Boy or Girl? Genetic Testing

Saticoy's PCR products in an agarose gel

On March 10, thousands of Condor Cam viewers watched as an endangered California condor chick emerged from its shell. The chick, named Saticoy by an online vote, is still being followed by thousands of people on Wildlife Conservancy’s Condor Cam. As viewers watched the downy chick grow, many wondered if they should call Saticoy “he” or “she.” That’s where the San Diego Zoo Institute for Conservation Research’s Genetics Division comes in.

California condors are sexually monomorphic, and it’s not possible to tell the male and female birds apart. It is important for management purposes, however, to know early on the gender of a newly hatched condor. Initially, determination of bird gender involved a highly invasive examination, but genetics techniques have allowed for less invasive sexing since the California condor recovery program began in the early 1980s, and with current methods, we can determine a condor’s sex using only a small drop of blood, a feather, or even a piece of eggshell membrane.

Our Genetics Division has genetically determined the sex of over 170 condors hatched at the San Diego Zoo Safari Park, as well as all other condors hatched at collaborating institutions or in the wild. But we don’t stop there. In addition to condors, we determine the sex of several other bird species for San Diego Zoo Global collaborative recovery programs, including San Clemente loggerhead shrikes and four species of native Hawaiian birds. This important practice supports animal care managers and field biologists in their efforts to develop sustainable populations of endangered species.

The process of sexing Saticoy began when we received a small blood sample from the chick’s first health exam performed by veterinarians at the Safari Park (see post Condor Chick: First Health Exam). Only a single drop of blood (about 10 microliters) is needed to perform gender determination using genetic techniques. First, the DNA is extracted from the blood cells by placing the cells into a tube, exposing them to enzymes, and incubating them in a water bath to release the DNA contained within.

After several steps of removing contaminants and washing the sample, pure DNA is available for use in the next step, the polymerase chain reaction (PCR). During PCR amplification, only a small amount of the DNA is required to obtain millions of copies of a particular DNA region of interest, which can then be used for further analyses. Birds have a sex-determination system like the XY system of humans, but in birds, the females are the heterogametic sex with chromosomes ZW, while the males are the homogametic sex with chromosomes ZZ. In the case of sexing condors, we amplify a gene that is found in both males and females and is able to show variation in sequence length between the two female sex chromosomes.

The final step is to run gel electrophoresis to analyze the PCR samples. Here, DNA separates within an agarose gel depending on the size of the DNA fragment produced by PCR. The gene amplified from a female’s W chromosome is longer and produces a different size fragment compared to the DNA fragment produced by the Z chromosome. The males, therefore, show only one band while females show two distinct bands in a gel. As the gel picture shows, Saticoy’s DNA sample produced one band by PCR, and we can then say…it’s a boy!

Heidi Davis is a research coordinator and Asako Yamamoto is a research technician for the San Diego Zoo Institute for Conservation Research.

24 Responses to Boy or Girl? Genetic Testing

  1. Hi. There seems to be something wrong with the camera the past couple of days. It cuts in and out.

    Moderator’s note: We’ll have someone look into it.

  2. I’m curious, how social are CA Condors in the wild? I mean among themselves. I’ve been watching little Saticoy since he hatched and he just seems so so lonely the older he gets… too bad they only raise one at a time…

  3. I am curious about the development rate of baby condors. In addition to your condor cam I have been watching some bald eagle cams and noticed that these 3 bald eagle chicks (blog(dot)nwf(dot)org/2011/04/eagle-cam-iowa-bald-eagle-eggs-hatching-live/) are 2-3 weeks younger than Saticoy but seem much more advanced in terms of their growth, development, feathering etc. Do condors develop at a much slower rate? Just curious…

  4. I went to visit the condor enclosure this past weekend, and it was closed for repairs. I was wondering when the exhibit will be open again.

    Moderator’s note: The condor exhibit at the Safari Park is being repainted. It will re-open May 11.

