There are 3 species of Amaurobiidae in the UK and we are fairly certain we have recorded at least two of them in the garden.
The image here we believe is either Amaurobius fenestralis or A.similis. Apparently the only way to tell them apart for sure is by close examination of the genitalia. According to at least one field guide * A.similis is more often associated with gardens and perhaps makes our specimen more likely this species. Our only record of this species as of April 2022 has been this single record, found within a folding garden chair near the house.
The other Amaurobius species we have recorded is A.ferox, which was a larger and darker spider as shown below, recorded in the leaf litter near the compost bin. Again to date we have only recorded this species on one occasion.
This specimen was entering a silken funnel it had constructed beneath a piece of deadwood under leaves. It’s feeding strategy is to wait until something wanders by and sends vibrations down into its silken den. It feeds on all sorts of invertebrates, including woodlice, beetles and other insects.
What can we do to encourage this species? Well, it seems to need little encouragement and will set up its den in old cracked masonry, fences and beneath stones and in our case deadwood/bark. We have plenty of such opportunities already but have also put down old roof tiles and stones, dotted around the place. Although the wolf spiders seem to have taken over these as they have most the garden.
*1. Bee, L & Oxford G & Smith H. (2020) Britain’s Spiders: A field Guide. Second edition. Oxfordshire: Princeton University Press