Niue, a sovereign state in free association with New Zealand, uses two official legal tender currencies. The New Zealand Dollar is the circulation currency for daily transactions, while the government also authorises legal tender coins in the Niue Dollar currency for collector's purposes.
A number of mints issue a large variety of commemorative, bullion and collector coins under the authority of Niue. These coins are dedicated to historical or general popular culture themes not related to Niue itself. Many of them are made using "smartminting" techniques and have features not generally found in circulation coins - e.g. high relief, full colour printing and/or different forms, including fully three dimensional (3D).
Some coins are marketed in standard bullion sizes, like half ounce silver, one ounce silver etc, and some of those are also denominated as $1, for which see respective lists; this particular coin denominated as One Niue Dollar is not in a standard ounce-based size.
This coin is part of the Fascinating World of Birds series and features the Golden Oriole.
The Mint says about it:
"This beautiful series was created to take us to the captivating world of birds, enchanting us with the riot of colours and astonishing variety of species. The Goldfinch is one of the most colourful birds of our yards. Its cheerful twitters and trills are melodious and variable; you will easily recognise it during a spring walk in the park.
The goldfinch ( Carduelis carduelis ) is a little extravagant and very distinctive little bird. The most conspicuous feature of the goldfinch - the bright red mask - contrasts with white and black stripes on its head. The bird has a light brown mantle and creamy white rump and underparts. The tail of the goldfinch is slightly forked. The upper wing is black with bright yellow bar. Dark flight feathers and rectrices on the tail and wings are white-tipped." | 
Search for Niue: One Dollar Silver 2017 Goldfinch on eBay 