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Red-winged blackbirds. Photo: Jerry Segraves

It started with the mysterious deaths of in Arkansas on New Year’s Eve. Reports of other seemingly strange wildlife deaths soon followed: 500 blackbirds in Louisiana; dozens of jackdaws in Sweden; 1,000 turtle doves in Italy; 2 million spot fish in Chesapeake Bay. More keep popping up on blogs and in news stories.

The “string” of puzzling events has caused confusion and concern, and has some religious bloggers saying it’s a the end is near.

(Not to mention all the “aflockalypse” and Hitchcock jokes. On NPR’s "," Tom Bodett quipped: “Somewhere in a small retirement cottage in California, Tippi Hedren went ahh, I've seen this before.” Charlie Pierce followed with, “I was telling my wife, as we were walking down by the River of Blood the other day, there's no reason at all to be worried.”)
 
Wildlife experts, however, say such mass events are normal. “Mass bird die-offs can be caused by starvation, storms, disease, pesticides, collisions with man-made structures or human disturbance,” says Greg Butcher, Լ����Ƶ’s director of bird conservation.

Fireworks likely caused the Arkansas incident. Same with Louisiana. In Sweden, it may have been in a mix of fireworks, cold weather, and lack of food. The doves in Italy were likely suffering from “massive indigestion brought on by over-eating,” the reports.  And in the Chesepeake, “Cold water stress exacerbated by a large population of the affected species (juvenile spot fish) appears to be the cause of the kill,” the concluded.

(A repeat event is unlikely with Fourth of July fireworks, when blackbirds, common grackles, and European starlings are spread out. In the winter blackbirds flock together in roosts containing tens of thousands to 20 million individuals or more.)

A quick look at the shows how frequently such events happen. Take the deaths logged during a one-month period this past fall:

 
So why all the frenzy and efforts to link the most recent die-offs? Blame it on technology allowing us to learn about isolated events and our impulse to look for patterns.
 

Information at your fingertips:  allows users to track mass animal deaths.

Isolated die-offs don’t pose a significant threat to our native bird populations, says Melanie Driscoll, Լ����Ƶ’s director of bird conservation for the Mississippi River Flyway. “Far more concerning in the long term are the myriad other threats birds face, from widespread habitat destruction and global climate change to inappropriate energy development and invasive species.”