# Cached fungi in non-native conifer forests and their importance for red squirrels (Sciurus vulgaris L.)

> In autumn, red squirrels in the spruce plantations of northern England and southern Scotland tuck mushrooms onto branches right next to the trunk. Walking forest transects, researchers found 58 cached mushrooms, most of them yellow russulas, with squirrel tooth marks, more along forest edges than inside the trees. Most were gone within two weeks, but the authors estimate each squirrel’s range may hold one to two days’ worth of food in these stores.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/1998-lurz-south-cached-fungi-non-native/

## Citation and access

- **Authors:** P. W. W. Lurz and A. B. South
- **Year published:** 1998
- **Journal or source:** Journal of Zoology (Communications from the Mammal Society, No. 77)
- **Full citation:** Lurz, P. W. W. and South, A. B. 1998. Cached fungi in non-native conifer forests and their importance for red squirrels (Sciurus vulgaris L.). Journal of Zoology 246(4): 468-471.
- **DOI:** 10.1017/S0952836998291217
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.1017/S0952836998291217

## Tags

- **Species:** Mammals > Eurasian red squirrel
- **Region:** Europe > United Kingdom
- **Tracking:** Caches; Feeding signs; Sign surveys; Tracking; Tracks and signs identification
- **Behaviour and ecology:** Behaviour; Feeding; Food caching
- **Methods and technology:** Chi-square test; Descriptive statistics
- **Data type:** New field data
- **Observer qualification:** Not reported
- **Discipline:** Behaviour and ecology; Wildlife tracking
- **Year published:** 1998

## Detailed keywords

- **Species:** Studied: red squirrel (Sciurus vulgaris). Fungi found cached: common yellow russula (Russula ochroleuca), sickener (Russula emetica, printed “R. metica” in the abstract and results), bare-toothed russula (Russula vesca) and spotted tough-shank (Colybia maculata). Other fungi found in the plantations but never cached: Clitocybe nebularis, Cystoderma aminthinum, Hygrocybe pustulatus, Lactarius deterrimus, Lactarius rufus, Lycoperdon perlatum, Marasmius androsaceus, Russula atropurpurea, Russula quelti and Tricholomopsis rutilans. Trees: Sitka spruce (Picea sitchensis), Norway spruce (Picea abies), lodgepole pine (Pinus contorta) and Japanese larch (Larix japonica).
- **Location and habitat:** 11 sites in commercial conifer plantations: 8 in Wauchope Forest, Border Forest, Scotland, and 3 in Spadeadam Forest, part of Kielder Forest, described in the paper as Cumbria, England. Sitka spruce, alone or mixed with Norway spruce, lodgepole pine or Japanese larch, with no shrub understorey or ground cover. Transects ran along forest edges and rides (forest roads and clearings) and inside plantations.
- **Topics:** food caching (hoarding) of fungi; fungi as food for red squirrels; caches placed on branches next to the trunk; tooth marks to confirm the cacher; forest edge versus plantation interior; cache lifespan; energy value of stored fungi; low-density squirrel populations in food-poor conifer plantations; variable tree seed crops.
- **Statistics or models:** Chi-square test (edge versus inside, chi-square = 25.12, P < 0.001, 1 degree of freedom); mean wet weight (8.15 ± 3.85 g, 10 fruiting bodies); a simple scaling estimate of caches per home range (number found divided by transect area, times a mean home range of 9.13 ha, minimum convex polygon). Inconsistencies: (1) the methods say each transect was 1800 m long, but Table 1 gives lengths from 500 m to 1800 m; (2) Table 1, site 7, gives a length of 500 m but 900 m inside plus 400 m edge; (3) Table 1 site totals add to 59 fruiting bodies, while the text reports 58 (site 9 shows a total of 17, but 2 inside plus 14 edge make 16); (4) with the stated figures (42.23 fruiting bodies, 8.15 g, 90% water, 15.96 to 21.84 kJ per g dry weight) the energy works out at about 549 to 752 kJ, not the 525 to 714 kJ reported; (5) the transect width used for “transect area” is not given beyond “2 rows of trees on either side”.
- **Data type:** New field data. Each transect walked twice, October to November 1997.

## Synopsis

### 1. What they did

In the commercial conifer plantations of northern England and southern Scotland, red squirrels live at low density. These forests are mostly Sitka spruce, with no shrubs or ground cover, and tree seed crops vary a great deal from year to year. Fungi are one of the few other foods. Red squirrels in Finland were known to store mushrooms on tree branches, so the authors set out to see how often squirrels cache fungi in these plantations, and how much food the caches could provide.

They chose 11 sites in Wauchope Forest (Scotland) and Spadeadam Forest (part of Kielder Forest). Earlier surveys and feeding signs (stripped cones) showed red squirrels lived at every site. In October and November 1997 they walked a transect at each site twice, scanning the branches of two rows of trees on either side. They recorded the number and species of fungi on branches and, where possible, collected the fungi and checked them for tooth marks to confirm a red squirrel had put them there. They weighed a small sample.

### 2. What they found

- The squirrels placed fungi on branches right next to the trunk, from 0.6 m to about 8 m above the ground. They stored single mushrooms, or three to six mushrooms placed one by one at different heights in the same and nearby trees.

- Across the 11 transects they found 58 fruiting bodies with squirrel tooth marks: 49 common yellow russula, 7 sickener, 1 bare-toothed russula and 1 spotted tough-shank. This is a minimum, since caches higher in the crowns would have been out of view.

- The two most common cached species were also the most abundant fungi in the plantations. Ten other fungi species were seen, but none of them was cached.

- More fungi were cached in trees along forest edges and rides than inside the plantations.

- Most caches were short lived: the majority had gone within 2 weeks.

- Ten fruiting bodies weighed on average 8.15 g (wet).

- Scaled up to an average home range of 9.13 ha, the authors estimated at least 42 cached fruiting bodies per squirrel, worth about 525 to 714 kilojoules (kJ). That covers a red squirrel’s energy needs (330 to 420 kJ a day) for 1 to 2 days.

### 3. What they concluded

- Squirrels in these plantations live with large changes in seed supply from season to season and year to year, and their flexible home ranges, habitat use and movements seem to be a response to this.

- The many Russula caches most likely reflect how abundant these fungi were at that time of year.

- More caches at the edge may come from better drying conditions there, or from squirrels spending more time at the edge, where trees are known to produce bigger cone crops.

- The caches are vulnerable to other squirrels, other species and weather (strong wind, frost), so how many are recovered may vary.

- A more detailed study is needed to learn how important fungi are in the squirrels’ diet, and whether squirrels help spread fungal spores.

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

The study is a sign survey. The authors walked transects looking for one kind of sign, fungi stored on branches, and confirmed that red squirrels had cached them by checking for tooth marks. Squirrel presence at each site was confirmed partly by feeding signs (stripped cones). No trailing was reported.

### 5. Tracker or observer certification

Not reported. The paper does not say who identified the tooth marks or how. Helen Thompson is thanked for help with fieldwork, and Gordon Beaks for help identifying the fungi.

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

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

- Fungi wedged against the trunk on a branch, with tooth marks, are a clear and easily overlooked sign of red squirrels in conifer forests.

- Because most caches disappeared within 2 weeks, finding them points to recent squirrel activity, and repeat visits are needed to see how they change.

## Cite this summary

Lawrence, K. 2026. Summary of: Cached fungi in non-native conifer forests and their importance for red squirrels (Sciurus vulgaris L.) (Lurz and South, 1998). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/1998-lurz-south-cached-fungi-non-native/