Rigor Vitae: Life Unyielding

Tuesday, June 12, 2007


Fifty-five years ago this summer, a sleek, smallish falcon with a broad, light eyebrow and dark belly band perched alone on the edge of a stick nest outside of Deming, New Mexico. Gray fuzz still clung to the young bird's forehead as it cackled loudly and furiously flapped its wings. Barely aware of what was happening, it suddenly found itself lifted by a stiff breeze, and it sailed across the chaparral, to land inelegantly on a Palo Verde. No one is quite sure why, but another Aplomado Falcon (Falco femoralis) would not fledge in the United States for the rest of the twentieth century. Two hundred years ago, these lovely birds were rather common across the brushy deserts of what is now northern Mexico and the southwestern U.S., but during the first half of the twentieth century their numbers declined severely. Livestock are often blamed for the crash, but large numbers of cattle grazed this land for many years with no apparent detriment to the falcons, as is still the case today in the Chaco of northwestern Paraguay. By the time Aplomado numbers began to dwindle, cattle grazing was about half as intensive as it had been 50 years earlier. DDT has been shown to thin Aplomado eggshells in Mexico, but their decline began well before the use of chlorinated hydrocarbons. By 1950, the species was all but extinct north of Colombia; only in a portion of southern Mexico did they occur in any numbers.

Named for the gray plumage of their mantle (Aplomado is Spanish for Leaden), F. femoralis superficially resembles its Neotropical congeners the Bat Falcon (F. rufigularis) and Orange-breasted Falcon (F. deiroleucus), but tends to occur in drier, more open areas than do those jungle birds. Also, its build is more Accipiter-like, with long legs and tail. Combined with an intense disposition, these features make the Aplomado reminiscent of a Cooper's Hawk in many ways—much more so than any other Falco species. Like the even more accipitrine forest falcons of the genus Micrastur, Aplomados are largely crepuscular, often hunting when it is quite dark. Small birds and insects make up the bulk of the prey, usually spotted from a perch and taken from the air. Three eggs are the norm—they are laid in the abandoned nest of a hawk or raven.

Encouraged with their successful reintroduction of Peregrines (F. peregrinus), the Peregrine Fund began captive breeding of Aplomados in the 1990s, and hacking the resultant young in southern Texas. Though a complete understanding of the birds' rarity is elusive, the reintroduction has been very successful. Within a decade, more than 40 breeding pairs were sustaining a viable population, and in 2005 further South Texas releases were deemed unnecessary. Last year that population successfully fledged 56 young. Meanwhile, back at the P. Fund, 132 captive eyasses were produced in 2006, 115 of which were hacked off in West Texas. In New Mexico, a pair turned up and fledged a brood last year. It was decided to undertake an experimental reintroduction on Ted Turner's Armendaris Ranch in that state, where 11 Aplomados were released last summer. It's now been been confirmed that from those birds a successful pair has already been formed, and a brood of two-week-old eyasses is reportedly doing well.
upper: SMOKE JUMPER--APLOMADO FALCON-detail (1995) acrylic 18" x 30"
lower: APLOMADO FALCON & SPOTTED BAT (1982) pen & ink 21" x 16"


Anonymous Anonymous said...

That's a superb painting!

1:15 PM  
Blogger Steve Bodio said...

Libby has made the hypothesis that the proliferation of poles-- telephone, electric-- and their abundant offering of hunting posts for big Buteos like redtails, which are known nest predators for Aplos-- could have tipped the balance. Same for Great Horned owls......? We see literally hundreds in the winter and maybe more than historically in breeding season?

6:37 PM  
Blogger Carel Brest van Kempen said...

Roger: Thanks, Roger!
Steve: ...not to mention Golden Eagles...and I'd expect Prairie Falcons would take them, too. The installation of pole lines in open areas certainly changed raptor hunting behavior in the immediate localities. You never see grouse leks within view of a pole line, for example, and I don't expect Aplomados ever nest within sight of one. I wonder if there was any positive impact in buteo/eagle populations from installing those poles. It would be interesting to look into the history. I doubt that the poles would directly advantage large raptors in preying on Aplomados.

8:17 AM  
Blogger Carel Brest van Kempen said...

Here's something interesting: I just learned that the young New Mexican pair is using an old Raven's nest...on a power pole.

12:43 PM  
Blogger JD(not the one with the picture) said...

John Langford first successfully bred captive Aplomados at the old Chihuahuan Desert Research Institute in Alpine, Texas, in the early 1980's. I know because I saw them there. He later worked in the Peregrine Fund project, I believe.

6:28 PM  
Blogger Carel Brest van Kempen said...

Thanks, James. I don't know how involved Langford actually was with the Peregrine Fund, but he certainly was an inspiration for the Aplomado reintroduction program.

4:52 PM  
Anonymous Anonymous said...

Does anyone know where John Langford is now?

8:16 AM  
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