BLOG POST / Whio Files: Incubation

Updated: Dec 21, 2020

In our last post, we introduced you to our beautiful South Island whio and talked about our very special breed-for-release programme. In exciting news, another four ducklings have hatched since, bringing the total so far to ten that have been sent off to wild duck school this season.

We also currently have five more beautiful eggs in our incubator due to hatch on Christmas Day!

Our current (and third) clutch ready to go into the artificial incubator

Co-Parenting for Conservation

Once our female lays the last egg in a clutch, she is then rarely spotted out on the pond during the day. This usually tells the team that she has started incubating and we leave her to do this for twelve days before carefully removing and transporting the eggs into our incubation room. Eggs have a much better chance of developing normally when they are incubated naturally which is absolutely critical at the start, but by removing the eggs during the incubation stage, the pair are also able to produce more clutches each breeding season which is crucial for the survival of this species. So we share the role for the best results! After the eggs are carefully removed from the nest by the team, they are placed into an artificial incubator with a humidity pump.

Six beautiful fertile eggs from our first clutch this season


The development of each egg is then closely monitored by the wildlife team for 24 days which is always an exciting part of the job. We have to check our artificial incubators often to make sure they are always within the recommended parameters. These incubators maintain set temperatures and humidity which can be altered slightly when needed. Eggs are porous so they are able to exchange gases and moisture with the surrounding environment. As the ducklings develop, it is normal for the egg to lose weight. The team just needs to ensure that the eggs are losing the right amount of weight, which for whio is between 12-20%. This is calculated every time the eggs are weighed, which is twice a week to begin with. Each time we weigh the eggs, they are also ‘candled’ to take a peek and ensure the ducklings are developing normally.

Don’t worry we don’t use a real candle! Specialised torches are used which produce little to no heat. By shining a light through the egg, we can look out for the common signs of development. When the eggs are brought in initially, the first thing we look out for are veins. If we see these, it means the egg is fertile! In the later stages we then look out for movement, shadows in the right places and a big change in the air cell. If this big change is observed, it is because the duckling has broken through the membrane which separates the air cell from the rest of the egg and there is more gas exchange. A small, faint shadow is then spotted for the first time in the air cell indicating that the duckling has now moved into this space. This is called ‘internally pipping’.

Candling during ‘external pip’. Can you see the shadow of the duckling’s bill? How about the crack in the shell?

As the days go by, the duckling becomes more obviously present in the air cell and starts to work away at the outer shell. We begin to see a crack form and when candling, can spot their bill pecking away in that same spot for a couple of days. This crack is called the 'external pip site' and is the beginning of hatch!

Today is day 26 out of a 36 day incubation stage, so we will expect to see our current clutch reaching the 'internal pip' stage in the next few days. We can't wait for our Christmas ducklings!

Stay with us to learn all about the hatching stage and what happens next!

211 views0 comments

Recent Posts

See All