Bees, Butterflies and Other Wildlife
Accompanying the loss of flower rich meadows, hedgerows and other valued habitat recorded over the last 50 years, there has been a decline in the insects, birds and other wildlife that depend upon them. Naturalists are reporting reductions in numbers in a wide range of species. Notably this includes common species that we may take for granted like the skylark and house sparrow as well as rare and specialised animals that one might expect to find in a nature reserve.
Since Emorsgate first started promoting wild flower seed mixtures in 1980 many thousands of acres of new plant habitat have been created with the hope that at least some of the losses of plant habitat diversity can be offset. Whilst these newly created habitats cannot replace the value of ancient sites lost or damaged they have, over time, proven their worth as a new resource for wildlife.
Increasingly people are asking how they can maximise this potential and add value for specific types of insects, birds, reptiles or mammals. Specific advice is sought either as part of a local policy or BAP (Biodiversity Action Plan), targeting particular species or habitats in decline, or simply to develop or promote the interests of particular individuals or groups.
In general terms, to be successful animal species need to be able to find the resources they require to complete their lifecycles. They need food and they need shelter. Plants sit at the bottom of the food chain and so directly or indirectly provide food in the form of leaves or pollen and nectar. Plants through the structure of the different vegetation types also offer shelter which may include nest sites in which to lay eggs or rear offspring and hibernation sites in which to overwinter.
For diversity of wildlife it is good therefore to have a diversity of plant species and also a diversity of vegetation structure. It is perhaps important to point out at this stage that all the elements an insect or bird species require to complete its life cycle will not always occur within one habitat. A flower rich meadow for example will be a rich source of pollen and nectar in summer, but after hay removal and through the winter is a poor refuge for many animals who may have to move to woods and scrub. In this way the location, arrangement and connectivity of a habitat is as important as the habitat type.
Our advice is firstly to sow and plant wild flowers and create plant communities for their own sake for their natural beauty and diversity. Research and our own experience over many years is that sowing wild seeds to create meadows and other new habitat does yield real benefits for insects and other wildlife. We believe that taking a holistic approach to sowing and managing botanically diverse habitats is the best way to provide the universal requirements for food and shelter for the widest variety of animals. The complex and often poorly understood requirements of the many species we may wish to encourage limit the rewards that can be expected from a more targeted species by species approach.
To thrive, bees need a continuous supply of suitable pollen and nectar from early spring, through summer and into autumn. Bees will collect from a variety of species but do show strong preferences for legume species. When available, legumes (Birdsfoot Trefoil, Clovers and Vetches) can make up 60% of the pollen loads of bumblebees, and red clover in particular may account for 30%. Clover alone however will not supply a continuous or reliable source of pollen and nectar and other species are also very important.
Areas with a high density of suitable flowers are most attractive to bumblebees and flower rich meadow and grassland mixtures are the most dependable resource for foraging bees, offering both a quantity and diversity of pollen and nectar with plants such as selfheal, yellow rattle, knapweeds and scabious being particularly sought after. Cornfield Annual seed mixtures containing species like cornflower and corn marigold can also provide a very rich if only temporary source of pollen and nectar.
Bumble bees also require suitable places in long grass, banks or hedgerows in which they can nest. These sites are easy to provide and studies show that it is not lack of nest sites that limits the success of bumble bees but lack of pollen and nectar.
Butterflies and Moths
The life histories of butterflies and moths are complex, with caterpillars and adults having quite different food and habitat needs. Some species are quite mobile and as adults can easily move to find new habitat to meet their needs, other species are more sedentary/fixed and need to find all their requirements for nectar, larval food plants and over-wintering hibernation shelter within the same location.
Adult insects mainly feed on nectar and need habitats rich in flowers at the time of year they are in flight. Flower rich meadows and grassland offer a diversity of nectar sources which attract butterflies and moths. Nectar rich plants like Birdsfoot Trefoil, Knapweeds, Vetches and Clover are important, particularly for those species associated with grassland such as meadow brown, gatekeepers, skippers and common blue. Plants whose flowering period coincides with the flight period of particular species are particularly well visited. Later flowering field, small and Devilsbit Scabious are all very attractive to later broods of Tortoishells, Peacocks and Commas, as are wild marjoram on chalky soils and hemp agrimony and fleabane in wetlands.
Larval food plants
A key habitat requirement for all species will be the availability of suitable food plants for caterpillars. Grasses are larval food plants for a large number of butterfly and moth species. Some species like skippers and ringlets prefer tall coarser grass species, others like gatekeepers, meadow browns and marbled whites prefer fine grasses such as bents and fescues. Other food plants worth noting are Birdsfoot Trefoil for Common Blue, Garlic Mustard for Orange Tip and Green-veined White, and Common Sorrel for Small Copper. All these species are easily provided as common components of meadow seed mixtures, or hedgerow/woodland mixtures in the case of garlic mustard. In practice the contribution sowing these food plants makes to population sizes of a given species will vary.
