Abundance–Occupancy Relationships are Informed by Species Temporal Occupancy

Understanding the relationship between species occupancy and abundance is a central goal in macroecology. The positive link between species spatial occupancy-the fraction of sites in which a species is present-and mean local abundance has been dubbed a 'macroecological law'. However, this relationship fails to capture changes in occupancy over time. Temporal occupancy-estimated as the fraction of times a species is recorded in each site-has been used to explore species persistence in local communities but has no clear relationship with mean local abundance. That is, do more persistent species tend to occur at higher abundance? Further, how might species temporal occupancy relate to their spatial occupancy? We explored the relationship between spatial and temporal occupancy, and their respective relationships with mean local abundance using standardized sampling data of small mammal communities from the National Ecological Observatory Network (NEON). These sampling data spanned across the United States from 2014 to 2019. Except for several range-restricted species, species that occupied a greater fraction of sites also tended to occupy individual sites more frequently. Additionally, species that were more widespread (high spatial occupancy) and/or more persistent (high temporal occupancy) tended to occur with greater local abundance. However, the highest local abundance was observed for geographically restricted but temporally persistent species. This indicates that while there is support for the positive abundance-spatial occupancy relationship, spatial occupancy alone may underestimate the abundance of range restricted species. In such cases, high local abundance may be better explained by the temporal frequency in which species occupy sites. Taken together, these results demonstrate the positive relationship between spatial and temporal occupancy and highlight the utility of considering temporal occupancy alongside spatial occupancy for understanding abundance patterns.