Birds in Lincolnshire
Woodlarks in Lincolnshire 2000
Woodlarks in Lincolnshire 2000 with reference to the breeding population data from 1984 onwards.
[Please note that the Woodlark is a Schedule 1 breeding species and is subject to the terms of the Wildlife and Countryside Act 1981]
Lincolnshire Woodlark Photograph Gallery
Introduction
Year 2000 saw the fourth attempt at a full breeding season survey covering all of the suitable Woodlark breeding habitat in Lincolnshire. It is pleasing to report that the Market Rasen area woodlands received much better coverage during the spring with the result that several pairs were located after what amounted to an apparent ten year absence. On the down side the Kirkby and Woodall areas again suffered from a lack of detailed coverage. This is disappointing as this broad area has been identified as having the greatest potential for further colonisation of anywhere in the county. A record from Woodall Golf Course in 1999 (M Tartellin pers com) has just come to light and this is one of the sites that was not covered at all in 2000. In the north-west of the county the number of birds and the wide areas now being utilised is making effective survey work more difficult year on year as the vast majority of the work is still undertaken by just two observers. The resulting totals for the county should therefore be regarded as minima. It is likely however, that the majority of the breeding pairs were located and the totals given are probably within 85-90% accurate.
Results
Both the number of pairs and the total of territorial male Woodlarks rose again in 2000 to their highest levels ever with 62 males and 51 pairs proven in the county. These figures represent a 19% increase in the number of males over 1999 and a 50% increase in the number of proven pairs. More significantly there has been a 55% increase in the number of males on territory since the first full recent survey in 1997 with a consequent increase in pairs in the order of 59%. Proven pairs formed 82% of the overall total of males found in 2000. This is the highest proportion of pairs to males to be recorded in recent times, exceeding the 80% recorded in the National survey in 1997 and is in fact the highest proportionate total since 1988 when only four males were located all being paired.
Unfortunately the differences in levels of coverage in the three main areas of the county, the north-west heaths and forests, the Market Rasen forests and the Woodall-Kirkby heaths and forest make an accurate assessment of the rates of increase in different areas rather tentative. The north-west area has had the most consistent coverage over the four year period and here there has been a 48% increase in males and a 52% increase in pairs during 1997-2000. Coverage of the Market Rasen area has been less intensive. The 800% and 600% increase in males and pairs over same period, from none to eight and six respectively, is a reflection of the increasing area of forest clear fell now becoming available at Linwood, Willingham and Walesby. By contrast the number of males and pairs located in the Woodall-Kirby area have both declined by 28% in males & 20% in pairs during 1997-2000. This may well in part be due to poor coverage but certain areas, notably Moor Farm, have obviously suffered habitat loss due to reduced rabbit grazing. More thorough coverage of the whole area around Woodall and Kirkby would no doubt reveal other pairs and this is a suitable project for anyone wishing to get involved with the census.
The full details of annual census projects are shown in the attached chart but it should be stressed that coverage was not total in 1994 and was much reduced in both 1995 and 1996 so the figures for the latter two years are certainly underestimates.
Habitat
From 1984, when the first of the recent run of breeding Woodlarks were found, to 1990 all of the early nesting attempts were concentrated on coniferous forest clear fell sites. Woodlarks were first found away from forest clear fells in 1991 when one male held a territory on a natural heathland site that had been recently subjected to extensive birch clearance. This total increased to three territories in 1993 rising to at least nine by 1996 and peaked at 22 in the 1997 National survey year. Since then the number of heathland territories has remained fairly stable at 19-22 while forest clear fell territories have shot up from 18 in 1997 to 43 in 2000. (Details are shown in the chart below which shows the total number of territorial males and those recorded in heathland and forest clear fell habitats.)
