Ireland is an island, off an island (Great Britain), off a continent (European mainland).  And Sligo and Leitrim are Counties in north-west Ireland at the very fringe of Europe, on the edge of the vastness of the Atlantic Ocean.

Using the coordinates of latitude and longitude, the area described herein lies between +53o49'N & +54o28.5'N latitude and -7o35'W & -9o9'W longitude.

Irish Ordnance Survey maps have had grid lines printed over them since the late 1960‘s, a system that is referred to as the ‘Irish Grid’. At a small scale the island is divided into 25 squares of 100 km x 100 km which are labelled from A to Z (excluding ‘I’) (see below).  It is of relevance to note that the 8oW line of longitude, that almost exactly divides Ireland into east and west halves (see above), is used as the central anchor line for the Irish Grid.

The area occupied by Sligo and Leitrim falls mostly within 100 km square 'G' (or 1,3 on the numerical system).  A small area around Lough Gara falls within 'M' (1,2) and parts of east Leitrim are in 'H' (2,3) whilst south Leitrim falls within 'N' (2,2).

54o North

8o West

Map of Counties Sligo & Leitrim overlain by 10 km square (hectad) grid





The 100 km x 100 km grid can then be further sub-divided into 10 km x 10 km squares (called hectads) as is shown by the next map.  Each of these hectads has an address comprising of a letter (the 100 km square) and of two numerals representing the eastings (vertical line forming the left boundary) and the northings (horizontal line forming the lower boundary).  For example, the square coloured blue is H.14.


The following section describes how Sligo and Leitrim relate to the land divisions of Ireland which are arranged in a hierarchy from Provinces and Counties to Baronies and Townlands.


Ireland has been divided into provinces from early historic times.  There were originally five provinces but since the 17th century there have been four, and Sligo and Leitrim are in the Province of Connaught.  Connaught is the smallest province :-

Provincial boundaries have featured strongly in Irish history and so it is significant that the eastern boundary of Leitrim borders the Province of Ulster.  An earthwork called the ‘Black Pig’s Dyke’ roughly equates to a part of this boundary.  The south-eastern boundary of Leitrim, that is formed by the River Shannon, is also the boundary between Connaught and Leinster.


In the fourteenth century the whole of Connaught was called a county, but between 1570 and 1585 it was sub-divided into seven counties including Longford and Cavan (Edwards 1981) which are now placed in the Province of Leinster.  The five counties remaining in Connaught today are :-

Thus Sligo and Leitrim are by far the two smallest counties in Connaught.

Of the 32 counties in Ireland, Sligo ranks as the 22nd largest (11th smallest) and Leitrim as the 26th largest (7th smallest).

[Source of above statistics : O'Connor (2001)]

According to Kilgannon (1907), when County Sligo was first defined the northern boundary was the River Erne but this cut County Leitrim off from the sea.  In the fifteenth century a petition was accepted by the government to cede the strip of land that now forms the narrow coastline of Leitrim.  The result is that both Sligo and Leitrim are coastal counties, Sligo having 110 km of shoreline but Leitrim has the shortest coastline of any Irish county with only 4.5 km.

Counties tend to have a strong regional identity in the minds of people inhabiting them, and many aspects of the environment are usually managed by County Councils.  County boundaries often create problems for environmental management because they tend to pass through natural features and wildlife habitats.  For this reason the modern approach to environmental management is to use the river catchment as the management unit, as recommended by the EU Water Framework Directive.

In the case of this work, the ‘Natural History of Sligo & Leitrim’ most of the problems created by habitats being divided by county boundaries are minimised, because most of the difficulties occur along the Sligo / Leitrim boundary.  It is not an accident that these counties are being studied together as they share so much similar habitat ‘in common’.  and they make a very natural pairing.

Six other counties share a common border with this region, and in some cases major natural features and wildlife habitats are divided by county boundaries :

Co. Mayo lies to the west and south

Co. Roscommon is to the south and drives a wedge between the southern parts of Sligo and Leitrim taking in some of Lough Gara, the Curlew Mountains, small parts of Lough Arrow and Lough Skean, the southern area of the Carran Hill / Kilronan Mountain ridge as well as cutting through Lough Allen.

Co. Longford borders on the south-east part of Leitrim

Co. Cavan lies to the east and north of Leitrim

Co. Fermanagh takes in most of Lough McNean and a part of Lough Melvin

Co. Donegal has a common border with a small part of north Leitrim

County boundaries tend to run along rivers, through lakes and along mountain ridges.  They therefore cut through wildlife habitats rather than divide the landscape into its natural units.  For this reason this work includes small parts of Fermanagh, Mayo and Cavan.  In the case of north Roscommon, so many important wildlife habitats are shared with counties Sligo and Leitrim that a greater area of County Roscommon has to be included for completeness.

The boundaries of counties are generally fixed and have remained stable for hundreds of years.  However, the boundaries of various counties were redrawn for administrative reasons and transferred under the Local Government Act, 1898.  A case in point was when the boundary of County Sligo with County Mayo had to be adjusted because the town of Ballina, that is also an important administrative centre in Mayo, began to encroach over the border into Sligo.  Seven townlands (comprising 776 ha. or 1,917 acres) in the parish of Castleconnor in the western most part of the county near Ballina, were annexed to Mayo (see map shown below).



