Post-Release Studies

brown pelicans

Post-Release Studies

How long do rehabilitated oiled animals survive after release, and do they return to normal biological function? Post-release survival is a critical knowledge gap in understanding the overall effects of oil in wildlife.

Several reports in the scientific literature suggest that oiled and rehabilitated animals survive for only days, not months or years. Other reports show examples of birds surviving decades after being cared for during an oil spill event. However, relatively few large-scale scientific studies have been undertaken to define the success of oiled wildlife rehabilitation efforts.

To address this lack of information, the OWCN has conducted specific studies on the post-release survival of rehabilitated oiled wildlife since 1995. When possible, OWCN conducts such projects on every spill in California.

Post-release studies are collaborative efforts between the OWCN and appropriate experts, with funding coming from a reserve within the OWCN budget. This research is crucial not only to determine that treated animals survive and return to normal after release, but also that protocols are improved based upon the success of the animals in their natural environment.

Overview of Studies

To date, several post-release projects on oiled seabirds have been initiated by the OWCN:

  • 1995: Following American coots following a crude oil spill in Long Beach
  • 1997: Evaluating Western gulls after the Torch/Platform Irene spill off the central coast
  • 1999: Evaluating common murres after the Stuyvesant oil spill in northern California
  • 2007: Tracking surf scoters affected during the Cosco Busan oil spill in San Francisco
  • 2015: Following brown pelicans after the Refugio oil spill off of Santa Barbara

Each project used tracking devices attached to rehabilitated and control birds and followed animals after release.

In addition to these intensive studies, all birds released after an oil spill are individually identified with a federal leg band. This enables others to report sightings of rehabilitated birds in the wild.

In 2017, the OWCN and OSPR published a compilation of post-release information detailing the successes of oiled wildlife collection and care, and addressed the ongoing questions of whether oiled wildlife response is “worth it”

Results of Studies

In each study, findings suggested that overall success (as determined by survival) was better than previously thought – largely due to the development of the OWCN and other spill response organizations around the world.

To report a green-banded pelican sighting, please fill out and submit this online form.