Dear All
I'm going to collaborate for studying a few species of migrating birds, of different size, from 150g to 1kg, roughly. We are going to purchase different models of GPS transmitters but given the long deployment, I'm wondering how can I avoid that the back feathers will cover the solar panels. I can clip them at deployment of course, but this does not solve the problem for long deployments.
What is the best way to avoid this problem, in your opinion?
thank you very much
I think the best approach is to go for very good SP with high performance, then you may do some sort of mechanical modification like fixing the panel higher than the feather growth zone.
Some researchers apply a neoprene pad as a base between the transmitter package and the body of the bird to elevate the package above the feathers. Neoprene is an important material because it will not absorb water.
I had that same problem with sage-grouse (back feathers covering the solar panel on dorsally-mounted GPS transmitters) and solved it entirely by: 1) mounting transmitters on T-shaped neoprene pads, and 2) using thicker neoprene (0.635 cm, or 1/4") to raise the panel higher off the back. Assuming your antenna is at the back end of the transmitter and bird (extending out over the rump/tail), the top of the "T" goes toward the front of the transmitter so that any feathers emerging in front of/above the transmitter and along the sides of the front half of the transmitter cannot cover the panel. When correctly deployed, the neoprene extends 1.25 cm in all directions from the front half of the transmitter (may need to be longer on larger birds with longer back feathers). Feathers emerging further back than that don't affect the transmitter, so to minimize weight, the neoprene only needs to be as wide as the transmitter at the back. Consider minimizing impacts on birds by eliminating scent (glue fumes, human scent, etc.), reducing visibility (paint transmitters to match color/pattern of back feathers if deployed on prey species), and sewing elastic into harnesses to increase flexibility while maintaining a snug fit (esp. for younger birds that might still grow a little more). Good luck!
I experienced this problem with ravens - they have relatively long neck feathers. The suggestion of Brett with the T-shaped neoprene is generally a good idea, however some species like ravens will likely tear it off soon or "ask" a conspecific to do so ;-) . In this case it can be usefull, if the tags are wider at the Solar Panel and more narrow below, additionally you might need to elevate the tags with neoprene pads. The drawback is that tags can get quite bulky and cause a lot of drag - caution especially with migratory species.
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