Hawk Watch: Spring Brings More Than Flowers to Anza-Borrego

My first (and, so far, only) hawkwatch—a play in one act


[curtain rises: a ridge in Morrison, Colorado]


Hawk Enumerator 1:  I’ve got a bird—over the microwave tower, moving north.

Me:  *searches for the microwave tower, wonders which way is north*

HE2:  Got ‘im!  Looks like an American Kestrel, male.

Me:  *might have found the microwave tower on the distant ridge; still not sure which way north is*

HE3:  Accipiters in front of Mt. Morrison, just below the clouds—7, I’d say.  Whadya think—sharpies or coops?

Me:  *Sharpies?  Coops?  What are those? Does Sibley list those species?*  [lowers binoculars, picks up field guide]

HE1:  I count 9.  I’m seeing quite a bit of head, so I’d rule out sharpies.

Me:  [drops book, raises binos again] *These guys can see heads?  I can’t even find the dang birds.*

HE2:  Flying railroad tie coming from the south, this side of Pikes Peak.

Me:  *Flying railroad tie?  What the heck?*

HE3:  Yep—Bald Eagle it is.

Me:  *Sees nothing.  YET AGAIN.*

Me:  [sighs, starts to pack up]  Well, I think I’ll just head back down to the car.

HE1, 2, 3:  [in unison, binos and scopes still glued to their sky-scanning faces]  Thanks for coming!


[curtain falls]


My husband worked as a hawk enumerator on the Dinosaur Ridge HawkWatch in Morrison, Colorado for more than a decade.  Every day from mid-March to early May, he’d trek up the ridge early so he could claim his favorite scope spot.  He loved the camaraderie with other raptor-philes, the many species of raptors that passed by, the challenge of identifying those beauties from afar.  Really afar.  Miles afar.  I went with him once (see above).  I couldn’t even find the birds in the sky while those folks seemed to be able to tell what each one had had for breakfast.  I liked the idea of a hawkwatch, but the reality of the distant views there was too much for me.


A favorite at this hawkwatch was the Swainson’s Hawk because it was usually the latest-arriving raptor species.  On powerful wings, Swainson’s Hawks make one of the most spectacular annual odysseys—for some birds, perhaps exceeding 14,000 miles round-trip.  This hawk feels most at home on open grasslands, be they the breeding grounds on the prairies of western North America or the wintering grounds of the ecologically similar Pampas of Argentina.  As a result, a Swainson’s Hawk spends almost a third of its life, four months every year, moving between these two geographic areas defining its existence.


The Swainson’s Hawk is a medium-sized, rather slender, long-winged, and long-tailed member of the Buteo genus (which also includes Red-tailed and Red-shouldered Hawks).  When perched, its wingtips reach its tail tip—a solid identification point since other buteos’ wingtips fall short of their tails.  The species’ plumage can show a light morph, a dark morph, or a confusing array of intermediate plumages.  The adult light morph (the most common plumage) features unpatterned dark brown above and white below, a dark gray or chestnut bib, and a white face and throat that can gleam like a beacon.  No matter what the plumage, though, the dark trailing edge of the underwing contrasting with the light wing linings distinguishes this species from most other hawks.  In fact, those in the know recognize this pattern as the exact opposite of the distinctive underwing pattern of a Turkey Vulture.  When soaring, a Swainson’s holds its wings in a slight V (called a dihedral), also much as a Turkey Vulture does.


The breeding-season diet of the Swainson’s Hawk parallels other temperate-zone buteos: rodents, rabbits, and reptiles. Once the breeding season ends, though, this hawk shifts to an almost exclusively insectivorous diet, with a special penchant for grasshoppers—so much so that, on its wintering grounds of Argentina, locals call it the “locust hawk.”


Both its scientific name (Buteo swainsoni) and its common name honor William Swainson, a 19th-century British naturalist and artist who also lent his name worldwide to a thrush, a warbler, a sparrow, a flycatcher, and a toucan (to name just a few).  The genus name, Buteo, arises from Latin for a common buzzard.  The term “hawk” draws from Anglo-Saxon hafoc, that language’s name for this type of bird.


Unfortunately, Swainson’s Hawks have experienced a major contraction of their North American breeding range as well as mass deaths from pesticide poison­ing in South America.  Although a fairly common breeder in San Diego County early in the 20th century, Swainson’s Hawks no longer nest in Southern California.  Listed as Threatened in California, our state’s

population has dropped as much as 90% from its estimated historical levels about 200 years ago.


As a result, over most of San Diego County, Swainson’s Hawk is now just a rare migrant.  But you can catch these magnificent migrators at the Borrego Valley Hawkwatch between mid-February and mid-April.  During this period, thousands of Swainson’s pass through, setting down in the evenings to feast on caterpillars among the desert wildflowers and taking off in large numbers in the mornings.  During the 2017 watch, the Borrego Valley enumerators counted a total of 11,690 Swainson’s, nearly one third more than the previous season high of 8,917 (set in 2016).  On just one day last year, in mid-March, enumerators tallied 3,713 Swainson’s, which was the most ever in a single day there.  And you often don’t have the curse—er, challenge—of finding far-distant birds.  (I’m lookin’ at YOU, Dinosaur Ridge HawkWatch.)  Since the hawks often lift off there at close range, Audubon has ranked the Borrego Valley Hawkwatch as one of the eight best hawkwatches in the nation for photographers.  You can keep an eye on the hawkwatch’s happenings here.


So if you have an early-morning ramblin’ itch this month, trek over to Borrego Springs to catch the morning lift-off around 8 a.m. (east of Borrego Springs, head north on Di Giorgio Road to the end of the pavement and just look for the birders with their scopes).  You too can witness a tiny fraction of one of the most spectacular of all bird migrations—up close and personal!

Leave a Reply