What we can do before we meet our new life

The Magellanic penguins living at Sumida Aquarium are extremely busy during their breeding season from February to April! In the February column, we introduced "preparation for breeding," and this time we'll continue that with a look at "from egg-laying preparations to hatching"! How do they care for each penguins and how do they handle the eggs that are laid to bring new life into the world? We'll show you behind the scenes of the animal care staff, which we can't fully cover in our exhibits!
(Exhibition and Breeding Team, Yoshimoe Kasuga)

■Is the female's weight important before spawning?
Like many other animals, egg-laying is a major event for Magellanic penguins. In order for them to lay good eggs and get through the laying process in good health, it is essential that they build up their physical strength beforehand. Therefore, our animal care staff set a target weight for each female penguins who is about to breed, and significantly increase the amount of food they eat about one month before the egg-laying season.

That's more than three times the usual amount! Depending on the individual, their favorite fish may change during the breeding season, and they may not even open their mouths unless it's a sardine, even though they usually eat horse mackerel.

Difference in body shape between normal and breeding season (in the case of Choco)

From my experience raising them, I have noticed that there are two ways in which penguins gain weight: one where they gain weight quickly and then maintain it, and one where they gain weight gradually.By regularly measuring their weight and carefully checking the changes in each individual, I can determine the weight gain pattern that suits each individual and adjust the amount of food they eat each day, the type of fish they eat, the number of times they are fed, and so on.

■ Don't miss the beginning of life <br /> Just as human babies can be seen with an ultrasound, penguins eggs can also be seen with an ultrasound. An ultrasound is performed each year as the egg-laying date approaches, when the penguins no longer need food, or when their facial expressions change. Depending on how the eggs look during this test, it is even possible to predict how long it will be until they lay an egg! For example...here.

Ultrasound image of eggs Left: Eggs about 4 days away from laying Right: Eggs less than 3 days away from laying

In the image on the left, only the yolk is visible. When this happens, there are about four days until the egg is laid. If the egg shell is clearly visible, as in the image on the right, the egg will be laid within about three days. I get very excited every year during this ultrasound examination, and at the same time, when I see the shadow of the tiny new life on the screen, I renew my resolve, thinking, "How precious... I will definitely protect it!"

The eggs may be incubated by the parent penguins who laid them, or they may be incubated artificially in an incubator like the one pictured below. A stable environment is essential for the chicks inside the eggs to grow properly!

Therefore, before egg laying begins, we test the incubator to see if it is safe to install it in a safe location, and whether it is maintaining the right temperature and humidity. These conditions change depending on the season and time of day, so we make fine adjustments many times until they are stable, and we continue to make adjustments even after we start to actually incubate the eggs. If the temperature and humidity are unstable, there is a risk that the eggs will not hatch properly, so we really have to be on our toes every day!

Inside the incubator and eggs

■ "Dummy eggs" are important for post-spawn care
Many people wonder if nothing is left for the parents when eggs are placed in an incubator. This is where imitation eggs, made from lime, come in handy!

There are three main reasons for giving imitation eggs:

① Don't confuse the parent penguins . Naturally, the parents will be confused if the eggs disappear. By providing them with dummy eggs, they will calmly continue to warm the eggs (incubation), and will be able to maintain the incubation rhythm and the habit of switching roles with their partners.

② Preventing further egg-laying <br /> If the eggs are not incubated, the parent penguins may feel that they have not laid an egg and may lay another egg. Repeated egg-laying puts a strain on the female's body and can cause delays in the annual breeding season.

3) Reduce the risk to the eggs .<br /> When penguins experience egg-laying and incubation for the first time, they may not be able to incubate the eggs properly, causing them to cool down, or in some cases, they may accidentally break the eggs. By practicing on a dummy egg, they can practice incubating the eggs without losing them.

penguins incubating eggs

When you see a penguins like "Chochin" on the left incubating an egg for the first time, you'll be impressed and say, "Wild instincts are amazing!" and "Where did you learn that?" However, there are also penguins like "Omochi" on the right who can't hold the egg properly at first and just hold it in their arms, and you can't help but say, "You can't hold it!" But after that, they'll be able to incubate the egg properly! The instincts of living animals are amazing after all!

■The mysterious time of egg inspection <br />Eggs kept in incubators are inspected regularly to check whether the chicks are developing normally. The first inspection is done one week after the eggs are laid, and the eggs are examined by shining a light on them in a pitch-black room.

If blood vessels are visible inside the egg at this time, it is a "fertilized egg" (see image below), and if there are no blood vessels, it is an "infertile egg." Unfortunately, if the egg is infertile, it will not develop further. Egg candling is one of the most moving moments in my work as a breeder! The joy I feel when I can see a tiny life developing inside the egg is indescribable!

Fertilized eggs in advanced development (7 days after spawning)

On average, it takes 42 days for Magellanic penguins to hatch from egg laying. Once the eggs are confirmed to be fertile, the chicks are checked every five days. It's a joyous occasion when we see the chicks growing, but not all eggs develop smoothly, so we are keenly aware of the weight of the responsibility that comes with dealing with life. For this reason, we watch over these precious lives every day, paying close attention so as not to miss even the slightest change. It's safe to say that there isn't a single day of rest during the breeding season!

Because we have been preparing and watching over the eggs carefully since before they were laid, the moment when the chicks are safely born is an unforgettable experience, no matter how many times we witness it. The hatching of the eggs is a major milestone, but it is not the end goal; there is still much progress to be made in order to raise the newborn creatures properly! Please continue to keep a warm eye on the animals living at our aquarium!