Investigations into the widespread death and illness of local pelicans in recent months have found that higher-than-normal levels of a naturally occurring toxin may be the source of their ailments.

The International Bird Rescue Research Center has reported a higher than normal “die off” of adult pelicans on the Pacific west coast this year, as well as conditions indicating illness in the population. The center sites numerous incidents of disorientation – birds landing inland, being found in neighborhoods and roads, and flying far from their normal migratory patterns – that may indicate a neurological problem.

A press release issued from the IBRRC last week reported that three out of six birds sampled tested positive for domoic acid, a naturally occurring toxin that has been known to adversely affect the health of pelican populations. According to Heather Nevill, the IBRRC’s veterinarian leading the group’s pelican investigation, domoic acid may not be solely responsible for birds’ failing health.

“We believe these results are significant but do not explain all the signs we are seeing in the pelicans,” she said. “We are seeing a number of conditions that are not typical of domoic acid toxicity or a domoic acid event. Therefore we are continuing to collect samples, keeping an open mind and considering all possibilities.”

So far, the IBRCC has recorded 265 dead and ailing pelicans from Baja California, Mexico to Washington State, with at least 100 of the birds receiving treatment. Additional blood and tissue samples conducted over the next two weeks are expected to provide further insight into the causes of these illnesses and deaths.