Tagging & Database

The Tagging

A major advantage of the method of tagging red kites used in this project is that the GPS tracking of birds and the post-mortem analysis work "in real time" and enable quick action. In contrast to other methods, a representative sample of all causes of death in a large geographical area can be determined independently.

The GPS transmitters are equipped with small solar panels that make it possible to permanently record the route of the tagged red kites via satellite and to transmit it via the mobile phone network. From 2020 to 2024, red kites and other birds of prey (white-tailed eagles, imperial eagles & black kites) in around 40 project areas in 12 countries were or will be equipped with GPS transmitters, which means that their activities can be permanently traced. Since numerous project partners and cooperation partners of the project provided data from many other tagged red kites (which were tagged between 2013 and 2024), the sample already includes (as of 09/2024) 3,070 tagged red kites  throughout Europe (with the exception of from UK), whereby 10 individuals were caught again due to a defect on the transmitter and tagged again as adults or immature. So far, a total of 3,060 different individuals of the red kite have been tagged.

3,070 tagged red kites by the LIFE EUROKITE project and numerous cooperation and project partners
throughout Europe (excluding UK).

 

3,070 tagged red kites by the LIFE EUROKITE project and numerous cooperation and project partners
throughout Europe (excluding UK).

 

Migration and flight movements

The migration towards the winter quarters takes place mainly in September and October. Spain and southern France are the most important wintering areas for the red kite population.

Young birds born in Central Europe the previous year remain in their winter quarters much longer than adult birds (until February), mostly until March or April. Only a few one-year-old young birds (= 2nd calendar year) also spend the summer in the wintering area.

Red kites show great variability in migration strategies. Most individuals in northeast Europe are migratory, but there is also a growing number of sedentary individuals.

Differences between juveniles and adults were observed during spring migration. Adult red kites began spring migration to the northeast in February-March, while immature individuals began much later and had a longer time span (February-June). Adult individuals also took significantly fewer days to reach their destination (12 ± 5 days) and covered more distance per day (134.2 ± 37.1 km/day) than juveniles (19 ± 11 days and 98.9 ± 21.2 km/day). The spring migration was significantly faster and with fewer stopover days than the autumn migration (Garcia-Macía et al. 2021).

The migratory behavior can vary greatly in different red kite individuals. Young birds from the same nest can choose different wintering grounds (Literák et al. 2019). GPS data also revealed that Italy and the Balkans are important wintering areas for red kites from Central Europe. Several sea crossings by red kites could be evaluated using the GPS data (Raab et al. 2017).

Number of different red kite individuals with telemetry points in a 10 x 10 km grid from 2013 to 2022 in Europe
(excluding UK). A total of 1,933 individuals in Spain, 1,746 in France, 1,472 in Germany and 388 individuals in
Austria have been documented so far.

Telemetry data points from 144 red kites tagged in the Benelux countries (Belgium, Luxembourg and the Netherlands).

Telemetry data points from 491 red kites tagged in Central Germany (Hesse, Saxony-Anhalt & Thuringia).

Telemetry data points from 171 red kites tagged in the vicinity of the border triangle AT/SK/CZ (Austria, Slovakia &
Czech Republic).

Roosting sites

In winter, as soon as the sun goes down, red kites gather at so-called “roosting sites”. These roosting sites can be individual trees, groups of trees and forest edges. Many different tree species can be used as a place to sleep. Some roosts can even be just a few hundred meters from villages. However, there is no evidence that red kites are sleeping directly in the village. Red kites often first gather at a "gathering place" before flying together to the roosting site. Normally, these sleeping places are used for several nights and also for several years. Sudden changes in sleeping places are mostly due to disturbances. The number of red kites varies greatly at the roosting sites and is regionally dependent. During the winter count in January 2021, 110 red kites were observed on the border of Austria and Slovakia. The number at a roosting site in Spain, on the other hand, can be significantly higher. In January 2021, 697 red kites were counted at a single roosting site in Spain (LIFE EUROKITE 2021). We thank the National Coordinators and the 581 volunteer counters who took part in this census. The full report can be viewed at https://www.life-eurokite.eu/de/publikationen.html.

