There are lots of publications showing what was learned using geolocators. But who has done fieldwork or knows of fieldwork in which none or few of the geolocators remained attached, or stopped functioning because the birds destroyed the device, light stalk, etc? I am especially interested in songbirds with geolocators attached with leg loop harnesses.
The most recent issues of The Auk (130: 211-222) and The Journal of Field Ornithology (84: 121-137) have reviews of the advantages and problems associated with light-level geolocators. Neither paper mentions destruction of the devices, but the Auk paper notes the need for greater reporting of problems such as harness failure. I would say your questions is another good one where more data are needed. The best way to answer that question would be to put dummy devices (same shape, weight, etc.) on non-migratory species or captive individuals of the species you want to use. That way, you can observe them for extended periods and see how they react to the device.
Dear Kevin,
I don't know of any studies regarding the way geolocators are removed by the birds, but I lean to think that in almost all cases the sample size in these studies is reduced because of the high mortality rate of the birds (especially passerines). If one uses geolocators there is no way to find out what happened to the geolocator (and this is why GPS tagging is better, although there are next to useless in case of small passerines). I would suggest fitting geolocators on adults in good condition of species with low mortality rates.
Kind regards,
Attila
I have heard of Orioles destroying the geolocators as well as Northern Flickers. Can direct you to the individuals involved if you wish.
Hi Steven, Thanks for your reply. Please do send me an email with the individuals involved. We are putting GL on Orchard and Baltimore orioles -- I had heard Sievert Rohwer had problems with Orchard Orioles, which is why I posted the original question. I wonder if anyone has had problems with other Icterids? They do have that unique prying bill.
Not a songbirds, but I know that storm petrels can remove them. I mean, a friend recover last year thre stormies that were supposed to carry geos and none of them had it.
I guess it deppends on how are they attached to the species...
Hi Fernando et al. This year we recovered GLs from both Baltimore and Orchards and neither seemed to damage the GLs. We were very happy to hear that the rumors about Orchards seem not to be warranted. I think it has a lot to do with the quality of the units. We have had good luck with two commercial brands.
Sure Kevin, not only quality of the attaching parts, but also how are handled and attached to the birds.
I was just chatting with someone who used them on bobolinks and found they bite the stalk off. I can put you in touch if you wish