The townland is the smallest administrative division and they date back to pre-Norman times.  Having said that, it is possible to find townlands of only a few hectares up to thousands of hectares in mountainous regions.

A large number of townland names are topographical in origin, their core elements reflecting natural features of the landscape, or they may be named after the families living in them (see Place Names).

In the 1830’s, after the Ordnance Survey had mapped the entire country, they gathered data on place names and listed 62,205 townlands in Ireland.  The population census of 1851 was the first census after this mapping exercise to adopt the townland as the basic statistical unit.  Since then the townland has become the most basic territorial division and the linchpin of all spatial and administrative organisation in Ireland.

In the Placenames Database for Ireland there are 1,303 townland names listed for County Sligo and 1,503 townland names listed for County Leitrim.  On the other hand the websites :



list 1514 townlands in County Leitrim and 1360 townlands in County Sligo.  The differences between these figures probably comes from the fact that many townland names are duplicated which may cause some confusion.

Because villages are often poorly defined in Ireland, it is usual to attach a townland name to a biological record along with the grid reference.  However, the Ordnance Survey sheets in common use, often place townland names where there is otherwise no detail on the map rather than in the centre of the townland, and this often leads to the wrong townland name being ascribed to a biological record.


Map showing the counties of Ireland with an arrow indicating the part of County Sligo taken away and given to County Mayo in 1898.


Edwards, R.D. (1981)  An Atlas of Irish History. (2nd. edition).  Methuen, London.

Kilgannon, T. (1907)  County of Sligo.  Page 60 in Kilgannon’s Almanac and Directory.  T. Kilgannon, Sligo.

O'Connor, P.J. (2001)  Atlas of Irish Place Names.  Oireacht na Mumhan Books, Limerick.

Petty (1728)  Petty’s Atlas.  “A Geographical Description of the Kingdom of Ireland newly corrected and improved by actual observations.  The whole being laid down from the best maps viz : Sir Wm. Petty's Mr Pratt's etc.”

Ecclesiastical Land Divisions

When Christianity grew in importance in Ireland it established a hierarchy of Bishops and Priests who were given areas to manage and control.  The ecclesiastical system was thus transposed on to the physical landscape of the country.  By about 1100 the basic pattern of ecclesiastical land-divisions was established and it persists in a broadly similar form to the present time.

The largest administrative unit is the Diocese which comes under the control of a bishop and would contain many parishes.

The Parish is a familiar division and each parish would typically have its own priest.  Parishes date from the 12th and 13th centuries and would originally have been the commonly used administrative unit of the countryside.

The boundaries of parishes have often been altered by the churches to correspond with shifts in the human population.  Over the centuries the Church of Ireland parish boundaries have stayed the same or grown larger whilst the Roman Catholic parish boundaries have often been divided.  The result is that parish boundaries are different between Christian faiths and can cross barony and county boundaries, so are no longer compatible with government units of administration, and are not useful in environmental work.


Counties are further sub-divided into Baronies, and Baronies into Townlands for the purpose of administration, which in the past was done to aid in the colonisation of land.  These divisions are still used today for the purpose of the collection of census statistics, but they have little relevance in most people’s lives today.

Sligo and Leitrim are each divided into five baronies :

Sligo :Carbury, Coolavin, Corran, Leyney (Leny), Tireragh & Tirerrill (Tirerril)

Leitrim :Carrigallen, Dromahaire (Drumahair), Leitrim, Mohill & Rossclogher

A brief description of counties Sligo and Leitrim appear in Petty (1728) that outlines the baronies, and this is now quoted : -

"In Connaught circuit are : 1. The County of Sligoe, which is much of it mountainous and boggy, but in its lower Grounds and bottoms are found a good Soil, both for the Ploughman and Grazier : Its Content is 241550 Acres of Land, and has these six Divisions, viz. The Baronies of Carbury, Tirerril, Corran, Coolavin, Leny, Tireragh.

The chief Places in it are 1. Sligoe, a Sea-Port and Corporation, it is well situated and inhabited, the Shire-Town of the County, and the only Burrough in it, which sends Members to Parliament : 2 Colloony, a small Market Town near the confluence of the Rivers Unshenagh and Avenmore : 3 Achonry, a Bishop's See united to Killala, but now a small Village."

"5.  The County of Leitrim, tho' wild and mountainous, produces a good Head of Gras, and breeds abundance of black Cattle : It contains 206830 Acres of Land, and is divided into the 5 Baronies of Rossclogher, Drumahair, Leitrim, Carrigallen, and Mohill : It is scarce amenable to the Law, by reason of the Mountains and Faftnesses, and not having any Seaport, cannot have much Trade, nor consequently any considerable Towns.

The chiefest that can be found are : 1. James Town, formerly wall'd : and 2. Carrickdrumrusk, both on the Shannin, and successively Shire Towns of this County, and Corporations, which send Burgesses to Parliament."

Baronies map for Sligo and Leitrim

(modified from http://www.rootsweb.ancestry.com/~irlkik/ihm/barony-map-ireland.htm)