Remember, when we were kids and people said that the birds "flew south" for the winter?
Well, believe it or not, that was about all we knew for a lot of species. Birds disappeared flying south in the Fall and came back, flying north, in the Spring. Where these birds went, exactly, and what they did when they got there, were a bit of a mystery.
All of that changed with the devopment of very small micro-transmitters capable of uploading information to satellites.
Three of the very first transmitters capable of being carried by a bird were attached to Swainson's hawks back in 1994. Within a few days, two of the transmitters conked out, but the transmitter on the third bird retained power and showed the hawk traveled from southern Canada down the American Midwest into Mexico, Guatemala, Costa Rica, and past Ecuador into the Pampass region of Venezuela.
Scientists quickly scurried off to see if they could locate the animal.
What they found in Argentina was both amazing and disturbing.
The amazing part was the Swainson's hawks (which are solitary hunters in North America) assembled into large communal flocks of as many as 7,000 birds on their winter hunting grounds.
The scary part was that in Argentina Swainson's hawks lived on swarms of locust-like grasshoppers, which were being systematically poisoned by organo-phosphate pesticides.
The bug spray, in turn, was killing off the Swainson's hawks in droves.
As they drove into the area where the hawk's signal had last been heard from, the scientists were alarmed to find thousands of dead hawks already dead under their roosts.
To make a long story short, that year 25 percent of all the Swainson's hawks in the world were killed by pesticides in Argentina -- a phenomenon that would never have been known had it not been for wildlife tracking telemetry.
The good news is that by switching to different type of pesticides, Argentina's farmers were able to sharply reduce grasshopper infestations while doing little serious harm to wildlife --a "win-win" for all sides.
The two tracking transmitters at the top of this post are made by an outfit that specializes in micro-tramsitters for bats, birds and other wildlife . The very smallest of birds can now carry tracking trasmitters glued or harnessed onto their backs or tail feathers, with batteries providing power for 30 days or more.
The tiny collar, pictured at right, holds the even tinier dot-like transmitter next to it.
The transmitter pictured at the very top of this post is even smaller than the one at right, and is arrayed for a tail mount on a very small bird. This is a complete rig with battery, transmitter and aerial, believe it or not.
Either one of the two micro-transmitters shown have an above-ground trackable range of 1-2 kilometres. .
4 For more information on wildlife and terrier transmitters on this blog, click here.