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Jersey NARRS Report 2007 - 2012: Results of the first full NARRS cycle in Jersey: setting the baseline

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Abstract and Figures

In 2007, the States of Jersey Department of the Environment (DoE) launched the National Amphibian and Reptile Recording Scheme (NARRS) in Jersey. The scheme forms part of the Department’s integrated ecological monitoring programme for Jersey in order to carry out 'State of the Environment Monitoring’. NARRS is coordinated by the UK organisation Amphibian and Reptile Conservation (ARC) and Jersey's scheme is run in partnership with the DoE and the Jersey Amphibian and Reptile Group (JARG). The scheme is financed by the States of Jersey but is based almost entirely on volunteer recorders, making it highly cost-effective. Jersey possesses three amphibians (the agile frog, toad [crapaud] and palmate newt) and four reptiles (the grass snake, slow-worm, wall lizard and green lizard), meaning seven native species of herpetofauna in total. Ecological data on these species are collected over a six-year cycle in order to (a) generate sufficient records on which to base an assessment of conservation status and (b) investigate changes in species’ occupancy over a realistic timescale. The use of established survey protocols is intended to provide a robust basis for conservation decision-making. Jersey NARRS uses trained volunteers to carry out surveys within an allocated 1 km survey square. At annual training events, arranged by the Department of the Environment and JARG, participants are trained in NARRS species identification, survey methodologies, bio-security and health and safety, and given survey forms to fill in and other materials facilitating the completion of their surveys. The first Jersey NARRS training event was conducted at the Frances Le Sueur Centre in 2007 and subsequent events have been held at Howard Davis Farm and Les Noyers training centre (Durrell). Jersey NARRS data (2007 – 2012) are presented here for the first time. For an earlier, interim assessment of Jersey’s NARRS results, see Wilkinson & Arnell (2010) and for more information on NARRS, see www.narrs.org.uk. Jersey data is analysed separately from the UK NARRS results because of Jersey’s unique herpetofaunal composition. Data concerning species which co-occur (in Jersey and in “GB”) may, however, be usefully compared.
Content may be subject to copyright.
J.W. Wilkinson, G.C.A. French & T. Starnes
Jersey NARRS Report 2007 - 2012
Results of the first full NARRS cycle in Jersey: setting the baseline
2
ACKNOWLEDGEMENTS
The authors would like to thank Nina Cornish, Christian
Marcos, John Pinel and David Tipping of the States of Jersey
Environment Department, and Rob Ward of DICE, University of
Kent, for their assistance with producing this report, and the
States of Jersey Environment Department for funding its
production.
This report is dedicated to the members of Jersey
Amphibian and Reptile Group, and other NARRS surveyors,
without whom it would not have been possible.
Suggested citation: Wilkinson, J.W., French, G.C.A. & Starnes, T.
(2014) Jersey NARRS Report 2007 - 2012: Results of the first full
NARRS cycle in Jersey: setting the baseline. Unpublished Report to
the States of Jersey Environment Department.
PHOTOS
page
Palmate newt male (JWW)
cover
Grass snake neonate (JWW)
cover
Green lizard (Chris Dresh, ARC)
6
Young toads (JWW)
7
Wall lizards (JWW)
8
Slow-worms (Chris Dresh, ARC)
27
CONTENTS
page
Acknowledgements
2
Photos
2
Contents
3
List of Tables and Figures
3
1. Introduction to Jersey NARRS
4
2. Methods
5
3. Results
7
4. Discussion and Recommendations
23
References
29
Appendices
30
3
LIST OF TABLES AND FIGURES
page
Table 1. Pond occupancy rates for Jersey amphibians
2007 2012
7
Table 2. Square occupancy rates for Jersey reptiles 2007
2012
8
Figure 1. Jersey NARRS amphibian squares 2007 - 2012
9
Figure 2. Jersey NARRS reptile squares 2007 - 2012
10
Figure 3. Baseline occupied Jersey grid squares for the
toad Bufo spinosus (from NARRS surveys 2007 2012)
11
Figure 4. Baseline occupied Jersey grid squares for the
palmate newt Lissotriton helveticus (from NARRS surveys
2007 2012)
12
Figure 5. Baseline occupied Jersey grid squares for the
agile frog Rana dalmatina (from NARRS surveys 2007
2012)
13
Figure 6. Baseline occupied Jersey grid squares for the
slow-worm Anguis fragilis (from NARRS surveys 2007
2012)
14
Figure 7. Baseline occupied Jersey grid squares for the
wall lizard Podarcis muralis (from NARRS surveys 2007
2012).
