Transect Monitoring
Transect recording in Hertfordshire & Middlesex
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Over 50 transects are currently being
walked in Hertfordshire and Middlesex.
If you would like to just help out on a
transect now and again, please
to be put in contact with a transect near you.
A number of recorders now also record
in March. It is possible to input data from the last week of
March (week 0) into Transect Walker software. Data from this
week is used in phenology plots, but currently the counts are not
used for Annual Indices
TRANSECT RECORDING INSTRUCTIONS
Much of this account is adapted from Butterfly
Monitoring Scheme Instructions to Independent Recorders, by Marney
L. Hall, published by the Institute of Terrestrial Ecology in
1981.
- A butterfly transect is a way of
monitoring changes in butterfly numbers at one particular site,
both within the season and from year to year.
- It is the main method by which declines in
species can be followed, and as such is extremely important.
- Transects should only be carried out by
experienced observers who can recognise virtually all the common
species on the wing.
- The method consists in walking the same route at least once a
week between April 1st and 29th September under standard weather
conditions of temperature, wind and sunshine, and noting the
numbers of each species of butterfly seen within a set distance
from the observer, usually 5 metres.
STARTING A TRANSECT
First choose your route carefully, as once chosen, the
route should not be altered. Annual comparisons are dependent upon
the same route being walked, mainly by the same person, from year to
year.
The site should be near you, preferably within about
10 or 15 minutes' walk or drive, as you can then take advantage of
short spells of sunshine during otherwise cloudy periods.
The route should cross different habitats that are
representative of the locality as a whole. The length of the route
should only be as long as is easily manageable, bearing in mind that
at the height of the season, when there are large numbers of
butterflies on the wing, counting will take longer than earlier in
the year. A walk of about 30 minutes is about the right length, as
this will increase to 1 to 11/2 hours during the Meadow Brown season
in July. It is better to restrict the route to rides or paths, but
if there are no such paths across the site, the route can be marked
with canes or posts, or other clear landmarks such as trees can be
used, to ensure the same route is followed each time.
Try
and avoid covering the same section twice, but if this is
unavoidable, count the butterflies only on the first occasion. If
you see an unusual butterfly there the second time around, make a
note at the bottom of the form, rather than within the boxes on the
form itself. It is usually convenient to choose a circular route so
that you return close to your starting point at the end.
Only count butterflies within about 5
metres distance of you. The exact
distance is not important, but
should remain the same from year to year. When setting up the
transect, it is a good idea to have a tape measure with you, so that
you can appreciate how far 5 metres is in the different parts of the
route. To help, you may note bushes or other features that are 5
metres from the route, or alternatively choose a convenient clearly
marked boundary such as a hedge or stream as your limit for counting
in some parts of the transect.
SECTIONS
Once the route has been chosen, it
should be divided into sections (no more than 15). Each section may
be a discrete habitat type, or a subdivision of the same habitat
which is being managed differently. The divisions between each
section should be clearly defined so that they remain the same from
year to year.
MAP AND DESCRIPTION
Once the route and sections have been chosen, an
accurate map should be made. This should preferably be based on
Ordnance survey 1:25000 or larger scale maps (the Ordnance Survey
county road atlases are excellent for this). Each section should be
marked, together with the landmarks that mark the divisions between
each section. A description of the transect should also be produced,
in which each section is described, and any "local rules", such as
county boundaries, defined. Notes of the habitat types and
vegetation in each section should also be included, and any details
on how they are managed, if known.
You may also want to keep a
photographic record of each part of the transect. This would provide
a valuable record for future years, and could be updated every few
years as the habitat changes.
WHEN TO RECORD
The transect season begins each year on April 1st. You may walk
the transect earlier in the year out of interest, but when analysing
the data, for most purposes only those transects walked between
April 1st and September 29th will be included.
The transect should then be walked at least once
every week for the 26 weeks April 1st to September 29th.
