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May 25, 2011

African penguin Reproduction: Egg Development and Making Decisions

At the California Academy of Sciences, normal African penguin  incubation is 37-38 days. The eggs “Jahzara” laid are now at Day 45 and Day 41 into incubation. We need to make a decision to evaluate whether the chicks are still developing and need assistance or if the eggs stopped developing somewhere in the incubation process.  This is a difficult decision, because if we open the eggs too early, the chick could potentially stop developing. And if we open too late, the chick could potentially not have enough oxygen or yolk resources and not make it out of the shell. Having candled the eggs this morning with no additional change in air cell or internal pip, I opened the Alpha egg. This egg had been fertilized, but the embryo had stopped developing in the first trimester. The Beta egg was then opened with the same outcome. The candling photos that were taken at Day 9 showed clear vessels and a clear embryo. Now, having opened the eggs and evaluated the candling photos from Day19, 34 and 38, the dark area was bacteria reproducing in the egg likely post mortem. As this is a first time couple, we did expect that the chance of success in reproduction would be low.  The Nest cam that has been capturing “Agulhas’s” and “Jahzara’s” incubation has assisted our staff in evaluation of their first time skills as a couple. They have established normal reproductive behaviors including successful copulation, laying two normal sized eggs and taking turns incubating eggs. These will prove valuable in the future as our contribution to the reproduction of this endangered species. This couple will likely lay another clutch of eggs in the next 2-6 months and based on statistics should have a higher rate of success in the future. -Pamela Schaller

Filed under: CAS Penguin Colony — Penguins @ 2:25 pm


  1. Definately a hard decision to make. So sad to hear they did not make it past the first tri-mester. Hopefully a second clutch will bring better results. Tony

    Comment by Tony — May 25, 2011 @ 2:49 pm

  2. They seem to be a caring couple. We appreciate you sharing this experience with all of us and look forward to a new clutch soon!

    Comment by vieuxcarrie — May 25, 2011 @ 6:12 pm

  3. Is it possible to prevent bacterial infections in the developing embryo? Can the source or cause of infection be determined? Do bird eggs have any natural protections against infection? Would a longer incubation period outside the nest, under more sterile conditions, be beneficial? Are egg infections common in other bird species? How will a future egg be more successful in overcoming infection?

    Comment by Tom Shamp — May 26, 2011 @ 9:17 am

  4. How do I get the Feeding Time audio? I can’t find a link.

    Comment by Lynn — May 26, 2011 @ 10:34 am

  5. Hi Lynn, The audio is available during the 10:30am and 3:00pm feeds. It should come up automatically if you are watching the Cams during those times. Try htting the refresh button on your computer while watching.-Pamela Schaller

    Comment by Penguins — May 26, 2011 @ 11:08 am

  6. Hi Tom, These are all questions we examine after any loss in case there are any lessons that can be learned. The first trimester of embryo development is the most precarious. This is often when mortality is seen in developing bird eggs. There are a variety of reasons including genetics, improper temperatures and humidity. First time couples are often inadequate at incubating. They may not cover the eggs completely or not properly relieve each other of incubating duties, leaving the eggs alone too often. If the egs are properly incubated from a young, genetically healthy couple; generally the embryos have protection from bacteria while in the egg shell. Bird eggs, including penguins, are best incubated by their parents. Their brood patch and burrow provide the proper protection and environment for success in hatching. Incubation is something couples become better at after a few times nesting.-Pamela Schaller

    Comment by Penguins — May 26, 2011 @ 11:21 am

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