent characteristics of the species (e.g. rate of reproduction and dispersal ability), may place serious limitations on the ability of species to track suitable climate. Some species will be unable to reach regions with suitable future climatic conditions, leading to the proposed use of species translocations as a tool to overcome this stranding effect: species at risk would be moved to those areas expected to be suitable for their growth. This procedure is termed, here, Assisted Colonisation (AC). There is considerable current debate concerning the application of AC as a conservation tool for dealing with the threat of climate change. The issues associated with the use of such translocations are directly relevant to species conservation in Scotland. The current SNH-Macaulay partnership project, of which this literature review is a part, aims to consider the application of species translocations as a conservation tool for the establishment or protection of populations in northerly and/or montane environments in Scotland. This literature review provides information to help focus later stages of the project. Main findings Although there is no shortage of possible targets for research projects exploring the application of AC, we would suggest that the following are priority areas for action:  Developing assessment processes to attempt to identify candidates for AC.  Investigations of dispersal abilities and genetics.  Practical trials of transplant methodologies for particular species groups.  Better understanding of what constitutes “last resort”.  Exploring the best locations from which to source material for AC relative to current and future climatic conditions.  Developing predictive techniques for selecting sites that will be suitable for future survival.
... Een weloverwogen herintroductie van de soort op het voormalig militair domein zou het regionale voortbestaan van deze soort mogelijk kunnen waarborgen. Dergelijke herintroductie-initiatieven werden reeds met succes toegepast in het Verenigd Koninkrijk (waarmee het uitsterven van de soort kon worden voorkomen) en in Nedersaksen, Duitsland(Pearce-Kelly et al. 1998;Hochkirch et al. 2006). Wij pleiten er alvast voor om dit uit te voeren in dit gebied, bijvoorbeeld met individuen uit de populaties in de Laanvallei, die zich door toenemende verbossing in een kritieke toestand bevinden. ...
... Many translocation programs have been carried out in many rare, threatened and keystone species to conserve species and genetic diversity. For example, European bison [29], Lake Sturgeon [30], Persian wild ass [31], green and golden bell frog [32], red wolves [33], and a few insects, (i.e., damselfly [34], field cricket [35] and fireflies [25]). Most of them have involved vertebrates, especially mammals and birds [36]. ...
Chapter
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Conservation translocation is frequently used to conserve the threatened fauna by releasing individuals from the wild or captive populations into a particular area. This approach, however, is not successful in many cases because the translocated populations could not self-sustain in the new habitats. In this chapter, I reviewed the concept of translocation for conservation and the factors associated with the success rate. I used example problems from several cases involving different insect taxa. With its often high potential to mass rear in captivity, captive breeding can be a powerful tool by assuring large population size for insect translocation, which can result in a high success rate. However, genetic consequences from inbreeding and genetic adaptation to captivity can reduce the fitness of the captive population to establish successfully in the wild. Additionally, as the evidence in Japanese fireflies shows, the genetic differences between the translocated and local populations should be considered for a sustainable translocation program. A case study involved genetic and behavioral evaluation of S. aquatilis populations to assess the possibility of including the species for the firefly translocation program in Thailand. Although the results revealed no genetic variation among populations, examination of the variation in flash signals showed that the long-distance population had a longer courtship flash pulse than other populations in the Bangkok Metropolitan Region. With no geographical barrier, the light pollution and urbanization are probably important fragmented barriers causing adaptation of flash communication to increase the fitness. As a consequence, firefly translocation should consider flash variation between populations to prevent this potential pre-mating isolation mechanism from resulting in probable lower translocation success rates.
... Alate Orthoptera are known to have outstanding flying abilities, although this varies from species to species (Picaud & Petit, 2007). It has been proved that vegetation height can be correlated either positively or negatively with Orthoptera Vegetation cover and vegetation structure also influences Orthoptera assemblages (Clark, 1948;Gardiner, Pye, Field, & Hill, 2002;Hochkirch, Witzenberger, Teerling, & Niemeyer, 2007) and especially by affecting the microclimate (Joern 1982b). Fluctuation of both species richness and abundance between 2010 and 2011 was measured with the same dynamic (values dropped between 2010 to 2011) for the three treatments considered in the study. ...
