GPS Tagging Griffon Vultures

A vulture feeding frenzy

GPS Tagging Griffon Vultures

 

“Through rewilding – the mass restoration of ecosystems – I see an opportunity to reverse the destruction of the natural world.” George Monbiot

1. In the Côa Valley

2. An Invaluable Insight

3. Trophic Chain Restoration

4. GPS Collars & Tracking the Vultures

5. Data Collected

6. Naming the Vultures

“Through rewilding – the mass restoration of ecosystems – I see an opportunity to reverse the destruction of the natural world.” George Monbiot

1. In the Côa Valley

2. An Invaluable Insight

3. Trophic Chain Restoration

4. GPS Collars & Tracking the Vultures

5. Data Collected

6. Naming the Vultures

In the Côa Valley

For our third rewilding impact project we headed to the Côa Valley in northern Portugal, the location of our Wildlife Restoration project, where our members could vote between the following interventions:  

A feasibility study for the reintroduction of roe deer

Boundary & internal fencing

The GPS tagging of vultures 

It was the latter that took the vote, and so in July '19 we sponsored and assisted in GPS tagging 5 griffon vultures in partnership with Rewilding Portugal.

Rolling green hills that make up the coa valley

In the Côa Valley

For our third rewilding impact project we headed to the Côa Valley in northern Portugal, the location of our Wildlife Restoration project, where our members could vote between the following interventions:  

A feasibility study for the reintroduction of roe deer

Boundary & internal fencing

The GPS tagging of vultures 

It was the latter that took the vote, and so in July '19 we sponsored and assisted in GPS tagging 5 griffon vultures in partnership with Rewilding Portugal.

Rolling green hills that make up the coa valley

An Invaluable Insight

The main objective of this intervention was to shed new light on the birds’ foraging behaviour, the data collected from the GPS transmitters will support the restoration of natural food chains in the area and underpin the continued comeback of this magnificent species. Incidentally, this was the first time that the area’s griffon vulture population had been monitored in such a way!

A portrait image of a Griffon vulture
A portrait image of a Griffon vulture

An Invaluable Insight

The main objective of this intervention was to shed new light on the birds’ foraging behaviour, the data collected from the GPS transmitters will support the restoration of natural food chains in the area and underpin the continued comeback of this magnificent species. Incidentally, this was the first time that the area’s griffon vulture population had been monitored in such a way!

The transmitters fitted to the birds, which were mostly breeding adults, were equipped with an accelerometer, which shows when they're resting, flying or foraging. Data supplied by the devices will provide invaluable insights into where the vultures feed and the types of carrion they feed on.

Trophic Chain Restoration

An essential element of rewilding the Côa Valley is the restoration of trophic chains. At the moment, local populations of both Griffon and Egyptian vultures rely on a network of artificial feeding stations. One aim of this project is to increase the availability of natural carrion in the area by encouraging Portuguese authorities to allow local farmers to leave domesticated carcasses in the field.

“The tagging will allow us to see whether the vultures are feeding mostly on the carcasses of domestic livestock, or also on wild herbivores, and how often they visit vulture feeding stations, which will ultimately enable us to improve the management of food sources for the birds and support the restoration of trophic chains.” says Carlos Pacheco, a raptor expert at ATNatureza.

A Griffon vulture flying low
A transmitter being placed on a Griffon vulture

GPS Collars

The GPS transmitters fitted take the form of a “backpack” and are designed to have a minimal impact on the birds’ behaviour while maximizing their detectability. The weight of the collar is unobtrusive at just 5% of a vulture’s body weight. What's more, the adhesive used on the ribbon ties is designed to biodegrade and release from the vultures after 2 - 3 years.  

 

Data Collected  

Very early on in the project we learnt that the vultures bristle their feathers often thereby covering the solar panels on the GPS loggers. This caused intermittent losses of power, which became more severe once the autumn started. Despite a slight delay, the team managed to obtain invaluable data on the vultures' movements. You can now explore their movements as they search for food and resting places in this interactive map.

