Assessing Black Rat Population Abundance and Persistence at the Oceano Dunes State Vehicular Recreation Area

• Main Authors: Lu, Mars, Perez, Julia Kristina
• Format: Text
• Language: unknown
• Published: DigitalCommons@CalPoly 2022
• Subjects: Biology; Rattus rattus
• Online Access: https://digitalcommons.calpoly.edu/biosp/45; https://digitalcommons.calpoly.edu/context/biosp/article/1051/viewcontent/R._rattus_Report.pdf

The black rat, Rattus rattus, is considered one of the most destructive and widespread invasive species around the world, with the ability to damage crops, kill native species, and spread disease. The Oceano Dunes State Vehicular Recreation Area (ODSVRA) is home to numerous at-risk species such as the Western Snowy plovers (Charadrius nivosus nivosus) and California Least Tern (Sternula antillarum browni). Black rats have been detected at the ODSVRA in studies conducted in 2015 and 2018, and may be a potential threat to nesting seabirds like the plover and the tern. In addition, they may also serve as competitors for native mammals, as well as pests for the locals. Black rats are considered commensal with humans and are often associated with our properties, in particular trash. Semi-permanent human encampments were observed around the Dune Preserve area back in 2018, which may serve as a vector for black rats to spread. This study was developed to investigate if black rats remained at the site where they were detected back in 2015, and if there was a relationship between abundance of black rats and proximity to human encampments. Two plots were set-up with numerous camera stations, one following the same grid done in 2015 (called Dune Preserve 2), and one spanning part of the plot done in 2018 (called Dune Preserve Rattus Transect). Cameras were left at both sites for 3-4 days in April of 2022, and pictures of numerous species of rodents were collected. The rodent images were then identified by eye and evaluated for their respective hypothesis. The Dune Preserve 2 plot found that black rat populations have persisted at the site since their detection back in 2015, and may have potentially grown and spread. This is due to a higher number of black rats detected, as well as more stations detecting black rats than before. The Dune Preserve Rattus Transect did not find a significant relationship between black rat abundance and proximity to human encampments. However, rats were still captured at a majority of the ...