Oransay is the smaller tidal island to the south of Colonsay. It houses the Oransay Priory and is an important habitat for choughs, corncrakes and other wildlife.
Please notice that Oransay farm is tenanted by RSPB (Royal Society for the Protection of Birds) and it is operated in a bird-friendly manner. It is vital to their management programme that needless disturbance is avoided; visitors are asked to keep any dog under strict control, and to co-operate with any guidance that may be issued from time to time. There is, of course, no restriction on one's legal "right to roam" but some of the habitats are particularly vulnerable.
More information will appear here shortly. In the meantime, do look at the National Biodiversity Network listing to get some idea of the importance of the site. By the way, if you are researching Oransay (Gaelic: Orasa) online, do note that it is normally rendered as "Oronsay" by officials and non-residents. Locally, either spelling is acceptable.
Crossing To Oransay
You will find that the best time to cross is in the two days following a New Moon or a Full Moon; low-water will be in the early afternoon and you may be able to take 4 or 5 hours over the round trip. Tide tables can be found here and also posted at the CalMac office - add 1 hour to the time of low-water (to convert it to BST), then deduct 10 minutes for local conditions - this gives you the mid-point of low-water. Aim to follow the tide out, by being at the Strand (say) 2.5hrs before that mid-point time. Note the time at which you are actually able to cross, and then calculate the time by which you must return.
Check your estimates in advance with any local person, and beware of winds from the south and east (which may sometimes make a crossing impossible). Follow the route marked on the map, do not ever take a "short-cut" in a vehicle, or even on foot when the tide is coming in. Do not take your vehicle if you can avoid it - if you make a mistake, the fuel will leak out and pollute the area whilst the vehicle is submerged.