Vulture Update - May 2020

Findings from initial analysis of GPS tracker data

Table of contents

The griffon vultures that we GPS-tagged in the summer of 2019 have generated huge amounts of data which had to be processed to reveal the most interesting insights and patterns. Here is a summary of the main findings that emerged from data about the behaviour of 4 of the tagged birds. The analysis was performed by our partners Sara Ali谩car, Andr茅 Couto, Carlos Pacheco, Jo茫o Neves and Jo茫o Paulo Silva.

Mortality

Almofala, one of the griffon聽vultures聽we tagged in the summer of 2019 was found dead after the tracking data suggested it had not moved for several days. Although this is unfortunate, events like this can lead to聽important insights into the causes of mortality in the population. In this case, the bird appears to have died of natural causes because the necropsy showed no evidence of shooting or poisoning.

The remaining聽vultures聽(Algodres, Brava, and Jardo) stayed active until the GPS signal was lost allowing a large amount of valuable information to be collected.

Griffon vultures gathered on a rock. Unlike most raptors, griffon vultures  are highly social. Breeding in colonies and feeding in groups.
Unlike most raptors, griffon vultures are highly social. Breeding in colonies and feeding in groups.

Feeding

Birds were tracked for an average period of 148 days and the combined position and accelerometer data have allowed 160 potential feeding events to be identified. This has given us the first insight into their foraging behaviour.

The great majority of feeding events took place in Spain. Interestingly, abandoned carcasses in extensive farming areas appear to be providing most of the food for these griffon vultures. However, there was also evidence of feeding in natural areas and intensive or semi-intensive farming areas. Only a small percentage of the feeding events took place at vulture feeding stations, which are maintained to provide supplemental feeding for endangered scavengers such as the Egyptian vulture.

Griffon vulture among the vegetation at the project area in the C么a Valley
Griffon vulture among the veggetation at the project area in the C么a Valley. A detailed analysis of GPS data is revealing where the vultures are feeding and what they are feeding on.

Interactive map

This interactive map was created with the data from 4 of the Griffon vultures tagged in the summer of 2019. You can follow the journey of each individual and see the distance travelled up to that point (by clicking on the bird's icon).