Article
In the last few years, legislation in more and more countries has stipulated compensation for impacts on biodiversity. France was one of the first countries to include compensation in its national law on nature preservation (1976), but habitat banking was only recently introduced into the mitigation regulatory framework. It was applied for the first time in 2008, when the first French Natural Asset Reserve was created in the plain of La Crau (Southeastern France), the last semi-arid steppe in Western Europe. This project was realized through mitigation banking and involved the ecological rehabilitation of an abandoned conventional orchard to a dry Mediterranean grassland habitat for the rare and protected steppe birds typical of this area. Here, to measure habitat rehabilitation success and validate the mitigation banking principle, we use Orthoptera as rapid and integrative indicators. Performing a six-year study (2008–2013), we assessed Orthoptera assemblages before rehabilitation (2008), when the conventional orchard was abandoned; during rehabilitation (2009); and for four years after rehabilitation (2010–2013). Three areas were considered: the area that was rehabilitated, the surrounding undisturbed steppe considered as reference ecosystem and the edge between them. The rapid recovery of typical Orthoptera assemblages measured in terms of species richness, abundance and composition confirms the successful rehabilitation of the habitat, allowing the return of steppe birds, the objective of the compensation project.
... Gryllidae (mainly the species Gryllus campestris) and Tettigoniidae were found to be the most abundant Orthoptera families in the diet during this period. The high proportion of Gryllidae in the diet indicates that Lesser Kestrels forage in non-fragmented dry grasslands (Hochkirch et al., 2007) at some point during the breeding season (the exact stage in the breeding period cannot be identified, as all pellets were collected at the end of the breeding season and seasonal distribution of prey items in the diet are unknown). It should be mentioned here that, since we focus on an urban colony, birds might be restricted in their foraging movements. ...
Article
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Assessing the variation in diet composition of a species, over different years and between periods, offers insights to comprehend its ecological niche as well as to define different feeding strategies. We studied the diet of the Lesser Kestrel (Falco naumanni) by analysing 1040 regurgitated pellets collected in the city of Ioannina (northwestern Greece). We compared diet composition between the breeding period (data from years 2010–2015) and the pre-migration period (data from 2013–2015) at the study site. A total of 8920 prey items were identified and classified into 13 different prey families. The Lesser Kestrel shows a consistent pattern of diet composition throughout years, displaying significant differences between breeding and pre-migration periods. The diet is rather diverse during the breeding season (Levins' diet breadth, B=4.12) and is composed mainly of Orthoptera and Coleoptera, while during pre-migration, the species shows a more narrow diet breadth (B=1.98) and feeds more often and on larger amounts of Orthoptera. These results indicate a specialised feeding strategy during pre-migration. In addition, the examination of the Orthoptera consumption during this period indicates a peak in the abundance of grasshoppers (Acrididae) in the second half of August. We suggest that at this time birds exploit high elevation open grasslands around the roosting site where grasshopper abundance is high. Thus, such areas are of high conservation importance as Lesser Kestrels depend on this localised abundance of Orthoptera in order to fuel up before their trans-Saharan migration.
... In fact a local SAP was deemed unnecessary. However, it can be argued that a period when populations of localized rare species are healthy presents the greatest opportunity to increase the number of populations, providing other necessary factors are also in place [67]. Third, our study illustrates the value of monitoring programmes for rare species. ...
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The conditions required by rare species are often only approximately known. Monitoring such species over time can help refine management of their protected areas. We report population trends of a rare moth, the Dark Bordered Beauty Epione vespertaria (Linnaeus, 1767) (Lepidoptera: Geometridae) at its last known English site on a protected lowland heath, and those of its host-plant, Salix repens (L.) (Malpighiales: Salicaceae). Between 2007 and 2014, adult moth density reduced by an average of 30–35% annually over the monitored area, and its range over the monitored area contracted in concert. By comparing data from before this decline (2005) with data taken in 2013, we show that the density of host-plants over the monitored area reduced threefold overall, and tenfold in the areas of highest host-plant density. In addition, plants were significantly smaller in 2013. In 2005, moth larvae tended to be found on plants that were significantly larger than average at the time. By 2013, far fewer plants were of an equivalent size. This suggests that the rapid decline of the moth population coincides with, and is likely driven by, changes in the host-plant population. Why the host-plant population has changed remains less certain, but fire, frost damage and grazing damage have probably contributed. It is likely that a reduction in grazing pressure in parts of the site would aid host-plant recovery, although grazing remains an important site management activity. Our work confirms the value of constant monitoring of rare or priority insect species, of the risks posed to species with few populations even when their populations are large, of the potential conflict between bespoke management for species and generic management of habitats, and hence the value of refining our knowledge of rare species' requirements so that their needs can be incorporated into the management of protected areas.
