Leybourne Lakes Country Park - Bird monitoring 2003
Leybourne Lakes Country Park is an extensive area of former sand and gravel workings located to the North of Leybourne Way and separating the built up areas of Larkfield and Snodland. Mineral extraction ceased in the 1970's, resulting in the Park and much of the surrounding area being designated as a Site of Nature Conservation Interest (SNCI). As a site identified in the ‘Tonbridge and Malling Local Plan' for development of a Country Park, a partnership between Tonbridge and Malling Borough Council and Berkeley Homes Ltd was initiated to bring this vision forward. Berkeley Homes in consultation with the Council have created housing development at the eastern end of the site the under the proviso that any built development should be no greater than that to be essential to ensure the development of the remainder of the site as a Country Park . The ownership of the Country Park will then be handed over to the Council in the summer of 2004 and the Council will manage and enhance the site as a Country Park .
As well as having a high botanical and entomological interest this site qualifies for its SNCI status on the bird interest alone and partially abuts the site of Holborough to Burham Marshes Site of Special Scientific Interest (SSSI). The Country Park includes some important bird habitats with much of the surrounding area, either elsewhere within the SNCI or in the adjacent SSSI, of high importance. This report concerns only the land designated within the Country Park and is produced as part of the agreement between Tonbridge and Malling Borough Council and Berkeley Homes Ltd., with Berkeley Homes initiating a wildlife monitoring programme.
Wetland Birds counts (WeBS)
Wintering birds have been monitored using the WeBS standard method for counting wildfowl and wading birds on estuaries and inland waters developed by the British Trust for Ornithology. Counts of all those species listed on the WeBS recording sheets were made on the specified WeBS count date for the months of January to March and November and December. The species covered by WeBS counts includes all waterfowl, all waders, all gulls and Kingfisher.
Other scarce and interesting species that were observed on these visits were also recorded.
Transect based monitoring of most of the bird species present.
To provide an index of the commoner breeding species it is important that as many of the variables as possible are standardised from year to year. The amount of effort put into recording, the route taken and the time of day of the count must remain constant for the results to be meaningful. Tonbridge and Malling have indicated that they are not aware of any proposed changes to the Country Park in the foreseeable future that would necessitate changing the route of the transect.
Two non-intersecting 1 km. transects (see map) were defined in such a way to cover all of the various habitats and every lake. Three visits were made during the breeding season to each pre-defined route, recording all birds, except Cetti's Warbler, Reed Warbler and Nightingale, either heard or seen. The wildfowl, ducks, Coot and Moorhen were also recorded on these visits, which were made in the early mornings between dawn and 09.00 hours at the following times of the year,
Between the 1 st and 10 th April
Between 25 th April and 5 th May
Between 21 st and 31 st May
Mapping of Cetti's Warbler and Nightingale
Cetti's Warbler and Nightingale are the two most important species breeding on the site and we used a mapping technique to monitor theses two species. This involves plotting the locations of singing birds found on each visit and analysing the plotted positions to determine the number of pairs present. The peak song period of Cetti's Warbler which is a resident species is earlier than that of Nightingale, which is a migrant, so five mapping visits were made as outlined below. These were made between dawn and 09.00 hours in the following periods
Between 6 th and 12 th April, for Cetti's Warbler only.
Between 20 th and 26 th April, for both species.
Between 4 th May and 10 th May, for both species.
Between 18 th May and 24 th May, for both species plus the Reed Warbler count.
Between 1st June and 7 th June, for both species.
About 20 th June for second Reed Warbler count.
Any other scarce species that bred or were present transiently were recorded and monitored.
As shown above the fourth mapping visit was used to count the singing Reed Warblers. Reed Warblers begin to arrive at the end of April and continue to arrive for a period after this, the male sings from arrival. Reed Warblers occupy and call from small territories all of which are located in Common Reed. At the peak song period it was relatively easy to visit each small patch of reed and count the number of singing birds, thereby making more complicated mapping techniques unnecessary for this species. The period of maximum song is variable, but in most years will fall within the time period for mapping visit number four. Some birds arrive very late, so a second visit around the 20 th June was made to pick up theses late arriving birds.
Great Crested Grebe
Counts of adults together with any young were made on the first and third transect visits; all waters have been checked on both visits.
Five different techniques were used to monitor the birds of the Country Park .
A transect based method to provide an index of the common breeding birds
A mapping technique to monitor Cetti's Warbler and Nightingale
A count of territory holding Reed Warblers
A count of breeding Great Crested Grebes together with an assessment of their breeding success
A winter monthly (January to March and November to December) count of wildfowl
The authors would like to thank Rod Thompson and Darren Lanes of Tonbridge and Malling Borough Council for their support and the supply of maps and information for this project. We would also like to thank Alan Woodcock who has methodically carried out all of the fieldwork, and Tim Loseby for the photograph of the Tufted Duck.