Northern Harrier – Filling a Niche

In the winter, the Lowcountry of South Carolina has a tremendous diversity of birds that migrate through and reside in this area.  Due to the variety of wetlands and other habitats, this area attracts songbirds, waterfowl, raptors, and many other birds.

One of the most fascinating to me is the Northern Harrier or Marsh Hawk (Circus cyaneus).  This raptor or bird of prey has adapted to fill a niche that few other raptors have even come close t o filling.  Instead of the sit and wait approach to hunting prey that is employed by many raptors or the soar and flyover technique with peregrines, eagles, and other raptors, the harrier uses the back and forth, make something happen technique!

Being adapted for this type of technique, the harrier takes a little bit of adaptation from different birds and makes it his own.  Harriers have the ability of slow, hovering flight, enabling them to fly slowly, just above the grasses and shrubs, looking for prey.  Holding their wings in a very noticeable shallow “V” or dihedral, they can fly slowly, back and forth over rice fields, marshes, and other grasslands, searching for prey.  Upon detection, the harrier wheels around and dives, or just drops from the sky in hopes of surprising small birds, rodents, and other prey.  Also aiding the marsh hawk (its other name) in its hunting efforts is an adaptation taken from its night-time cousins, the owl.  Marsh hawks have facial disks similar to owls, and just like in owls, the facial disks help funnel sound to the hawks ears, helping them hear and zero in on their potential dinner.

One of my favorite features of the harrier doesn’t have anything to do with its hunting adaptations, but in the fact that it is one of the few raptors that is sexually dimorphic, meaning the female and the male appear different.  The female marsh hawk is brown with a buffy, tannish underside, looking like many other birds of prey.  The male, however, is smaller and is gray on the back, with a much brighter and pale belly.  Both birds have a long tail and a conspicuous white rump patch that makes them easily identifiable in the field.

Take a trip to the Savannah NWR and keep your eyes open for the northern harrier or marsh hawk.  If you look closely, you make be lucky enough to see both male and female methodically flying over the marsh in search of their prey.



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