Technology advancements move so fast that even in the eleven years since we started leading Whooping cranes south, we have seen great changes. We now have handheld GPS systems with moving map displays and digital audio devices to broadcast brood calls loud enough to be heard over the sound of the aircraft engine. We can also stream live video from a remote pensite and send text messages to communicate without talking near the birds.
One of the real advances is the GPS – PTT units that are now fitted to three ultralight birds (#’s 4*, 7* & 9-11*) and three DAR birds. A PTT is a platform terminal transmitter which broadcasts to a satellite receiver. That in itself is an achievement considering it weighs only ounces, fits on a leg band yet is powerful enough to be heard by a satellite 540 miles away.
The GPS option records its location and stores that information in its memory. Once every three days the device uploads its present position and the GPS track history so we know where the bird is every third day plus where it was on the previous two. As I mentioned there are three birds fitted with these devices and they are set to report on consecutive days. That means that we get a location from one of them every day. So far all three units are still together so it reasonably safe to assume that all nine birds are travelling as a flock as they make their first northward migration flight.
Although the technology is fascinating, the real excitement for us, is knowing what course the birds are taking. When we had to end the last migration in Alabama, we loaded the birds into transport crates and took them 45 miles east to the Wheeler NWR. That was the first time we had crated all of the birds. In the past there has always been a few that made the trip on their own even if we had to crate some.
Ever since we have been worried that that trip in the back of our van may have broken their chain of knowledge and left them disoriented. We were confident that they would head north but if they flew directly north they would eventually arrive over Gary, Indiana where they might decide to go right as opposed to left. That mistake would take them into Michigan and the lake would create a barrier, stopping them from returning to Wisconsin.
As the GPS data indicate, our birds covered ~231 miles on their first full migration day and made it to Gallatin County, Illinois. The interesting part, however, it that they flew slightly northwest upon departing Wheeler and crossed the migration route we showed them. It would appear they roosted the first night only 10 miles from our stopover site in Union County, Kentucky.
Who knows what system they use to navigate but hopefully they are now in familiar territory. With luck they will make it back to the White River Marsh area in Wisconsin.
With the combined effort of all the people it took to get them south and the million years of instinct they need to get themselves back, maybe luck doesn’t have much to do with it.
(* = equals female)