15
Figure 8. Baseline occupied Jersey grid squares for the
green lizard Lacerta bilineata (from NARRS surveys 2007
2012)
16
Figure 9. Baseline occupied Jersey grid squares for the
grass snake Natrix natrix (from NARRS surveys 2007
2012)
17
Figure 10. Number of amphibian species per square (%) in
18
Jersey NARRS amphibian squares 2007 2012
Figure 11. Number of reptile species per square (%) in
Jersey NARRS reptile squares 2007 2012
19
Figure 12. Total (amphibian and reptile) species per
square in Jersey NARRS squares 2007 2012 (“NARRS
Hotspots”)
20
Table 3. Summary of species richness by square
21
Table 4. Descriptors of amphibian habitat (HSI) in Jersey
21
Table 5. Descriptors of reptile habitat in Jersey
21
Table 6. occupancy summary and ability of Jersey NARRS
baseline results 2007 2012 to detect significant changes
in occupancy rates
22
4
1. INTRODUCTION TO JERSEY NARRS
In 2007, the States of Jersey Department of the Environment (DoE)
launched the National Amphibian and Reptile Recording Scheme
(NARRS) in Jersey. The scheme forms part of the Department’s
integrated ecological monitoring programme for Jersey in order to
carry out 'State of the Environment Monitoring’. NARRS is
coordinated by the UK organisation Amphibian and Reptile
Conservation (ARC) and Jersey's scheme is run in partnership with
the DoE and the Jersey Amphibian and Reptile Group (JARG). The
scheme is financed by the States of Jersey but is based almost
entirely on volunteer recorders, making it highly cost-effective.
Jersey possesses three amphibians (the agile frog, toad
[crapaud] and palmate newt) and four reptiles (the grass snake,
slow-worm, wall lizard and green lizard), meaning seven native
species of herpetofauna in total. Ecological data on these species
are collected over a six-year cycle in order to (a) generate sufficient
records on which to base an assessment of conservation status and
(b) investigate changes in species’ occupancy over a realistic
timescale. The use of established survey protocols is intended to
provide a robust basis for conservation decision-making.
Jersey NARRS uses trained volunteers to carry out surveys
within an allocated 1 km survey square. At annual training events,
arranged by the Department of the Environment and JARG,
participants are trained in NARRS species identification, survey
methodologies, bio-security and health and safety, and given
survey forms to fill in and other materials facilitating the completion
of their surveys. The first Jersey NARRS training event was
conducted at the Frances Le Sueur Centre in 2007 and subsequent
events have been held at Howard Davis Farm and Les Noyers
training centre (Durrell).
Jersey NARRS data (2007 2012) are presented here for
the first time. For an earlier, interim assessment of Jersey’s NARRS
results, see Wilkinson & Arnell (2010) and for more information on
NARRS, see www.narrs.org.uk. Jersey data is analysed
separately from the UK NARRS results because of Jersey’s unique
herpetofaunal composition. Data concerning species which co-
occur (in Jersey and in “GB”) may, however, be usefully compared.
Jersey NARRS also has a “focus species” in most years,
often subject to wider recording efforts and publicity. The present
report includes comparisons with the slow-worm survey of 2012 and
palmate newt “hunt” of 2013.
Since the previous NARRS report (Wilkinson & Arnell,
2010), the Jersey toad has been discovered to be a distinct species
from Bufo bufo (the common toad found on the GB mainland) and
should now be referred to as Bufo spinosus (see Arntzen et al.,
2014); the same species is also found in North Africa, Iberia and
western France.
5
2. METHODS
NARRS surveying in Jersey is carried out using the same protocols
as are used throughout the other jurisdictions taking part. A 1 km
survey square is randomly allocated to each surveyor.
Amphibian surveyors identify the pond nearest the south-
west corner of their survey square and, where necessary, obtain
permission to survey it from the landowner and/or tenant. Letters of
introduction are provided if required. Up to four (sometimes more)
visits are carried out using (i) visual searching, (ii) netting, (iii) night
torching and (iv) where appropriate and if the surveyor is
confident bottle-trapping in order to detect the amphibian species
present. In practice, bottle-trapping rarely occurs during NARRS
surveys in Jersey. Use of multiple methods over four survey visits
result in the best chance of detecting all amphibian species present
in a pond (Sewell et al., 2010). Survey conditions (weather etc.),
species present and habitat characteristics are recorded. For
amphibian surveys, the latter take the form of the Habitat Suitability
Index (HSI), developed for use with great crested newt surveys
(Oldham et al., 2000). Obviously, this species is not found in Jersey
but the HSI is a good comparative, standard metric with which to
investigate any changes in pond habitat between surveys.
Reptile surveyors use maps or aerial photographs to identify
potential reptile habitat in their survey square and obtain permission
to visit promising areas as necessary. Up to four (sometimes more)
visits are carried out using (i) visual searching, (ii) checking existing
refugia and (iii) checking artificial refugia (where it has been
possible to lay these) in order to detect all reptile species present.
The use of refugia is particularly important in finding slow-worms
and grass snakes (sensu Sewell et al., 2012) and they are also
used by green lizards. Particular efforts to encourage the use of
refugia were made in 2012 to coincide with slow-worms being the
NARRS focus species for that year. Survey conditions, species
present and habitat characteristics are recorded. It is particularly
important for reptile surveys to be conducted during appropriate
conditions (e.g. of sun and temperature) to maximise detection
probability. A variety of habitat descriptors are recorded in reptile
surveys as no equivalent of the pond HSI is currently available for
reptiles.
For both amphibians and reptiles, if no pond or habitat
exists, or survey permission is refused by a landowner, alternative
squares are identified by examining the square immediately to the
north of the original, then moving around that square in a clockwise
direction until a suitable one is found (though this is usually
unnecessary).
