The lovable owl-parrot
If you don't know what a kakapo is yet, you need to get it in your life (see kakapo and Stephen Fry). This is a parrot with an interesting ecology, an endangered past and an adorable personality.
Kakopo is the Maori for night parrot and Strigops means owl-eyes; together these names sum up much of their ecology. The kakapo is endemic to New Zealand and, like the kiwi before it, has lost the power of flight in the absence of terrestrial enemies. Despite this, the kakapo's wings are not redundant but are used to parachute down through the branches up which it ably climbs with sturdy legs. Predators were not, however, absent altogether in the evolution of the kakapo. The existence of visually proficient aerial predators (such as the Haast's eagle or yore) pressurised the kakopos to stay low and hidden, employing cryptic green plumage and a freezing response to danger. At night, they could skulk in relative safety, using their huge eyes, whisker-like vibrissae and keen sense of smell to navigate and forage for plants, fruits and seeds.
As one might imagine, this suite of adaptations offers little protection against a relatively recent threat. Arriving in New Zealand around 700 years ago, the Maoris (formerly Polynesian) and their dogs hunted kakapos for food and feathers and had no problem picking the petrified parrots from the forest floor. Fast-forward 600 years and European settlers began to arrive, bringing with them their own mammalian entourage of cats, rats, stoats and ferrets which made a quick meal of the kakapos and their eggs. The ruthless efficiency of naturalists also played its part, each scientist or collector desperate for a kakapo in their cabinet of curios. Soon it was extinct on North Island and fast declining on South Island.
Into the 20th century, naturalists began to find and relocate kakapos to relative safety which tended to be islands or rugged glacial valleys. However it became apparent during the 1970's that only males were being identified until a small population was found on Stewart Island. A kakapo recovery programme set about relocating all kakapos to islands where predators could be removed and vegetation managed. Strangely, the sex ratio of relocated kakapos was skewed towards males (2:1) which was a concern for conservationists.
A typical conservation strategy may provide supplementary feeding for individuals to increase health and reproductive success. When applied to kakapos, however, the sex ratio became even more skewed in favour of males! In steps the Trivers-Willard hypothesis which states that a mother should manipulate the sex ratio of her offspring based on her condition. The idea is that her condition is correlated with her offspring's condition and condition matters more to males. Females are likely to breed regardless of their size and health however in males (i.e. the competitive sex) a big male may have many offspring whilst a small male has few to none. Thus a well fed female should have male offspring. This insight from evolutionary biology identified both the problem and the solution. The solution was to feed females up to their threshold for reproduction but not so far as to reach their male-biased threshold. The population is now (slowly) recovering and evolutionary theory saves the day!
Day 48: Major Mitchell's cockatoo - Lephochroa leadbeateri
A big fan
The cockatoos (superfamily Cacatuoidea) are one of the three superfamilies in the parrot order Psittaciformes, the others being Strigopoidea (kea, kaka and kakapo) and Psittacoidea (true parrots). All parrots possess a huge, sharp beak which is generally used for crushing fruit and nuts. They also have unusual, zygodactyl feet which means two toes face forward and two face backward. This adaptation makes parrots both impressive climbers and manipulators of food and even tools.
Major Mitchell's cockatoo is one of many cockatoo species in the Cacatuidae family which are confined to Australasia. The cockatoos are noted for their splendid crests: long, often colourful feathers which they fan out when aroused. The word cockatoo has Indonesian origins where it refers to cockatoos' vice like bills. These are kept sharp by the slow grinding of the mandibles. Cockatoos are able to tackle very tough nuts which no animal can deal wiith, pinning them against the roof of their beak whilst the lower mandible dismantles them.
Cockatoos are prevalent in the pet trade. Like many parrots they are colourful and intelligent and they can live for many years with a Major Mitchell's cockatoo called Cookie celebrating his 82nd birthday this year! This cockatoo is named after Major Thomas Mitchell, a 19th century explorer who remarked that 'few birds more enliven the monotonous hues of the Australian forest than this beautiful species whose pink-coloured wings and flowing crest might have embellished the air of a more voluptuous region'.
Day 49: Papuan lorikeet - Charmosyna papou
Red lorikeet, yellow lorikeet
The Papuan lorikeet is a stunning examples of the tribe of Australasian parrots known as lories and lorikeets (Loriini). The dichotomy between lories and lorikeets is not taxonomic but simply a grouping based on tail length with the latter having much longer, tapering tails (this distinction applies to parrots and parakeets too). Like most parrots, lories and lorikeets are also very colourful. The most well known is probably the rainbow lorikeet (Trichoglossus moluccanus), a raucous and conspicuous denizen if Australian suburbs. In my humble opinion, there is such a thing as an overly colourful bird so I chose the slightly more refined Papuan lorikeet.
Unusually amongst the parrots, the Loriini are specialised nectarivores. The genus Trichoglossus refers to their hairy ('tricho') tongue ('glossus') which is covered in tiny papillae that hold on to the nectar as the tongue is withdrawn into the mouth. The lorikeets are joined by the pint-sized fig-parrots and the budgerigar of pet fame in the parrot subfamily Loriinae.
Day 50: Eclectus parror - Eclectus roratus
Who wears the bright trousers?
Given the sexual dimorphism and dichromatism we have encountered so far on this journey it may not surprise you that male eclectus parrots look different from females. What is surprising, however, is both the extent of the dichromatism and the fact that it is the female that stands out most, in scarlet and blue, compared to the predominantly green males. This disparity has confused biologists for centuries who even originally recognised males and females as separate species.
The appearance of eclectus parrots reflects a unique and complex interplay of ecology, reproduction and evolution. The main constraint for eclectus parrots in the rainforests of Australasia is nesting availability. They require hollow tree cavities to nest which are hard to come by. Females invest much of their time competing for nest holes leading to 'social selection'. Social selection is a term used by some biologist to encompass the evolutionary change resulting from the pressures of social interactions including, but not limited to, classical sexual selection. It is well understood in evolutionary theory that males that compete with each other for females can avoid damage by honestly signalling their health and ability with colours and ornaments. Well the reasoning goes that there will be situations where conspecifics compete for commodities other than mates which result in the same pressure to appear impressive. Thus, competing female eclectus parrots evolved their colouration in competition for nest holes.
In this situation, the sex roles have not been reversed (as they were for jacanas and phalaropes); males still compete for females yet male eclectus parrots look so...green. Well that green is perfect camouflage for the male as it forages amongst the foliage, dodging the keen eyes of falcons and owls. However, in the arena around the nest hole, the green plumage suddenly stands out and the males are able to compete in the traditional fashion. Similarly the females plumage is effective camouflage when she dives into the safety of her cavity. Moreover, unbeknownst to the keen-eyed predators, these parrots are even more eclectic in ultraviolet light, part of the spectrum which parrots but not peregrines can see in.
Limited nest holes have further implications for the eclectus parrot. When females can only breed in cavities the limiting factor becomes, not females, but holes and sometimes there aren't enough to go around. As a result, females cannot afford to leave their hard-won homes so they desperately need food provisioning. She will, therefore, mate with multiple males (polyandry) and the uncertainty of paternity causes the potential fathers to all help out. This isn't the best situation for a male when holes, and thus mating opportunities, are rare and the offspring they're feeding might not even be their own! To maximise their reproductive success, males occupy huge territories which include multiple nesting holes. This complicated and unique (amongst birds) mating system is known as polygynandry: the only way to succeed is to cheat!
