Intensification of grassland management
Tuesday 23 July 2013, by
All the versions of this article: [English] [français]
The intensification of grassland use varies from region to region. Measures such as drainage, flood control and fertilization allow ever earlier mowing. The more frequent dry conditions in Spring in the Loire Valley tend to alter plant cover and encourage farmers to use intensive inputs, allowing several annual mowing operations.
Increased mechanization, earlier mowing and faster mowers are leading to a significant increase of mortality during mowing. The earlier mowing destroys broods, both eggs and chicks, and inhibits egg-laying. In breeding areas, some fields occupied by breeding Corncrakes may be cut within a few days, often in June, whereas, in the past, these areas were cut over a longer period, providing opportunities for Corncrakes to take refuge. Thus, the habitat can quickly become unsuitable for the Corncrake.
In addition, the brooding females themselves are often killed during incubation, including when they are accompanied by chicks. It is estimated that conventional and early mowing kills more than 80 % of young and adults; when the mother bird is killed, mortality is particularly heavy, since the younger birds are unable to find their own food during the first week. Adults are especially affected during the post-nuptial moult when the flight feathers are lost simultaneously. Although unable to fly, they would still be able to escape quickly enough from the mower provided it was not too fast and efficient.
Most of the alluvial flood plains located near the large French rivers are concerned. In terms of sites still occupied by the Corncrake in recent years, the threat is particularly high in the Charente valley, both upstream and downstream.
- Restriction or inhibition of laying eggs or rearing broods by the Corncrake.
- Limitation of trophic resources due to plant cover depletion ;
- Direct destruction of nests, inability to produce young which might have returned to breeding sites the following year
- Destruction of breeding Corncrakes.