Choosing a PTT

Are you tracking a bird?

Our PTTs are designed to be deployed on birds in a backpack configuration. We have modified our PTTs for other applications (for example, tracking flying foxes), however you should contact us first to discuss your project to determine if the PTTs are suitable for a non-avian application.

What size of PTT?

The general convention has always been to use a PTT weighing no more than 3% of the weight of the bird. However, we know of instances where researchers have successfully tracked birds using PTTs weighing up 7% of the weight of their birds. Obviously, this may depend on the species involved; a heavier PTT may not be suitable for long range migrants.

As our PTTs get smaller and lighter, researchers are often tempted to use the smallest PTT available. However, the smaller PTT is not always an appropriate choice.

The smaller PTTs are made of lightweight materials and as a result are not as robust as the larger models. Particularly destructive birds, such as geese and eagles require the largest, sturdiest PTTs they can safely carry.

Is a solar PTT appropriate?

We have been able to reduce the weight of our PTTs while extending their operational life through the use of solar rechargeable batteries. A solar PTT may be the answer to a multiyear study’s requirements as it has the potential to run for 3 years or more.

To successfully track birds with solar PTTs the bird must be able to tolerate a backpack attachment.

Solar PTTs need several hours of direct sunlight to charge. Charging occurs much more slowly in dim light (for example, shade or stormy weather).

Solar PTTs are not suitable for tracking in the Polar Regions. Despite long summer days, the angle of the sun is not favorable for charging.

The PTT’s solar array must remain completely exposed to efficiently charge the PTT. If a feather or dirt covers any part of the solar array the PTT will charge much more slowly.

Is the bird’s behavior to be considered?

Is your bird likely to fuss with the PTT? (Geese are notorious for this.) If so, you should only consider the sturdiest models.

Does your bird have long feathers and/or is it likely to preen feather over the PTT? If so, solar powered PTTs would not be appropriate for this species.

Does your bird spend time in burrows, caves or deep shade? Solar PTTs must be regularly exposed to direct sunlight to charge, hence are not appropriate for tracking these species.

Can your bird wear a backpack?

The standard configuration for our PTTs is backpack. For GPS enhanced and solar models the PTTs must be worn as a backpack to remain properly positioned for GPS data collection and battery recharge, hence these models are not appropriate for leg bands or neck collars. Battery powered PTTs can be modified for neck collar or leg band attachment. We also offer implantable PTTs for waterfowl that dive.

How long is your study?

Battery powered PTTs will run until the battery is spent. Operational life is dictated by the size of the battery, hence our larger battery powered PTTs have a longer operational life than the smaller battery powered PTTs. The battery life of a PTT can be extended to cover a study period by the use of duty cycle programming.

For multiyear studies, a solar powered PTT should be considered, as these PTTs have the potential to run for years (regardless of their size) provided they continue to receive adequate exposure to direct sunlight to recharge their batteries. (Please see above, “Is a solar PTT appropriate.”)

Microwave Telemetry, Inc.
8835 Columbia 100 Parkway, Suites K&L
Columbia, MD 21045
410.715.5292