What is animal movement data used for?
Animal tracking data helps us understand how individuals and populations move within local areas, migrate across oceans and continents and can give key insights into their daily behaviours and routines. This information is being used to address environmental challenges such as climate change, habitat destruction or degradation, the loss of biodiversity and the presence of invasive species.
Where does animal movement data come from?
Scientists have been systematically tracking individual animal movements since around 1900, when the first bird ringing (also known as bird banding) schemes were started. In the late 1950s, researchers began using radio transmitters to track wildlife. In the late 1970s, the Argos satellite system provided a new method for tracking animals globally and in the early 1990s, the Global Positioning System (GPS) began to be used, providing the potential to obtain high-resolution tracking data. Continually improving communication systems, shrinking battery sizes, and other technological developments have led to a range of methods for tracking animals.
The primary trade-offs with choosing a tracking method are between size, price, and amount and ease of data collection. The ideal tag would be lightweight enough to be safely carried by the animal, cheap enough to put on many individuals, and able to transmit high-resolution data to a satellite so that it did not need to be captured again. In reality, a scientist must choose the best available method based on the size and movement patterns of the study animal, the study budget, and the research questions they want to address.
Animal tracking data helps us understand how individuals and populations move within local areas, migrate across oceans and continents and can give key insights into their daily behaviours and routines. This information is being used to address environmental challenges such as climate change, habitat destruction or degradation, the loss of biodiversity and the presence of invasive species.
Where does animal movement data come from?
Scientists have been systematically tracking individual animal movements since around 1900, when the first bird ringing (also known as bird banding) schemes were started. In the late 1950s, researchers began using radio transmitters to track wildlife. In the late 1970s, the Argos satellite system provided a new method for tracking animals globally and in the early 1990s, the Global Positioning System (GPS) began to be used, providing the potential to obtain high-resolution tracking data. Continually improving communication systems, shrinking battery sizes, and other technological developments have led to a range of methods for tracking animals.
The primary trade-offs with choosing a tracking method are between size, price, and amount and ease of data collection. The ideal tag would be lightweight enough to be safely carried by the animal, cheap enough to put on many individuals, and able to transmit high-resolution data to a satellite so that it did not need to be captured again. In reality, a scientist must choose the best available method based on the size and movement patterns of the study animal, the study budget, and the research questions they want to address.
How do scientists record a species location?
Band or ring
A band or ring is a physical tag with a unique code or number that is attached to the animal. To record movement, the individual must be seen or caught again, and the number and location must be reported to the banding center. These tags contain no electronic components and are most commonly used on birds. They are lightweight, very inexpensive, and can be attached by trained volunteers, meaning that large numbers of animals can be tagged. Because most of these animals are not caught again, however, only a small percentage of these tags result in movement data, and most of the movement data include only two locations per animal. Bird banding programs have been in operation since the early 1900s, and so large long-term datasets are available for this type of tracking.
Light-level geolocator
Light-level loggers are, as the name suggests, tags that collect measurements of light levels. The tagged animal must be recaptured and the tag removed to access the data. The light level information is used to estimate sunrise and sunset times, which in turn are used to estimate the movement of the animal. These tags can be lightweight and are relatively inexpensive, and provide the only available method for tracking movements of some smaller migrating animals as well as many marine species that spend most of their time below the ocean surface where they cannot be tracked by satellites or radio receivers. However, the location estimates can have very large errors, which vary depending on the time of year and location of the animal.
Very high frequency (VHF) radio transmitter
A VHF radio transmitter is an electronic tag that emits a very high radio frequency signal that can be used to locate the animal. The user must track the signal using a receiver and directional antennae, which must typically be within a few kilometres or less of the animal to detect the signal. The signal can be tracked by foot, car, or plane, or using a stationary system of receivers placed throughout the study area. The tags are relatively lightweight, inexpensive, and can have long battery lives. However, it can be very labour intensive to follow the animals with the receiver
(imagine trying to track snow leopards in the high Himalayas on foot). This method can be used on small animals but is most useful for populations that stay within a geographically restricted area.