For reference the dates of each week are as
follows:
| Week 1 ~ April 1 - 7 |
Week 10 ~ June 3 - 9 |
Week 19 ~ Aug 5 - 11 |
| Week 2 ~ April 8 - 14 |
Week 11 ~ June 10 - 16
| Week 21 ~ Aug 12 - 18 |
| Week 3 ~ April 15 - 21 |
Week 12 ~ June 17 - 23 |
Week 21 ~ Aug 19 - 25 |
| Week 4 ~ April 22 - 28 |
Week 13 ~ June 24 - 30 |
Week 22 ~ Aug 26 - Sep 1 |
| Week 5 ~ April 29 - May 5 |
Week 14 ~ July 1 - 7 |
Week 23 ~ Sep 2 - 8 |
| Week 6 ~ May 6 - 12 |
Week 15 ~ July 8 -
14 |
Week 24 ~ Sep 9- 22 |
| Week 7 ~ May 13 - 19 |
Week 16 ~ July 15 - 21 |
Week 25 ~ Sep 16 - 22 |
| Week 8 ~ May 20 - 26 |
Week 17 ~ July 22 -
28 |
Week 26 ~ Sep 23 - 29 |
| Week 9 ~ May 27 - June 2 |
Week 18 ~ July 29 - Aug
4 |
|
The transect can be
walked on any day within each of the above weeks, provided the
weather is suitable (see below). If a week has to be missed through
holiday or other enforced absence, contact John Murray who will try
and arrange a replacement recorder (who will need to be taken over
the transect beforehand). Weeks 12 to 22 (mid-June to the end of
August) are particularly important, as many butterflies are on the
wing and things change rapidly, so it is particularly important not
to miss a week in this period if at all possible. If you have the
time, walking the transect twice a week in this period is very
useful.
A week missed early or late in
the season may not be too serious, but try never to miss more than
one week in a row. The weather should be preferably warm and sunny
with little wind. Wait until 10:45 in the morning before starting,
and do not record after 15:45 in the afternoon. The exact weather
requirements are as follows:
- Do not walk the transect if the wind is
greater than force 5 or 6 (small trees in leaf begin to sway;
large branches move, telephone wires whistle)
- Do not walk the transect when the
temperature is below 13ºC
- Between 13º and 17ºC, a transect may be
walked if there is at least 60% sunshine
- Above 17ºC, a transect may be walked in any conditions,
providing it is not actually raining
Unfortunately, particularly early in the season,
there are some weeks when the weather may be too poor for the above
standards. In such circumstances, it is better to walk the transect
if it is slightly too cold or too cloudy, within reason.
Butterflies may venture forth happily in
temperatures of 10º or 11º provided there is no cloud and no wind,
for example.
Alternatively, if it is 13º
but too cloudy, you may stop the walk each time the sun goes in and
only record butterflies seen when it is shining, but always make a
note if you do this.
Spring mornings
often begin as a brilliant, cloudless day, until 10:45 when patches
of cloud appear from nowhere and the entire sky is overcast in a
quarter of an hour. If such weather persistently occurs, starting
the transect at 10:15 is better than not walking it at all if the
weather is warm enough. In all such cases, make clear notes as to
what you are doing.
Generally speaking, it is best to walk
the transect early in the week even if conditions are a bit too
poor. Then if better conditions are met later in the week, the
transect can be walked
WIND SPEED
Record the
wind speed according to the Beaufort scale, which is:
Force
0 Calm, smoke rises vertically
Force 1 Very slight
wind; smoke drifts slightly
Force
2 Wind can be felt on face; leaves
rustle
Force
3 Leaves and twigs begin to move
Force
4 Dust raised, small branches move
Force
5 Small trees
in leaf begin to sway
Force 6 Large branches
move; telephone wires whistle
TEMPERATURE
Hang a thermometer in the shade at
about chest height, well away from buildings and where the air can
circulate easily, before leaving home. Most thermometers need a
little while to equilibrate, so it is best to do this before about
10:30 in the morning. Make sure that no sun falls on any part of the
thermometer. When the temperature has reached the required value
(see above), you may set off for the transect site. Before you begin
walking it, hang the thermometer in the shade (a good leafy tree is
best) at chest height at the start of the transect and record the
temperature when you return.
WALKING THE TRANSECT
Before starting, note your name, the site name,
the year, date and time to the nearest minute at the top of the
form. Always bring a net with you if you have one; this saves a
great deal of trouble waiting for active butterflies to settle and
be identified.
Walk the transect at a
slow, even pace, paying attention to flower heads and other likely
butterfly perches. Only count those butterflies which come within 5
metres in front of you, or within the limits defined in each
section. If an individual butterfly is encountered more than once
and you are certain that it is the same butterfly, record it only
once. However, if there is any doubt, record it on both occasions.
When you come to the end of each
section of the transect, write the number of each species of
butterfly seen there in the box provided, note whether it has been
mainly sunny or cloudy (S or C) in that section at the bottom, and
note the time to the nearest minute before starting off again for
the next section. Sunny (S) means that shadows are cast. If no
shadows are cast, write C.
When you
come to the end of the final section, note the finishing time and
note the temperature on the thermometer left at the start. Add up
the values for each species and put the total in the column at the
right, and then add up the total of all species seen in each section
in the row at the bottom. Total these in the square at the bottom
right, and then check this value by adding up the totals for each
species, which should be the same.
