At approximately one month of age, our California condor chick, Luhui, should weigh around 4 pounds, 6 ounces (2 kilograms). The parents, Siwon and Sola, have already started leaving the chick alone overnight, sleeping near the nest. Although California condor chicks can thermo-regulate at three weeks of age, if the weather is cool the parents may continue to brood overnight. Even though the parents are increasing their time away from the chick, they remain VERY vigilant and protective of their nest and especially their chick. Some field biologists have even seen wild condor parents chasing black bears away from the nest area!
Up until now, the chick has been scooting around the nest on its tarsal joints. We refer to that as a “tarsal crawl.” It’s not uncommon, at this age, to see the chick standing all the way up on its feet, teetering around the nest, holding its wings out for balance. As its legs get sturdier, the chick may even approach the parent, begging for food. The “wing-begging” behavior we’ve been seeing will get more pronounced: lots of wing-flapping, head-bobbing, and trying to position itself in front of the parent.
It is possible that the parents, who are offering larger quantities of food per feeding session, might be providing a small amount of fur/hair in the chick’s diet. (Part of the adults’ diet includes mammals, like rats and rabbits.) Condors can digest just about every part of the animals they eat, except for fur. This fur accumulates in the digestive tract and is eventually regurgitated as waste. We refer to this as “casting.” A condor’s cast is composed of predominantly fur, whereas a cast from an owl has fur and bones; owls can’t digest bones, but condors can. We have seen condor chicks cast hair pellets as young as three weeks of age. When the chick casts, it throws its head forward several times, mouth open, until the pellet is ejected from its mouth. It can look like the chick is in trouble, but it is perfectly normal, and good for the chick.
At 45 days of age, Luhui will get its first health exam. We will obtain a blood sample for the lab to make sure it is healthy and send a portion of this sample to a lab in the Conservation Genetics Division of the San Diego Zoo Institute for Conservation Research, located adjacent to the San Diego Zoo Safari Park. From this blood sample, the geneticists can determine if Luhui is male or female. Also, during the exam, we will weigh Luhui—it should weigh around 7 to 8 pounds (4 kilograms)—and we will implant a transponder chip as a form of identification. It’s the same kind of chip you can get for your dog or cat at the veterinarian.
Most importantly, this exam allows us to administer a vaccine for West Nile Virus. West Nile Virus is disease that originated in Africa and was accidently introduced to North America by humans. North American wildlife, including condors, usually don’t have a natural immune response to West Nile Virus, so we are trying to give the chicks as much of a head start as we can. This exam will be the first time that Luhui will see humans, so it will naturally be disturbing for it. We try to be as quick as we can be (9 to 10 minutes) to minimize the disturbance. Additionally, we will keep Luhui covered with a towel to reduce its exposure to humans and to provide it a bit of security.
Siwon and Sola are usually away from the nest when we perform the procedure in order to keep them as calm as possible, as well. We have to keep in mind that we don’t want Luhui to become accustomed to or feel reassured by our presence; we want it to be a wild condor, uninterested and wary of humans, so that it may someday fly free in California, Arizona, or Mexico.
Luhui will look very large at this age compared to how big it was at hatch, but remember that it is still less than half of its adult weight. There is much more growth and fun to come!
Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous blog, California Condor Chick Watch: One week to One Month.