Argos Doppler
Argos Doppler tags (known as platform transmitter terminals, or PTTs) are electronic tags that send periodic signals to Argos transmitters on polar-orbiting satellites. Receiving stations located around the globe collect the data from the satellites and send it to a processing centre, where location estimates are made by measuring the Doppler shift on the signals sent by the tag. The location estimates are typically much less accurate than those made with a GPS, but the tags can be much lighter than GPS units and can also be used to transmit GPS locations if the tag is properly equipped. Compared to the types of tags described below, these tags are relatively expensive and heavier, but allow for location measurements from anywhere on the globe. Find out more about the Argos System at argos-system.org.
Global positioning system (GPS)
A GPS tag calculates the location of an animal at specific time intervals using positions estimated by a network of satellites. These locations can be stored on-board the tag or transmitted to the user through a communication network (for example, Argos satellite or GSM phones) or through ad hoc wireless downloads. These tags can provide thousands of very accurate location estimations for animals. However, these tags are relatively expensive and heavy, and so are usually limited to use on larger animals and require a large research budget if many animals will be tagged.
Band or ring
A band or ring is a physical tag with a unique code or number that is attached to the animal. To record movement, the individual must be seen or caught again, and the number and location must be reported to the banding center. These tags contain no electronic components and are most commonly used on birds. They are lightweight, very inexpensive, and can be attached by trained volunteers, meaning that large numbers of animals can be tagged. Because most of these animals are not caught again, however, only a small percentage of these tags result in movement data, and most of the movement data include only two locations per animal. Bird banding programs have been in operation since the early 1900s, and so large long-term datasets are available for this type of tracking.
Light-level geolocator
Light-level loggers are, as the name suggests, tags that collect measurements of light levels. The tagged animal must be recaptured and the tag removed to access the data. The light level information is used to estimate sunrise and sunset times, which in turn are used to estimate the movement of the animal. These tags can be lightweight and are relatively inexpensive, and provide the only available method for tracking movements of some smaller migrating animals as well as many marine species that spend most of their time below the ocean surface where they cannot be tracked by satellites or radio receivers. However, the location estimates can have very large errors, which vary depending on the time of year and location of the animal.
Very high frequency (VHF) radio transmitter
A VHF radio transmitter is an electronic tag that emits a very high radio frequency signal that can be used to locate the animal. The user must track the signal using a receiver and directional antennae, which must typically be within a few kilometres or less of the animal to detect the signal. The signal can be tracked by foot, car, or plane, or using a stationary system of receivers placed throughout the study area. The tags are relatively lightweight, inexpensive, and can have long battery lives. However, it can be very labour intensive to follow the animals with the receiver
(imagine trying to track snow leopards in the high Himalayas on foot). This method can be used on small animals but is most useful for populations that stay within a geographically restricted area.
Argos Doppler
Argos Doppler tags (known as platform transmitter terminals, or PTTs) are electronic tags that send periodic signals to Argos transmitters on polar-orbiting satellites. Receiving stations located around the globe collect the data from the satellites and send it to a processing centre, where location estimates are made by measuring the Doppler shift on the signals sent by the tag. The location estimates are typically much less accurate than those made with a GPS, but the tags can be much lighter than GPS units and can also be used to transmit GPS locations if the tag is properly equipped. Compared to the types of tags described below, these tags are relatively expensive and heavier, but allow for location measurements from anywhere on the globe. Find out more about the Argos System at argos-system.org.
Global positioning system (GPS)
A GPS tag calculates the location of an animal at specific time intervals using positions estimated by a network of satellites. These locations can be stored on-board the tag or transmitted to the user through a communication network (for example, Argos satellite or GSM phones) or through ad hoc wireless downloads. These tags can provide thousands of very accurate location estimations for animals. However, these tags are relatively expensive and heavy, and so are usually limited to use on larger animals and require a large research budget if many animals will be tagged.
How can location data be turned into movement data...and how can it this tell us something about a species behaviour?
A single spatial location point can tell us only a limited amount about a species but lots of location points can reveal a surprising amount of detail about a species movement patterns and many other variables.
By collecting multiple spatial data points it possible to determine what habitat preferences the species has by looking at where it spends most of its time and if those preferences change throughout a day or over a year. Data on what features of a habitat are selected for or against eg. altitude, slope, aspect, land-surface ruggedness type, vegetation type, and specific topographic feature; Horizon distances calculated; Prey presence; human presence are all derived from first determining where species spend their time. Its possible to look at the size of a species home range. We can see if certain parts of a home range are favoured and by combining this information with other known data begin to determine why these areas as so important for the species.