In the breeding area and thus during the breeding season, such roosting sites are rather rare, since the red kite shows territorial behavior during this time. However, small gatherings can occur near abundant food sources. When the breeding season is over, the young and old birds gather again at sleeping places. While in January (2013-2022) there were a total of 787 tagged red kite individuals in Spain, the number of tagged red kite individuals in July (2013-2022) was only 339. A different picture emerges in Germany. In January (2013-2022) only 40 tagged red kite individuals were in Germany, while the number of tagged red kite individuals in July was significantly higher at 698. Some Red Kites have stayed in several countries over the years and during migration, which is why the sum of red kite individuals from all countries combined significantly exceeds the total number of tagged red kites.

Number of red kites at 267 selected red kite roost sites across Europe during the
winter count in January 2021 as part of the LIFE EUROKITE project.

Overnight spots of 2,019 tagged red kites in January in the period 2013 to 2024 across Europe and the number of
individuals per country.

Overnight spots of 2,627 tagged red kites in July in the period 2013 to 2024 across Europe and the number of
individuals per country.

Mortality reasons

At the moment (09/2024), 1,377 tagged red kites have died (506 red kites with transmitter failures). 195 tagged red kites died from poisoning and 54 from illegal shooting. 622 tagged red kites died from other anthropogenic and natural causes such as predation, collision, electrocution or disease.

Since the pathological examinations usually take several months, it is not yet possible to make a definitive assessment of the cause of death for all birds.

Most birds were tagged in the nest. As a result, losses in the nest (mainly predation) are also taken into account, which occur disproportionately often compared to the other causes of death. The causes of death and the distribution of causes of death may differ per country. For example, poisoning and illegal shootings as well as electrocution from power lines occur much less frequently in Germany than in other European countries.

The extremely extensive database of the LIFE EUROKITE project offers the opportunity, not previously available to this extent, to provide the basis for discussion and decisions on a strictly scientific basis and both with an open outcome and without any preference or preconceived opinion. The aim is never to stand up for or against something, but to provide objective and scientifically reliable facts for the decision-makers.

The final scientifically based analysis of the causes of mortality is currently being carried out by independent scientific institutions in several European countries. Compliance with internationally accepted scientific standards *) is of course also mandatory for EU-funded research projects by the MEGEG and its scientific cooperation partners.

*) https://www.allea.org/wp-content/uploads/2018/06/ALLEA-European-Code-of-Conduct-for-Research-Integrity-2017-Digital_DE_FINAL.pdf

Interim results of the dead finds of the 1,377 deceased and tagged redi kites in the years 2013 to 2024 across Europe.

Interim results of the poisoning cases of 195 deceased and tagged red kites in the years 2013 to 2024 across Europe.

Interim results of the shooting cases of 54 deceased and tagged red kites in the years 2013 to 2024 across Europe.

Research & Monitoring

Telemetry-based spatial use analysis (tRNA)

Statistical modeling is used to determine the habitat potential and the use of space by the birds. The telemetry-based spatial use analysis (tRNA) learns the behavior of tagged birds (e.g. red kites, white-tailed eagles or black storks) through "data mining" and predicts the species-specific probability of residence based on land use (e.g. settlements, forest, roads and railway lines, wetlands, agricultural use, altitude). A distinction is made between the use of space by breeding birds and the habitat potential for young birds and non-breeders. While the probability of stay of breeding birds can be predicted spatially very precisely and in absolute time, taking into account the nest, only relative habitat suitability can be given for young birds and non-breeders. This model thus predicts the length of stay to be expected for the species.

Example of a model of the habitat suitability for non-breeders of the Red Kite in
the 2nd calendar year based on telemetry data and land use data in the
Halberstadt area, Saxony-Anhalt (Germany).