Results from Jersey NARRS surveys were used to calculate
occupancy rates (the percentage of surveyed squares occupied) for
each species and for amphibians and reptiles overall. These were
mapped on the Jersey grid to provide a visual representation of
6
species square occupancy. “Hotspots” of herpetofauna species
occupancy and amphibian and reptile species richness by square
were also calculated. It is theoretically possible for species
occupancy rates to remain stable over time whilst species richness
changes, thus perhaps indicating a change in habitat
characteristics.
For amphibians, mean HSI, and percentages of ponds with
“good” (scoring over 0.7) HSI and “bad” (scoring under 0.3) HSI
were calculated. Reptile habitat was assessed by quantifying the
mean length and range of length of survey route. Longer surveys
are possible in squares with a greater extent of habitat. Reptile
habitat connectivity, isolation and designation status was also
quantified from the data recorded by surveyors.
Finally, the statistical power of Jersey NARRS results 2007
2012 was examined in order to determine the ability of the
present methods to detect “real” changes in species’ occupancy
rates. Analyses were carried out using two-tailed power proportion
tests in the statistical package “R”. These tests assess the ability of
changes survey results between samples to detect either increases
or decreases in occupancy rates, and therefore to give an objective
quantification of trends in distribution. In other words, they can be
used to target and prioritize conservation for species that are
becoming less common.
7
3. RESULTS
For the purposes of analysis, all surveys from within the NARRS
cycle period 2007 2012 are treated as one sample (in this case
the baseline sample for Jersey against which future results can be
compared). This sample included 38 unique amphibian squares (7
of which were surveyed in more than one year) and 50 unique
reptile squares (again 7 of which were surveyed in more than one
year). Both taxa were surveyed for in 26 squares. Of squares that
were surveyed in more than one year, one amphibian survey
detected a species (toad) that had not been recorded previously.
Repeat surveys of reptile squares, however, resulted in two new
slow-worm, two new grass snake, and one new green lizard
records. Overall, 62 squares on the Jersey grid are now established
as NARRS squares for either amphibians, reptiles, or both taxa
(see Appendices A and B).
Results on the same measures from NARRS surveys over
the same time period elsewhere in the British Isles are also
presented for comparative purposes.
3.1 Species Occupancy Rates
Table 1. Pond occupancy rates for Jersey amphibians 2007 2012.
Species (% occupancy in NARRS squares)
Bufo
spinosus
Lissotriton
helveticus
Rana
dalmatina
Other
Overall
amphibian
occupancy
(all spp.)
Pond
occupancy in
Jersey
61%
34%
11%
0%
68%
Palmate newt
survey
47%*
Pond
occupancy
in GB
N/A
27%
N/A
<1%
82%
*This percentage represents the proportion of occupied NARRS survey squares
adjusted for additional positive records resulting from the palmate newt survey of
2013.
Jersey NARRS amphibian squares and those occupied by each
species are listed in Appendix A.
8
Table 2. Square occupancy rates for Jersey reptiles 2007 2012.
Species (% occupancy in NARRS squares)
Anguis
fragilis
Podarcis
muralis
Lacerta
bilineata
Natrix
natrix
Other
Overall
reptile
occupancy
(all spp.)
Square
occupancy
in Jersey
24%
8%
58%
6%
0%
72%
Slow-worm
survey
42%*
Square
occupancy
in GB
22%
N/A
N/A
22%
3%
52%
*This percentage represents the proportion of occupied NARRS survey squares
adjusted for additional positive records from the slow-worm survey of 2012
Jersey NARRS reptile squares and those occupied by each species
are listed in Appendix B.
9
Figure 1. Jersey NARRS amphibian survey squares 2007 2012 (n = 38).
10
Figure 2. Jersey NARRS reptile survey squares 2007 2012 (n = 50).
11
Figure 3. Baseline occupied Jersey grid squares for the toad Bufo spinosus (from NARRS surveys 2007 2012).
12
Figure 4. Baseline occupied Jersey grid squares for the palmate newt Lissotriton helveticus (from NARRS surveys 2007 2012).
13
Figure 5. Baseline occupied Jersey grid squares for the agile frog Rana dalmatina (from NARRS surveys 2007 2012).
14
Figure 6. Baseline occupied Jersey grid squares for the slow-worm Anguis fragilis (from NARRS surveys 2007 2012).
15
Figure 7. Baseline occupied Jersey grid squares for the wall lizard Podarcis muralis (from NARRS surveys 2007 2012).
16
Figure 8. Baseline occupied Jersey grid squares for the green lizard Lacerta bilineata (from NARRS surveys 2007 2012).
17
Figure 9. Baseline occupied Jersey grid squares for the grass snake Natrix natrix (from NARRS surveys 2007 2012).
18
3.2 Species Richness
Species richness by square for amphibians and reptiles (respectively) is presented and compared with GB in Figs. 10 and 11 (GB data are
shown for comparison). A combined map of species richness for both taxa is presented in Fig. 12.
Figure 10. Number of amphibian species per square (%) in Jersey NARRS amphibian squares 2007 2012.
GB
3%
24%
42%
31%
1% 4%
17%
30%
30%
18%
19
Figure 11. Number of reptile species per square (%) in Jersey NARRS reptile squares 2007 2012.
GB
2%
22%
48%
28%
1% 1% 5%
15%
30%
48%
20
Figure 12. Total (amphibian and reptile) species per square in Jersey NARRS squares 2007 2012 (“NARRS Hotspots”).
