With 46 individuals being tagged with GPS-loggers (26 with UvA-Bird Tracking System (UvA-BiTS) and 20 with E-obs tags), we currently have an almost continuous data-flow on the spatial behaviour of more than 15% of the birds on Fuerteventura. This allows us to determine the use of space both by territorial individuals and birds in the pre-adult stage and answer specific ecological questions on how birds deal with the current availability of resources and the identification of factors determining dispersive processes and territory recruitment.
Why studying movement ecology?
Canarian Egyptian vulture are just bouncing back from the brink of extinction, but with a current estimated population size of only 300 individuals, their situation still needs to be treated with particular caution. Indeed, despite a current population growth trend indicating a positive effect of enacted conservations measures in the past two decades, the islands are still being the scenario of rapid environmental changes, including farm intensification, tourist development, and the apparition of new infrastructures like wind farms. To ensure a future for Canarian Egyptian vultures, continuous monitoring of the species is still needed, not only to increase our knowledge of the species, but also to further fine-tune conservation efforts in response to current and future changes.
In this PhD project, Marina García Alfonso, will continue the EBD-work by focussing on (1) movement behaviour to help to inform local authorities in urban planning and, (2) to deepen into resources use and territory settlement to determine the (ecological) factors that may determine vultures’ habitat requirements or preferences as well as possible social influence in territory settlement.
- Humans’ perception of vultures as ecosystem service-providing units to determine if the perception of farmers towards vultures is based on the real existence of such service or derived from social factors.
- Use of power lines by Canarian Egyptian vultures, to know how Canarian Egyptian vultures use power lines. Apart from defining current and future most risked stretches, I will study which factors determine the selection of specific poles and certain stretches against others, to stimulate new conservation measures.
- Wind farm planning in relation to vultures’ movements to understand the potential effects of wind turbines on the survival of the Canarian Egyptian vultures.
- The study of the movement ecology in relation to the availability and predictability of resources. This work aims to determine the selection criteria Canarian Egyptian vultures use for scavenging on specific livestock farms.
- The identification of factors related with the history of the breeding population and territories which are determining dispersive processes and territory recruitment.
We use two different GPS systems to track our birds. Both devices have a solar powered GPS tag with rechargeable batteries and multiple on-board sensors, including a tri-axial accelerometer. Apart from geographical coordinates, these devices provide us with information on the altitude, speed and tridimensional movements according to a time interval chosen (in our case 2-5 minutes during daytime). Both devices are data-loggers, which means the collected information is first stored on the devices. Both systems differ, however, in the way data is retrieved from the loggers.
UvaA-Bird tracking System (UvaBits)
UvaBiTS devices use Bluetooth signal for data-transfer and downloading of data requires a base-station consisting of an antenna and a laptop with necessary software. Data is downloaded automatically when birds are in the reception area of the base-station. Using a relay (‘signal repeater’) this area can cover a distance of up to 14km (distance between the repeater and the main antenna) in perfect landscape and weather conditions. The device can be programmed remotely, allowing new measurement settings to be uploaded. The diverse measurement scheme features make it possible for the user to create a scheme that takes high resolution measurements at certain times, locations, or under other special conditions and lower resolution measurements at other times. For further details see http://www.uva-bits.nl/system/
E-obs devices use the GSM-GPRS signal, which is the same as mobile phones use. Hence, this system doesn’t require the use of a base-station, which facilitates the downloading of data, which is particularly convenient for those birds living in remote areas of the island and/or do not visit the feeding stations very often. Devices are also equipped with a high-speed radio-link for wireless on-site data download, in case of absence of mobile phone towers. All information collected by the e-obs devices is being sent on a daily basis at a specific time. If a device does not connect for any reason, data are kept until a new connection is made. In addition, we can localize any target individual using radiotracking. For further details see www.e-obs.de
Tagging of individuals started in spring 2013, with 17 individuals being equipment with UvA-BiTS loggers. In subsequent years, another 10 were tagged with these loggers. In autumn 2015, 20 individuals were equipment with e-obs loggers (one of them was previously tagged with an UvA-BiTS logger).
In total, data on space use is available for 22 males and 24 females of which 8 males and 11 females are currently territorial. A number of birds are also part of a polygynous and polyandrous trio. Current age of tagged males varies between 2-14 years, while for females this is between 4 and 12 years
Currently (April 2016) these devices have collected more than 2.4 million GPS fixes