My friend Anna sent me to find a tag that a wood thrush had shed its tag. I went to the last known location with my Kenwood hand held VHF radio in AM mode. I got a strong signal but could not pin point the tag. I used my three element yagi antenna to try to find the tag. I could not zero in on a less than tag in the leaf litter or maybe in the top of a tree. I switch to the radios antenna. The problem is that the tag does not transmit continuous so it is had to locate by signal strength. I decided to come back later with a less sensitive antenna but snow is expected soon and the location is a long way from any road. Any one have luck finding finding a tag that a smart bird have been able to disloge.
Hi Glenn, we have managed to track down a dropped tag from a WOTH before and it was not easy at all but the following did help:
- reduce the gain on the receiver to make it less sensitive and therefore only show a strong signal when you are in the right area.
- When close, if possible, change the 3 element Yagi for a unimodal Whip antenna or remove the 3 element Yagi and just rely on the signal received by the receiver with no antenna attached. This makes the receptor more sensitive to changes in signal strength even if you are only 3 m away from the tag!
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That what I had plan to do is use and less effective antenna then no antenna. The signal was very strong over a wide area.Last night that indicated to me that the tag may be high in a tree. It is the exact location were the bird was tagged. When I pointed the three element vertical the signal did not decrease. That was a clue to me that the tag may be in a tree. I have been and active Ham radio operator for over 50 years so have a bit of experience chasing weak signal but that does not mean I can not learn some thing new. Now if the snow fall is not to heavy.
I second what Nick said about turning down the gain and using a less effective antenna. One of my crew this past summer successfully pinpointed the location of a tag in the leaf litter to within less than 0.5 m by turning the gain down and folding in the arms of the handheld Yagi.
Nick’s ideas are solid. If it is on the ground, and you can narrow down the area, you can use the wire disconnected from the yagi and touch it down to the litter. Then move in and out of the high probability areas. We have found loose tags and annimals underground in burrows.
@user949 This post is a bit old, but you may want to have a look at the solution @user1234 posted here: https://community.motus.org/t/finding-dropped-tags/1154/5
Thanks for information. The tag I was looking for turn out to be high up in a tree. Not having equipment or ability to clime the tree we left it there.