Lesser Kestrels GPS Tagging

A Species that Spans Continents 

Physical description

As their name suggests, the Lesser Kestrel is smaller than the Common Kestrel at 27-33cm in length and with a wingspan of 63-72cm (versus the Common Kestrel’s 32-39cm length and 65-82cm wingspan). Males are distinguishable by their chestnut back and a blue-grey crown, neck, rump, and tail. Their belly is a creamy pink with small brown streaks. While females have brown backs and head with a pale belly, and a streaked brown belly and back. Juveniles are more similar to females. 

Migration, habitat & diet

Lesser Kestrels are a migratory species, breeding over a large range covering the Western Palearctic south and wintering in Africa. The largest congregations of wintering Lesser kestrels have been discovered in Senegal, Mauritania, West Mali and Niger. They migrate in small or loose flocks at around 2,000m above sea level. 

In Europe, their habitat includes lowland areas with steppe-like grasslands and farmland where there are open areas for them to hunt. They don’t favour dense forests, vast treeless wetlands and mountains.

In terms of hunting, they are very adaptable, taking advantage of whatever’s on offer and make use of their strong beak and sharp eyesight and claws. They mainly eat a variety of large insects like grasshoppers and beetles but also voles, shrews, birds and lizards to name a few. Known for being opportunistic at farmlands, they hover above scoping their prey in a memorising manner. The sheer variety of animals they catch gives the Lesser Kestrel an important role of regulating other species on the food chain. They often heap praise from farmers for their ability to catch a number of crop-damaging animals.

The Threats & Why They Need Help

The loss of habitat in its Western Palearctic breeding grounds is what drove the Lesser Kestrel’s dramatic decline last century. This was mostly attributed to the growth in agricultural land, but also afforestation of low-productive farmland with wood plantations, land abandonment and urbanisation. All of these factors have reduced their natural hunting grounds. The story is similar at migratory sites in South Africa where grasslands were replaced with farmlands. 

Further to this, kestrels lose nesting sites in places such as old buildings, when they are neglected or restored. This leads to the birds seeking alternative nesting sites which aren’t safe from predators. It also puts them at greater risk of extreme temperatures and their chicks falling out of nests. High rates of chick mortality that have been recorded during unusually hot weather is another concern amidst rising global temperatures. Threats could also include pesticide or rodent poisoning.

Although the Lesser Kestrel’s status is ‘Least Concern’, the high rate of juvenile mortality and lack of data on why this is happening has raised concern amongst conservationists. This is why we’re dedicating our efforts to gaining a better understanding and safeguard the species’ populations.

GPS Tagging Juveniles: A key component of the wider project

Effectively monitoring the newly fledged nestlings once they head out into the wild is vital to the success of the project’s aims. Using GPS tagging enables us to gather detailed data on their movements and gain new insights into potential threats the young birds come across on their journeys.

Upon reaching an appropriate age (6 weeks old) and size (150g), the juvenile kestrels are fitted with non-invasive loggers weighing 5g and secured like a backpack with Teflon ribbons across the bird’s breast. These ribbons are designed to naturally release after 2-3 years. 

Monitoring the birds in this way has the possibility to produce unexpected results that can reveal new information on a species’ behaviour. As illustrated by a previous DEMA project to GPS tag the Iberian Imperial Eagle. Tagged in Spain, the eagles were tracked surprisingly crossing the strait to north Africa where a number of birds were electrocuted at a faulty electric pylon. The use of this technology not only allowed DEMA to work with the relevant entities to address the problem, but it also shed new light on the dispersion area of the eagle.