The CRT is lucky to have three talented Monitoring Officers, this month they met in person at Green Farm to monitor the site as a Team. Dr Vince Lea tells us all about their trip.

Green Farm is one of the CRT’s more specialised sites for wildlife, being mainly a commercial forest operation on former heathland in the Surrey Hills. There are some areas maintained as heathland within the Green Farm holding, some sweet chestnut coppice and an area of grassland, orchard and horticulture. The previous owner, John Broadbent-Jones, bought the land as a conifer plantation, but his vision was to replace this with a mix of native broadleaved trees, with a long-term view to their profitable harvest, something which will not be happening within our lifetimes. This programme is still underway, and the site is a mix of pre-existing conifers still waiting to mature and be harvested, and newly developing broadleaf woodland. The landscape is wonderfully contoured, with deep steep-sided dry valleys cut through the gravel beds, no doubt all post-glacial features.

The main wildlife interest at Green Farm is related to the heathland nature of the site, which develops wherever trees are cleared. Some areas are maintained in this state in perpetuity, requiring regular mowing and management to keep them open, but heathland also develops in the clear-fell areas where conifers are harvested, and persists for several years while the new trees establish. Harvesting blocks of conifers as and when they reach commercial size means that new cleared areas are regularly created, and various compartments are at different stages of regrowth at any one time. This mosaic of different stages of growth means that there is something for a wide range of wildlife. The short, recently cleared areas can be good for pioneering species, especially spiders and the creatures that feed on them, such as common lizards and woodlarks.

As the heathers, bracken, dwarf shrubs and various trees colonise clearings, the vegetation thickens up and it starts to suit other birds, such as nightjars which nest in the cover, various warblers that feed in the thickets and adders which lurk in the cover. As tree growth dominates in later years, the ground gets shaded and loses much of the heathland element, but the mature trees provide a lot more foliage for caterpillars of many species of moth, and the trees produce more and more seed which supports a different array of birds, particularly various finches.

On a recent visit, myself and other members of the wildlife monitoring team Ruth Moss and Andy Fale, saw several woodcock with their peculiar dusk roding flights, and half a dozen moths which flew into the traps we set. We were lucky enough to hear a Dartford warbler on the clear-felled area of heath, which has not yet been recorded during the years I’ve worked for the CRT. This is a species which fluctuates in numbers and is particularly impacted by hard winters but when numbers are good, they colonise new areas of suitable habitat. With maybe 3000 pairs in the UK this is one of the rarest birds to call CRT property ‘home’.

Reptiles are synonymous with heathland, and Green Farm is well known for adders among the regular visitors. We set up a few reptile-monitoring mats with a view to long term monitoring of the numbers. In the orchard, we found some of the pre-existing mats which slow worms were making good use of. Despite their name, these are in fact reptiles, not worms. I’ve never seen slow worms here before, and we are currently investigating if this is a new record for the site or not. On our first inspection there were a male and female slow worm under one mat, on the second day this rose to five females, which, given the poor weather conditions and small amount of the site we sampled, represents a healthy population. The only common lizard we came across was dead with puncture wounds in its flanks (possibly dropped by a kestrel). On sunnier days these species are usually seen.

While the Dartford warbler was undoubtedly the star bird, another rare species made itself known as we concluded our visit at the lovely Elizabeth’s Wood part of the farm; the high-pitched song of a firecrest cascaded down from the leafy canopy of a mature beech. Sadly, like the Dartford, it remained hidden from view as the next shower of rain put an end to our time at Green Farm. This species used to be considered by the ‘Rare Breeding Bird Panel’ which covers all species with around 3000 pairs or fewer; in recent years, the firecrest population has grown, probably in response to a warming climate, but it remains a gem among the bird world and hopefully next time we’ll get to see one of these stripy sprites.