radio / satellite tagged kestrels?

Does anyone know if there are tagged kestrels? I ask as a few weeks back, I took some pics of a hovering kestrel and when I looked at them, I noticed a something sticking out underneath the bird's 'belly'! This isn't the best pic of the bird, but is better for showing this 'thing'! Is is a tagged bird, or has unfortunately been speared by something? It was hovering and hunting quite happily which leads me to think that it was more likely a tag! Anyway, be interested to hear your thoughts!

"All weeds are flowers, once you get to know them" (Eeyore)

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