21
Table 3. Summary of species richness by square.
Amphibian Species Richness
(number of squares)
Reptile Species Richness
(number of squares)
Both Groups: "NARRS Hotspots"
(number of squares; see Fig. 12)
5 species
-
-
2
4 species
-
-
3
3 species
1
1
3
2 species
9
11
19
1 species
16
24
21
0 species
12
14
15
3.3 Measures of Habitat Quality
Table 4. Descriptors of amphibian habitat (HSI) in Jersey.
Mean
(range)
Ponds with HSI
>0.7
Ponds with HSI
<0.3
Jersey HSI*
0.52
(0.21 0.72)**
4.76%***
9.52%****
GB HSI
0.53
(0.12 0.94)
19.61%
10.77%
* This is a 9-factor HSI, which ignores bias in the score due to location
** n = 21 *** n = 1 **** n = 2
Table 5. Descriptors of reptile habitat in Jersey.
Mean length
of survey
route
(range)
Surveys in
which
survey
route was
part of
larger area
of good
habitat
Surveys in
which
reptile
habitat was
isolated*
Surveys
within
protected/
designated
areas
Jersey
1.54 km
(0.1 5 km)
32.00%
28.00%
40.00%
GB
1.70 km
(0.1 10.0 km)
23.18%
48.44%
24.52%
*completely isolated or isolated by sub-optimal habitat
22
3.4 Using the Baseline Results
Table 6. Occupancy summary and ability of Jersey NARRS baseline results 2007 2012 to detect significant changes in occupancy rates*.
Species
Number of NARRS
Squares
2007 2012
Occupancy Rate
(% Squares Occupied)
“Real” Change
Detectable by Future
Surveys (%);
α=0.05, power=80%
“Real” Change
Detectable by Future
Surveys (%);
α=0.1, power=65%
Number of Squares
Difference Indicative
of “Real” Change;
α=0.1, power=65%
Bufo spinosus
38
61
44
34
8 squares
Lissotriton helveticus
(with newt survey)
38
47
64
49
9 squares
Rana dalmatina
38
11
N/A**
N/A**
Any change
Anguis fragilis (with
slow-worm survey)
50
42
64
48
11 squares
Podarcis muralis
50
8
N/A**
N/A**
Any change
Lacerta bilineata
50
58
43
33
10 squares
Natrix natrix
50
6
N/A**
N/A**
Any change
* two-tailed power analyses assuming equal sample sizes
** rare species any change in occupancy rate indicates further study required
23
4. DISCUSSION AND RECOMMENDATIONS
4.1 Species Occupancy rates
Most species occupancy rates have not changed substantially
since the 2010 interim NARRS Report (Wilkinson & Arnell, 2010). A
focus on the use of refugia in reptile surveys has, however, resulted
in better information on slow-worm presence and an increase in
occupancy rate from just 11% to 24%. Additional data from
supplementary “focus” surveys have also increased our knowledge
of the distribution of both slow-worms and newts in Jersey, with a
concurrent increase in occupancy rate in NARRS squares (42%
and 47% occupancy respectively, Tables 2 and 1). These additional
data should be added to the NARRS survey square results (see
Appendices and below).
The toad or crapaud Bufo spinosus
Though toads have undoubtedly declined in Jersey (e.g. Tonge,
1986), they remain the most widespread amphibian in the island
(Fig. 3). The NARRS baseline data presented here confirm the
south and west of the island as a stronghold for this species but do
not yet reflect the return of breeding toads to Ouaisne (JWW, pers.
obs.); this should nevertheless be picked up in the next cycle of
NARRS surveys (2013 2018).
Now that Jersey toads have been revealed to be a separate
species from B. bufo, with its own distinctive ecology (Arntzen et al.,
2014), it is probably inappropriate to continue to compare
occupancy rates between Jersey and GB toads, despite declines in
both jurisdictions. The responses of these respective species to
prevailing habitat and development conditions would likely be very
different (see Wilkinson et al., 2007).
The conservation of Jersey toads will be further informed by
the continuation of Toadwatch, an analysis of the data from which is
currently being carried out by Amphibian and Reptile Conservation
(in prep.). This will include the results of a predictive model,
highlighting the areas most important for population connectivity
and where to target conservation.
The palmate newt Lissotriton helveticus
Data from both NARRS square surveys and additional newt
observations now suggest that the palmate newt is less ubiquitous
in Jersey than it formerly was (or has been assumed to be). Current
information (Fig. 4) suggests a near-absence of the species from
the island’s agricultural centre, most records originating from the
south west. It is also notable that palmate newt NARRS square
occupancy in Jersey is just 77% of the occupancy rate of the toad
(Table 6), even though the latter species is known to have
undergone declines in the island.
24
Five NARRS squares turn positive for palmate newts when
data from the additional survey are added (see Fig. 4 and App. A).
These data will be incorporated into the NARRS baseline dataset
and efforts should be made to re-locate the species in those five
squares during NARRS surveys in the second cycle.
The occupancy rate of palmate newts in Jersey is now
higher than that found for the species in GB (47% as compared to
27%), perhaps unsurprising in the absence of competition from
other newt species in Jersey. Nevertheless, factors influencing the
distribution of palmate newts in Jersey need further investigation.
This should include a multi-season trapping study in order to
examine population sizes and local trends, and comparisons with
local water chemistry.
