An on-going feature of kākāpō breeding to date has been the high number of infertile eggs. Since 1985, 40% of all eggs laid have been infertile with another 20% of embryos dying early in development. This level of infertility is much higher than that observed in other parrot species; usually around 10-15%. If we can reduce the number of infertile eggs produced, we will produce more kākāpō.
We suspect the underlying reason for this high infertility is inbreeding; most kākāpō from Stewart Island share an unusually high proportion of genes. Some males have a high number of abnormal sperm which could explain the high incidence of infertile eggs and dead embryos.
To try to reduce infertility we have removed some of the poorest performing males from the breeding population.
We know that those females who mate more than once lay significantly more fertile eggs than those that mate only once. We don’t know how to encourage a female kākāpō to mate more frequently, but with artificial insemination (AI), we can replicate a second mating and thereby hopefully improve fertility.
As well as increasing fertility, AI has the potential to minimise the loss of genetic diversity. We can use DNA fingerprinting (see Kākāpō Genetic Studies) to select males with rare genes and relatively few offspring as donors for AI. When the chicks have hatched we can use DNA fingerprinting to determine whether they are the result of AI or natural mating.
To do this work, we are collaborating with experts in the field of cryo-preservation and AI. Dr Juan Blanco (Centro de Estudios de Repaces Ibericas) is an expert in this field with non-domestic birds such as eagles and falcons in Spain. Dr Serean Adams (Cawthron Institute, Nelson) has made breakthroughs in the cryo-preservation of shell-fish sperm. Both Juan and Serean contribute their expertise to our programme.
We produced the first chicks from AI in the 2009 season.