Even for coots -- a generally tough waterfowl called by many rehabilitators the "velociraptor" of birds -- survival after an oil spill, even with rehabilitation, is filled with uncertainty. A new UC Davis study of recovery after a 1995 Unocal-Metrolink oil spill in Huntington Beach published this spring examined both behavioral and physiological responses to an oil spill. The work examines both the oiled coots and a control group of wild coots, mixed and temporarily confined to a habitat on the UC Davis campus for the duration of the study. While the confinement appears to have taken a toll on the wild birds, the effects of having been oiled did the most harm. The rehabilitated birds showed a 50 percent mortality rate compared with 24 percent for the captive, wild, non-oiled, coots, according to the study published in the journal Environmental Pollution. "It's another study that shows survival even after rehabilitation is likely to be impaired, when compared with normal populations. It shows that oil spills have greater long-term effects than we originally thought," said Dan Anderson, co-author of the study and a UC Davis professor of wildlife, fish and conservation biology. While Anderson examined the lingering effects on survival, condition and behavior, co-investigator Scott Newman, a wildlife veterinarian with UC Davis' Wildlife Health Center, conducted one of the first studies of blood indicators in a controlled setting. Newman found that the rehabbed oiled birds had several problems: they had evidence of an inflammatory response, decreased immune responsiveness and trouble metabolizing iron. "We know now that these physiological conditions and elevated blood parameters are associated with decreased survival, but we don't yet know the mechanisms that result in these conditions," Newman said. The work hopefully will lead to future studies to determine the reason survival is impacted, Newman said, and to help scientists develop "biomarkers" that could indicate earlier in the process of rehab whether a bird could survive. The most unique part of the study, Newman said, "is that birds received a full medical evaluation, to see if blood parameters were good predictors of survival." Although the rehabbed coots had diminished survival, Newman says, in this study "we saw that by three and a half months after oil exposure, 50 percent of the rehabbed birds survived, and at that point, we couldn't discern differences between the healthy control birds and the oiled birds."