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Useful links:
A fifty year vision - HEF's Biodiversity Action Plan

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Herts and Middlesex wildlife trust website

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Herts Bird Club

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Herts & Middlesex Butterfly Conservation

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English Nature

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Herts & Middlesex Bat Group

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Current report

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Disclaimer

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Wildlife

Hertfordshire's wildlife remains in balance

Hertfordshire's biodiversity is essential to our inspiration and enjoyment whilst indicating the health of our environment. The impact of built development and intensive farming are weighed against environmentally-friendly developments and agri-environment schemes aiming to deliver wildlife-friendly farming. Understanding how this affects our wildlife and natural environment remains a prime concern.

Indicator WH1 - Water voles¹

Water vole

Water voles are perhaps Britain's most rapidly declining mammal. Now extinct in many rivers across the country, 1990s national surveys show over 90% have disappeared in just a few years. Intensive agriculture, inappropriate river management and predation by the American mink, against which water voles are defenceless, have all contributed to the decline. The Hertfordshire Water Vole Project carried out surveys between 2004 and 2006 along 50kms of rivers, ditches and lake banks. Overall it found that 24% of sites surveyed had signs of water vole activity with strongholds remaining on the River Chess, River Mimram, River Purwell and parts of the Lea Valley. American mink were also recorded on all main rivers in the county.

Indicator WH2 - Birds²

The British Trust for Ornithology's Breeding Birds Survey (BBS) records 70-80 plots in Hertfordshire annually to identify national bird population changes. Four species were selected to measure the quality of particular habitats or land-use types in the county. Below are a summary of the results from the 2005 BBS Report and the 2003 Hertfordshire Bird Report.

1. Wetlands Indicator - Grey Heron

Grey Heron

This bird is listed on the national Green List of Birds of Conservation Concern. Nationally its population increased by 10% (1994-2005). Whilst its population declined in the Eastern Region by 3% (1994- 2005) this was an improvement over last year's 28% rate of decline. In the county the number of sites being used to record breeding (numbers of nests) rose from 2 to 7 sites. Amwell Gravel Pit's nests increased from 15 to 25, Verulamium Park reduced from 18 to 15 whilst the new sites at Broad Colney, Brocket Park, Frogmore Gravel Pit, Stocker's Lake and Wilstone Reservoir had 1, 28, 6, 12 and 27 nests respectively.

2. Farmland Indicator - Skylark

Skylark - Photograph: Tony Blake

Nationally skylarks are on the Red List of Birds of Conservation Concern and Biodiversity Action Plan species. Between 1994 and 2005 numbers declined in England by 18% and by 20% in the Eastern Region. In the county numbers increased by 1% (2002-2003).

3. Woodlands & Mixed Farmland Indicator - Song Thrush

Songthrush - Photograph: Tony Blake

Although widespread, this bird is also on the national Biodiversity Action Plan species list and Red List of Birds of Conservation Concern. Numbers rose in England by 14% but declined by 18% in the Eastern Region(1994-2005). In the county numbers increased by 1% (2002-2003).

4. Urban Environment Indicator - House sparrow

House Sparrow

Classified on the national Red List, numbers in England fell by 9% during 1994-2005. Regionally, they also fell by 24% but in Hertfordshire numbers rose by 2% in 2002-2003.

Indicator WH3 - Wildlife Sites³

Wildlife Sites are the most important places for wildlife outside legally protected land such as Sites of Special Scientific Interest (SSSI's). Hertfordshire now has 1984 sites which cover about 10% of the county and are key to achieving biodiversity conservation in the wider countryside. Along with statutory sites and nature reserves, they are central to the county's natural assets, playing a vital role in Hertfordshire's Biodiversity Action Plan. Given knowledge of Wildlife Sites, owners, planners and conservation bodies can make informed decisions about the future of these sites to help protect and maintain the county's biodiversity. Over 430 planning applications affecting Wildlife Sites have been assessed or responded to by the Wildlife Sites Partnership. In 2006 a team of volunteer surveyors also carried out botanical surveys on 43 Wildlife Sites across the county to assess their continued value.

The Hertfordshire Wildlife Sites Partnership is coordinated by a Wildlife Sites Officer. It consists of a number of conservation and farming organisations. For more information contact the Wildlife Site Officer at Herts & Middx Wildlife Trust (HMWT) on 01727 858901 or visit their website www.wildlifetrust.org.uk/herts/.

