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Insects and birds

In 1999, a local TV station's Doppler weather radar detected millions of mayflies heading for Presque Isle in blue and green splotches on the radar in clouds measuring 10 mi (16 km) long. These insects were a sign of Lake Erie's move back to health, since the mayflies require clean water to thrive. Biologist Masteller of Pennsylvania State University declared the insects to be a "nice nuisance" since they signified the lake's return to health after 40 years of absence. Each is 1.5 in (38 mm) long; the three main species of mayflies are Ephemera simulans, Hexagenia rigida, and H. limbata. The insects mate over a 72-hour period from June through September; they fly in masses up to the shore, mate in the air, then females lay up to 8,000 eggs each over the water; the eggs sink back down and the cycle repeats. Sometimes, the clouds of mayflies have caused power outages and roads to become slippery with squashed insects. Zebra mussels filtering extra nutrients from the lake allows the mayfly larvae to thrive.

Incidents of birds dying from botulism have occurred, in 2000 and in 2002. Birds affected included grebes, common and red-breasted mergansers, loons, diving ducks, ring-billed gulls, and herring gulls. One account suggests that bird populations are in trouble, notably the wood warbler, which had population declines around 60% in 2008. Possible causes for declines in bird populations are farming practices, loss of habitats, soil depletion and erosion, and toxic chemicals. In 2006, concerns arose of possible avian influenza (bird flu) after two wild swans on the lake were found diseased, but they did not contain the H5N1 virus. Sightings of a magnificent frigatebird, a tropical bird with a 2 m wingspan, happened over the lake in 2008.