Goldcrests, Britain’s smallest bird, are resident in both Mercers Wood and Castle Hill Wood, and they are the best places to see one in the Gainsborough area. I have seen them in both places regularly.
On March 24th 2018 there was a male, with its crest raised, displaying in front of a female near the beehives by the Mercer Street entrance to Mercers Wood.
The Mercer Wood Goldcrests seem to associate with Long-tailed Tits in the winter months, and if you see a flock of Long-tailed Tits moving through the branches of a tree at this time, it’s worth looking carefully as there may be a Goldcrest amongst them.
I have occasionally seen Goldcrests around Morton, and I often hear one singing around the Floss Mill Lane area. I have also seen Goldcrests on Front Street and Walkerith Road, and at Morton Cemetery.
Elsewhere, there were two Goldcrests in the trees outside John Coupland Hospital on January 14th 2017.
Goldcrest (picture from Wikipedia)