麻豆淫院

New Zealand's nocturnal and flightless parrot, the , may be famous for trying to , but this unique species is facing some serious challenges.

With fewer than 160 birds alive, 办腻办腻辫艒 are critically endangered. One reason for their dwindling numbers is that they only breed every few years, when native trees produce masses of edible fruit or seeds.

Our suggests that the birds' breeding success depends on oestrogen-like hormones (phytoestrogens) found in these native plants.

Hormone boost from plants

Our study included 办腻办腻辫艒 (Strigops habroptilus) and two other New Zealand native parrots, the endangered (Nestor meridionalis) and (Nestor notabilis). All three have infrequent breeding success.

K膩k膩p艒 in particular have a low reproductive rate and together with the 办腻办腻, only breed successfully every three or four years, during mast years, when mass fruiting of native trees occurs.

2016 was a mast year and a - the best since New Zealand's Department of Conservation began managing and monitoring the night parrots 25 years ago.

This link between the parrots' successful breeding and high levels of fruiting in native plants has focused our investigations on potential stimulants present in their food plants that might activate or improve reproduction.

is that steroid-like compounds in the fruits of certain native plants provide a trigger for breeding. It proposes that 办腻办腻辫艒 don't produce enough of the hormone oestrogen to make a fertile egg, but by eating these fruits and the phytoestrogens they contain, the birds supplement their own hormone levels.

This increases the production of egg yolk protein, which in turn leads to eggs that have a better chance of being fertilised successfully.

We know from other studies that 办腻办腻辫艒 seek out the fruit from the native rimu tree (Dacrycarpus cupressinum) during mast years. We believe that this is how 办腻办腻辫艒 get extra oestrogen from their diet, and that rimu and other native plants provide a hormone boost that is key to 办腻办腻辫艒 reproduction.

Parrots more sensitive to oestrogen

In our current study, conducted by PhD graduate Dr Catherine Davis, we examined the receptivity of New Zealand and Australian parrots to a range of steroid compounds, including oestrogens, and compared it to those of other birds.

We tested various native plant species for oestrogenic content and we found that indeed there is a high amount of phytoestrogens in some of New Zealand's native plants.

We then looked at the receptivity of parrots to this plant hormone. We studied the genetic makeup of the receptor that is activated by oestrogens in 办腻办腻辫艒, kea, 办腻办腻, 办腻办腻riki, the Australian cockatiel, and compared this with those in the chicken.

We found that the parrots' oestrogen receptor was different. All of the parrot species have a unique sequence in the receptor gene, which may make them more sensitive to oestrogen, compared to other bird species, or humans.

In parrots, this receptor contains an extra eight amino acids in the region that binds the hormone.

Increasing fertility

By adding this amino acid sequence to a computer modelling programme based on the human oestrogen receptor, we have shown that this difference in the parrot-specific receptor would change the strength with which it binds to the oestrogen hormone.

The down-stream effects of this may be an increased sensitivity to plant oestrogens in parrots. This research supports the notion that the parrots' oestrogen receptor responds differently to oestrogenic compounds in native trees in New Zealand during mast years.

We have previously confirmed the in key compounds present in rimu and t艒tara (Podocarpus totara), as well as extracts from a number of New Zealand plant species that 办腻办腻辫艒 are known to graze. However, the chemical structures of the oestrogenic materials of most New Zealand native plants are not known.

The question remains why the rate of successful breeding of 办腻办腻辫艒 in mast years is lower than that of other parrot species. The identification of plant chemicals capable of binding to the parrot oestrogen receptor together with information about plant grazing behaviours of parrots may provide new insights into the conservation of the species that are in decline.

With further research, we are hoping to identify the specific compound in native plants that elicits these oestrogenic properties. This information may enable us to synthesise this compound in the lab. It could then be administered in some way to increase the fertility of our native parrots.

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