Although some birds have several common names, only a few have what I would call a nickname. These names, from what I can tell, are used mostly by birders.
The yellow-rumped warbler is called a “butterbutt.” And the sharp-shinned hawk is known as a “sharpy.” So, who has the moniker of “The Gray Ghost?” The male northern harrier. Why, and why just the male?
Northern harriers, unlike most raptors, are strikingly sexually dimorphic, meaning the adult male and female birds look quite different from each other. You could easily mistake them for two different species of hawk. Most raptor genders are very similar with the most common difference being that the female is larger than the male. This size difference is also true of the northern harrier. But what really sets the genders apart are their distinctly colored and patterned plumages.
The female is a dark rich brown with strongly patterned light and dark stripes on the underside of her wings and tail. Sometimes it almost looks like a checkerboard. Her body has dark speckles and striations and her head is brown. From above, her wings are dark. Juvenile northern harriers look similar to the females but with a buff-colored breast. The male, on the other hand, is a beautiful ghostly gray and white. The body often has light streaking. The wings are light gray and tipped in black. See the photographs below.
Both males and females have a white rump patch and an unusual owl-like face. They look forward more than other hawks and have a feathered facial disc, similar to an owl’s, that helps them hear rodent movements on the ground.
Northern harriers are experts at low altitude gliding over fields and marshes which makes them easy to identify. Most hawks rely more on sharp eyesight than sound and fly much higher above the ground. Harriers fly so low that, especially on the whitish male, green reflections from vegetation can sometimes be seen on the underside of wings.
Seeing a northern harrier sailing over the coastal prairies, agricultural fields and the San Francisco Bay marshes is relatively common but always a thrill. Like a ghostly apparition they appear and disappear so quickly that you can wonder if you really saw it at all.
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