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Dutch Dragonfly Monitoring Scheme
A Manual
 Dutch Dragonfly Monitoring Scheme; A Manual
Dutch Dragonfly Monitoring Scheme; A Manual
Text:
Jaap Bouwman, Dick Groenendijk, Tim Termaat & Calijn Plate
Report number:
VS2009.015
The Dutch Dragonfly Monitoring Scheme is part of the national Network Ecological Monitoring
(NEM), financed by the Ministry of Agriculture, Nature and Food Safety. It is the result of a collaboration between Dutch Butterfly Conservation and Statistics Netherlands.
Coordination:
Dick Groenendijk
Jaap Bouwman
Tim Termaat
Dutch Butterfly Conservation
PO Box 506
6700 AM Wageningen
phone: +31-317467346
email: info@vlinderstichting.nl
www.vlinderstichting.nl
Illustrations: Jaap Bouwman (pp. 2, 4, 5, 6); Kars Veling (front cover, 1) & Geert de Vries (3);
lay out: Nicoliene Peet; english text advice: Claire Hengeveld.
This publication should be referred to as:
Bouwman, J., D. Groenendijk, T. Termaat & C. Plate (2009) Dutch Dragonfly Monitoring Scheme.
A Manual. Report number VS2009.015, Dutch Butterfly Conservation, Wageningen & Statistics
Netherlands, Den Haag, Netherlands.
This manual is a strongly revised translation of the original Dutch manual:
Ketelaar, R. & C. Plate (2001) Handleiding Landelijk Meetnet Libellen. Report number
VS2001.028, 3rd printing, Dutch Butterfly Conservation, Wageningen & Statistics Netherlands,
Den Haag, Netherlands.
Calijn Plate
Statistics Netherlands
Den Haag
www.cbs.nl
DUTCH BUTTERFLY CONSERVATION 009 
Content
Chapter 1 / Introduction 4
Chapter 2 / The Dutch Dragonfly Monitoring Scheme 5
Chapter 3 / Fieldwork 6
Chapter 4 / The recording form 11
 Dutch Dragonfly Monitoring Scheme; A Manual
Chapter 1 / Introduction
The Dutch Dragonfly Monitoring Scheme
enables us to follow changes in dragonfly numbers closely. This is usually done
by counting individuals, but in some cases exuviae, the discarded larval skins,
are counted. In this way, we can discern
a negative trend at an early stage and
try to counter it. In the Netherlands,
most information is collected by volunteers. This manual shows what monitoring involves and how you can take part
in the scheme.
Dragonflies - how are they doing at the
moment? Are numbers of Calopteryx virgo
recovering now that streams are less subject
to nitrification? Is Sympetrum pedemontanum
still on the increase and is this linked to climate
change? How quickly are the numbers of
Coenagrion hastulatum decreasing, and will the
species be able to recover once restoration is
carried out? To answer such questions, Dutch
Butterfly Conservation and Statistics Netherland started the Dutch Dragonfly Monitoring
Scheme in 1998.
The main aim of the monitoring scheme is to
keep a record of changes in numbers – it can
be regarded as a thermometer on which you
can read how well or badly dragonflies in a
particular area are doing. Besides determining
national trends, data can also be used for
calculating trends locally. Is Ceriagrion tenellum doing better or worse in the north of the
country compared to the south? Is the sudden
increase of Brachytron pratense in a nearby
canal due to warm weather or has the improved water quality played an important role? Is
Orthetrum coerulescens on the increase after
restoration measures have been carried out?
We can only begin to protect dragonflies when
we know how these changes in number are
developing, and the reason behind the change.
Monitoring Schemes need to run for many
years and standard methods should be used.
The longer a project runs, the more reliable the
data are. And the longer a transect is walked,
the more insight you obtain concerning the
location, and any changes that may be taking
place. This manual is written for people who
would like take part in the Dutch Dragonfly
Monitoring Scheme. Foreign readers might like
to adopt this method in their own country. So,
if you live outside the Netherlands, this manual
can help you to set up a similar monitoring
scheme in your own country. The method is
described in detail in Chapter 3. Everyone who
has a working knowledge of dragonflies can
participate in such a monitoring scheme.
DUTCH BUTTERFLY CONSERVATION 009 
Chapter 2 / The Dutch Dragonfly Monitoring Scheme
The Dutch Dragonfly Monitoring
Scheme is the result of a collaboration
between Dutch Butterfly Conservation
and Statistics Netherland. It is part of
the national Network Ecological Monitoring (NEM), which is financed by the
Ministry of Agriculture, Nature and Food
Safety. Most of the observations are collected by volunteers in the field. Without
their work and enthusiasm, the monitoring scheme would not exist.
Who can join in?
Everybody with a working knowledge of
dragonflies can participate in this project.
Although it is not necessary to identify all
species at a glance, it is important to be able
to recognise the dragonflies in your neighbourhood fairly easily.
Different possibilities to count
Dragonflies are counted along fixed transects
that have been set out along the waterside.
Transects are walked several times a year.
Each transect is important, also those where
not so many species can be seen. All dragonfly
species are important although the emphasis
is on Red List species. If you know a site with
a Red List species, it is even more important
to know how its numbers are developing. Most
populations are in nature reserves which are
usually far from human habitation. To survey a
Red List species, a single-species transect has
to be made, which should be walked at least
three times a year. Walking a single-species
transect can be an attractive alternative for
someone with limited time who still wants to
take part in the monitoring scheme. Besides, it
is also a pleasure to count rare species, which
in most cases occur in beautiful habitats.
Everybody with a working knowledge of dragonflies can take part in the monitoring
scheme.
Fixed transects are usually counted every two weeks using a standard method.
Special attention is given to Red List species on single-species transects.
A single-species transect is counted at least three times a year.




