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

The management of African penguin eggs includes marking eggs, record keeping and candling (as reviewed in previous blogs). Knowing when eggs are laid assists the staff in planning for expected offspring. Because African penguins lay 2 eggs usually 3-4 days apart it is important to differentiate between the eggs. Sometimes that is done by size (often the first egg is larger), however it may be difficult to tell by size.  Marking the eggs with a pencil is useful in egg management. Above are 2 eggs, one is marked with an Alpha (upper left egg in photo) designating the first egg. The second is marked with a Beta. As eggs develop, the air cell (located at the fat end of the egg) enlarges and eventually tilts. The air cell is seen upon candling. By drawing the edges of the air cell on the outside of the shell, staff can predict that the egg is close to hatching. The chick draws it’s first breath of air into their lungs in this air cell- this is called the internal pip. Within 12 hours they begin to externally pip (break through the egg shell). Records are kept for each time the eggs are candled and are especially important very close to the internal and external pip. This is called the pip to hatch interval. Writing on the eggs, record keeping and candling are important management tools for chick survival. Below are three candling photos, the first photo is of an African penguin egg at 19 days into incubation, second photo is 34 days into incubation and the third is 38 days. The dark area is growing bacteria likely post mortem, compare this to the previous penguin blog photo when the embryo and blood vessels were obvious at 9 days into incubation.-Pamela Schaller

African penguin egg: Day 19

African penguin Egg: Day 34

African penguin Egg: Day 38