Laura Erickson's For the Birds

Wilson Bulletin

I love to sit down with a brand new ornithological journal and read all the articles. The current issue of The Wilson Bulletin has a bunch of interesting papers. One is about a male sparrow found in Massachusetts for three years beginning in 1999. It sang a simplified Song Sparrow song, but didn’t look like one—it had features far closer to a Grasshopper Sparrow and a Savannah Sparrow. The bird was captured and banded, and a small blood sample was extracted which established that its mother was almost definitely a Grasshopper Sparrow. Although the identity of its father is somewhat uncertain, because there wasn’t any genetic bank submissions for Savannah Sparrows for comparison, the bird had more characteristics of Savannah than Song Sparrow.

Hybrid birds aren’t too uncommon in nature, but this bird had several unique characteristics. For one thing, its beak was significantly larger than any of the possible three parent types. And although for the first two years, it sang a simplified Song Sparrow song, in 2001, it started singing a typical Savannah Sparrow song, too, alternating with the simplified Song Sparrow song. That year it attempted to mate with a female Savannah Sparrow, and was observed feeding baby Savannah Sparrows and disposing of their fecal sacs. It was observed interacting with Savannah Sparrows on many occasions, but never with any Song Sparrows.

This poor, confused bird is probably the result of a female Grasshopper Sparrow’s inability to find an appropriate mate in 1998 or earlier. Grasshopper Sparrows are very rare in Massachusetts, with only 18 known breeding sites in the entire state. Failing to find an unattached male Grasshopper Sparrow, she apparently hooked up with a male Savannah Sparrow. But the song is very puzzling. Many male birds have a basic song in their genetic code, which they modify by learning, as they hear their father and other neighboring males during their nestling stage. Somehow this one picked up a Song Sparrow pattern, though the simplified version is normally not what it would hear a real Song Sparrow singing. But interestingly, alternating between two song types, as the bird did in 2001, is something many Grasshopper Sparrows do. I love these ornithological mysteries wherein we can make guesses, but can never be certain.

One hopeful article in the same issue of The Wilson Bulletin is about White Terns on Oahu. When I went to Hawaii a few years ago, one of my goals was to get pooped on by this beautiful all-white bird, because the first bird that ever pooped on me was a Black Tern and it seemed like a fine way to bring my pooped-upon list full circle. So my family dropped me off at Kapiolani Park near Waikiki Beach so I could sit in the right place under a White Tern until the wrong time. White Terns had been pretty much wiped out on Oahu by 1961, when only a single pair lived on the island, but now about 250 pairs are breeding there. The paper in the Wilson Bulletin suggested that even as they’re increasing, White Terns are having a harder and harder time nesting in Kapiolani Park because the pigeon population there is growing even faster, but they’re doing well in other spots on the island. Oddly, White Terns seem to thrive in high traffic areas where humans are active 24-hours a day. Apparently, although these conditions are hardly ideal for the terns, they make life even harder for predators. The paper gives some suggestions for helping White Terns to continue to thrive—a welcome “tern” of events that will not only ensure the survival of a beautiful bird, but will also allow anyone who wants to build up their pooped upon list, too.