Although little quantitative work has been undertaken on productivity of breeding pairs in the county there is circumstantial evidence that pairs breeding on heathland rear more young per brood than those on forest sites. It is therefore unusual that the number of territories on heathland have not kept pace with the rise in forest populations. There are a number of possible reasons why this may be:
a.. restricted areas of suitable heathland remain for colonisation
b.. loss of suitable sites due to agricultural intensification (known to have occurred)
c.. fragmented nature of remnant heathland sites
d.. lack of sufficient coverage of fragmented sites and marginal areas
e.. large increase in forest clear fell sites of suitable age offering alternative breeding sites
f.. rabbit populations are again falling and being actively reduced which can lead to heathland sites becoming overgrown and thus unsuitable for Woodlarks
Heathland sites if maintained in suitable condition by grazing, preferably by rabbits, and good management offer a more stable breeding environment than forest clear fells. The latter if restocked are a transitory habitat for the Woodlark with most being abandoned after three to five years as the young trees and ground cover make the habitat unsuitable for the larks. Even when such clear fells are maintained as open space areas within forests they need to be managed to prevent them becoming overgrown within a short period of time. Active management is being undertaken in parts of Laughton Forest and further clear felling over the next few years will maintain large suitable areas of habitat there. Similarly at Willingham there appears to be potential for further increases in the population as more forest area is clear felled. Marginal areas around the forest edges may well also pay dividends as the local population expands.
In some of the north-west heathland sites management to clear bracken and graze open heathland sites plus restoration of heathland sites on marginal agricultural areas under various incentive schemes is maintaining and increasing the area of suitable Woodlark habitat in core areas. Creating areas of Woodlark habitat on marginal sandy soils around known breeding areas is one method of increasing the present population and maintaining a core population when forest sites begin to disappear as they will inevitably do as major areas are completely restocked.
Colour ringed birds
Just one colour-ringed bird was located in the county in 2000. By coincidence this bird, a male ringed Orange, Green, Metal, Yellow was found on a clear fell at Walesby within 200m of where the first county colour-ringed male was found in 1988. This male had been ringed in the Breckland area of East Anglia as a pullus on June 30th 1999. It was the sixth colour-ringed male Woodlark from the Breckland scheme to have occurred in Lincolnshire since 1988. It seems somewhat surprising that the number of birds occurring has not increased in line with the number of birds being ringed in the Brecks. The majority of the birds seen in the county since 1996 have been closely scrutinised for rings and the number of birds found with single BTO rings has increased markedly during the same period suggesting a source away from the Breckland area most probably Nottinghamshire.
Occurrence and site occupancy
A party of four Woodlarks wintered at Gibraltar Point from December 1999 to February 2000 when a fifth bird appeared and an odd male was heard in song in March. The origin of these birds is unknown and we still have no clues as to where Lincolnshire breeding Woodlarks spend the winter.
The earliest record of a Woodlark from a known breeding site in the county is February 5th 1999 prior to which February 14th had been a long standing record date.
As in previous years my search for the first Woodlark of the 2000 season started on mild days in late January but it was February 15th before the fluting song of a newly arrived male was heard. On the same date a flock of eight birds were found feeding avidly on a sandy field out-with the forest environs. From observations over a number of years I consider that Lincolnshire's breeding Woodlarks do not winter close to their breeding sites. In spring the first males are usually seen flying over forest clear fells giving often only brief and half-hearted songs and they are clearly not established on any particular territory. In recent years I have also encountered small flocks of birds feeding on fields around the forest edges. These birds seem to be constantly feeding, behaviour typical of birds arrived following an (extensive?) migration. The flocks will on occasions break up and reform as males begin to sing for short periods obviously driven by a opposing necessity to refuel and the desire to establish a territory and attract a mate, before re-joining the flock. Such behaviour is however, short lived and a few days after arrival males will be back on favoured territories with the best sites being occupied first. If the birds were spending the winter in close proximity to the breeding sites it could be expected that males would visit possible territories on suitable warm and sunny days through the late winter. They would presumably be well fed at the start of the breeding season and lack the obvious flocking instinct that is visible in the recently arrived parties. Such small flocks may well have wintered together somewhere. Different breeding sites, as far apart as Kirkby and Appleby are usually first occupied within a few days of each other. This again suggests to me that this may well be as a result of an obvious migratory movement from a common wintering area spurred on by the same set of migratory conditions. Spring arrivals are somewhat protracted. Although the bulk of the breeding population has usually arrived and set up breeding territories by early March, with eggs often laid by mid March, it is clear that some birds are still on the move through to at least late April. The latter may well be first-summer birds which have failed to locate a territory in another breeding site and thus move to possible new areas. Alternatively they could be birds displaced from breeding sites for some reason or maybe just late migrants? Without intensive studies of Lincolnshire populations it is impossible to know just what interchange there is of birds between different locations within and between years so the effects of habitat loss and change are difficult to interpret in the context of Woodlark movements.
