Data sources
Bird and terrestrial mammal data
BBS
BBS survey squares are randomly selected from a list of all 1-km squares in the National Grid that comprise the UK, Channel Islands and the Isle of Man, excluding coastal squares with less than 50% land. The use of volunteers is maximised through a stratified random sampling design. Initially, the number of squares allocated to each of the BTO’s 83 regions (roughly counties or groups of counties) was a fixed proportion of the number of potential volunteers in the region, estimated using BTO membership information. For regions with relatively few potential volunteers, a minimum level of coverage was set. Within each region, squares are selected randomly, and allocated to volunteers through a network of voluntary Regional Organisers (ROs). ROs receive a list of target squares for their region, and to maintain the random design of the survey, are asked to allocate them in the order generated. Squares are identified by Ordnance Survey (OS) grid references indicating their southern and western boundaries that enable their positions to be located on a 1:25,000 OS map. The aim of the survey is for as many of the same 1-km squares to be surveyed every year, ideally by the same observer, although there is likely to be some changeover of volunteers. If a square cannot be surveyed, for example, if there is no possibility of gaining access permission to the land, or if the terrain is dangerous to cover, then it is deemed to be ‘uncoverable’, and is subsequently removed from the active list.
BBS survey methodology;
BBS fieldwork involves three visits to each survey square per year: a reconnaissance visit and two bird recording visits. During the reconnaissance visit, the transect routes are planned out. The ideal survey route comprises two parallel lines, each 1km in length, about 500m apart, and about 250m from the edge of the square (see Figure 1). Transects are divided into 200m sections, making a total of ten 200m sections per square. For practical reasons there is often substantial deviation from the ideal route.
Bird and mammal counts are carried out on the second and third visits. Visits are timed so that the first is in the early part of the breeding season (April to mid-May) and the second at least four weeks later (from mid-May to the end of June). Volunteers are asked to begin their counts between 0600 and 0700 hours so that they coincide with maximum bird activity, but avoid concentrated song activity at dawn. Volunteers record all the birds they see or hear as they walk methodically along their transect routes. However, only adult birds are used in the analysis of the population trends. Birds are noted in four distance categories, three measured at right angles to the transect line (within 25 m, between 25-100 m, or over 100 m from the transect line), and those seen in flight only.
Recording birds in distance bands gives a measure of bird detectability and allows relative population density to be estimated. The average visit time is around 90 minutes. Observers record the starting and finishing times for each of the two halves of the transect. Observers are discouraged from conducting bird counts in heavy rain, poor visibility, or strong winds when activity is dampened.
It is important to note that zero counts are not included in these data. For example, if no robins were seen on a visit to a square, there will simply be no record for robin for the square (as opposed to there being a record ‘Robin’ = ‘0’).
Figure 1 Diagram of an ‘ideal’ transect route, showing 10 200m sections and the distance bands (numbered 1, 2 and 3 at the top of the square).
See http://www.bto.org/bbs/index.htm for further details.
CBC
The Common Birds Census (CBC) was a major volunteer fieldwork project of the BTO during almost forty years between 1962 and 2000, funded by JNCC. Its main function of monitoring trends in the UK populations of common breeding birds has now passed to the BTO/RSPB/JNCC Breeding Bird Survey (BBS).
The CBC used a full version of the territory-mapping census method. As well as numbers of territories, from which population trends were assessed, this method produces a map for each species, census plot and year to show exactly where the birds were (and were not) holding territory.
CBC was enthusiastically supported by BTO members, several of whom achieved more than thirty continuous years of mapping censuses. It was the work of CBC volunteers that drew attention to a number of serious declines among common and widespread species, such as Skylark and Willow Tit, and provided the evidence by which they (alongside a number of rare birds) have become high priorities for conservation effort. CBC also documented how, for species such as Sparrowhawk and Stock Dove, environmental change brought recovery and population expansion. Sharp drops in population, for Wrens and other small birds after cold winters and for Whitethroats after the failure of rains in West Africa, helped to demonstrate the importance of these factors in determining the abundance of these species. More than 10,000 CBC surveys were completed, at more than 1,500 different sites. Results to 1988 were documented fully in a popular book, Population Trends in British Breeding Birds.
Although the CBC is no longer running as a wide-scale project, data from the CBC remain constantly in use for the assessment of long-term population changes. Maps of well over a million bird territories are archived in new storage areas at the BTO HQ in Thetford, and are accessed frequently for a variety of research projects.