Wildlife sites in Hertfordshire

District	No.of WS	Total no.of sites notified	Percentage notified
Broxbourne	91	66	73
Dacorum	246	209	86
East Herts	609	450	74
Hertsmere	129	102	80
North Herts	343	277	80
St Albans	197	147	74
Stevenage	41	36	75
Three Rivers	150	110	74
Watford	33	22	65
Welwyn Hatfield	207	168	81
Total	1984*	1587	80

Source: Herts Biological Records Centre (HBRC) and HMWT³ - disclaimer
*The total number of Wildlife Sites is less than the sum of individual district because some sites cross district boundaries

Indicator WH4 - Bats⁴

Some bats hibernate in underground sites during winter. Since the 1990s licensed members of the Hertfordshire and Middlesex Bat Group monitored ten sites, making a count each January and February, giving an annual population trend for 1997- 2004. Natterer's bats, a Hertfordshire Biodiversity Action Plan species, were most numerous (48%) followed by Daubenton's bat (41%) then the Brown Long-eared bat (10%). Under 1% were found to be Pipistrelle and Whiskered/Brandt's bats. Overall, the total number of bats increased until 2001 but now there appears to be a steady decline to 1998 levels. (At the time of going to press no new bat data was available so this information is from 2005.)

Bat counts

Source: Hertfordshire and Middlesex Bat Group 2006
download and view this data in excel - disclaimer

Indicator WH5 - Butterflies⁵

2006 was both a good and bad year for butterflies in Hertfordshire. National news stated that 17 species had become extinct in the county over the last century - more than anywhere else in Britain. Media interest in this story reached a peak on July 24th. Ironically this was the same time as butterfly enthusiasts all over the county reported seeing the Silverwashed Fritillary which became extinct as a breeding species around 1985! The best year for over 20 years for this species, they are now believed to be breeding at Bricket Wood after wide open rides and woodland clearings were established.

BAP species of conservation concern

There were good signs for the Dingy Skipper, Grizzled Skipper and Green Hairstreak, which have shown worrying declines in recent years. Analysis of data collected showed that all quadrupled in 2004-2005. However, their numbers are still very low - 87 for all three species - with most of the increases being at one site, Tring Park. The Purple Emperor continued to thrive and in 2005 was recorded in 19 sites in six 10km squares. Its presence in the National Nature Reserve at Broxbourne Woods now attracts regular crowds of photographers during July, a positive story for a butterfly considered virtually extinct in the county ten years ago.

1. Chalk grassland species

Chalkhill Blue - Photograph: Tony Blake

Chalkhill Blue numbers remain constant at known sites in the north and northeast with the occasional sighting in the far west at Aldbury Nowers raising hopes that it may return there.

2. Neutral grassland/damp meadow species

Brown Argus - Photograph: Tony Blake

The number of Meadow Brown substantially rose by 51% in 2004-5, but the Marbled White fell by 18% during the period. Both Marbled White and Brown Argus, which used to be confined to chalk, have greatly widened their range in recent years with 28% more of the latter species found in 2005 than 2004. New sites were mainly across central Hertfordshire and include wasteground and road verges.

3. Acid grassland/heath/bracken species

Small Copper - Photograph: Tony Blake

Numbers of Small Heath butterflies remained about the same but the Small Copper continues to show serious decline with numbers being down 40% this year for the second year in a row.

4. Mature broad-leaved woodland species

White Admiral - Photograph: Helen Bantock

Although numbers at monitored sites remained constant, the White Admiral butterfly extended its range by 70% in 2004-5, turning up not only in new woodland sites but also in private gardens too.

5. Woodland ride and glade species

Silver Washed Fritillary - Photograph: Tony Blake

Since 1985 the Speckled Wood butterfly has spread across the county from a few sites in the far west. Numbers at monitored sites showed a slight drop of 7% in 2004-5 but this was coupled with a 4% rise of sites where it was found. The most dramatic event for woodland glade species was the return of the Silver-washed Fritillary (see above) but appropriate management such as coppicing, to create open habitats, is critical. Numbers of Purple Hairstreak remained constant but the White-letter Hairstreak grew by 42% in number and 81% in range.

6. Scrub/hedgerow species

Gatekeeper - Photograph: Tony Blake

The number of Gatekeeper butterflies rose for the third year running and was reported from more sites. The number of Ringlet butterflies remained constant but its range expanded 21% and it is gradually extending into south central Hertfordshire.

Overall, the picture looks hopeful for some butterflies but their future remains in delicate balance. Climate change may provide opportunities for many species, but the loss of wildflower meadows, heathland, woodland rides or clearings and lack of appropriate management, will impede the survival of other butterflies. Even successful woodland species require open habitats for critical parts of their lifecycles. The perception that felling trees is harmful and that leaving or planting trees is always beneficial does not take account of ecological dynamics. This belief must be challenged where appropriate to secure the survival and recovery of certain species.

Indicator WH6 - Condition of SSSIs⁶

Sites of Special Scientific Interest receive statutory protection for their biological or geological interest. By October 2006, within the county, 70% (by area) of these were considered by English Nature to be in generally favourable condition. In terms of individual units assessed, 88% of open water units were considered favourable, 56% of grasslands/heaths and fens and 74% of woodlands were favourable and the rest of these were unfavourable. In general this represented an improvement over 2005 although not all sites are regularly recorded each year. Open grassland habitats that require grazing continued to suffer from a decline in both livestock and willing graziers. Rising deer numbers also remain an issue in woodlands. These problems affect management of the wider countryside as much as protected sites, although progress in new agri-environment schemes may begin to address some of these issues.

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