Yesterday was a gray, drizzly day and a great birding day at Moraine State Park in Butler County. I went there to see ducks, hoping to find Tundra Swans.
Moraine State Park was built in 1970 from strip-mined land assembled by the Western Pennsylvania Conservancy. Its centerpiece is a 3,225-acre lake formed by the damming of Muddy Creek. Lake Arthur is one of the few large lakes in western Pennsylvania and a major stopover for migrating waterfowl.
When I got to the Pleasant Valley beach area there were many ruddy ducks and coots, but the big surprise was around the corner at the south shore overlook. In the middle of the lake were hundreds of common loons. Birding friends of mine counted over 300. This is truly amazing because loons migrate alone or in small groups and are rarely seen in large numbers. In one glance I saw more loons than I've seen in my entire life. A loon fallout!
The word fallout usually means something bad - radioactive fallout from a nuclear explosion or political fallout from a bad decision - but in birding it's exciting. When migrating birds hit bad weather, the flocks have to land. This results in so many birds in one place that they seem to have fallen out of the sky.
So why loons? I can only imagine it happened like this: On Saturday evening fifty or more small flocks of loons each made the individual decision that it was time to leave the Great Lakes for the coast. They all headed southeast for Chesapeake Bay but when they reached western Pennsylvania they found the leading edge of bad weather, fog and rain. They realized it was only going to get worse so they had better land at Lake Arthur.
Loons have few choices on where to land. Because they eat fish for a living, they are excellent divers but their bodies are heavy and hinged incorrectly for walking. If they land on anything except a large area of open water, they cannot take off again and will die, stranded. Lake Arthur was their best - perhaps their only - choice.
Chuck Tague once found a common loon on a beach in Florida, pictured here. It may not have been stranded because the tide was going to come in, but it was definitely out of place. As you can see, the loon's legs are far back on its body, making them good for swimming, but not good for walking. This loon is in winter plumage, mostly a uniform gray instead of the striking black and white pattern of breeding season. The loon's belly is white but you can't see the belly when they are riding the water.
After watching the loons for a while, I parked and hiked. It was cold so I walked fast and finished early. Again I drove the south shore loop to see if anything changed. This pass was even better. The loons were still there but this time I saw three bald eagles. An adult pair (the male is noticably smaller than the female) circled up around an immature eagle. Immature bald eagles are brown with blotchy white on their bodies. Their heads and tails are not white. The adult eagles seemed to be showing the young eagle that they claimed the lake as their territory. They didn't chase him, just gave him a show of strength.
And my Best Bird of the day was there too. Perched on a bush at the water's edge was a Northern Shrike, a rare northern visitor. What a cap to my day! The only way to improve it would have been if I'd seen Tundra Swans.