The agile frog Rana dalmatina
Though the occupancy rate recorded by NARRS surveys for this
species has not changed substantially, there are in fact twice as
many squares now occupied as compared to 2010 (up to four
squares from two in 2010). This change represents a real
improvement in the status of agile frogs in Jersey as a result of
ongoing conservation efforts (spawn protection, head-starting),
rather than being an artefact of more survey results. Power analysis
(Table 6) is not required to detect “real” changes in occupancy for
this species. Any future reduction detected should be regarded as a
decline and additional squares should be surveyed for agile frogs
as the species continues to expand to new breeding sites.
The slow-worm Anguis fragilis
Extra efforts to employ refugia during NARRS surveys, and
additional survey data, have improved knowledge of slow-worm
distribution and substantially increased the occupancy rate since
Wilkinson & Arnell’s (2010) report. As with the palmate newt, data
from slow-worm surveys for the nine additional positive records
from NARRS squares will be incorporated into the NARRS baseline
dataset (see Fig. 6 and App. B), and efforts made to re-locate the
species in those squares during the second NARRS cycle (to
2018). Slow-worms appear to remain widely distributed in the island
(Fig. 6) though the addition of further presence records from central
Parishes would confirm this. As a fossorial species, detection rates
are poor in areas without refugia present.
An intensive study on the slow-worm (and grass snake) is
currently underway by a PhD student from DICE, University of Kent.
Search effort and methodology is not comparable to those of
NARRS surveys, however, so the data ultimately resulting should
not be added to the NARRS dataset. This study will nevertheless
add substantially to our knowledge of distribution and ecology of
slow-worms in the island.
25
The wall lizard Podarcis muralis
An increase in the number of NARRS squares surveyed since 2010
has doubled the positive NARRS squares for wall lizards from two
to four (Fig. 7). The distribution of wall lizards in Jersey is well
known and the species has been the subject of MSc research
(Cornish, 2011). It is possible, however, that the species could turn
up in existing NARRS reptile survey squares where it has not yet
been recorded. As with agile frogs, the restricted distribution of the
wall lizard means that any apparent future reduction in occupancy
rates should be seen as a possible decline.
The green lizard Lacerta bilineata
Green lizard records from the west of Jersey remain abundant and
NARRS data indicate that it is by far the most widespread Jersey
reptile (Fig. 8). Future NARRS cycles should attempt to detect the
species in other coastal survey squares. NARRS records may also
arise from elsewhere in the island as the species is sometimes
reported away from the coast.
The grass snake Natrix natrix
The grass snake is Jersey’s most endangered reptile and
unsurprisingly has the lowest occupancy rate (Table 2, Fig. 9). As
with slow-worms, data from the present PhD study should not be
used to augment the NARRS baseline because of the intense
survey effort involved in the former study. It may be hoped,
however, that the data resulting from that PhD can be used as a
basis for conservation actions resulting in positive population trends
which future NARRS cycles will be able to monitor.
Wilkinson & Arnell (2010) speculated that part of the reason
for the rarity of Jersey’s grass snakes may be the species’
dependency on amphibian prey. Now that at least some Jersey
amphibian populations are apparently recovering (e.g. the toads at
Ouaisne), there may also be some recovery of grass snakes that
will track this. The present PhD study had not begun at the time of
the interim report (Wilkinson & Arnell, 2010) and will likely reveal
more data on the importance of connectivity and egg-laying site
availability that will benefit the species in Jersey long-term. It should
remain a goal for the species’ occupancy rate in Jersey to approach
that for grass snakes in the UK (22%).
As with agile frogs and wall lizards, any reduction in the
occupancy rate of grass snakes detected in future NARRS cycles
should be regarded as a possible decline. Because of this species’
high mobility, however, an apparent change in the squares where
the species may be detected does not necessarily represent a
change in distribution. The effective distribution of Jersey grass
snakes will be better informed once egg-laying sites are discovered
and egg-laying condition requirements in the island become better
understood.
26
4.2 Species Richness
Species richness data presented here establish the baseline for this
parameter in Jersey for 2007 2012 surveys. The pattern seen in
Wilkinson & Arnell (2010) remains true, in that reptiles occupy
relatively more squares in Jersey than they do in GB, the reverse
being true for amphibians (Figs. 10 and 11). Though reptile species
richness might be accounted for at least partly by the relatively
gentle climate (for reptiles) in Jersey, the amphibian figures
probably reflect the recent and well documented declines in
amphibians recently seen there (e.g. Gibson and Freeman, 1997;
Racca, 2002, Wilkinson et al., 2007). At present, over 70% of
NARRS squares for both taxa have either zero or one species
recorded from them, a situation which may change with ongoing
conservation measures and which should be picked up in future
NARRS surveys.
Now that the 2007 2012 NARRS survey cycle is complete,
it has also been possible to create a “NARRS Hotspot” map
showing overall herpetofauna species richness in Jersey NARRS
squares (Fig. 12 and Table 3). Just four Jersey grid squares contain
four or five species (out of a potential seven), three-quarters of
these are in the south west. Another three squares, however
contain three species and these are all in the north of the island, of
especial note being the one in the north east (St. Martin). This new
metric can be used to track the combined status and fortunes of
Jersey’s herpetofauna (through comparison with future data), as
well as to highlight those areas of most importance for amphibian
and reptile conservation in Jersey, and to inform development
control.