Who can join in?
Figure 1: Many rare species are found in beautiful habitats.
 Dutch Dragonfly Monitoring Scheme; A Manual
Chapter 3 / Fieldwork
Dragonflies are counted along fixed transects using a standard method. Counting
is only carried out during a certain time
of day and under specified weather conditions. A monitoring transect is usually
100 metres long up to a maximum of
500 metres.
The monitoring transect
If you want to take part in the Dragonfly
Monitoring Scheme, you should contact your
regional monitoring coordinator; a transect
is set out in mutual agreement. If you have
suggestions concerning the transect, keep the
following in mind:
Look for locations that are easily accessible.
Choose a transect that can be walked in the
same way each year. Are there points in the
landscape that are easy to recognise?
Be sure that the transect is sunny in both
spring and summer.
Set up the transect along the waterside
where the habitat type is uniform.
A transect is usually 100 metres long. This
is long enough to make a reliable count of
Zygoptera and the anisopteran Sympetrum
species. It is split into two sections of 50
metres, 1A and 1B.
Some all-species transects are shorter than
100 metres or longer:
Shorter, if there is not enough suitable
habitat present. This may be the case
with transects along small pools or
where just a small part of the waterside
is accessible. A transect has a minimal
length of 25 metres. In that case, the
transect contains only one section.
Longer, in order to make counts reliable
for Anisoptera other than Sympetrum








species. Sections of 100 metres are added to make a transect of a maximum
length of 500 metres. Such longer
transects can be along canals, lakes,
streams and other larger water bodies.
A single-species transect is set out for a
Red List species in a location with a good
population.
For most species of Zygoptera and
Sympetrum, the single-species transect
has a maximum of ten sections of 50
metres long.
For Calopteryx species, Sympecma
species and all other Anisoptera, the
single-species transect has a maximum
of 10 sections of 100 metres long.
In general, it does not take much time to walk
a transect, and therefore it is possible to count
transects within close vicinity on one day.
Not only is it fun to count at more than one
location, it also makes the monitoring scheme
more robust.



