â-  Culprit was likely fungal pneumonia caused by rotting, moldy crops

NEWS-TIMES PHOTO: TRAVIS LOOSE - Since August, tens of thousands of cackling geese have descended--and ascended, as shown here--to and from Fernhill Wetlands on the edge of Forest Grove. They are migrating south to Mexico from Alaska, according to Clean Water Services Reuse Manager Jared Kinnear.The mystery of the dying geese at Fernhill Wetlands has taken another turn since six specimens were first analyzed in September.

From Aug. 25 to Oct. 22, more than 100 dead cackling geese (similar to Canada geese, but smaller) were found in ponds and along the shoreline of the popular wetlands in Forest Grove. They were among tens of thousands of "cacklers" that have descended on the nearly 200-acre natural area since August, when they began migrating south from Alaska.

Initially, Fernhill-based Clean Water Services staff worried the geese were dying from toxic blue-green algae, which was found at hazardous levels in a couple of Fernhill ponds in late August.

When the CWS staff sent some dead geese to the Oregon State Veterinary Diagnostic lab for analysis, however, results showed large amounts of grass in the birds' crops, fluid in their lungs, and the presence of phosphine in the intestinal contents — all consistent with zinc phosphide poisoning.

Dale Mitchell of the Oregon Department of Agriculture wondered whether a farmer was incorrectly using the pesticide, perhaps sprinkling it on top of the ground — where cackling geese tend to feed — instead of burying it where it would be found by the mice and voles it's designed to kill. He began thinking about an investigation.NEWS-TIMES PHOTO: TRAVIS LOOSE - This dead cackling goose was one of more than 100 that showed up over the past several months in ponds and near the waters edge at Fernhill Wetlands in Forest Grove.

But as further batches of dead cacklers from Fernhill were analyzed, Julia Burco, a wildlife veterinarian with the Oregon Department of Fish & Wildlife, found different symptoms: nearly empty intestinal tracts and significant lesions on their lungs and air sacs, indicating they died from fungal pneumonia caused by the systemic infection Aspergillosis.

It's a common infection that birds get when they eat moldy crops that have been sitting so long they start to rot, Burco said. Cacklers are more susceptible to the disease during the stress of migration.

Geese contract Aspergillosis every year, she said, but it's possible that small changes this year in certain environmental factors created more optimal conditions for the disease.

It's also possible that more dead geese were found this year due to the huge numbers of cacklers at Fernhill, along with an increase in visitors to the newly redesigned natural area, which would mean more people around to notice them, Burco said.

The geese deaths have died down in the last few weeks, said CWS Spokesman Sheri Wantland.

Local birding experts say the cacklers spend their winters in a broad area ranging from lower British Columbia to northern Mexico. Some will "overwinter" at Fernhill until next March, when they begin returning to Alaska.

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