Great joy among bird lovers: the meadow harrier, which is listed as critically endangered on the Red List, has experienced a boom this year. Around 270 breeding pairs of this very slender bird of prey with more than 740 fledged young birds have been counted across Bavaria. “These are record numbers that make us very happy,” says Julia Ott, who coordinates the work with birds of prey at the LBV nature conservation association. In 2022, the LBV registered 156 breeding pairs with 264 fledged young birds. The reason for the boom: This year there were particularly many field mice in the meadow harrier areas. Rodents are the main prey of birds of prey. The parents therefore had plenty of food for their offspring.
Circus pygargus, the scientific name of the meadow harrier, is a medium-sized bird of prey with a wingspan of over one meter. The males are slightly smaller and significantly lighter than the females. The males are also predominantly gray in color, the underside of the torso from the middle of the abdomen and the tail is feathered whitish, the middle of the abdomen is streaked with rusty brown. Parts of the wings are black. The females, on the other hand, mostly have brown feathers, the wings are partly gray or blackish. In addition, their underside is significantly lighter than their upper side.
Meadow harriers are ground nesters. They usually build their nests on dry or slightly moist ground. They used to be found in large numbers in damp lowlands, fens and in the floodplains of river valleys. There you could easily observe them on their hunting flights for mice and small birds. Meadow harriers eat grasshoppers, dragonflies and larger beetles. With the drainage of the wetlands, the population of Circus pygargus collapsed dramatically from the mid-1950s at the latest. Since then, the species has been on the Red List and was temporarily listed in the endangered category.
Today, the vast majority of meadow harriers can be found in grain fields, preferably in areas where winter wheat and winter barley are grown. From mid-May onwards, the females usually lay between three and five eggs in their ground nests. The breeding season lasts just over four weeks and the nestling season lasts approximately another five weeks. This means that the young meadow harriers fledge around mid-July. That’s the problem. The harvest time for winter wheat and winter barley often begins before the young ones go out. However, combine harvesters and other heavy agricultural machinery pose a deadly danger to the animals. The main distribution area of the meadow harrier in Bavaria is Franconia, the Nördlinger Ries in northern Swabia and the Gäuboden in Lower Bavaria.
Free State finances a species aid program
The Free State has had a species assistance program for meadow harriers since 1999. As part of this, LBV volunteers mark meadow harrier nests in the fields so that farmers can leave them out during the harvest in exchange for a loss payment. As a result, stocks have at least stabilized somewhat. “A good and intensive exchange with the farmers is the cornerstone of the meadow harrier program,” says LBV woman Ott. In the meantime, the Bavarian young birds as well as their parents have long since flown to their wintering grounds in West Africa.
By the way, strong annual fluctuations in breeding numbers, such as those between last year and this year, are completely normal for meadow harriers. “The field mouse population is also subject to enormous annual fluctuations,” says Ott. “But normally populations recover from a slump like 2022 only gradually over a few years.” That’s why the current meadow harrier boom came as quite a surprise to the LBV experts.