4.3 Measures of Habitat Quality
Amphibian habitat: mean Jersey pond HSI is remarkably similar to
that in GB. HSI data is available only for 21 out of a total of 38
established NARRS amphibian squares in Jersey, however, so the
proportions of “high” and “low scoring habitat are based on very
few squares (n=1 and n=2 respectively). This indicates that more
data are required; Jersey NARRS training in 2015 should
emphasize the need for recording habitat parameters.
Reptile habitat: there is currently no HSI or equivalent for
reptile habitat. Jersey reptile survey routes were, on average,
shorter than those in GB, which may perhaps be expected. Jersey
reptile surveyors, however, recorded relatively more connectivity
(and less isolation) for reptile habitat than in GB (Table 5). This is
undoubtedly good news for Jersey’s reptiles, where overall reptile
occupancy and species richness is higher than in GB (Table 2; Fig.
11). The fact that 40% of Jersey NARRS reptile surveys occurred in
protected areas also suggests that designation of sites with reptile
interest is currently proving effective.
27
4.4 Using the Baseline Results
Wilkinson & Arnell (2010) created an artificial “confidence index” to
try to ensure sufficient effort was put into generating robust,
comparable survey results. Efforts were, broadly, very successful,
with 50 NARRS reptile squares and 38 NARRS amphibian squares
being surveyed in the island between 2007 and 2012. It is desirable
to add a few more amphibian squares in the next survey cycle, if
practical, to add to the comparative power of future surveys.
Now that NARRS baseline data have been generated (this
report), we are able to use more informative statistics to examine
the ability of Jersey NARRS to detect future changes in status of
the island’s herpetofauna. Occupancy rates and the results of
power analyses showing the ability of future surveys to detect
changes are presented in Table 6. Detection of highly-significant
changes with very high statistical power is, however, problematic in
Jersey, simply because of the total number of survey squares
potentially available in the island. Power analyses at conventional
thresholds (α=0.05, power=80%; Table 6, column 4) indicate that
repeat surveys of the present number of squares may only detect
changes of around 40 60% occupancy (i.e. substantial changes)
for any species. This is rather lower than may be useful and
practical (i.e. occupancy changes of that order of magnitude may
only demonstrate substantial conservation problems). Nevertheless,
if slightly lower thresholds are used (α=0.1, power=65%; Table 6,
column 5), detection of more informative changes closer to 30%
(range 33 49%) become achievable (see column 6 of Table 11).
In summary, a drop in occupancy rate of eight or more
squares over a six-year NARRS cycle may indicate genuine
declines in any of Jerseys widespread species (toad, palmate newt,
slow-worm and green lizard). These results (Table 11) can
therefore be used as an alert that would trigger detailed
investigation into possible conservation problems with any of these
species. N.B. any reduction at all in occupancy rate for restricted-
distribution species (agile frog, wall lizard and grass snake) should
be regarded as worthy of further investigation.
28
4.5 Recommendations for the Future
The above analyses suggest the following key recommendations to
ensure the success of herpetofauna monitoring, trend detection and
conservation initiatives in Jersey:
1. Any reduction in square occupancy for agile frogs, wall
lizards or grass snakes over a six-year NARRS cycle
should be regarded as a possible decline worthy of
investigation.
2. A reduction in square occupancy of eight or more
squares over a six-year NARRS cycle should trigger
investigation into possible real and substantial declines
for toads, palmate newts, slow-worms or green lizards.
(Conversely, an increase of the same magnitude would
likely indicate “real” range expansion/increase.)
3. NARRS training in 2015 (and beyond) should include a
field element that emphasizes and demonstrates the
collection of habitat data (i.e. pond HSI).
4. The results of recent slow-worm and palmate newt
surveys should be incorporated into NARRS results
(where those species were detected in NARRS squares
by these supplementary surveys) and strive to detect
the species in those squares during the next NARRS
cycle (2013-2018).
5. Increase the number of Jersey NARRS amphibian
squares to 40 (or more) if possible.
6. Continue to promote the use of refugia in NARRS
surveys.
7. Continue to promote autecological research on Jersey’s
herpetofauna species, including at this time the island-
specific ecology of the palmate newt. It is recommended
that newt population sizes and trends are investigated
through an aquatic trapping study and compared with
abiotic (water chemistry) and habitat factors, and
possibly genetics.
29
REFERENCES
Arntzen, J.W., Wilkinson, J.W., Butot, R. & Martinez-Solano, I.
(2014) A new vertebrate species native to the British Isles: Bufo
spinosus Daudin, 1803 in Jersey. Herpetological Journal 24: 209-
216.
Cornish, N. (2011) Genetic Diversity and Conservation of Wall
Lizards (Podarcis muralis) in Jersey, British Channel Islands. MSc
Thesis, DICE, University of Kent.
Oldham, R.S., Keeble, J., Swan, M.J.S. & Jeffcoate, M. (2000)
Evaluating the suitability of habitat for the great crested newt
(Triturus cristatus). Herpetological Journal 10: 143 155.
Sewell, D., Beebee, T.J.C. & Griffiths, R.A. (2010) Optimising
biodiversity assessments by volunteers: The application of
occupancy modelling to large-scale amphibian surveys. Biological
Conservation 143: 2102 2110.
