Although Hob Moor is mainly pasture, its boundary hedges are also of interest. If you stand at the centre of Hob Moor and look at the boundaries, you will see a number of hedges that are left to grow naturally. At first glance it seems as though they are all hawthorn, or May-tree, but look closer and you will find many varieties including alder, ash, blackthorn, dog rose, elder, crab apple, elm, etc. and together they make a very significant contribution to the overall ecology of the Moor.
Untended hedges offer food, shelter and breeding sites to all sorts of insects, birds and small mammals. They can also act as a corridor along which animals can move, safe from predators.
Each type of insect has specific habitat requirements and the greater the variety of species of shrub in a hedge, the greater the number of species of insects found there. In Britain, hawthorn supports 150 types of insect. Untrimmed hedges, like those on Hob Moor, attract butterflies, bees and other insects that feed on nectar and pollen. These insects and the larvae of butterflies and moths fall prey to a wide variety of predators, which in turn become food for others.
Hawthorn hedges provide breeding grounds for many birds: the robin, song thrush, blackbird, chaffinch, whitethroat, dunnock and yellowhammer. Because the shrubs are exposed to the light, those allowed to grow naturally produce a heavier crop of berries than those in woodland, and birds visit this larder frequently.
Around Hob Moor, hedges run along the beck sides, usually only on one side. Originally there would probably have been a hedge on each side, perhaps to stabilise the banks and at the same time prevent animals from falling into the ditch, but over time lengths have been removed on one side, probably for ease of access for maintenance of the ditch.
As well as on the boundaries, a hawthorn hedge runs down the centre of North Lane Field, following the curved line of the medieval field-strips. By the 1950s, this hedge had tall trees of other species at intervals along it. These were removed, resulting in a number of gaps which were later filled with new hawthorn bushes in 2006-7.
There are two lengths of species-rich hedge on Hob Moor. The first of these is along the eastern boundary of The Triangle and contains coppiced hazel, English elm, willow, ash, crab apple, elder, holly, oak and blackthorn as well as hawthorn. The second is between Hob Moor and North Lane Field and includes English elm, hawthorn, blackthorn, dog rose, elder and, on the north side next to the beck, guelder rose, which is particularly associated with old hedges. It has a flower-head of pale cream flowers; the tiny central ones are surrounded by larger, five-petalled infertile ones. The leaves are maple-like and toothed. There is also an apple tree which is possibly a hybridised Beauty of Kent and a reminder of the 19th century orchards nearby.
It is generally agreed that the greater the number of species, the older the hedge. Studies have revealed that, for a sample 30m (100 feet) length, each species represents approximately a hundred years of age of the hedge. The two species-rich hedges mentioned above are both along very old boundaries of Hob Moor. The boundary between Hob Moor and North Lane Pasture is marked on Samuel Parson’s map of 1624 and calculating this way gives the age of the hedge as being in the region of six hundred years.
Along the beck separating Hob Moor from The Triangle, between the Holly Bank access and the underpass, the hedge contains alder, ash, beech, dog rose, elder, English elm, wych elm, hawthorn, holly, sycamore, willow and yew.
The hedge along the northern boundary of the Moor is mainly hawthorn but also contains ash, blackthorn, crab apple, elder, English elm, wych elm, holly, poplar, silver birch, yew and some garden shrubs.
In 2006 and 2007 York Council carried out a programme of hawthorn planting on Hob Moor. As well as the section in the middle of North Lane Field mentioned above, a large number of gaps in the hedges all the way round the boundary were filled. Over time, these will grow to provide more natural habitats for the local fauna.