Inbreeding danger for little spotted kiwi – study
By 3 News online staff
While rising populations of little spotted kiwi are encouraging, the rapid growth could be masking the damaging effects of inbreeding, new research shows.
A Victoria University study shows some populations that are descended from one pair of kiwi have resulted in brother-and-sister pairings in subsequent generations.
When the little spotted kiwi experienced a bottleneck of five birds just over 100 years ago, they were moved to Kapiti Island, and some of their numerous descendants were then transferred to predator-free locations.
Study author Helen Taylor, who graduates with a PhD in ecology and biodiversity in December, has studied the genetics of the two very different little spotted kiwi populations - Long Island in the Marlborough Sounds, and Wellington's Zealandia eco-sanctuary.
"I wanted to see to what extent inbreeding was occurring in these two locations, and the effect it is having on hatching success and population composition," she says.
While the Long Island population numbers 50 and is descended from one pair, the Zealandia population numbers 120 and is descended from 50 pairs.
"It's been assumed that little spotted kiwi are doing really well because the numbers are increasing, and that could be the case in populations like Zealandia with larger numbers of founders, but the Long Island population illustrates that this species is not immune to the harmful effects of inbreeding and must be managed carefully."
The birds can live for 45 to 80 years in the wild and the continued reproductive success of founding pairs could be masking problems with later generations, she says.
"This certainly seems to be the case on Long Island, where the majority of the population is composed of the two founders and their first generation offspring.
"That first generation are all brothers and sisters so subsequent generations of chicks are highly inbred and seem to be failing to survive to adulthood."
The birds in the study had small radio transmitter tags fitted with Chick Timer software attached to their legs.
These provided information on the incubation progress of eggs as well as the birds' activity patterns. Only male birds were studied as, in this species of kiwi, they sit on the eggs.
Ms Taylor urges caution with using population size to gauge the overall success of conservation efforts.
"The research demonstrates the danger of relying on population growth as a measure of success—by itself it's not always enough."
source: newshub archive