Walking the transect
In order to be able to compare results from
year to year, it is of utmost importance that
dragonflies are counted each year along the
same transect using a standard method.
Counts should be made as follows:
Make counts every two weeks depending
on the weather conditions and the time you
have available.
As far as possible, space out counting sessions evenly over the counting period: 1st
May till 15th September
When circumstances force you make counts
that are closer together, see that there
are at least two whole days between one
count and the next, e.g. if you counted on



DUTCH BUTTERFLY CONSERVATION 009 
The monitoring transect:
You choose your transect in mutual agreement with the monitoring scheme coordinator.
The transect should be located in a uniform habitat type.
The all-species transect is usually 100 metres long, divided in two sections of 50 metres.
A shorter all-species transect is set out if there is not enough suitable waterside habitat,
but is never shorter than 25 metres.
A longer all-species transect is used for getting a better count of Anisoptera and
Calopteryx species. Sections of 100 metres are added to a total transect length of 500
metres.
A single-species transect is used for Red List species.






Figure 2: Example of an all-species transect with a length of 200 metres.
Figure 3: Example of a single-species transect for Calopteryx splendens with a total length of 400 metres.
 Dutch Dragonfly Monitoring Scheme; A Manual
Monday, you should not count again until
Thursday.
If you do not manage to count at all during
a two-week period, for whatever reason,
make two counts in the following period,
but with at least two whole days between
counts.
If you already know that you will be unable
to count in a certain period, try to count
twice in the period before your absence,
or look for someone else to count for you.
Gaps in the records make the data less
valuable: try to avoid creating them!
Only count during ‘good’ dragonfly weather,
that is, in conditions when most dragonflies
are active.
Before starting your count, check the guidelines concerning weather and time of day
carefully. Also, note that conditions near
a sheltered pool possibly meet the criteria
more easily than, for example, those near a
stream in an open, windy landscape.
Guidelines for ‘good’ dragonfly weather:
Count between 11.00 and 16.00. When the
temperature is above 22 °C, counts can be
done between 10.30 and 16.30. On days
with temperatures above 30 °C, do not
count during the hottest hours.
Count during sunny weather; cloud cover
must be less than 75%.
Do not count if the wind force is stronger
than 4 on the Beaufort scale.
Do not count at temperatures lower than








17 °C. Exceptionally, in sunny weather with
practically no wind, counts can be made
at a slightly lower temperature, but never
lower than 15 °C.
Do not count when it is raining.•
Walking the transect
Walk slowly, looking from side to side over 2
metres of waterside and over 3 or 5 metres
of water.
Count smaller species over 3 metres of
water and larger species over 5 metres.
Count a tandem or copula as two individuals.
Do not worry if you cannot identify all dragonflies in one go. In that case, it is better
to walk the transect twice; the first time
count the smaller (Zygoptera and Sympetrum) species, and the second time, the
larger Anisoptera. The chance of missing an
individual is much less.
Try to identify a species on sight; close
focus binoculars are useful.
Only catch dragonflies if you really have to.
It disturbs them and costs you time.
Do not count freshly emerged individuals as
they are difficult to identify.
However, juveniles which have clearly been
flying around for some time, are counted.
Distinguishing species within a genus can
be a problem:
Count all look-alikes.
Catch a sample of about 10-15 indivi










DUTCH BUTTERFLY CONSERVATION 009 9
Figure 4: Sometimes you may have to count dragonflies from a boat.
duals.
Identify them. In which proportion are
different species present? For example:
You saw 100 individuals of Lestes. You
caught 10, of which 2 turned out to be
L. dryas and 8 L. sponsa.
Extrapolate this for your record: your
count is 20 L. dryas and 80 L. sponsa.
Only an estimate is needed of large numbers of dragonflies: count to the nearest 10
Make counting easier by dividing your transect into smaller sections; this helps keep
track of the numbers.
All-species transects:
Count every two weeks.
Count the first part of a transect of 100
metres in two separate sections, A and
B, of 50 metres.
On transects longer than 100 metres:
for the first 100 metres, count all
dragonflies including the smaller
dragonflies, namely the Zygoptera
and Sympetrum species (see figure
5).
for the following sections, note
only the larger dragonflies, namely








1.
2.
the Anisoptera (but not Sympetrum
species) and Calopteryx species.
As these species are easier to
recognise at a distance, walk if
you like at a slightly quicker pace,
recording individuals that you see
over a distance of 2 metres waterside and 5 metres water.
Single-species transects:
Count at least three times within the
peak flight period.
Finally:
Carry a small notebook, not only for
recording numbers, but also for noting
changes in the habitat.
No dragonflies on your transect walk?
This zero count is as valuable as any
other. Record it!
When in doubt, contact your coordinator.