By recoding multiple location points over a set time period is possible to work a rate of travel, for example daily movement distance can be calculated. By observing changes to movement rates through a 24 hour or seasonal cycle its possible to determine at what times of day a species is most mobile and if they have and variation in their movement rates across the seasons. When lots of data points are acquired greater variations in a species movement rates can be acquired. For example its possible to work out whether a species is active (travelling to a new distinct location); active (local movement); inactive (resting). Taking these measurements over time can reveal differences in movement types across different times of day or seasonal can also be measured.
When multiple individuals are tagged it can be possible to determine their proximity to each other and how much their home ranges overlap.
Other conservation linked data such as how much time a species spends outside of protected areas can easily derived from data on a species location.
A single spatial location point can tell us only a limited amount about a species but lots of location points can reveal a surprising amount of detail about a species movement patterns and many other variables.
By collecting multiple spatial data points it possible to determine what habitat preferences the species has by looking at where it spends most of its time and if those preferences change throughout a day or over a year. Data on what features of a habitat are selected for or against eg. altitude, slope, aspect, land-surface ruggedness type, vegetation type, and specific topographic feature; Horizon distances calculated; Prey presence; human presence are all derived from first determining where species spend their time. Its possible to look at the size of a species home range. We can see if certain parts of a home range are favoured and by combining this information with other known data begin to determine why these areas as so important for the species.
By recoding multiple location points over a set time period is possible to work a rate of travel, for example daily movement distance can be calculated. By observing changes to movement rates through a 24 hour or seasonal cycle its possible to determine at what times of day a species is most mobile and if they have and variation in their movement rates across the seasons. When lots of data points are acquired greater variations in a species movement rates can be acquired. For example its possible to work out whether a species is active (travelling to a new distinct location); active (local movement); inactive (resting). Taking these measurements over time can reveal differences in movement types across different times of day or seasonal can also be measured.
When multiple individuals are tagged it can be possible to determine their proximity to each other and how much their home ranges overlap.
Other conservation linked data such as how much time a species spends outside of protected areas can easily derived from data on a species location.
Case Study: Space For Giants
In order to effectively manage the problem of elephants raiding local farmers crops Space for Giants are combining spatial data and dedicated elephant researchers on the ground.
Human-wildlife conflict, in particular crop damage by elephants, can cause an immediate subsistence crisis for local people resulting in enormous resentment and anger of elephants and the broader ecosystem. Elephants and other wildlife are injured and killed in retaliation and it becomes difficult if not impossible to implement conservation projects under these circumstances. Human-wildlife conflict is not easy to solve and requires large investments of time and resources in order to address it. The best thing we can do is prevent human-wildlife conflict from occurring in the first place. In the case of consistent crop-raiding individuals (invariably males) Space for Giants are trailing non-lethal approaches for their management. The latest of these is the E-Fence system where smart GPS collars are placed on known crop-raiders. When the elephant approaches a designated boundary the collar sends a text message to a group of people who mobilise a response to scare the individual away before it causes any damage. Space for Giants hopes that this feature will allow them to keep track of elephants that are vulnerable to poaching and to help prevent crop-raiding elephants from getting too close to places that they shouldn’t go. You can learn more at http://spaceforgiants.org/
In order to effectively manage the problem of elephants raiding local farmers crops Space for Giants are combining spatial data and dedicated elephant researchers on the ground.
Human-wildlife conflict, in particular crop damage by elephants, can cause an immediate subsistence crisis for local people resulting in enormous resentment and anger of elephants and the broader ecosystem. Elephants and other wildlife are injured and killed in retaliation and it becomes difficult if not impossible to implement conservation projects under these circumstances. Human-wildlife conflict is not easy to solve and requires large investments of time and resources in order to address it. The best thing we can do is prevent human-wildlife conflict from occurring in the first place. In the case of consistent crop-raiding individuals (invariably males) Space for Giants are trailing non-lethal approaches for their management. The latest of these is the E-Fence system where smart GPS collars are placed on known crop-raiders. When the elephant approaches a designated boundary the collar sends a text message to a group of people who mobilise a response to scare the individual away before it causes any damage. Space for Giants hopes that this feature will allow them to keep track of elephants that are vulnerable to poaching and to help prevent crop-raiding elephants from getting too close to places that they shouldn’t go. You can learn more at http://spaceforgiants.org/