November has passed and we’ve received our first frosts, albeit light ones. Things have dried out and turned dull. Enter December – when we turn our collective gaze to our first serious chances for winter precipitation and truly cold temperatures, and the return of many migratory birds. December is prime time for viewing a wide range of cool weather wildlife.
One of my favorite species is the northern harrier – a sleek, swerving hawk. Given that harriers don’t breed in southern Arizona, we generally see them from November through April, when they add a unique avian predator to our already diverse retinue.
Telling a northern harrier from other hawks generally presents no great conundrum in the field. This is a medium-sized, graceful, and rather delicate hawk that effortlessly sails through the sky. It does so with a distinct “V” or dihedral shape to its wings, much like our resident turkey vultures. This wing posture minimizes caloric loss, while maximizing opportunities to both secure prey and to minimize the chances of succumbing to predation.
Either way, the dihedral allows harriers to bank swiftly and precipitously. While they do sometimes soar, particularly during migration, you should normally scan low and medium heights to find harriers. Mature male harriers are a ghostly gray, while adult females are dark brown with some rufous. Northern harriers sometimes are polygynous, with one male mating with multiple females.
The old name of the northern harrier, “marsh hawk,” refers to one of its preferred habitats. Indeed, some individuals and populations live wholly or partially in marshy domains for at least part of the year. Where I grew up in Philadelphia, I certainly associated them with local marshes. Many Arizonan harriers, however, use grasslands, scrublands, and other low-stature plant communities that offer the correct mix of both plant height and prey mix. Dense woodland or forest is normally not within their purview. Within the right habitats, northern harriers certainly live up to their moniker. First, they are the northern-most harrier species in the New World, with most related species lurking in the Old World. Secondly, and most pertinent to their would-be victims, they use their banking skills
to test the mettle of many potential prey items. As a harrier flies low over open habitat,
it keeps both its eyes and ears peeled for a quick meal. Like most hawks it is keen-eyed
with a powerful visual acuity. This alone may be sufficient to pounce upon a fleshy meal
with both talons and raptorial beak. Add to this an almost owl-like ability to listen for
prey, and you can see why historically this species was so successful. The key to its auditory prowess lies in the partial, owl-like facial disk of feathers that serves to funnel sounds — even the faint rustling of a small insect or vertebrate—to its ears.
Small mammals, such as mice and shrews, are the mainstay of these wheeling wizards of
woe. Northern harriers also regularly consume small birds, such as sparrows. Locally, they have the relative “pick of the lot” in this regard, as our Sky Islands host the most sparrow species on Earth! Add in a few larger invertebrates, such as grasshoppers, and there you have a balanced diet.
The story does not end there, for we all have our day of reckoning. Harriers can and do fall prey to larger raptors, such as golden eagles, red-tailed hawks, and great-horned owls. As always in nature, what goes around comes around!
Vincent Pinto and his wife, Claudia, run RAVENS-WAY WILD JOURNEYS, their Nature
Adventure & Conservation organization devoted to protecting the unique biodiversity of the Sky Islands region.