  5. I agree wih Michele. It does seem that the baby is lonely. Does he need companionship or doesn’t he mind being by himself most of the time? It must be a normal thing, otherwise the condor team would have been in there to help him. It seems hard to believe that he won’t fly until he’s five or six months old, because he flaps his wings and tries so hard already. Once he leaves his nest, will he ever return to it?

  6. I was wondering if you had any sound feeds of what Saticoy sounds like? It looks like on the cam he is calling out to his parents so I was wondering if you had recorded any of his noises. Love the condor cam and thanks for giving us the opportunity to see a baby condor grow towards independence :)

  7. Hmmm…. Yes I was wondering the same thing about Saticoy being lonely..
    seems like he would move around more if he had something to play with?

  8. The same thought occurs to me about Saticoy being lonely. He seems to just stare at the walls or is asleep. Haven’t seen his parents for a few days. I know they return with food but I guess I miss them.

  9. Goodness what happened to the camera? Was it attacked?

    Moderator’s note: How’s it doing now?

  10. Yes, I agree. Right now he looks like he just dropped where he was standing and is exausted! I was wonder the same thing as Tia, does he call out to his parents? I saw one day where one of the parents came to the stoop and just sat for awhile and fed the little guy, I thought that was so cool. Thank you for the “viewings”. I really enjoy watching him.

  11. I am with everyone above. It appears that Saticoy is bored and lonely. What kind of nesting situation do they have in the wild? I know he is just a bird but there is NO stimulation and nothing to see or anything in that box. It makes it hard to observe him seeing his struggles to jump/fly up to the hole that opens up to the wide world. :(

    Moderator’s note: Ron has prepared a blog to address these concerns. Check back soon!

  12. Any chance we can get sound? If not live, can a recording be made? Looks like he is calling out some times.

    Moderator’s note: Good suggestion! I’ll ask if a sound clip can be made to share with Condor Cam viewers.

    Condor Team responds: Sorry, no recording is available, and there are no microphones in these cameras.

  13. Saticoy is adorable. He lays there with his legs stretched out like he’s tanning. I see why his parents stay out. He is full of beans and picks them. Yesterday one of his parents was sitting at the opening and he was stretching up nibbling on their toes. If they’re in there he picks anything he can. I’m sure he’s fine. The people in charge would not have it any way but the best way.

  14. I was wonder too, if he gets lonely, I just watched as one of the parents #28 was in the nest with him and when the parent left, Saticoy looked so sad, (if that’s possible) he just kept looking at the opening. Can you put some sort of sensory object in there with him, like a small ball?, just to see what he will do with it? I don’t know, just a thought.

    • Or…maybe you could put some twigs in there with him?

  15. I just watched one of the parents come back in and love on the baby! It was so touching! Thank you for the webcams!

  16. I haven’t seen the parents for a few days. Does anyone know what times they come by to feed the growing boy, so I can see them again? I hope we get all our answers soon about Saticoy being lonely, etc.

    Moderator’s note: Look for it on Monday.

  17. Could Ron please address the positions Saticoy seems to favor with feet outstretched and laying on his sides as to whether condor chicks do this in the wild also?

  18. I got to see Saticoy spread his wings this evening… wow has he grown in this past week… :) amazing to say the least!

  19. could we learn about what kinds of vocalizations Saticoy makes? it seems like he is developing plumage under his wings pretty steadily. when do you expect his feathers to grow in fully? when would he start to practice flying and how?
    in response to others’ comments about loneliness, I thought he was doing pretty well napping and playing with stuff around the nest. but he seems to be awake more of the time (or I’m just catching him between naps) so I wonder what other kinds of behaviors he will learn to pass the time. are condors supposed to be social?

    • are there plans to give Saticoy any enrichment toys? or is that only appropriate for animals which would not be released in the wild?

      Moderator’s note: Check back soon for a blog post that addresses this question.

  20. Love the web cam but unfortunately has not been working . Out again today. looking forward to lonliness blog!

    Moderator’s note: It’s working for me at 6:30 p.m. I hope it’s working now for you.

  21. My camera is working, but it stays in one place all the time. If the baby isn’t where the camera is pointed, then we’re out of luck.


    Moderator’s note: See post Condor Chick: Lonely?