Hunters Use Thermal Drones to Save Ground-Nesting Birds from Farm Machinery

Drones and thermal-imaging devices, used by people who understand both farmland and wildlife behaviour, are becoming a practical tool for saving hundreds of chicks each spring. In this case, the conservation work is being led by local hunters and gamekeepers.

The impact of farming on bird reproduction is one of the major concerns for conservationists. That includes hunters who are using modern technology to reduce direct mortality caused by agricultural machinery during forage cutting, cereal harvesting and other mechanised field work.

Scientific studies have shown that ground-nesting birds are especially vulnerable because their eggs and chicks remain hidden in vegetation at times that often coincide with farm operations.

Mowing, harvesting, haymaking, ploughing and sowing can destroy entire nests, kill chicks that are not yet able to fly and even kill incubating females. Researchers around the world have documented the problem, including in Canada in a remote-sensing study on the impact of mowing events on habitat selection by the Eurasian curlew.

Researchers have estimated that mechanised farming operations are a significant source of mortality for many breeding birds in agricultural landscapes, to the point that they can become a relevant demographic factor at population level.

The curlew case: one of the best-studied species

The Eurasian curlew is one of the European waders whose relationship with mowing has been studied in the greatest detail. Recent research in European agricultural grasslands has shown that curlews significantly change their habitat use after mowing events.

The authors found that the birds increase their activity in newly mown fields, illustrating how strongly agricultural practices can influence breeding behaviour and chick survival.

At the same time, numerous conservation programmes in northern Europe have identified early mowing as one of the main threats to the species’ breeding success, because chicks remain hidden in vegetation for several weeks after hatching.

Hunters saving curlew chicks

Today, however, tools are available that can help reverse some of the consequences of agricultural work.

British hunters and gamekeepers describe the work in these terms: “Modern game management focuses as much on conservation and habitat creation as it does on protecting gamebirds. On our estates in the Yorkshire Dales, the two are closely connected.”

“This footage shows some of our gamekeepers using their thermal drone to locate curlews and oystercatchers in hay and silage fields before cutting. The method is proving highly effective and, together with predator control and nest protection, is safeguarding dozens of endangered waders.”

“It does take time, and weather conditions have to be suitable for drone flights. But our gamekeepers are committed to the task and, in recent years, have become highly skilled at detecting tiny, almost imperceptible heat signatures.”

“They do not seek recognition for this work, but we believe they deserve it, because they are making a major difference to breeding success on the edge of the moor and in the adjoining meadows where many waders come to nest. Congratulations to everyone involved, and to the farmers working with the gamekeepers to make it possible.”

Harvesting is also a documented threat in Spain

In Spain, the best-known example is the Montagu’s harrier, a raptor that nests directly in cereal fields.

Numerous studies and conservation programmes have found that mechanised harvesting destroys nests and kills chicks when crops are collected before young birds are able to fly.

This has led to specific campaigns to locate and protect nests in regions such as Castile and León, Castile-La Mancha and Madrid.

Researchers at Spain’s Game and Wildlife Research Institute, known as IREC, have warned that without protective measures, harvest-related mortality can threaten the viability of some breeding populations.

The problem is not limited to the Montagu’s harrier. Other species linked to traditional cereal landscapes, including the great bustard, little bustard, pin-tailed sandgrouse, black-bellied sandgrouse and even the short-eared owl, are affected by agricultural intensification through the loss of nesting cover, reduced food availability and the accidental destruction of clutches during field work.

For birds that breed directly on the ground, mechanised harvesting and the reduction of fallow land have been identified as some of the factors behind the sharp declines recorded in recent decades across many parts of the Iberian Peninsula.