# Pine marten (Martes martes) distribution and abundance in Ireland: A cross-jurisdictional analysis using non-invasive genetic survey techniques

> By walking over 1200 km of forest trails and DNA-testing the scats they found, researchers mapped pine martens across the whole island of Ireland for the first time. Martens have spread widely in the Republic over 30 years, to an estimated 2740 animals, but Northern Ireland holds only about 320, still clustered in the west.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2012-omahony-oreilly-pine-marten-martes-martes/

## Citation and access

- **Authors:** Declan O’Mahony, Catherine O’Reilly and Peter Turner
- **Year published:** 2012
- **Journal or source:** Mammalian Biology
- **Full citation:** O’Mahony, D., O’Reilly, C. and Turner, P. 2012. Pine marten (Martes martes) distribution and abundance in Ireland: A cross-jurisdictional analysis using non-invasive genetic survey techniques. Mammalian Biology 77(5): 351–357.
- **DOI:** 10.1016/j.mambio.2012.04.001
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.1016/j.mambio.2012.04.001

## Tags

- **Species:** Mammals > Pine marten
- **Region:** Europe > Ireland; Europe > United Kingdom
- **Tracking:** Scat; Sign surveys; Tracking; Tracks and signs identification
- **Behaviour and ecology:** Range expansion
- **Methods and technology:** Bootstrapping; Distribution mapping; DNA; Geographic Information System (GIS); Population estimation; Population trends
- **Data type:** Existing data; New field data
- **Observer qualification:** Reported but not validated
- **Discipline:** Behaviour and ecology; Wildlife tracking
- **Year published:** 2012

## Detailed keywords

- **Species:** Studied: pine marten (Martes martes). Mentioned but not studied: red fox (Vulpes vulpes), discussed as the main potential competitor and predator of pine martens in Ireland, and whose scats the DNA test can also identify. Forest trees named: Sitka spruce (Picea sitchensis) and lodgepole pine (Pinus contorta).
- **Location and habitat:** The island of Ireland: the Republic of Ireland and Northern Ireland (United Kingdom). Pilot survey in County Fermanagh, Northern Ireland. Transects in forest and scrub, mostly along vehicle tracks and walking trails (over 85%), otherwise minor paved roads or animal trails. Most forest is commercial conifer plantation; Ireland is the least forested region of Europe (about 10% forest cover in the Republic, under 7% in Northern Ireland). Killarney National Park is named as a reintroduction site.
- **Topics:** distribution survey; scat-based transect surveys; DNA confirmation of scat identity; occupancy; range expansion and historical change over 30 years; core population range; population abundance estimates; reintroductions and relocations; afforestation; legal protection; persecution and predator control; red fox competition and intraguild predation; human–wildlife conflict and predation on birds; conservation status and red list assessment; forest management.
- **Statistics or models:** McNemar test with continuity correction (change in occupancy between surveys); occupancy as the proportion of 10 km grid squares with pine marten detected; core range as a minimum convex polygon with at least 90% detections; abundance from occupied habitat area divided by mean territory size, with 1000 bootstrap resamples (accelerated bias-corrected percentile method) for 90% confidence intervals. Possible inconsistencies in the paper: (1) the number of grid squares with detections rose “by 65” (28.4% to 63.9% of 183), but 68 squares gained detections and 4 lost them, a net change of 64; (2) the reported McNemar value (34.3) does not match what the stated counts would give; (3) Northern Ireland forest cover is given as 8800 ha (6.5% of land area), but 6.5% of 14,148 km² would be about 92,000 ha.
- **Data type:** New field data: scat transect surveys June to September 2005 to 2007, with a pilot survey in June 2005. Existing data: historical distribution in the Republic of Ireland, 1978 to 1980 (O’Sullivan 1983), and territory sizes of seven radio-tracked martens from an earlier study (O’Mahony 2009).

## Synopsis

### 1. What they did

Pine martens live at the western edge of their world range in Ireland, one of the least forested regions in Europe. They declined heavily over the 19th and 20th centuries through forest loss, poisoned baits, persecution and trapping for fur. Before this study there had been no survey covering both the Republic of Ireland and Northern Ireland, and nobody knew how many martens there were.

The authors set out to map where pine martens live now, see how this has changed in about 30 years, and make the first estimates of their numbers:

- Scat surveys. In June to September of 2005 to 2007, they walked an average of three transects of about 1.5 km in forest or scrub within each of 258 squares of 10 km by 10 km (228 in the Republic and 30 in Northern Ireland). In all, 762 transects covered over 1200 km. Each transect was walked once, only in good weather. They collected scats that looked like pine marten scats by their shape, plus any uncertain ones: 765 scats in total.