Proof that locally reared birds return to breed at Lincolnshire sites has been obtained on a number of occasions. A partially albino female occupied two territories over three years at Laughton in 1987-89 and a colour ringed male ringed as a juvenile in the forest in 1989 was seen on two different territories in 1990 and 1992. More recently a colour ringed male from the Brecks found as a four year old bird at Laughton in 1997 returned to exactly the same territory the following year at the ripe old age of five years having lost two colour rings during the intervening winter. On the other hand a colour-ringed male which nested at Walesby in 1988 had been replaced by a non ringed male in 1989 at a site which held only one pair of birds.
Late autumn Woodlarks are not easy to find in their breeding areas. After the complete moult in July-August even family parties can be very difficult to locate. Indeed some of the breeding sites appear to be quite unsuitable for the species due to summer vegetation growth by August so just where do they go? And how soon do they actually migrate away from the county if we assume they do indeed leave?
The latest recent record of Woodlarks from known breeding sites appears to be that of a flock of 15 birds at Laughton village on October 7th 1998. This flock was feeding on fields adjacent to the forest albeit in an area where a number of pairs breed. Coastal records in September-November appear more likely to refer to continental migrants as they often appear during falls of species from Scandinavia or the near continent.
Summary
The present Lincolnshire population of Woodlarks is at its highest known level. The population is however, dependent upon a very precise and limited type of habitat within the county. Alterations to this habitat, deliberate, accidental or even natural could quickly return the species status to that of a very rare bird. It is hoped that monitoring of the population can be continued but it is becoming increasingly difficult to keep tracks of the expanding number of birds at the present time. Volunteers willing to dedicate themselves to a couple of months of searching in the Kirkby-Woodall area would be much appreciated in 2001.
Woodlarks are somewhat plain in appearance, their plumage subtle shades of buff and brown, and generally unobtrusive in nature but once a male launches into his song flight this is one of the truly joyous sights and sounds of the bird world. To see and hear a male tooodlooing high over a Lincolnshire heath or clear fell is one of the joys of the spring and a truly characteristic sound of the heathland environment. They have a charm all of their own and a fascinating life style about which we still have a lot to learn in the county. Where birds go in autumn and winter are two of the key areas about which we know so little.
Acknowledgements
A number of observers supplied information on breeding Woodlarks during the year and I am particularly grateful to the following; Howard Bunn and the Grimsby area Lincolnshire Bird Club group for surveys at Willingham, Linwood and Walesby, Stuart Britton for information from the same areas plus Osgodby and Ostlers, Andrew Powers Laughton, Niel Drinkall for extensive assistance in survey work in the north-west of the county, M & P Hickerton for reports of the colour ringed bird at Walesby and Andrew Henderson. Forest Enterprise kindly supplied a grant in connection with their Wildlife studies scheme to assist with the census at Laughton Forest.
References
Catley GP 1988 The Woodlark in Lincolnshire and South Humberside Lincolnshire Bird Report 1988 p15-19
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