National Bat Monitoring Programme
Field Survey design
Surveyors are allocated 1km squares, randomly selected from the ITE National Land Class strata, in proportion to land class availability. Volunteers are allocated sites within 10km of their home address. The priority is to allocate an available repeat site (i.e. a previously surveyed site that is not currently allocated to a volunteer) if there is one within 10km of the volunteer’s address. Otherwise the volunteer is provided with a few grid refs from the randomly generated list and asked to select one that looks most accessible for repeat surveying. Coverage is largely determined by the distribution of NBMP volunteers but effort is made to target areas with low participation through running NBMP bat detector workshops in these areas. The aim of the survey is for as many of the same 1km squares to be surveyed every year, ideally by the same observer, although there is likely to be some changeover of volunteers. If a square cannot be surveyed, for example, if there is no possibility of gaining access permission to the land, or if the terrain is dangerous to cover, then it is flagged as ‘dangerous/inaccessible’ to ensure it is not allocated in future.
Field Survey methodology
A predetermined ‘ideal’ triangular transect route, roughly 3km in length, is marked onto a map of the 1km square. Twelve stopping points, four on each side of the triangular route, are also marked onto the map. During the day, surveyors identify a walkable route around all of the stopping points, attempting to follow the ideal route. If the site is a repeat site then the daytime visit involves following the previous surveyor’s route map in order to ensure familiarity with the route and check that it is still safe and accessible. Where stopping points cannot be reached, points close by in the same habitat are selected. Ideally two evening surveys, using a heterodyne bat detector, are made in July, though sometimes only one survey is managed. One survey is made between 1st-15th July and a second survey made between 16th-30th July. The survey begins approximately 20 minutes after sunset. Surveyors walk between spots, with detectors tuned to 25 kHz in order to identify serotine and noctule and count the number of passes, then when each spot is reached, the detector is re-tuned to 50 kHz, and the observer records numbers of common pipistrelle and soprano pipistrelle passes for two minutes while stationary. On each survey evening, observers record the start and end time of the survey and total bat count. Weather conditions are recorded at the start of the survey: ambient temperature (degrees Celsius), cloud cover, wind speed and rain status. Observers are requested not to conduct counts in poor weather conditions (strong winds, heavy rain, very cold temperatures). Bat detector model is also recorded.
Diagram of a typical transect route, showing the ‘ideal’ triangular transect, the actual route walked, and the twelve stopping points.
Note also that there are relatively few data for 2001 – this was due to a restriction on access to the countryside because of the foot and mouth disease outbreak that year.
Waterway Survey design
Surveyors are allocated a six figure grid reference of an Environment Agency River Habitat Survey site along a waterway within a 1km square. Sites not surveyed by EA are also selected if the surveyor does not live near a site on the RHS list. Surveyors are allocated sites within 10km of their home address. The priority is to allocate an available repeat site (i.e. a previously surveyed site that is not currently allocated to a volunteer) if there is one within 10km of the volunteer’s address. Otherwise the volunteer is provided with three or more grid refs from the RHS list and asked to select one that looks most accessible for repeat surveying. Coverage is largely determined by the distribution of NBMP volunteers but effort is made to target areas with low participation through running NBMP bat detector workshops in these areas. The aim of the survey is for as many of the same 1km stretches of waterway to be surveyed every year, ideally by the same observer, although there is likely to be some changeover of volunteers. If a square cannot be surveyed, for example, if there is no possibility of gaining access permission to the land, or if the terrain is dangerous to cover, then it is flagged as ‘dangerous/inaccessible’ to ensure it is not allocated in future.
Waterway Survey methodology
During the day, surveyors identify a roughly 1km route along the waterway, which includes the grid reference. Along this route, ten stopping points by the side of the river are identified, a minimum of 100m apart, and spaced equally where possible. If the site is a repeat site then the daytime visit involves following the previous surveyor’s route map in order to ensure familiarity with the route and check that it is still safe and accessible. Ideally two evening surveys using heterodyne bat detectors are made in August, although sometimes only one is managed. One survey is carried out between 1st-15th August and a second between 16th-30thAugust. The survey begins 40 minutes after sunset. The detector is tuned to 35 kHz, a torch is used to scan the water surface, and Daubenton’s bat passes are recorded for four minutes at each of the ten spots along the waterway. The number of “unsure” bat passes, which sound like Daubenton’s bat but where a visual confirmation is not possible, are also recorded. Weather conditions are recorded at the start of the survey: ambient temperature (degrees Celsius), cloud cover, wind speed and rain status. Observers are asked not to conduct counts in poor weather conditions (strong winds, heavy rain, very cold temperatures). Bat detector model is also recorded.
Diagram of a typical transect route, showing a 1km stretch of waterway centred around the allocated 6-figure grid reference (the red spot) with ten stopping points marked out along the route.
Note also that there are relatively few data for 2001 – this was due to a restriction on access to the countryside because of the foot and mouth disease outbreak that year.
