Montagu's Harrier - Population Trends

Population Trends

The population for the western Palearctic is estimated at 35,000–50,000 pairs. The global population is unknown and could be anything between 150,000 to 200,000 individuals(Birdlife International, 2004). This uncertainty is due to the fact that most of the world's population is situated in Russia and former Soviet republics where it is not quantified.

The evolution has been paradoxical throughout the 20th century. In the beginning of the century up to the 1940s, during a period when other raptors greatly decreased because of human persecution, the Montagu's Harrier actually increased its population and breeding range, breeding for the first time in Denmark in the 1900s, and greatly increasing elsewhere. However, from the 1940s onwards it has decreased rapidly. This is due to several negative factors: first, the massive use of agricultural pesticides such as DDT and other environmental poisons was extremely detrimental to the harriers themselves, as well as rarefying their prey, in particular large insects. The modification of agricultural practises, with an evolution towards more intensive farming also puts pressure on harriers, with faster growing crops preventing those birds that nest in farmlands from finishing their nidification before their clutches are destroyed by harvesting machines. Despite a generally negative trend there are local cases when the population has increased, such as in Sweden or in Germany in the 1990s. These local trends show that while they have access to suitable habitats and food supply there can still be positive developments.