A map tracking the location of Griffon vultures in north of Portugal

It has become evident that there are three main areas frequented for foraging by the tagged griffons; The Douro International Park in Portugal and Salamanca and Extremadura, in Spain. Spain seems to provide an important feeding resource for these griffon vultures. Most of them repeat routes to reach Salamanca and Extremadura, where they can spend various days feeding and resting.

Visiting and characterising the griffon feeding locations has allowed us to discover that, so far, they only feed on carcasses of domestic ungulates. Interestingly, Spanish farmers are permitted to leave livestock carcasses in the field, where this is not the case in Portugal.

Since a key aim is to increase the availability of carrion by encouraging authorities to allow Portuguese farmers to leave domesticated carcasses in the field, we're pleased to report that the responsible authorities are now happy to create this network with us in the Portugal's Côa Valley. We will begin by identifying five potential farms to be authorised by the end of this year.

Naming the Vultures

Finally, we also invited our members to vote on a name for each of the vultures from the following list: Brava, Côa, Algodres, Águeda, Malcata, Marofa, Almofala, Toirão, Rodrigo & Jardo. Each of the suggested names is a place of interest within the Côa Valley.

We had overwhelming feedback as well as some witty alternatives, but it was these names that took the vote:
Brava
Algodres
Malcata
Almofala
Jaro

A communitee of Griffon vultures gather in northern Portugal

The transmitters fitted to the birds, which were mostly breeding adults, were equipped with an accelerometer, which shows when they're resting, flying or foraging. Data supplied by the devices will provide invaluable insights into where the vultures feed and the types of carrion they feed on.

Trophic Chain Restoration

An essential element of rewilding Portugal's Côa Valley is the restoration of trophic chains. At the moment, local populations of both Griffon and Egyptian vultures rely on a network of artificial feeding stations. One aim of this project is to increase the availability of natural carrion in the area by encouraging Portuguese authorities to allow local farmers to leave domesticated carcasses in the field.

A Griffon vulture flying low

“The tagging will allow us to see whether the vultures are feeding mostly on the carcasses of domestic livestock, or also on wild herbivores, and how often they visit vulture feeding stations, which will ultimately enable us to improve the management of food sources for the birds and support the restoration of trophic chains.” says Carlos Pacheco, a raptor expert at ATNatureza.

GPS Collars

The GPS transmitters fitted take the form of a “backpack” and are designed to have a minimal impact on the birds’ behaviour while maximizing their detectability. The weight of the collar is unobtrusive at just 5% of a vulture’s body weight. What's more, the adhesive used on the ribbon ties is designed to biodegrade and release from the vultures after 2 - 3 years.  

A transmitter being placed on a Griffon vulture

Data Collected

Very early on in the project we learnt that the vultures bristle their feathers often thereby covering the solar panels on the GPS loggers. This caused intermittent losses of power, which became more severe once the autumn started. Despite a slight delay, the team managed to obtain invaluable data on the vultures' movements. You can now explore their movements as they search for food and resting places in this interactive map.

It has become evident that there are three main areas frequented for foraging by the tagged griffons; The Douro International Park in Portugal and Salamanca and Extremadura, in Spain. Spain seems to provide an important feeding resource for these griffon vultures. Most of them repeat routes to reach Salamanca and Extremadura, where they can spend various days feeding and resting.

Visiting and characterising the griffon feeding locations has allowed us to discover that, so far, they only feed on carcasses of domestic ungulates. Interestingly, Spanish farmers are permitted to leave livestock carcasses in the field, where this is not the case in Portugal.

Since a key aim is to increase the availability of carrion by encouraging authorities to allow Portuguese farmers to leave domesticated carcasses in the field, we're pleased to report that the responsible authorities are now happy to create this network with us in the Portugal's Côa Valley. We will begin by identifying five potential farms to be authorised by the end of this year.

 

A communitee of Griffon vultures gather in northern Portugal