UK Butterfly Monitoring Scheme
This scheme has monitored changes in the abundance of butterflies throughout the United Kingdom since 1976. Over the 32 years of the scheme, recorders have made over 170,000 weekly visits to 1500 separate sites, walking over 375,000 km and counting over 12.5 million butterflies.
The UKBMS is based on a well-established recording method and has produced important insights into almost all aspects of butterfly ecology. A fixed-route walk (transect) is established at a site and butterflies are recorded along the route on a regular (weekly) basis under reasonable weather conditions for a number of years. Transect routes are chosen to sample evenly the habitat types and management activity on sites. Care is taken in choosing a transect route as it must then remain fixed to enable butterfly sightings to be compared from year to year. Transects are typically about 2-4km long, taking between 45 minutes and two hours to walk, and are divided into sections corresponding to different habitat or management units.
Butterflies are recorded in a fixed width band (typically 5m wide) along the transect each week from the beginning of April until the end of September yielding, ideally, 26 counts per year. Transect walks are undertaken between 10.45am and 3.45pm and only when weather conditions are suitable for butterfly activity: dry conditions, wind speed less than Beaufort scale 5, and temperature 13°C or greater if there is at least 60% sunshine, or more than 17°C if overcast. Due to the vagaries of the British and Irish weather, it is rare in practice to achieve a full set of 26 weekly counts. However, a small number of missing values can be estimated using other counts during the season.
For further information see http://www.ukbms.org/
Aphid data
Aphid data are annual totals that have been extracted from the database known as 'EXAMINE'. The series only includes positive values recorded from suction trap catches. Thus, if a species was absent in a given year at a given site, it is not recorded in the datafile. A total of 18 English and Welsh sites were chosen for BICCONET. Sites were chosen from the network if they were i) English or Welsh ii) operating uniformly throughout the year (i.e. no half year sampling sites) and, iii) had a trap-year series that was equal to, or greater than five. The series starts in 1966 and finishes in 2006, although not many sites ran for the full series. A total of 22 species were selected for BICCONET. Two species were selected based on a hypothesis framed around a Forestry Commission document. The FC predict that beech will decline rapidly by 2050. Consequently, the woolly beech aphid (Phyllaphis fagi) which feeds on beech might be expected to show similar declines. The other species, Elatobium abietinum, is an aphid pest of spruces and is predicted to increase under climate change. The remaining species were selected during a trawl of the database. They either showed dramatic gross countrywide increases (e.g. Acyrthosiphon malvae, Capitophorus elaeagni) or decreases (e.g. Dysaphis (Pomaphis) plantaginea). Just for completeness, we have also included some species with no definite pattern nationally (e.g. Rhopalosiphum padi, Tubaphis ranunculina).
Moth data
Moth data are annual totals that have been extracted from the 'Tapes' database. The series includes all catch data, even zeros. Thus, if a species was absent in a given year at a given site, it is recorded in the datafile. The data are outputted as a square matrix. A total of 15 sites were chosen for BICCONET. Sites were chosen from the long term monitoring sites network if they were English or Welsh and operated uniformly. The series starts in 1976 and finishes in 2005 for all sites. A total of 17 species were selected for BICCONET. 14 moth species are specialists that feed on one or a group of closely related foodplants, and have been cited as vulnerable or endangered by IUCN due to their decline in their range and occurred sufficient numbers at the long term monitoring sites. he remaining three species are moths that are thought to be increasing and not at threat and occurred at the long term monitoring sites in sufficient numbers.
Common Plant Survey data
Background to Field Survey design:
Common plants play pivotal roles in ecosystems, providing habitats and food for our fauna. They can be used as indicators and help gain an insight as to the health of our countryside. Plantlife have chosen a set of 65 of the UK's common plants that are easy to identify and indicative of particular habitats. Survey participants look for these plants within a randomly selected 1km square close to where they live, work, or frequently visit. By surveying these random squares each year, Plantlife hope to build up a picture of the state of the British countryside. Random 1km squares are allocated because otherwise people might only survey areas where they know many of the 65 plants grow, and may skew the findings of the survey, giving an inaccurate picture of the state of our common plants and their habitats.
Field Survey methodology:
Surveyors are asked to visit a randomly assigned 1km square three times throughout the year – in April/May, June/July, and ugust/early September. This is in order to get a better overall picture of the plants that are actually present in the surveyed areas (e.g. some plants may be missed if not in flower during the first visit).
Surveyors look for the 65 common species within in two small plots situated within the 1km square. The ‘centre plot’ is at the very centre point of the square and can be found using an ordnance survey map. Once located a 5x5m plot is measured out and the survey begins. Surveyors identify whether any of the 65 species are present within the plot (using the identification flower guide provided) and note on survey sheet percentage coverage of the identified species. The ‘linear plot’ is the second sampling plot, surveyors are asked to find the nearest linear feature (e.g. path, hedgerow etc.) to their centre plot. A 1x20m plot is measured out and species presence and abundance is recorded as before. Once these two plots are surveyed the participant can provide more information by carrying out habitat plots. These are optional but useful, and there is room on the survey form to provide information on five additional plots. The habitat plots should focus on different habitats within the 1km square, can be 5x5km or 1x20km depending n whether the feature is linear.