10 Dutch Dragonfly Monitoring Scheme; A Manual
Figure 5: the counting zone
Walking the transect
Check guidelines for good dragonfly weather before and during walking your transect.
Count all-species transects every two weeks, spacing visits evenly; if unevenly spaced,
leave at least two whole days between counts
Count single-species transects at least three times within the peak flight period.
Carry notebook for noting numbers and habitat changes.
Try not to miss a count. Impossible? Find someone to do it for you.
Walk slowly, looking from side to side over 2 metres of waterside and over 3 or 5 metres of water.
Count smaller species over 3 metres of water and larger species over 5 metres.
A tandem or copula counts as two.
Try to identify a species on sight; close focus binoculars are useful.
Do not worry if you cannot identify all dragonflies in one go. In that case, it is better
to walk the transect twice; the first time count the smaller (Zygoptera and Sympetrum)
species, and the second time, the larger Anisoptera.
Do not count freshly emerged individuals.
Count juveniles that have clearly been flying around for a time.
Extrapolate for look-alikes
Estimate large numbers to the nearest 10














DUTCH BUTTERFLY CONSERVATION 009 11
Chapter 4 / The recording form
The results of your count have to be
recorded carefully and sent in to the
coordinator at the end of the counting
season. This can be done in two ways:
by filling in a (paper) recording form, or
by using the online monitoring form.
Two different recording forms are used, one for
all-species transects and another for singlespecies transects. Examples of both types of
Dutch recording forms are shown, with an
explanation of the information that is asked for.
Please note that some questions are only relevant for the Dutch situation. In other countries,
for example, restrictions in weather conditions
may differ.
The recording form for all-species transects
The form to be filled in by the volunteer should
at least contain the following items:
General information about the monitoring
transect:
Year: the year in which recording was done.
Transect number.
A rough indication of transect location, e.g.
coordinates of the grid square.
Contact information of volunteer:
Name of the monitoring transect (use a
unique name for each transect).
Name, address, telephone number, email
address of volunteer.
Personal code number of volunteer.
Significant changes in the transect in comparison to previous year; these are important for
interpreting the results:
Changes in habitat management? Yes/No
(e.g. start of grazing by livestock).







Changes in environment? Yes/No (e.g. rise
in water level, severe drought, etc.).
Other habitat changes? Yes/No (e.g. trees
on the bank have been cut, water has been
polluted, etc.).
Brief reminder of the most important ‘rules and
restrictions’:
Counting takes place once every two weeks,
from the second week of May until the first
week of September.
Counting mostly takes place between 11:00
and 16:00.
Only count in good dragonfly weather, that
is, when dragonflies can be active
Do not count when wind force is above 4 on
the Beaufort scale.
Do not count when it is raining.
At the bottom of the page: address to which
the completed form should be sent.
Information about date and circumstances of
the count
For each visit: Day, Month, Year, Time
counting started , Time counting finished,
Temperature, Cloud coverage and Wind
force is needed.
Space for extra remarks by volunteer.
A short list of explanations:
If no dragonflies were seen when walking the transect, this is a zero count
and should be filled in!
The temperature should be estimated
by the volunteer.
Cloud coverage should be estimated by
the volunteer in percentages.
The wind force should be estimated
by the volunteer. If it exceeds 4 on the
Beaufort scale: do not count. Use the
following descriptions to estimate the
wind force:
Direction of wind shown by smoke,














