Wing tags are large and can be read from a great distance but might in fact affect flight abilities and therefore survival, but homing experiments might do this, too (for a small extent)? So wing tags might be better for the bird's welfare if you can reduce the number of experiments (a classic trade off). Alternatively, you could use engraved colour-rings possibly adding a colour uncoded marker ring. You then have to come closer to the bird to read the ring. However, if this is only necessary at the home site, this should be easily possible with a good telescope.

Prof Serge Daan & his colleagues (Groningen Uni) used wing (patagial) tags extensively on F tinn & studied these birds in considerable detail back in 70s & 80s - to my knowledge, no ill-effect was noted. From memory, they also used small radio-tags, & calculated energy turnover & hunting efficiency of these birds. Key papers are by DirkJan Masman & Cor Dijkstra. Andy Village (author of The Kestrel) & myself also used wing tags in a number of different locations in UK back in 80's with no observed ill-effect. Because of their wind-hovering, kestrels are excellent subjects for wing-tags ... Good luck.

Dear Dimitri,

I have been working with kestrels for nearly the last 15 years and I have to agree with Joe Shelnutt against the use of patagial tags. I did use them in a few breeding females some time ago, and despite I didn't find any casualty, I think this is quite disturbing for the birds, and quite usually, they are trying to get rid of it. In my opinion, it wasn't necessary to go as far as detecting the effect of wing tags on survival, what I saw and I thought was enough to prevent using them. We had one female that got back the following year and one wing tag was missing. The main reason I do not like this way of marking kestrels is because the hover and keep flapping their wings continuously what make me think that hunting can be more energetically costly with wing tags. 

Another issue is to know where are you planning to perform the visual contacts, because if the area has plenty of trees, shrubs or whatever, the tags are going to be difficult to see if the bird is standing on them. 

I have also used PVC rings on fledging and adults. I did not find them very useful for adults if the porpouse of that was to individual identify them from the distance. They are detectable from quite far away with a telescope, but they need to be standing in a neat spot and most of the time their feathers cover part of it, like a letter or some other limitations (not in the right position, sun light, etc...).

Thus, I don't recommend using wing tags for kestrels and if you have money to expend to do homing stuff, I'd definitely go for appropriate radio tags or any other smart available systems, specially if you have the chance to capture them.

If you want further details of something I said here, please, don't hesitate to get back to me by my private email or through this way.

Cheers,

Jesús

It may be by plastic color line done to round because it easy and hamless for bird.

Dear all

thank you very much for your feedback. I would like to perform some preliminary experiments in order to test the feasibility of the investigation. Thus I prefer to avoid radio tags for the moment. I will probably use plain PVC colour rings combined with a temporary marking method more suitable for identifying birds from the distance (e.g. picric acid on feathers)

My personal experience from kestrels is, that they actively try to remove anything that is attached to them. We attached geolocators to 85 kestrels using teflon harness (the same system that is normally used for most species). Later we had evidence of birds trying to escape the harness. My worst fear is that some of them injured themselves when struggling with the harness, because the return rate next year was lower than usual - we got only 7 geolocators back. It seems that kestrels are very aggressive towards any object that is attached to their back. So I would suggest using only leg rings - its is also possible to glue a PIT tag to the pvc ring and set up readers in the territories where the birds are excpected tot return.