I hope this issue has not been covered already, I did search the archives and could’t find anything particularly relevant.
I’m interested to learn about folks’ experience with CTT lifetags in terms of multi-year longevity. I understand that in theory the tags should last indefinitely as long as they are exposed to the sun, but I think anyone who has tagged birds understands that there is a major difference between theoretical lifespan and actual lifespan. I’m interested in starting a project that would benefit immensely from tags that last for 2+ years. My question is whether anyone has experience from field studies that can speak to this expectation? I know these tags have only been available for a few years but it seems like plenty should have been deployed in 2017/2018 that could provide some initial data.
Thanks for any insight you are willing to provide!
Andy Boyce
Smithsonian Conservation Biology Institute
I’m hoping others will chime in too, but truth be told, most LifeTags were deployed in 2019 and 2020 thus far. We do have the following multi-year observations though:
At Bernheim Forest in Kentucky they had a multi-year detection for Louisiana Waterthrush (tagged in 2019, picked up in 2020).
At our station here in Cape May we tagged two Yellow-rumped Warblers in 2018 which returned in 2019. A Carolina Wren tagged in 2018 has returned for the las two years (likely a local bird that has moved outside of the Node grid and revisits from time to time).
I think there’s definitely going to be an effect of feather coverage following molting, so birds that are flying should beep more frequently than perched birds in subsequent years. Light tubes and other modifications can likely increase the probability of multi-year beeping as well. We currently add a section of flexible PCB to the LifeTag which allows for harnessing variation to get the tag away from feathers.
As for the tags lasting many years, we’ve had several tags mounted outside of the office since 2017 and they continue to perform as expected, so they represent the control against degradation in the field.
The following is summarized experience from Sahas Barve, who works on acorn woodpeckers (Sahas is not on this listserv!): We have been deploying various iterations of Life Tags for three years now in our resident population of acorn woodpeckers. The longest a tag has stayed on the bird is now about 3.5 years. She still lives at the same territory so her inability to disperse is helpful in this case I guess. We initially had problems with the mylar especially with the antennas falling off [Note: This is from a very early version of the tag that is no longer made.]. ACWOs are, I think, especially bad because they roost communally in cavities. So the antennas get bumped around each night on every bird. I also want to point out that we have had problems with the bungee cords we use for the leg loops. Some tags we have picked up fallen on the ground had cords that were really “stiff.” I don’t know if it’s the CA sun and the ACWO’s “baking in the sun at the tops of trees all day habit” that again makes them unusually vulnerable to this. Basically getting the most expensive bungee cord solved that problem. The tags do work well in really low light as well. As long you have receivers working, we pick up tags from sunrise to 10-15 mins post sunset and in cloudy weather.
I hope this is helpful, and feel free to get in touch with any additional questions!
