Readers’ wildlife photos: El cóndor no pasa

Brucy Lyon, evolutionary and behavioral ecologist at UC Santa Cruz, is back in spades with an amazing tale of encountering a California condor.  His words are indented and his pictures are stupendous.

I visited the park twice this spring. On the first visit I saw, from a great distance, 11 condors soaring around the picturesque High Peaks formation as they were coming into roost in the late afternoon. I could also barely make out birds landing on the tops of the pinnacles and spreading their wings to bask in the late afternoon trip. Even at a distance, the sight of these birds was impressive because they are so huge!

Below: On my second trip I made a beeline back to the area where I had seen the birds roosting on the previous trip. I arrived early in the morning to find about half a dozen condors roosting on the rocks and in pine trees, but they were far away.  A bit higher up the trail I had a nice view of a condor—it was perched on top of a pinnacle 60 feet away. All condors have wing tags with uniquely numbered IDs, and they also have tracking devices. According to the website with information about the tagged birds, a green tag (700 series) with the number zero means this bird’s ID number is 700. Bird 700 is a male born in 2013 at the World Center for Birds of Prey in Boise, Idaho and released in Pinnacles in 2015.

Below: I would have been happy with my initial encounter, but condor 700 had other ideas. He left the pinnacle and flew directly to me, landing ten feet away and perched and posed for a bit.

Below: Soon after, the condor decided that ten feet was too far and he hopped to within five feet of me. Here he is hopping.

Below: Since this is a critically endangered bird I did not feel comfortable being so close, so I slowly backed up until I was 30 feet away. The damn bird followed me and again got to within 5 feet of me. So, I backed up again, and again the bird hopped right up to me. I then decided that if I backed up just a bit the bird might stop following me so I moved ten feet away and tucked myself against a rock wall to be less conspicuous. The bird settled down and preened and just watched me and we enjoyed each other’s company for several minutes. Eventually I heard what sounded like a jet roaring overhead and looked up to see a condor swooping low 20 feet above me. Condor 700 took off to join the second bird. Here is a panoramic photo from my phone.

Below: I find that the face and neck is the most photogenic part of the bird, so I took a lot of head shots. I had no idea that the birds were this colorful. I also love the purplish unibrow. Both sexes of adults are similarly colored (juveniles are gray) and the adults have the colors year-round (so it is not just for mating). Apparently, the heads get more colorful (blush) when the birds are excited. Pretty mind-boggling to get a view like this of a bird that dropped to 27 individuals left in the world.

Below: I had not realized that condors have fairly long necks because the neck is normally scrunched up and hidden.

Below: Further along the trail I came across a second condor perched beside a cliff. I did not approach it and it did not approach me.

I chatted with a few other hikers who described seeing condors but, based on their descriptions, I wondered if some people were confusing turkey vultures (Cathartes aura) with condors. Vultures are far more abundant. As this photo-composite from park website shows, the two species differ in several ways and can easily be distinguished with practice: (1) condors are huge, with double the wingspan of vultures, (2) condors have relatively bigger heads, (3) vultures are paler on the hindwing while condors are paler on the forewing (and conspicuously white in adults), and (4) the primary projections or ‘fingers’ on the tip of the wings are more pronounced and numerous in condors. (Park Service photo)

The ‘fingers’ at the wingtips of condors and vultures are important for allowing these birds to circle slowly enough to remain in localized thermals of rising warm air without losing lift and stalling. In part, wings generate lift by causing differential airflow in which air pressure on the top of the wing is lower than the pressure under the wing. However, this pressure differential means that at the wingtip air from the higher pressure underwing curls around to the lower pressure top of the wing, and this air flow creates loss of lift (called ‘induced’ drag). This effect is particularly problematic at low speeds, which is a problem for birds that slowly spiral to remain in localized thermals. The primary extensions at the end of the wing help reduce this drag and allow the birds to fly more slowly than would otherwise be possible and to therefore spiral in tighter circles. We see these primary extensions in a variety of soaring birds like hawks, eagles, vultures and storks.

Below: This wingtip vortex effect occurs in aircraft too and also interferes with lift. When the cloud conditions are right, as in the photo below, one can see the pattern of air movement left behind the aircraft. Some types of aircraft have wingtip structures to reduce this type of drag and improve lift.

A nice study of African vultures showed that body mass relative to wing area (wing-loading) predicts how early in the morning different species of vultures become airborne from the rising air from thermals. I explained the geometry of wing-loading in a previous post about hummingbirds. Basically, larger birds have less lift per unit mass because wing area is a square of linear body size while mass is proportion to the cube of body length. Birds with lower wing-loading need weaker rising thermals to become airborne and can get aloft earlier in the day.

Below: I watched for this pattern at Pinnacles and it seems to hold—the smaller turkey vultures started soaring earlier in the day than the condors. The photo shows a few vultures starting to soar first thing in the morning but the condors were not up in the air until quite a bit later.

Below: Condors and vultures have shitty legs—literally. Check out the chalky white feet in the photo of bird 700 (and note the actual pink leg color at the top of the leg). The legs are white because the birds excrete urate-rich (white) urine on their feet. Studies of turkey vultures reveal that the evaporation of the urine cools the legs and that the birds are more likely to do this behavior in really hot weather. This behavior, called urohydrosis, occurs in New World vultures (which includes turkey vultures and condors) and storks. Kids, don’t try this at home.

Below: I took some video on my cellphone. At the time I noticed what I thought was the bird doing a display—it bowed and grunted. However, when I got home and looked at the video on my computer it turned out the condor was depositing a load of urine on its feet while grunting in the process. Here is the video.

Finally, in the event that readers want to see what a condor nest looks like, here is video of a nest cam at a nest in a giant cavity in a redwood snag in Big Sur, California. At Pinnacles, condors nest in small caves/cavities on cliff faces.