From the time since the decline of the wild rabbit Oryctolagus cuniculus in southern Europe, various techniques and methods have been explored with a view to restoring wild rabbit populations or increasing rabbit resilience, for both conservation and game purposes. Rabbit restocking and habitat management are among the measures most often applied. Some efforts have been made to increase refuges for wild rabbits, mainly through the construction of artificial warrens. The present study evaluates the response of a wild rabbit population introduced to artificial warrens of varying sizes. This involves comparisons of the density of rabbits in the warrens, rabbit density change between seasons of low and high rabbit population density and the productivity index for large and small warrens in rabbit populations living under semi-natural conditions. Our results show that large warrens had higher rabbit abundance than had small warrens, but significantly lower rabbit density. No differences in density increase or productivity index were found with respect to warren size. The results suggest that it is preferable to build many small warrens for conservation of wild rabbit populations, but, in the event that only a few warrens are built, it is advisable that they be large.