Focusing on a sympatric northern population of black-morph katipō (Latrodectus katipo) and invasive false katipō (Steatoda capensis) in Aotearoa New Zealand, I conducted monthly phenology surveys and lab assays over one year. I compared refuge choice and web construction in females and locomotor behaviour in males. Katipō showed clear seasonal peaks, whereas false katipō were active year-round and produced more egg sacs. False katipō males explored more horizontally, though both species shared webs and preferred V-shaped refugia. These findings suggest some niche partitioning but highlight ongoing reproductive and dispersal threats from false katipō. I recommend deploying artificial refugia and restoring dune habitats to bolster katipō conservation.