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We investigated temporal changes in diet composition of the Montagu's Harrier Circus pygargus breeding in natural habitat (calcareous peat bog) in SE Poland. We characterized diet composition in a three-year period (2007–2009), based on pellet analyses. We investigated whether diet composition was affected by years or stage of breeding. We compared diet of the studied population between 2000s and 1990s and with other populations. We found that the food of the studied population was dominated by insects and mammals (by number) and mammals and birds (by biomass). Biomass and abundance of main prey items differed between studied years because of different air temperatures. We found some interannual differences in contribution of some prey items including higher number of thermophilic prey (insects and am-phibians) in warmer years. Comparison of pellet composition in the 1990s and 2000s revealed significant increase in the abundance of thermophilic prey (insects and rep-tiles) and decrease of mammals including Microtus voles and birds. Those changes may be linked to habitat changes in areas neighboring peat bogs and climate change- induced changes in prey communities. The studied population was able to respond to changes in foraging habitats and prey composition by opportunistic foraging on easily available prey. The diet of the studied population is the most similar to the geographically closest populations foraging in similar habitats and characterized by high contribution of insects.
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Steppes and xerothermic grasslands are hotspots of biodiversity, but are threatened by habitat destruction and fragmentation. The heath bush-cricket, Gampsocleis glabra, is considered to be a specialist of xerothermic habitats and appears in national red lists as a threatened species in several European countries. The goal of the current research was to determine the habitat requirements of G. glabra in an isolated habitat patch in Poland, at the northern edge of its range. By comparing the composition of plant species and vegetation architecture of vacant and occupied sites in the summers of 2018 and 2019, it was found that this population of G. glabra still maintained a strict specialisation for the xerothermofilous Festuco-Brometea plant community. On the contrary to previous studies, however, Stipa-type grasses were not essential for the occurrence of the species and the majority of occupied areas were based on the plant Brachypodium pinnatum. The physiognomy of plant communities was crucial for the abundance of stridulating males, which showed a preference for dense grasses at 10 cm high. The habitat characteristics of patches occupied by males and females did not differ significantly. The study of habitat requirements of this endangered Orthoptera species in an isolated habitat patch could serve as a prelude to the restoration of similar locations before it becomes extinct. This study may also underpin the development of a global conservation strategy for G. glabra.
Article
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Conservation programs increasingly involve the reintroduction of animals which otherwise would not recolon-ize restored habitats. We assessed the long-term success of a project in which the Blue-winged grasshopper, Oedipoda caerulescens (L., 1758), was reintroduced to a nature reserve in Northwestern Switzerland, an alluvial gravel area where the species went extinct in the 1960s. In summer 1995, we released 110 individuals (50 females and 60 males) and 204 individuals (101 females and 103 males) into two restored gravel patches with sparse vegetation. We used a transect count technique to assess the population size of O. caerulescens in the years 1995–2004 and 2015–2016 and recorded the area occupied by the species. At both release sites, the populations persisted and increased significantly in size. Individuals that followed a newly created corridor established four new subpopulations. Seven years after reintroduction, O. caerulescens had reached a high abundance around the release sites and in the four colonized patches, indicating a successful project. At the same time, the dispersal corridor became increasingly overgrown by dense vegetation. Surveys 20 and 21 yr after introduction showed that the abundance of the Blue-winged grasshopper had strongly declined in the established subpopulations and moderately in the original release sites, owing to natural succession of the habitat and lack of disturbances, which reduced the area suitable for the species by 59%. Our study shows that reintro-ductions are unlikely to succeed without integration of long-term habitat management (in the present case maintenance of open ground).
Article
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During the last century, the decline of the apollo butterfly in the Pieniny mountains has been observed. This decline is attributed to environmental pollution, shrinkage of the area of open habitats inhabited by the species (as a result of introducing new, more expansive varieties of spruce in the area of Pieniny mountains), genetic erosion affecting small populations, and decimating this butterfly by collectors. The programme of the reintroduction of the apollo butterfly in the Pieniny National Park includes three main areas of activity: captive breeding of specimens to reinforce wild populations, preparation of habitats once inhabited by the apollo butterfly, including the removal of trees and shrubs and implanting the host plant, and research work. This was concerned with the ecology and dynamics of wild and reintroduced populations of the apollo butterfly, description of the decline process and explanation of its causal factors, and evaluation of the state of their habitat with special regard to the abundance and ecology of their host plant - Sedum maximum The five-years' reintroduction work has resulted in the triple growth of the native population inhabiting the massive of Trzy Korony (from c. 20 in 1991 to c. 60 in 1995); moreover, butterflies raised in captivity were released in four new, reconstructed localities. In 1995 migrations of specimens between all but one localities were observed.
