Magpies
(Pica pica)
Eye-catching, cunning and aggressive are all terms used to describe magpies. Eye-catching for their plumage, cunning due to the persecution they have received from gamekeepers over the past 250 years, and aggressive in their manner of raiding songbird nests for eggs and fledglings.
The magpie has always been associated with a degree of mythology, and it became a symbol of ill omen. This was in part due to the fact that it is a well-known thief, and its chattering calls during large gatherings in 'parliaments' aroused suspicion. This suspicion is revealed in the popular rhyme: one is sorrow, two is mirth, three a wedding, four a birth, five heaven, six hell, seven the devil's own soul. A slightly kinder version is: one for sorrow, two for joy, three for a girl, four for a boy, five for silver, six for gold, seven for a secret never to be told.
Magpies are distributed widely throughout the UK, their population increasing at the average of about 6% per year since about 1940. This increase has largely levelled out since the early 1990s and is currently fairly stable. The expansion in population has largely coincided with the fall in the numbers of gamekeepers from 25,000 in the early 1900s, and who now number in the region of 4,000. Gamekeepers treated magpies as vermin and controlled their numbers by every means possible. Many of the methods used are no longer legal.
The distribution pattern within the UK has also changed over the past 30 years, with an increasingly higher population in urban and suburban areas, showing the adaptability of the magpie. This has led to a degree of alarm within some local councils about the effect that they may have on songbird populations in their locality. In Denmark many local councils control the number of magpies, but it is not known if any do in the UK. However with urban songbirds following the same pattern of decline as their country cousins, it is a course they may well have to consider.
The density of magpie numbers over a given area is dependent on three main factors: the availability of food, the number of suitable nest sites, and lastly whether the area has a large proportion of game rearing land, where the magpie numbers are controlled. The area of land which a pair of magpies require as their territory for nesting is between four and six hectares (10-15 acres) and they will defend this territory aggressively against any other magpies. If all the main factors are in their favour, they can reach a density of up to 25 breeding territories within a square kilometre (65 per square mile). It is estimated that there are about 590,000 territories throughout Britain, mainly in the west and south. These territories become much fewer the further north you travel in Scotland. If the juvenile birds, which rarely mate in their first year, are included in the overall population figures, a total population of around 1.8 million magpies within the UK is arrived at. It is one of the most common and widespread birds in Europe, with an estimated population of between 7-12 million breeding pairs.
A breeding pair of magpies will take about five weeks to build their characteristic dome shaped nest during March and early in April. This nest is made out of twigs and lined with roots or grass. Sometimes the roof is made of thorny twigs to deter any predators, and the entrance to the nest is well concealed. Egg laying starts in April and the usual number of eggs laid is between five and eight. The incubation period is around nineteen days and is carried out entirely by the female. Once the eggs have hatched the fledglings are fed for about twenty seven days before leaving the nest and they remain with their parents until September.
Magpies are omnivores living on a diet of insects, cereals (maize), fruit and berries, carrion (road kills), household waste, plants and vertebrates. The most notorious part of their diet is the plundering of the nests of other birds, taking both eggs and chicks, and this predation has an effect on the populations of some of our songbirds. The cunning ability of a magpie to 'work' a hedgerow or garden in search of nests, or to sit quietly and watch the coming and going of nesting birds, and thus locate their nest is unsurpassed.
Opinion differs on the magnitude of the effect that magpie predation has on songbird numbers. We know that it is much larger than some bird protectionists would try to make out, especially amongst those songbirds which nest within the hedge or shrub framework, eg song thrushes, blackbirds and certain finches.
New research recently published in the Journal of Applied Ecology showed that where there were no magpies present, the reproductive output of song thrushes was much greater. This was well illustrated by two maps, one showing the distribution of magpies in Britain, the second showing the breeding success of song thrushes, and they demonstrated perfectly that where magpies were absent song thrushes thrived. A report entitled 'Large-scale spatial variation in the breeding performance of song thrushes and blackbirds', written by biologists from the British Trust for Ornithology (BTO) and the University of East Anglia, concluded that nest failure rate during incubation increased significantly where Corvids were present, and that most predation was by the smaller Corvids, particularly magpies. The significance of this report is that it is very large and thorough, and backs up the work performed by other biologists on nest predation in urban parklands by magpies, which is having a considerable impact on the local blackbird population.
Science is now proving what the gamekeepers of past years knew, that magpie predation of nests and fledglings is having a considerable impact on the reproductive capacity of other birds, and that their numbers must be controlled if we are to succeed in increasing our songbird population.
Provision is made for the control of magpies under the Wildlife and Countryside Act 1981. Licences to kill or take certain birds are the responsibility of Department of Environment, Farming and Rural Activities (DEFRA) in England, but Scotland, Wales and Northern Ireland have different arrangements.
The website www.defra.gov.uk has all the necessary addresses and contact numbers in its wildlife-countryside section. A copy of the General Licence to Kill or Take Certain Birds can be down loaded from this site. The licence does not require a specific name to be recorded, but it does have strict conditions attached to it. Magpies are one of thirteen species named on the licence which can be controlled by shooting or by the use of cage trap or net, or by any method not prohibited under Section five of the Wildlife and Countryside Act 1981.
© Estate of C.F. Tunnicliffe
The cage trap, often known as the Larsen (or Larsson) trap, is the most widely used method and is very effective. On some estates numbers in excess of 100 magpies per year are controlled by this method. The Larsen trap does have a number of licence conditions attached to it which state that it must be inspected every day, any birds caught should be removed immediately and killed quickly and humanely. When the cages are left in the open, but not in use, they must be rendered incapable of catching birds. It is the responsibility of the person using a Larsen trap to be well aware of the conditions of its use. In addition to the General Licence there are other licences under which magpie numbers can be controlled. These are WLF 100087, 100088 and 100089, which cover the destruction of nests and eggs. The latter (100089) allows the use of a decoy bird in a Larsen trap. The species included on this licence are crow, jackdaw, jay, magpie and rook.
The Larsen trap is a very simple and highly effective means of controlling magpies. In general terms it is a wire cage with three compartments. One compartment (half the cage area) is where the decoy bird is kept, and has a sliding door which enables the bird to be fed and watered. The other half of the cage is divided in two, and has a spring loaded door on the top of each section. This is held open against spring pressure by a piece of wood, which has been cut through in the middle. To the quarry it appears as a 'perch' on which it can sit to mob the decoy bird. The weight of the quarry on the 'perch' causes it to collapse downwards due to the fact that it is in two pieces. The quarry goes to the bottom of the cage and the spring-loaded door closes the top of the cage.
The control of predators like the magpie has resulted in dramatic increases in the songbird population, especially song thrushes, which has been admirably demonstrated by the Game Conservancy at their site at Loddington. The magpie is just one of the many predators, whose numbers have increased dramatically over the past 30 years, which has coincided with the large population decline in our songbirds and they are currently keeping a lid on any sustainable recovery in songbird numbers. Agri-environmental schemes will not succeed without the management of predators.