Last week we explored some aspects of endangered species behavior that often leave researchers at loose ends. These referred to parrots which migrate or those that are nomadic (with large home-ranges). The difference between these examples are a matter of known and unknown location and how that translates to control of conservation effort. A migratory bird has a distinct period of absence from your conservation land. During this period of absence we know that the bird is not to be found, having already departed to the summer/winter grounds. We can then plan conservation around the periods that the bird returns for feeding or breeding. Protection of the necessary habitat can be performed and negotiations can be entered with the people in the area where your parrot migrates too. In a wide ranging nomadic population like the Night parrot, when no birds can be reliably located, conservation managers have very little option for protecting this species. Today I want to talk about the New Zealand Kakapo (Strigops habroptilus) a very closely managed population of which every individual is known and carrying a radio-transmitter (tracking device). However despite this very precise monitory situation many unknowns hamper conservation efforts.
The Kakapo is the heaviest parrot in the world ( 2-4 kg) and one of the few non-cavity, ground nesting parrots. Although this is unique enough this long lived parrot is also entirely nocturnal, flightless and employs a Lek breeding system. We know a lot about the wonderful Kakapo, the males carve bowls out of the soft soil below boulders or at the base of dense shrubs, carefully positioned above a slope for greatest acoustic range. At night they inflate an air-sac and emit a number of deep-base notes. A number of males will occupy an ‘booming-arena’ where the female selects a suitable mate. The female will return every few days to mate prior to the laying of her subsequent eggs (which typically number 2-5 and hatch asynchronously). The male does not take part in the raising of the young, instead the female incubates all day then forages by night in order to feed herself and the growing chicks. Due to time and food constraints each nest typically fledges only two young. These chicks can be either bright green or olive colored and it is possible for both colors to occur in the same brood.
We know these factors of breeding biology from direct observation and close monitoring over nearly 20 years. The breeding season during which I worked produced 24 fledged bird from a source population of only 62 individuals. That represented over 30% increase in population during one breeding year. The problem is that these breeding years are few and far between (typical of an animal with a slow metabolism like Kakapo). The real problem is that researchers don’t know exactly what triggers this breeding and have no idea how to increase its frequency. Consequently we rely on maximizing the output of the few breeding events that occur. This year could be one of those monumental breeding seasons, triggered by a large seeding event from the native Rimu tree. We do know that breeding responds favorably to large seed fall and, mysteriously, that the birds predict this seed fall event three months in advance of the fruit falling. Such is the delicacy of the preparations for breeding. So in this example, we know almost all there is to know about the life and times of the Kakapo but are stumped when asked the question what makes them breed and how can be increase the number of breeding events from once every three years. In such a situation managers can only ensure that all young hatched survive and, prior to that, manipulate the pairing so that infertile males are not breeding with females and producing infertile eggs. In 2001 90 eggs where produced of which 40 were infertile (refer to photo of infertile Kakapo eggs in an egg carton).
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