Starlings in nest boxes now

I put up two nest boxes on the eaves above my bedroom window for swifts on
1st May, one of which was quickly occupied by a starling which raised a
brood.

For the last three weeks or so, both boxes have been visited by one or more
starlings every morning. It, or they, go into the box for around a minute,
sticking their head out and making a quiet warbling sound.

I wondered if anyone else has experience of starlings in nest boxes, and
whether this behaviour is to reserve the boxes for next spring.

Best wishes


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