The La Brea tar pits in Los Angeles, California, provide a unique opportunity to test ecological niche models and shifting distributions. This study modelled the distribution of bird species known to occur in the area, 86 of which have already been identified from skeletal remains entombed in the sticky tar for up to 40,000 years, and 97 for which remains from the pits have yet to be found.
Built using breeding survey data and GBIF-mediated occurrences for wintering and migrant species, the resulting models predicted presence at the Last Glacial Maximum (LGM) for more than 90 per cent of the identified species, suggesting reasonably accurate model range estimates.
The models also predicted suitable conditions at the LGM for more than 90 per cent of the species not present in tar remains but known to occur at La Brea, possibly because these were less likely to become trapped in the tar due to behavioural patterns or migratory habits—or they simply haven't been recovered yet.
Combined, the analyses revealed a small decrease in species richness from the LGM to today, likely due to distribution shifts following warming climates.