Sewell, D., Guillera-Arroita, G., Griffiths, R.A., & Beebee, T.J.C.
(2012) When is a species declining? Optimizing survey effort to
detect population changes in reptiles. PloS one 7(8): e43387.
Tonge, S. (1986) The herpetofauna of Jersey. British Herpetological
Society Bulletin 17: 18 21.
Wilkinson, J.W. & Arnell, A.P. (2010) Jersey NARRS Report 2010:
Results of the National Amphibian and Reptile Recording Scheme
in Jersey, 2007 2010. Unpublished Report to the States of Jersey
Planning and Environment Department.
Wilkinson, J.W., Beebee, T.J.C. & Griffiths, R.A. (2007)
Conservation genetics of an island toad: Bufo bufo in Jersey.
Herpetological Journal 17: 192 198.
30
Appendix A: List of Jersey NARRS Amphibian Squares 2007 2012, with Occupancy by
Each Species. Black fill = sp. detected in NARRS survey, blue fill = sp. detected in NARRS
square by supplementary survey.
Jersey Grid
Square
Bufo
spinosus
Lissotriton
helveticus
Rana
dalmatina
A10
A11
B9
B10
C2
C4
C7
C8
C11
D3
D9
E3
E4
E9
F2
F3
F6
F7
G1
G7
G9
H8
I6
J7
K5
L3
L7
M6
M8
N2
O2
O4
P1
P6
P9
Q3
Q7
R8
31
Appendix B: List of Jersey NARRS Reptile Squares 2007 2012, with Occupancy by Each
Species. Black fill = sp. detected in NARRS survey, blue fill = sp. detected in NARRS square
by supplementary survey.
Jersey Grid
Square
Anguis
fragilis
Podarcis
muralis
Lacerta
bilineata
Natrix natrix
A10
A11
B2
B8
B9
B10
B11
C2
C4
C5
C6
C7
C8
C11
D2
D3
D4
D5
D6
E3
E4
E9
E10
F1
F2
F7
G1
G2
G7
G9
H9
I6
J6
L5
L7
L8
M9
N1
N3
N8
N9
O4
P4
P6
P9
Q3
Q7
R5
R7
R8
... This report presents, for the first time, the results of Jersey NARRS data collected between 2007 and 2018. It follows previous baseline assessments carried out on data from the first cycle (Wilkinson et al. 2014) and an interim assessment of data from 2007-2010 (Wilkinson and Arnell 2010). We analyse Jersey NARRS data separately to that from the UK and other jurisdictions due to the different community of amphibian and reptile species present. ...
... Study sites consisted of 1-km squares (monads), as previously used in Jersey (Wilkinson et al. 2014) and the UK (Wilkinson and Arnell 2013). In total, 159 1-km squares intersect with Jersey's terrestrial surface above the mean high water line. ...
... whether a species was present or absent a site had no influence from the presence/absence status of the species at other sites). to gather data on particular focal species in some years (Wilkinson et al. 2014). These records were not filtered by geographical accuracy or certainty of identification; therefore, there may be inaccuracies in the data presented. ...
Research
Full-text available
Between 2007 and 2018, volunteers have surveyed ponds and terrestrial habitat to record native amphibians and reptiles across the island of Jersey as part of the National Amphibian and Reptile Recording Scheme. We analyse these data to look at the distribution and status of these species and to inform future monitoring efforts.
... Furthermore, there are limitations in detecting some species. For instance, research has shown the grass snake to require considerable survey effort for detection or a strong assumption of absence , and the presence of slow-worms and palmate newts was only detected in some squares (2007-2012 period) due to additional focal species efforts (Wilkinson et al. 2014). There are also separate but concurrent monitoring efforts for the agile frog (Ward et al. 2016). ...
Technical Report
Full-text available
Based on the Analysis of Jersey National Amphibian and Reptile Recording Scheme (NARRS) Data 2007‒2018 (Report A) the following recommendations were proposed: 1. Develop separate monitoring efforts for widespread (western toad, palmate newt, slow worm, green lizard) and restricted or difficult to monitor (agile frog, wall lizard, grass snake) species. 2. Utilise refugia more regularly and in greater numbers for widespread reptile surveys. 3. Employ site-based population monitoring of restricted and rare species. 4. Increase the number of repeat surveys for widespread amphibians to five. 5. Increase the number of repeat surveys for widespread reptiles to six. 6. Reduce the sampling grid from 1 km to 500 m for all lizard species. 7. Carry out water quality monitoring. 8. Carry out amphibian disease screening.
Article
Full-text available
Recent molecular and morphological studies have shown that Bufo bufo and B. spinosus are genetically distinct and morphologically diagnosable across a relatively narrow contact zone in northern France and should be regarded as different species. However, the species identity of the neighbouring populations of Bufo on the British Channel Island of Jersey has not been investigated. We here present new molecular (a mtDNA RFLP assay plus sequences of the nuclear RAG1 gene) and morphological evidence that these populations are to be assigned to B. spinosus, and can thus be considered an addition to the native British herpetofauna. Jersey toad populations are declining and have a distinct breeding ecology compared to other populations in mainland Britain. We discuss the results in the light of amphibian conservation efforts in Jersey.