1.
1 Dutch Dragonfly Monitoring Scheme; A Manual
Figure 6: Front page of the Dutch all-species recording form.
DUTCH BUTTERFLY CONSERVATION 009 1
but not by a weathervane.
Weathervane is moving and wind
felt on the face
Leafs and small twigs in constant
motion
Small branches moving, wind
raises dust and pieces of paper
Small branches with leaves make
sweeping movements, crested
wavelets: do not count.
Large branches in motion: do not
count.
Following pages: fill in the results and information about habitat changes.
List of common dragonfly species, and
some blank lines for rare species.
A column for each section of the transect
for filling in the numbers recorded for each
section: 1A, 1B, 2,…, 5.
Space for remarks on any habitat changes
in each section of the transect: coverage
(%) of duckweed/floating algae; rise in
water level in metres; drop in water level
in metres; other habitat changes (to be
specified by volunteer).
2.
3.
4.
5.
6.



The same page occurs 13 times, one page
for the results of each count.
Last page: Changes in habitat management
Table to fill in any changes in habitat management for each section. Activities that can be
mentioned here are:
Grazing
Grazing stopped
(Part of) bank mowed
Herbicides or pesticides used
Top-layer of soil removed
Water course filled in
Dimensions of water course have been
changed by digging
Water cleared of vegetation
Trees on bank cut
Other activities (to be specified by
volunteer)

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Figure 7: Being a member of the Zygopteran family, Ischnura pumilio is counted only on the first 100 meter of
a transect.
1 Dutch Dragonfly Monitoring Scheme; A Manual
Figure 8: Page 2 of the Dutch all-species recording form.
DUTCH BUTTERFLY CONSERVATION 009 1
Figure 9: Pages 3-15 of the all species Dutch counting form.
1 Dutch Dragonfly Monitoring Scheme; A Manual
Figure 10: Last page of the Dutch all-species recording form
DUTCH BUTTERFLY CONSERVATION 009 1
The recording form for single-species
transects
A different recording form has been designed
for reporting the results from counting a singlespecies transect. The form closely resembles
the one used for an all-species transect, but
has only two pages, one for information about
the volunteer and the transect itself, the other
for the results.
On the first page:
General information about the monitoring
transect:
Year: the year in which recording was done.
Transect number.
A rough indication of transect location, e.g.
coordinates of the grid square.
Contact information of volunteer:
Name of the monitoring transect (use a
unique name for each transect).
Name, address, telephone number, email
address of volunteer.
Personal code number of volunteer.
Significant changes in the transect in
comparison to previous year; these are








important for interpreting the results:
Changes in habitat management? Yes/No
(e.g. start of grazing by livestock).
Changes in environment? Yes/No (e.g. rise
in water level, severe drought, etc.).
Other habitat changes? Yes/No (e.g. trees
on the bank have been cut, water has been
polluted, etc.).
A table to fill in any changes in habitat
management for each section.
Brief reminder of the most important ‘rules
and restrictions’.
At the bottom of the page: address to which
the completed form should be sent.
On the second page:
Information on date and circumstances of
the counts.
The results and information on habitat
changes.
If you walked the transect but did not see
any dragonflies, please fill in the date and
record. This is a zero count, and important
for the data of this transect!








1 Dutch Dragonfly Monitoring Scheme; A Manual
Figure 11: First pages of the single-species counting form.
DUTCH BUTTERFLY CONSERVATION 009 19
Figure 12: Second page of the single-species counting form.
0 Dutch Dragonfly Monitoring Scheme; A Manual
The recording form online
For a few years now, Dutch volunteers have been able to report their results directly on the internet; a website http://meetnet.vlinderstichting.nl was made especially for this purpose. About 90%
of the volunteers use this possibility to enter their data. A great advantage of sending the data
directly to the website is that time and effort are saved in processing the data and, moreover, the
risk of mistakes is minimised. The questions on the digital form are practically the same as on the
paper one. The screenshots below are to give an impression of the online recording forms. If any
help is needed in making a comparable website, please contact one of the authors of this revised
version at Dutch Butterfly Conservation (info@vlinderstichting.nl).
DUTCH BUTTERFLY CONSERVATION 009 1

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