Finally, note the wind conditions, and add up
the number of sections where it was mainly sunny, and express this
as a percentage of all the sections, rounded up to the nearest 10%,
in the appropriate space at the top right.
Particularly at first, you may find
identification of some species a problem. Waiting for a butterfly to
settle can take a long time, and you may need to follow it a long
way from the route, so catching the butterfly in the net,
identifying it and releasing it will save a lot of time and trouble.
If you stray from the route to identify a butterfly, return to the
same point on the route before recording again, do not record other
butterflies as you do so.
Some species,
such as the Small and Essex Skippers, cannot be
distinguished in flight yet are very numerous. Rather than catch or
examine every one, record them in the row marked Small/Essex
Skipper, and only record those accurately identified as either Small
or Essex in the rows provided. The way to distinguish the two is by
looking at the underside of the antennae; the Essex Skipper has
jet-black tips, whereas the Small Skipper has light brown or orangey
tips. You can creep up head-on and bend down to identify the
species, though this may get you some strange looks, or else catch
them in a net to check, in which case you may risk the wrath of
people mistaking you for a collector. A new page has been added
which might help, if you are having problems - click
here for more details
You may need to catch specimens to distinguish Small and Green-veined
Whites; in both cases, try and identify a dozen or so
accurately (more if numbers are very large), the rest can then be
recorded as Small/Essex or Small/Green-veined. As long as all
uncertain sightings are separately listed in this way, we can derive
probable abundances from your records.
At the height of the Meadow
Brown season, you may be lucky enough to find swarms of
butterflies which at first are difficult to count, as they move
around constantly as you are trying to count them. Never be tempted
to guess the numbers; always try and count them as they fly around,
even if the numbers may not be as accurate as you would hope.
Provided the numbers are high enough, a few missed or counted twice
here or there will not affect the analysis too much. After a while,
you will become adept at counting even the most daunting-looking
clouds of butterflies.
Always walk the transect alone; two
people will see a lot more butterflies than one and spoil the
analysis, Alternatively if your friend is not a butterfly
enthusiast, chatting can distract your concentration quite
considerably and you will see fewer butterflies. If for social
reasons it is unavoidable, your friend may note the numbers down
whilst you observe; but the friend must be under strict instructions
not to say "look there's one" or otherwise induce you to record more
or fewer butterflies than you would normally see. Always make a note
if you are using someone else to write down the numbers in this
way.
SUBMISSION OF RECORDS BY POST
Please return all the forms to Dr J.B. Murray,
"Field End", Marshalls Heath, Wheathampstead, Herts AL4 8HS by 9th
November at the latest.
These should include the original recording sheets (or
photocopies of them) plus, if you have time, a summary sheet for the
whole year.
Click here to print an online copy of the
weekly transect form
Click here to print an online copy of the
summary form
A free version of Adobe Reader can be downloaded from http://www.adobe.com/uk/products/acrobat/readstep2.html
The summary sheet should list the weekly
totals for each species. If you have walked the transect more than
once in the same week, take the
average number seen in that particular week on the summary sheet,
unless one of the transects was walked under poorer weather
conditions than strictly allowed, in which case it can be left out
of the analysis.
If you
have had to miss a week, take the average of the weeks either side
of that missed for each species
Finally, add up the weekly numbers for each
species and put the total at right, and sum the annual numbers of
all species seen in each box at the bottom.
RECORDS SENT BY EMAIL
Please contact Andrew Wood for a copy
of his transect spreadsheet. If you can submit data electronically
either using the spreadsheets or Transect Walker it would be very
helpful. Data can be sent as a compact disc, floppy disc or emailed
as an attachment.
Butterfly Conservation's Transect Walker software is now
fully available for downloading by logging on to the UKBMS website
www.ukbms.org/transect_walker_v2.htm - Just
follow the links to register and download - note the software is
free of charge.COPYRIGHT POLICY
IMPORTANT: By submitting information on these forms I agree that it may be collated and disseminated manually or electronically, including via the Internet, for conservation, environmental decision-making, education, research and other public benefit uses in accordance with Butterfly Conservation's data access policy. Names and contact details of data suppliers will be used for administration and verification purposes only. Your contact details will not be passed to other parties without the consent of the data supplier, whilst your name will form part of the record that is collated and disseminated in accordance with Butterfly Conservation's privacy policy. For more details the Butterfly Conservation's Data Access Policy can be found at www.butterfly-conservation.org/bnm
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