Other Mammals, Reptiles and Insects Often Associated With Historic Sites

Squirrels

Two species of squirrel are found in England: the endangered native red squirrel (Sciurus vulgaris) and the common, introduced, grey squirrel (Sciurus carolinensis). Very occasionally albino (white) and melanic (black) forms of either species occur.

Red squirrels are a protected species. The population has declined considerably in the 20th century and they are restricted to a few locations in England – principally Northumberland, Cumbria and the Isle of Wight. They are rare and should be safeguarded on sites where they are present; and steps taken to stop grey squirrels invading.

Red squirrels do not pose a threat to trees, plant collections or other wildlife. They are generally extremely shy creatures and are not known to enter buildings or to pose a threat to staff or visitors on sites.

Grey squirrels are not protected and are common in most areas. They originate from North America. The first recorded introduction was in 1876 (although there are recorded sightings of grey squirrels as early as 1828) and this was followed by numerous other releases over the next 50 years. Once it became apparent that this species was spreading unchecked throughout the country a Prohibition Order, preventing their import or release, was issued in 1937.

Populations can reach proportions where damage is done to other wildlife, trees, gardens and properties. They will strip bark from trees particularly when their numbers are high. Bark stripping is extremely disfiguring to trees and can be lethal; it is therefore a serious risk in historic parks, woodlands and tree collections.

Grey squirrels can also damage other wildlife, particularly birds, stealing both eggs and nestlings. They are much bolder than their red cousins and are often found to enter roof spaces where they will gnaw cables and pipes. In many places they appear tame, but people forget that they are wild animals and over familiarity can result in painful bites or scratches.

In such situations you should take measures to control the squirrel population. It is an offence under the Wildlife & Countryside Act 1981 to release grey squirrels into the wild. This means that squirrels caught in non-lethal traps must be humanely destroyed and cannot be released elsewhere. The Forestry Commission provides guidance on managing threats to woodland from destructive animals like squirrels. Management measures are eligible costs in Countryside Stewardship grant schemes.

Great crested newts and other reptiles and amphibians

In England there are seven native amphibians all of which are protected under the Wildlife and Countryside Act 1981:

• Frogs and toads - common toad (Bufo bufo), natterjack toad (Bufo calamita), common frog (Rana temporaria), pool frog (Pelophylax lessonae)
• Newts - smooth newt (Triturus vulgaris), great crested newt (Triturus cristatus), palmate newt (Triturus helveticus)

There are also a number of non-native amphibians which have been introduced and become established in different parts of England, including two newts, two toads, seven frogs and the fire salamander (Salamandra salamandra).

There are three native snakes and three lizards:

• Snakes - grass snake (Natrix natrix), smooth snake (Coronella austriaca), adder (Vipera berus)
• Lizards - common lizard (Lacerta vivipara), sand lizard (Lacerta agilis), and the snake-like, legless slow worm (Anguis fragilis)

In addition, there are a number of non-native species which have been introduced and have become established in different parts of England. In particular this includes the red-eared terrapin (Tracemys scripta elegans) which is particularly devastating to native wildlife.

Natterjack toads, great crested newts, sand lizards and smooth snakes are also protected by European Directive.

Loss of habitat is the main reason for the decline of newts, reptiles and amphibians so sites which retain features such as moats, ponds, caves, boundary banks, old hedges, meadows, or scrub in their grounds are valuable. Some species may shelter in old walls.

The Amphibian and Reptile Conservation trust publishes a habitat management handbook.

Insects

Many historic sites, like parkland and wood pasture are important habitats for invertebrates such as butterflies, moths and beetles. BugLife's leaflet explains the importance of these habitats and how to help protect wildlife through sensitive management of sites.

There are very few native insects which cause damage to historic building exteriors, or to landscapes.

However, there are a wide range of insect pests (both native and introduced) which can cause problems to the interiors and contents of historic houses. Our Practical Building Conservation book on timber includes advice and guidance on insect damage. There are a growing number of invasive insects that are threatening our trees and other plants. The Forestry Commission provides guidance on individual tree pests and diseases.

There are 49 native invertebrates (butterflies, moths, beetles, crickets, dragonflies and spiders) protected under the Wildlife and Countryside Act 1981. All of these insects are rare and although some may be found on historic sites they are unlikely to cause damage. Veteran trees in historic parks are notable as important habitats for rare beetles and other insects.

• Pollinators

Bees and other pollinator insects play a crucial role in biodiversity and food production. Many insects, especially bees and wasps, are important pollinators and there are 'Bees Needs' initiatives underway as part of the government’s National Pollinator Strategy to ensure a thriving population. Historic site managers could consider whether there are opportunities to grow more pollen-rich flowers, shrubs and trees; let patches of land grow wild; cut grass less often; and not disturb insect nests and hibernation spots or use pesticides. The Royal Horticultural Society provides advice on native and non-native plants for pollinators.

• Masonry bees

The only native insect species likely to cause damage to historic structures are the solitary masonry bees, most commonly the red masonry bee (Osmia bicornis).

The females bore into soft crumbling mortars, and occasionally sandstones and limestones, to create tunnels to lay their eggs. The bees plug the holes, the eggs then hatch, and the larvae develop, pupate and hibernate over winter before emerging as adults in late March/April. The bees are often opportunistic and use existing spaces such as old nail holes or grilles, or gaps between stones and tiles. As well as clusters of bees buzzing around the wall from late March to June, and the little holes, you may see small freshly broken chippings on the ground.

Damage is usually minimal although sometimes females are attracted together to form groups and their prolonged activity can cause serious damage. Extensive burrows can undermine the integrity of the mortar and add to the deterioration of the wall.

Repairing the mortar can help break the bees' cycle of using the wall for nesting. Installing an 'insect hotel' can help provide alternative habitation for the bees.

• Stinging insects - honey bees, wasps and hornets

Honey bees, wasps and occasionally hornets will sometimes use buildings or trees for their nests. Where the entrances to these nests are near to staff or visitor routes safety concerns will arise. All three species, but particularly honey bees, will aggressively defend their nests and human activity nearby can provoke a response.

Hornet and wasp queens overwinter as individuals and build a new colony from scratch each year. If nests start to appear in inappropriate places then control at an early stage, before large numbers have built up, is advisable. There are no legal restrictions on control.

Honey bees are most likely to appear suddenly in a large swarm, detached from an existing colony, with a queen in the centre. These often rest in a place while scouts look for a suitable new home, so may only stay a few hours. If they find a suitable site and take up permanent residence in a place unsuitable for site safety, removal is the best option. Bee swarms are regularly sought by beekeepers and most will happily come out to site and expertly remove a swarm for free. The British Beekeepers Association will help you connect with local swarm collectors.