Surveyors are asked to make a note of the area so they can easily refind the same centre and liner plot in years to come. The aim is that surveyors revisit the same plots each year and from this information a picture of changes within a specific site can be drawn.
Note also that there are relatively few data for 2001 – this was due to a restriction on access to the countryside because of the foot and mouth disease outbreak that year
Gound beetles (ECN data)
Pitfall trapping has been used extensively and successfully for this group, and a well-developed protocol already exists (M.L. Luff, pers. comm.). Even though it is known that problems exist in interpreting data from such traps, active programmes of standardisation are in progress. Analyses of existing data have already shown that carabids can be sensitive indicators of changes in
management (eg Eyre et al. 1989). Many beetle species are known to be sensitive to temperature changes (Thiele 1977) and one species, Pterostichus madidus, has leg-colour morphs which may be sensitive to climate change (Terrell-Nield 1992); morphs of this species will be recorded separately. The ubiquitous harvestman, Mitopus morio, which has features which may respond
to environmental change, will also be collected from the pitfall traps. The method will, in general, conform with that developed by Dr M.L. Luff of the University of Newcastle upon Tyne. At each site, in or adjacent to the TSS, a pitfall trapping system should be instituted to sample Carabidae (ground beetles) and the ubiquitous opilionid (Harvestmen) Mitopus morio. Adult craneflies caught in the traps should also be retained in order to check their identification against the larvae extracted in soil cores. It will be necessary to measure the length of the second femur of M. morio; this changes with altitude and latitude and may react to environmental change. All carabid beetles (not just Carabus spp.) are of interest.
The pitfall traps are polypropylene cups, 7.5 cm diameter x 10 cm deep. A wire netting cage, made from chicken wire with a mesh size approximately 15 mm x 20 mm and approximately 70 mm high, is clipped to the rim of each trap so as to reduce the number of small mammals inadvertently caught in the traps. Each trap should have a cover which can be made cheaply from 5" diameter plant pot saucers and galvanised wire. This helps to prevent heavy rain from flooding the traps, keeps birds from interfering, and helps in their re-location.
Three transects should be selected, preferably within different vegetation types and including the TSS. Transects should not be placed where cattle have access. Ten pitfall traps should be established in each transect, with 10 m spacing between the traps. If possible, transects should be approached from different directions when attending to traps so as to avoid trampling damage to
the vegetation. If trampling is having an obviously deleterious long-term effect on the vegetation, a trapline can be moved each year but returned to the original position every three years. Any movement of traplines should be recorded and information sent to the Central Co-ordination Unit.
The traps are set out on the first Wednesday in May and are then emptied and replaced fortnightly for 13 sampling periods, until the end of October. Antifreeze is used as preservative. The undiluted preservative is poured into each trap to a depth of about 3 cm; if diluted by rain, the catch remains in the heavier, undiluted preservative at the bottom of the trap. Pre-filled replacement traps with marked lids are taken to the sample site. Each trap to be replaced is removed from the hole and the new trap with its lid is placed in the hole, its seating is checked, and its lid removed and placed on the trap containing the catch. Traps may be stored at 4°C prior to emptying. The catch should be stored at 4°C prior to sorting, but if sorting cannot be undertaken in less than three days after collection the catch should be transferred to 75% alcohol to avoid deterioration of the sample material. To sort, the contents of the trap are poured through a 1 mm mesh, 10 cm diameter test sieve (see Appendix I for supplier). The antifreeze is collected in a beaker placed beneath the sieve and is then poured back into a 5 litre aspirator for future use. The traps are rinsed with water to ensure that any adhering dirt which may contain beetles is washed through the sieve. The sieve is then inverted over a 10 cm diameter crystallising dish and the contents are washed into the dish with water. The taxa of interest are extracted carefully on a large white plastic tray under good light and adequate ventilation into individually labelled vials containing a mixture of 70% alcohol, 5% glycerol and 25% water. Particular care must be taken not to damage or remove legs of Mitopus morio specimens which are needed for measurement. The catch is labelled by writing the ECN site identification number, trap number and collection date on a piece of paper which is then placed in an empty, plastic-stoppered 5 cm x 1.2 cm specimen tube which is dropped into the storage bottle. The catch can now be stored for subsequent identification. Records of the catch from each trap should be kept separate until after identification, when the catch from ten traps
can be bulked and stored.
For further information see http://www.ecn.ac.uk/aboutecn/measurements/i.htm
