The distribution, spatial clustering, and density of trapdoor spiders in two California coastal dune ecosystems

 

The distribution, spatial clustering, and density of trapdoor spiders in two California coastal dune ecosystems

Abstract

Coastal dune ecosystems support endemic trapdoor spiders, yet population data for these species are limited. We conducted the first coastal dune trapdoor spider population estimation surveys at Moss Landing State Beach (California) and for Aptostichus stephencolberti Bond 2008 at Sunset State Beach using randomly selected 1m² quadrats across ~26,000 m² per site. Burrow densities were similar between sites (Sunset: 0.287 burrows/m²; Moss: 0.453 burrows/m²), yielding estimated population sizes of ~35,206 and ~30,959 individuals, respectively. However, spatial analyses revealed contrasting patterns of burrow distribution. At Sunset State Beach, burrow presence was strongly associated with vegetation and occurred closer to plants, despite vegetation being randomly distributed. In contrast, no vegetation–burrow association was detected at Moss Landing, although both burrows and vegetation were spatially clustered. These results indicate plant-associated burrow distribution at Sunset State Beach, whereas spatial clustering at Moss Landing State Beach was not significantly associated with vegetation, suggesting that conservation strategies should be site-specific and consider multiple ecological processes.

Keller, M. F., Dickinson, K. A., Jochim, E. E., Quayle, I. L., Campos, J. E., Briggs, H. R., Wiggins, C. R., & Bond, J. E. (2026). The distribution, spatial clustering, and density of trapdoor spiders in two California coastal dune ecosystems. Frontiers in Arachnid Science, 5, 1913353. https://doi.org/10.3389/frchs.2026.1913353