- DNA testing. Because of limited funding, they tested the most likely pine marten scat from each square first, and tested further scats only until one was confirmed as pine marten.

- Comparison with the past. For 183 squares in the Republic they compared their results with a 1978 to 1980 survey that relied mainly on scat identification, plus sightings and local knowledge.

- Core range and numbers. They mapped a core range (areas where at least 90% of surveyed squares had martens) and estimated numbers by dividing the occupied forest area by the average territory size of seven radio-tracked martens from an earlier Irish study (about 154 ha).

### 2. What they found

Where martens are

- Pine martens were confirmed in 153 of 258 squares (59.3%): 59.6% in the Republic and 56.7% in Northern Ireland.

- They were concentrated in the west and midlands of the Republic, with scattered populations in the southwest, southeast and east. They were largely missing from the south and southeast of the Republic and most of Northern Ireland.

- Of the 105 squares without martens, no scats were found in 45, and the scats collected in the other 60 were not from pine martens.

Change since 1978 to 1980

- In the comparable squares, occupancy rose from 28.4% to 63.9%, a significant increase. 68 squares changed from no martens to martens, and 4 the other way.

Core range and numbers

- Core range covered 51.5% of the Republic’s land area, 18.3% of Northern Ireland and 45.9% of the island.

- Estimated numbers: about 2740 pine martens in the Republic (90% confidence interval 1350 to 4330) and about 320 in Northern Ireland (160 to 510).

### 3. What they concluded

- Pine martens have expanded their range in the Republic over the last 30 years, probably from refuges in the west. Three likely reasons: forest cover nearly doubled since 1980; legal protection since 1976; and reintroductions, such as up to 30 martens released in Killarney National Park from the late 1980s to the mid 1990s. Relocations of “problem” martens and changes in red fox numbers may also play a part, but data are lacking.

- Even so, the present range is still much smaller than in the past, and the expansion happened without any planned conservation action.

- In Northern Ireland there is little or no sign of expansion despite legal protection and more forest. Small, fragmented populations may face barriers such as small numbers, poor survival when dispersing and illegal persecution. With numbers in the low hundreds, the authors call for a conservation strategy there immediately.

- Earlier assessments that rated the species as of least concern were partly based on estimates of 3000 to 10,000 martens; this study found fewer than 3000, so a reassessment seems prudent.

- More basic research is needed on abundance, social and spatial behaviour, habitat selection, breeding, survival and the effects of forestry.

### 4. How tracking was or was not used

The survey was a sign survey: observers walked transects looking for pine marten scats and picked them out by their shape. DNA testing then confirmed which scats were really from pine martens. The authors chose DNA confirmation because earlier scat surveys that relied on shape alone had been criticised for identification errors. No footprints or other signs were recorded, and no trailing was reported.

### 5. Tracker or observer certification

Reported but not validated. The senior author surveyed 216 squares (84%) and “trained field staff” surveyed the other 42 (16%). No certification or skill test is described. The paper does not report how many collected scats were correctly identified by shape, so observer accuracy cannot be judged from it.

### 6. Other technologies, skills or innovations

- A real-time DNA test that tells pine marten scats from red fox scats.

- A screening approach that tests scats one at a time per square until a pine marten is confirmed, to save costs. The authors note that this means scat abundance and habitat use could not be analysed at the transect level.

- Scats were bagged by turning a zip-lock bag inside out, to avoid contaminating the DNA, and stored frozen.

- Mapping in a Geographic Information System (GIS).

### 7. Implications for conservation (from the paper)

- Both jurisdictions need conservation strategies for pine martens, to secure the recent expansion, support further expansion and reduce conflict that could lead to illegal persecution.

- Returning martens may come into conflict with game rearing, livestock and the management of other species, especially birds. Management plans should accept that some predation is a natural part of a stable predator and prey system.

- Short-rotation commercial conifer plantations are the main habitat, and the effects of timber harvesting and of small, scattered private plantations are not understood.

- Regular monitoring is required by international obligations but may be limited by funding.

### 8. Implications for tracking (Original Wisdom's observations)

_These are Original Wisdom's observations, not the authors'._

- The study shows scat recognition as the first step in a large survey: observers chose which scats to collect, and DNA checked their choices. In 60 squares, none of the scats collected was assigned to pine marten by the DNA test. The paper does not say whether these scats came from other species or simply could not be tested, but it is a reminder of why the authors did not rely on scat shape alone.

## Cite this summary

Lawrence, K. 2026. Summary of: Pine marten (Martes martes) distribution and abundance in Ireland: A cross-jurisdictional analysis using non-invasive genetic survey techniques (O’Mahony and O’Reilly et al., 2012). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2012-omahony-oreilly-pine-marten-martes-martes/