In early June two years ago, Mashpee Wampanoag Tribal Police and town officials received reports that three herons had been found dead in the Mashpee River near the fish ladder off Main Street.
As the days went by, more and more herons turned up dead in the same area. By the end of June, a total of nine had been found dead.
The tribal police department had some tests done, but while they did find some irregularities, no cause for the deaths were found, although drowning had been ruled out.
Last year, the department did not receive any reports of dead birds and the mystery seemed to fade away.
But yesterday, two great blue herons turned up dead in the same area, along with a dead herring, a fish that birds eat.
The department warned tribal citizens not to eat the herring from the river, fearing that contamination could have led to the bird deaths. (While the state has issued a moratorium on taking river herring, tribal members have aboriginal rights to harvest the fish).
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“It seems like a red flag to me,” said Kevin M. Frye Sr., chief of the Mashpee Wampanoag Police Department.
One theory is that herons may have gotten stuck in the ladder and, after taking repeated blows from oncoming water, died from being pounded against the structure of the ladder. One heron saved from the ladder two years ago was extremely exhausted when the department finally did get him out.
Supporting that theory, the department had not received any reports of illnesses from tribal members who may have eaten contaminated fish. Town officials further reported that other fish-eating birds, like osprey, have not turned up dead. And all of the heron deaths have been reported near the ladder.
But the department has not ruled out contamination. It posted on social media that toxicology tests two years ago came back with multiple chemicals in the herons’ systems, although no official cause of death could be identified. At the time, budget cuts put an end to further testing.
The department has notified the Massachusetts Environmental Police, Massachusetts Department of Environmental Protection, as well as town officials, and the Mashpee Wampanoag Natural Resources Department.
Meanwhile, police will not arrest tribal members for eating the herring, but will keep the public informed.