Fertility ≠ Hatching Success ≠ Chick survival

 When the kākāpō live nest cam goes down for the weekend these are the kind of things that happen... poor unsuspecting  kākāpō fans who follow along on Facebook and go there to unsuspectingly make comments or ask simple questions of the Kākāpō Recovery Team - such as...

 

... and get replies like the following from kākāpōbirdnerds in withdrawal from their 24/7 kākāpō fix.... 

`````````````````````````````````````

For kākāpō, there isn’t really a single “normal” fertility percentage. It can vary a lot between breeding seasons depending on things like the age of the birds, which males mate, how many matings happen, and whether techniques like artificial insemination are used. 

Today’s population came from only a small number of surviving birds (40 founder birds contribute to the current populations gene pool - and the majority of those already came from a genetically restricted population). Low genetic diversity is a big part of the fertility challenge. In some past years fertility was devastatingly low - for example 2014 only 40% eggs were fertile. In 2016, 122 eggs were laid, with 59 initially classed as infertile (just above 50% fertility).

 In 2026, 256 eggs were laid and 148 of them were recorded as fertile. 

It is important to separate fertility from hatching success. More recent research has shown that some eggs once thought to be infertile were actually fertilised, but the embryo died very early in development. This is referred to as early embryo loss and is not visible with standard candling checks. Therefore some older infertility figures likely included very early embryo loss (maybe as many as three quarters of eggs thought infertile may actually have been very early embryo death). Infertile eggs are now part of research using intense microscope work to gather  more accurate data on infertility vs early embryo death.

Of this year's 148 fertile eggs, around 105 hatched. 

The Recovery team actively works to improve fertility rates. One tool used in recent breeding seasons is artificial insemination (AI). This is partly based on observations that females who mate multiple times, or with multiple males, have a higher chance of producing fertile eggs.

 For example - a female who mates twice with the same male has improved chance of fertile eggs; if she mates with two different males there is a 90% chance eggs will be fertile! AI can help replicate that effect and has improved fertility in recent breeding seasons (it is also a useful tool for increasing genetic diversity).

Another important consideration is chick survival. 

Fertility does not equal hatch success, and hatch success does not equal chick survival (Fertility ≠ Hatching Success ≠ Chick survival)

Even when improved fertility is achieved, kākāpō still have to contend with embryo deaths that reduce hatch rates, and then the hatched chicks must survive to fledge. There are perils after hatching as well! Of the 105 chicks hatched, so far only 11 have been lost to various causes.

The best thing we can do is talk about, follow and support the Kākāpō Recovery Team's mahi.

Kākāpō face many hurdles to population growth in the modern world (the above being just a few!), which is why the ongoing work of the Kākāpō Recovery Programme is so important in building a healthy, sustainable population for the future. I am very grateful to be able to follow their work! 

````````````````````````````````` 

     

 

 Yes.. I did that. I do realise this was a short Facebook question and I’ve responded like I’m defending a thesis.

I arrived to answer a question and somehow built a Kākāpō Visitor Centre.

In hindsight, “yes, it varies” was available to me.

I miss our kākāpō nest! 

If anyone needs me, I’ll be peer-reviewing my own Facebook replies.