We have observed an increase in Common Blue butterflies wherever we have grown Birdsfoot Trefoil on our Norfolk farm. Common Blue butterflies are a relatively mobile species and its food plant, Birdsfoot Trefoil, was not common locally until we started growing it. In contrast there is probably rarely any benefit in planting or encouraging nettles as a food plant for small Tortoishells, Peacocks and Comma butterflies as it occurs so widely and abundantly in all environments that it is never in short supply. And finally we sadly cannot make any claims that if you sow milk parsley you will attract a breeding colony of Swallowtail butterflies!!
The vegetation structure and management (=disturbance) of a site is also important and requirements can vary from species to species. For meadow brown butterflies the ideal habitat is traditionally cropped hay meadow (hence their name) where eggs can be laid after the hay has been cut mid summer. The caterpillars emerge and feed on the young autumn re-growth until they hibernate as part grown caterpillars at the base of the sward. Gatekeepers need shrubs as well as grassland and can be found at the edges of grassland in woodland rides and hedgerows.
Many species overwinter as caterpillars or pupae in the tussocky base of grass plants and will need some areas of rough undisturbed grassland to take refuge in. Continuously mown or grazed grassland is of limited use for many insects and even seasonal cutting of meadows can be quite disruptive for some species. In locations that are not over-managed there are usually rough corners and margins that if left undisturbed can provide a good refuge. In managed landscapes and gardens it is good to leave some grassland uncut through winter or perhaps sow a dedicated area with tall tussocky grasses (mix EM10).
Grasshoppers, Beetles and Others
Like bees and butterflies the basic habitat requirements of most other insect groups are for food and shelter. Some insect groups include species which are predatory or parasitic on other insects. The diversity of these species will reflect the diversity of host plant pollen and nectar feeders, and the diversity of these will in turn be affected by habitat and plant diversity. So once again by maximising the quantity and diversity of flowers for pollen and nectar, and plants for larvae and vegetation structure, the overall chances of attracting wildlife to your site are maximised.
Meadows and other areas of long grass are particularly valuable. You will notice the success of new areas of meadow grassland for grasshoppers and crickets when you hear for the first time their chorus on a summer day. The specific associations of plants with insects are too many and complex to mention, with many still to be discovered, but that is part of the interest in sowing a wide range of plants. Some plants seem to attract a diversity of bugs and other insects, such as hedge woundwort, others seem to have specific associations as figwort does with wasps for nectar. It has been shown that meadows and other diverse plant communities are important for hoverflies and predatory ground beetles which are important for pest control. These habitats undoubtedly also provide resources for pest species, but with a healthy functioning ecosystem both pest and predator are maintained and a balance is more assured.
When planning a sowing with bird interest in mind the first thought is often to try and provide seeds for seed eating birds. Teasel, Knapweeds and Goatsbeard are certainly very attractive to Goldfinches when we grow them as seed crops! For other birds which eat seed it is often the larger grains of annual wild flowers, weeds and crops that are most attractive. A sown cornfield annual mixture with Cornflower, Corn Marigold and Forget-me-not can be good and these sowings often also allow space for other annual weeds like Groundsel, Fat Hen and Knotgrass.
For many birds, however, it is not the supply of seed that is important so much as the supply of insects and grubs to provide protein rich food for rearing young, even for those species which we may regard as seed eaters. In this regard it is the diversity and volume of plants and vegetation that determines the range and quantity of caterpillars available; and for this sowing meadows, rough grassland and enhancing hedgerows and woodland pays dividends. For owls, kestrels and other birds of prey, tall grasses and meadows also provide good hunting ground as they are excellent habitat for voles and other small mammals.
Habitat and vegetation structure can be important as with other wildlife. Lapwings and Skylarks for example need some open space in short grazed or mown turf for ground nesting; other birds such as Tree Sparrows need dense cover for nesting as provided by hedges, woodland and scrub.
Small Mammals and Other Animals
The basic requirements for all animals are food and shelter. Grassland that is managed by mowing and grazing as meadows or pasture is best at providing a diversity of fresh nutritious herbage, whereas undisturbed infrequently managed areas provide the best shelter. Sites which provide a mosaic of both in space or over time offer the best overall potential for wildlife, and this is usually achieved through management and the timing and frequency of this management. Water voles, for example, benefit from a management plan in which waterside banks are only cut and cleared in short sections at any one time to provide patches of fresh vegetation near the waterline alongside areas of uncut rough cover for shelter. For many species it is the overall diversity of both plant species and the insects they support that yields benefits. A meadow that supports a wide variety of moths for example makes excellent night hunting for bats.
Clovers in seed mixtures
Red and white clover are natural components of many ancient meadows and grasslands. However simply adding clover to a wild flower seed mixture (especially cultivated forms) is not generally recommended, as their vigour and ability to fix nitrogen tends to push the sward to a more fertile grassy condition, creating management difficulties and a loss of overall diversity. Clovers (especially red clover) are also very prone to ‘boom bust’ cycles from year to year. Cultivated red clover will typically dominate the sward in the first two years, and then disappear completely in year three giving bee populations no long term stability. Within farmland environmental schemes ‘pollen and nectar’ mixtures based on clover are a popular and cheap way of providing a short term abundance of nectar. They are of some use if re-sown every 2-4 years and planned with other more diverse long term wild flower rich habitats to provide continuity. Clovers sown in other contexts (eg sown with lawn or grazing mixtures) can be of some benefit to foraging insects.