PIT Tags

(Passive Integrated Transponders)

Scientists use different types of tracking technologies to determine the location of a bird at a given point in time. Depending on the technology, we can use this information to determine whether a bird is alive and how it moves through its environment. The type of technology we use depends on our research question and limitations associated with the biology of the species we are studying. One type of technology we use to track birds is called a “Passive Integrated Transponder” or PIT tag.

This small bird (around 16 grams) is wearing a PIT tag around its left leg.

This type of tracking device does not require power. Instead, PIT tags have an internal microchip that is activated when it passes close to a special antenna. The antenna is connected to computer that records the identity of the tag and the time in which it was close to the antenna. A common example of this tag is the “EZ-Pass” that you may have seen your parents use on the highway. The EZ-Pass does not require power – toll gates actually contain a giant antenna that talks to the tag to determine the identity of the car and record when it passed the gate.

PIT tags can be attached to birds in a number of ways. The most common form of attachment is to glue the tag to a band (metal or plastic ring) that a bird carries on its legs. The tags can also be placed under a bird’s skin or even injected into the bird using a small needle.

PIT tags provide many advantages for researchers studying birds. The biggest advantage of this tag is that it does not need a battery. Because of this, a tag can last for the entire time that an animal is wearing it. Because these tags do not require batteries, they are also very light - they can fit on birds of any size. A bird house equipped with a PIT tag reader. It records every time the bird goes through the door. Also, these devices are very inexpensive, with the cost per tag typically much lower than $2.00. This means that scientists can deploy lots of tracking devices with very little investment.

Though PIT tags are great for exploring some aspects of bird behavior, their use is limited to only certain types of applications. The main drawback of the device is that is has to be very close to the antenna to transmit data – typically distances of a few inches to a few feet. Scientists will not retrieve any data if the bird is outside of that distance. Therefore, these devices can only provide data at the location of the antenna.

Despite this drawback, with the correct antenna placement, scientists can learn a lot using PIT tags. By placing an antenna in a location where you expect a bird to go, you can determine many things. For example, by placing an antenna under a bird’s nest, we can learn how often parents feed their young. By placing an antenna under a bird bath in an area without a natural source of water, we can determine how often a bird drinks or bathes.

Want to learn more? Check out this video!