Transformation of Scorpion Rock: A Key Nesting Area for Channel Island Seabirds

These photos taken at the same place 4 years apart show the transformation of shrub habitat on Scorpion Rock after restoration (Photo Credit: David Mazurkiewicz, National Park Service).

Biologists prepare for their final year of successful seabird restoration efforts on Scorpion Rock (SR) in 2015. Since the project started in 2008, the plant community has dramatically shifted from non-native invasive weeds to a rich, lush cover of 17 different native plant species. This shift in plant types on SR is important for nesting Cassin’s Auklets, a small pelagic seabird that breeds along the Pacific coast.

Cassin’s Auklets dig nest burrows under large native shrubs that protect them from predators and stabilize the soil around the nests. Before 2008, SR was mostly covered by a non-native ice plant that is not good at stabilizing soil and forms thick mats on the ground making these areas inaccessible to Cassin’s Auklets.

Restoring the Native Shrub Habitat

Biologists used several methods for removing the non-native ice plant and other weeds including hand-pulling and chemical treatments. At the same time, biologists and volunteers planted approximately 9,000 native plants over a five-year period that would eventually grow in areas originally dominated by ice plant. All native seeds were collected from Santa Cruz Island which is located just a few hundred feet from SR. Seedlings  were grown on Santa Cruz island in a nursery until they were ready to be planted. All of the hard-work has paid off since the planting began, and instead of a landscape dominated by ice plant, we now see a thriving native plant community!

The seabirds are recovering too. Biologists have seen a 3-fold increase in the number of natural Cassin’s Auklets burrows since the project started. Over the last few years, biologists have also observed a lower number of dead adult auklets which means that the native plants are providing adequate cover from predators.

GPS coordinates of Cassin's Auklet nest locations overlayed on an aerial image of Scorpion Rock. Artificial and natural nest burrows are indicated on the map (David Mazurkiewicz, National Park Service).

Final Year of Restoration in 2015

Upcoming efforts for 2015 on SR may include the use of social attraction for Cassin’s Auklets and another seabird, the Scripps’s Murrelets. Social attraction activities involve broadcasting breeding sounds of these seabirds from SR to attract more individuals to nest. Biologists will continue the annual maintenance plan for this project which includes weeding non-native plants and monitoring seabird numbers. As the restoration work winds down, we can reflect back to what this small islet looked like just six years ago and think about what the benefits will be to generations of seabirds in years to come!

 

 

-Gabrielle Dorr, MSRP Outreach Coordinator