Sunbathing or something else...?

We had a two hour drive from mid Devon over to our dentist in Sherborne, near where we used to live. Changing dentists is not easy for a variety of reasons. And they are all so busy..
Anyway. We have to walk from the closest car park through some beautiful gardens and I saw this bird making strange noises and spreading its wings in the earth.
A quick search revealed the following. However, it could still be sunbathing!
https://amp.theguardian.com/environment/2019/jul/30/country-diary-birds-with-itchy-feathers-flock-together

Taken from the article :

"It is often referred to as “sunbathing” but it is intended to counter one of birds’ best-kept secrets – the burden of louse flies, mites and chewing lice, the fungi and the bacteria that live in the warm moist conditions of the body down, where they eat the feathers. More than 150 species of invertebrate ectoparasite are known, and a single bird may have 12 varieties in its feathers; by exposing them to direct sunlight it reduces their effects."