Nearly 100 cliff swallows were found dead recently near the public dock at Lower Otay Lake and another five birds were found dead at El Capitan Reservoir.
Nikos Gurfield, the San Diego County veterinarian investigating some of the deaths, is looking for signs West Nile virus and avian influenza, as well as other possibilities. He said the deaths may be related to a lack of food for the birds, and is asking for a review from pesticide experts.