| Scots name | Cauf o Aidee[1] |
|---|---|
| Old Norse name | Kalfr |
Grey Head, the northern tip of the Calf. Sea caves, and the beginning of an arch can be seen in the cliff. | |
| Location | |
| OS grid reference | HY580393 |
| Coordinates | 59°14′N2°44′W / 59.23°N 02.73°W /59.23; -02.73 |
| Physical geography | |
| Island group | Orkney |
| Area | 243 hectares (0.94 sq mi) |
| Area rank | 98 [2] |
| Highest elevation | The Graand 54 metres (177 ft) |
| Administration | |
| Council area | Orkney Islands |
| Country | Scotland |
| Sovereign state | United Kingdom |
| Demographics | |
| Population | 0[3] |
| References | [4][5][6][7][8] |
TheCalf of Eday (Scots:Cauf o Aidee;Old Norse:Kalfr[7]) is an uninhabited island inOrkney, Scotland, lying north east ofEday. It is known for its wildlife and its prehistoric ruins.
There is aNeolithicchambered cairn in the southwest overlooking Calf Sound, which separates the island from Eday. Rectangular in shape, the cairn was excavated in 1936–37 and contains a small chamber with two compartments and a larger one with four stalls that has a separate entrance and was probably added at a later date.[9] Two similar structures have been identified nearby along with various other ancient ruins.[6]
From the 17th to the 19th centuries, the Calf of Eday was home to asalt works,[10] the remains of which can still be seen to the north of cairns.[6]
The pirateJohn Gow and his men successfully raided theHall of Clestrain on 10 February 1725, but when they attempted to attack Carrick House on Eday, they ran aground on the Calf of Eday, where they were captured.[11][12]

The Norse gave animal names to some islands, especially to small islands alongside a larger one, other examples being theCalf of Man and theHorse of Copinsay. The islands name inNorse times was thusKalfr.[7] "Eday" is a name derived from theOld Norseeið and means "isthmus island".[13][14]
In the 17th century Eday was also known as "Heth Øy" and the Calf's name is recorded byBlaeu as "Calf of Heth Øy".[15]
The dominant vegetation on the island is dry dwarf-shrub heath dominated by heather (Calluna vulgaris), with smaller areas of wet heath, semi-improved grassland and coastal grassland. The Calf of Eday supports 32 species of breeding birds and is designated as aSpecial Protection Area (SPA) for its importance as a nesting area. Gulls andcormorants (Phalacrocorax carbo) nest in the dry heath and grassland areas, whilstfulmars (Fulmarus glacialis),kittiwakes (Rissa tridactyla) andauks nest on the cliffs.[16] The island has been designated anImportant Bird Area (IBA) byBirdLife International because it supports breeding seabirds.[17]