Article
Throughout western Europe heathlands dominated by ericaceous subshrubs occur on poor soils. Mostly, these heaths have developed and have been maintained by human activities. Traditional management has perpetuated ecosystems of a low nutrient status in which plant succession is arrested. Traditional management has involved a complex interaction between grazing, arable cultivation and the use of turf and plant material from the heaths. This basic system occurs throughout the European heathlands but with local variants. This paper reviews and compares the various systems of heathland use and management with the aim of developing new methods to maintain these cultural landscapes.
Article
In Finland, Pseudophilotes baton schiffermuelleri is an endangered blue butterfly associated with open and dry esker habitats. During this century P. baton has been recorded from about 20 sites, but only one population is known to have survived, at Sakyla, SW Finland. Forest fires and from 1963 onwards shooting ranges have kept the SW slopes of the sandy esker open and suitable for the butterfly. The total adult population size was estimated in 1990 at c850 individuals. The number of males increased as the tree cover of the habitat decreased. The proportion of bare mineral soil and the coverage of the host plant Thymus serpyllum also contributed to the habitat preferences of the butterfly. Individuals flew on average >100 m, and females flew longer distances than males. A conservation programme is proposed, including active habitat management and a reintroduction plan. -from Authors
Article
Most extinctions estimated to have occurred in the historical past, or predicted to occur in the future, are of insects. Despite this, the study of insect extinctions has been neglected. Only 70 modern insect extinctions have been documented, although thousands are estimated to have occurred. By focusing on some of the 70 documented extinctions as case studies, I considered ways in which insect extinctions may differ from those of other taxa. These case studies suggested that two types of extinction might be common for insects but rare for other taxa: extinction of narrow habitat specialists and coextinctions of affiliates with the extinctions of their hosts. Importantly, both of these forms of extinction are often ignored by conservation programs focused on vertebrates and plants. Anecdotal evidence and recent simulations suggest that many insect extinctions may have already occurred because of loss of narrow habitat specialists from restricted habitats and the loss of hosts. If we are serious about insect conservation, we need to spend more time and money documenting such extinctions. To neglect such extinctions is to ignore the majority of species that are or were in need of conservation.
Article
In 1993 we conducted a follow-up study of the 1987 survey by Griffith et al. (1989) of 421 avian and mammalian translocation programs in North America, Australia, and New Zealand to reassess the programs’ status and the biological and methodological factors associated with success. Our survey response rate was 81%. Approximately 38% of usable programs in 1993 reported a change in outcome from 1987 (e.g., a translocated population was “declining” but now is “self-sustaining”), but the difference between the overall success rates was not statistically significant (66% in 1987 and 67% in 1993). Since 1987, an increase was observed in the median number of animals translocated per program (31.5 to 50.5), median duration of releases (2 to 3 years), and proportion of programs releasing more than 30 animals (46% to 68%). Multiple logistic regression analyses indicated that release into the core of the historical range, good-to-excellent habitat quality, native game species, greater numbers of released animals, and an omnivorous diet were positively associated with translocation success. Moreover, our results indicate that translocated birds were less successful at establishing self-sustaining populations than translocated mammals. Our findings, using comparable logistic analyses, generally corroborate the results of Grifftth et al. (1989). Variables not found to be significantly correlated with translocation success include species’ reproductive potential (number of offspring and first age of reproduction), number and duration of the releases, and source of the translocated animals (wild-caught versus captive-reared).
Article
The Dutch race of the large copper butterfly (Lycaena dispar Haw.), was introduced to Woodwalton Fen in 1927 and with careful management survived until 1969, following an exceptional July flood in 1968 which submerged the food plants, greatly reducing oviposition. This paper records the re-establishment of the butterfly in 1970 from caged stock and the population growth in the following three years in relation to weather conditions and fen management. It is suggested that the insect is not perfectly adapted to a fen environment because it has specialised requirements in terms of size and situation of the food plant. It is at risk from drowning if floods occur before or after the hibernation period and slight changes in the growth form of fen plants, which may overshade the food plant, can influence egg production. Experimental work suggests that when the fen vegetation is modified by cattle-grazing during June and July egg production increases because the food plants are made more accessible to the female butterflies. The heaviest mortality occurs in the period from oviposition to the beginning of hibernation but there is no known management technique which will reduce this. However, after emergence in the spring, protection in muslin cages significantly increases the survival rate. It is estimated that only about 30 ha of the Fen can be maintained in a suitable condition for the butterfly to breed successfully. It seems likely that this is too small an area for the insect to maintain itself without artificial aid such as protection for some of the larvae, creation of germination conditions for the food plant, continuance of a controlled grazing regime and the maintenance of a reserve stock in case re-introduction becomes necessary.