Article
Full-text available
Biodiversity monitoring programs need to be designed so that population changes can be detected reliably. This can be problematical for species that are cryptic and have imperfect detection. We used occupancy modeling and power analysis to optimize the survey design for reptile monitoring programs in the UK. Surveys were carried out six times a year in 2009-2010 at multiple sites. Four out of the six species--grass snake, adder, common lizard, slow-worm -were encountered during every survey from March-September. The exceptions were the two rarest species--sand lizard and smooth snake--which were not encountered in July 2009 and March 2010 respectively. The most frequently encountered and most easily detected species was the slow-worm. For the four widespread reptile species in the UK, three to four survey visits that used a combination of directed transect walks and artificial cover objects resulted in 95% certainty that a species would be detected if present. Using artificial cover objects was an effective detection method for most species, considerably increased the detection rate of some, and reduced misidentifications. To achieve an 85% power to detect a decline in any of the four widespread species when the true decline is 15%, three surveys at a total of 886 sampling sites, or four surveys at a total of 688 sites would be required. The sampling effort needed reduces to 212 sites surveyed three times, or 167 sites surveyed four times, if the target is to detect a true decline of 30% with the same power. The results obtained can be used to refine reptile survey protocols in the UK and elsewhere. On a wider scale, the occupancy study design approach can be used to optimize survey effort and help set targets for conservation outcomes for regional or national biodiversity assessments.
Article
A modification of the Habitat Evaluation Procedure (USFWS, 1976) applied to crested newt habitats is described, using ten key habitat criteria, based upon the assumption that habitat quality determines population size. Seven of these criteria (pond area, permanence, shading and density, macrophyte density, number of waterfowl and terrestrial habitat quality) are assessed using objective habitat measurements, the other three (site geography, water quality and fish occurrence) using qualitative rule-bases, to produce a Habitat Suitability Index for each site. Preliminary validation of the method for a set of 72 sites provides a significant rank correlation between indices of population size and of habitat. The procedure has the potential to provide a simple method of habitat assessment, for site surveying or selection of host sites for translocation, and can be upgraded easily as knowledge of crested newt habitat requirements improves. There was an incidental indication from the validation exercise that the number of newts caught by bottle trapping was affected negatively by the presence of macrophytes.
Article
On Jersey (British Channel Islands), common toads often reproduce in small, urban ponds. This atypical breeding strategy has implications for their persistence and they have declined on the island in recent times. We used polymorphic microsatellite markers to compare genetic diversity in Bufo bufo from five different ponds in Jersey with two populations from north-west France. Genetic diversity of Jersey toads was comparable with that of populations elsewhere in Europe. Numbers of breeding female toads in Jersey were correlated with pond area but estimators of genetic diversity were unrelated to pond area or female numbers. Fst estimates and isolation by distance tests indicated that there is little gene flow between breeding sites on the island. Jersey populations last shared a common ancestor with those of north-west France long before the island's physical separation about 6000 years ago. Toads have a long history in Jersey and were once probably very numerous there. The average effective historical population size of Jersey toads is estimated to be 15,000-16,000. Although genetic diversity of Jersey B. bufo is currently quite high, recent developments on the island may threaten this situation in the near future.
Article
Mobilising volunteers to carry out biodiversity assessments can help to identify priorities for conservation across broad geographical scales. However, even when volunteers carry out simple presence–absence surveys, there can be significant issues over false absences and subsequent data interpretation. Simple but scientifically robust protocols are therefore required for these programmes. Here we evaluate amphibian survey protocols for the National Amphibian and Reptile Recording Scheme (NARRS) in Britain, which aims to assess the status of five widespread amphibian species. Surveys were undertaken by trained volunteers and researchers in two contrasting landscapes over 2 years, and occupancy modelling was used to determine covariates of detection, and to optimise the number of surveys and number of methods required. Although surveys need to take into account seasonal and annual changes in the detectability of different species, there were also landscape effects. Frogs and toads were generally harder to detect in ponds in Kent than in Wales, while the converse was true of newts. Adding bottle-trapping to the suite of methods increased the detection of smooth and palmate newts in both areas, and of great crested newts in Wales. Overall, reliable assessment of the presence or absence of all five species at a site required four separate surveys, each using four different methods (visual encounter surveys during both day and night, dip netting and bottle-trapping). Our approach may prove useful for finding the best compromises between rigor and simplicity when volunteers are used in large-scale surveys.
Genetic Diversity and Conservation of Wall Lizards (Podarcis muralis) in Jersey, British Channel Islands
  • N Cornish
Cornish, N. (2011) Genetic Diversity and Conservation of Wall Lizards (Podarcis muralis) in Jersey, British Channel Islands. MSc Thesis, DICE, University of Kent.
The herpetofauna of Jersey
  • S Tonge
Tonge, S. (1986) The herpetofauna of Jersey. British Herpetological Society Bulletin 17: 18 -21.
Jersey NARRS Report 2010: Results of the National Amphibian and Reptile Recording Scheme in Jersey
  • J W Wilkinson
  • A P Arnell
Wilkinson, J.W. & Arnell, A.P. (2010) Jersey NARRS Report 2010: Results of the National Amphibian and Reptile Recording Scheme in Jersey, 2007 -2010. Unpublished Report to the States of Jersey Planning and Environment Department.