Which Cranes Get PTTs?
By Sara Zimorski, ICF

In the Beginning. . .
At first (2001) we put PTTs on the largest males and largest females since these birds would have to wear/carry two transmitters: a radio transmitter on one leg and the PTT on the other.

A Platform Transmitter Terminal (PTT) is a satellite tracking device that can be worn by an animal so its location is known. (This is on a plastic crane leg model.) Photo WCEP

Here the VHF radio transmitter is on the left leg and the PTT satellite transmitter is on the right leg.

Photo Sara Zimorski, ICF

Crane #208 has a PTT on the right leg and radio transmitter on the left leg (red/white).

Photo Sara Zimorski, ICF

Learning From Experience
By the time we were raising the 2003 birds, the tracking and monitoring data clearly showed two things:

  • The males tend to come right back to Necedah.
  • The females wander and sometimes settle farther away.

We therefore decided to put PTTs only on females. A PTT was almost wasted on a male that came right back to and settled down at Necedah. However, a PTT might be very useful on a female that wandered into another state. Again, because the bird would be carrying two transmitters, we chose to put them on the largest females. In 2003 we didn't have many females to choose from; we certainly weren't going to put one on #303, who’d had a leg injury and surgery to correct it.

Special Cases
In 2004 we had 4 females but only 3 PTTs available, so the youngest and smallest bird (#420) wasn't going to get one. Unfortunately #406, one of the few females, died. We were left with only 3 females, and each of them received a PTT during the banding and health check that took place after their arrival at Chassahowitzka. As for male #418, he was the first supplemental release (Direct Autumn Release, or DAR) bird in the Eastern flock. We didn't know what he would do or what might happen to him as he migrated on his own, so we decided to be extra cautious and put a PTT on him. That way we would always know where he was—in case he ever got away from us during the regular tracking. Because he was the first in this new type of release it was very important to document his migration: where he went, when, and how. The information would help to justify doing more releases of this type, or reveal the need for re-thinking the release strategy and method. Luckily #418 did super, and the Direct Autumn Release (DAR) experiment began in 2005.