# Improving reliability of scat counts for abundance and distribution estimations of Lumholtz’s Tree-kangaroo (Dendrolagus lumholtzi) in its rainforest habitats

> Lumholtz’s tree-kangaroos are hard to see in the rainforest canopy, so researchers count their scats instead. But how old is a scat, and whose is it? This study found that scats swell in the wet, shrink in the dry, turn mouldy within days, and in the forest are often eaten by dung beetles within 24 hours.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2012-heise-pavlov-meade-improving-reliability-scat-counts/

## Citation and access

- **Authors:** Sigrid R. Heise-Pavlov and Rhiana D. Meade
- **Year published:** 2012
- **Journal or source:** Pacific Conservation Biology
- **Full citation:** Heise-Pavlov, S. R. and Meade, R. D. 2012. Improving reliability of scat counts for abundance and distribution estimations of Lumholtz’s Tree-kangaroo (Dendrolagus lumholtzi) in its rainforest habitats. Pacific Conservation Biology 18(3): 153–163.
- **DOI:** 10.1071/PC130153
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.1071/PC130153

## Tags

- **Species:** Mammals > Lumholtz’s tree-kangaroo
- **Region:** Australia
- **Tracking:** Scat; Sign surveys; Spoor age estimation; Tracking
- **Methods and technology:** Analysis of variance (ANOVA); Detectability; Pearson correlation
- **Data type:** New field data
- **Observer qualification:** Not needed
- **Discipline:** Wildlife tracking
- **Year published:** 2012

## Detailed keywords

- **Species:** Studied: Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi), six captive animals (three adult females aged 48 months, 60 months and eight years; two adult males aged 28 and 36 months; one juvenile male aged 12 months). Scat consumers: dung beetles (Scarabaeoidea), caught in pitfall traps. Sympatric species whose scats can be confused with tree-kangaroo scats: red-legged pademelon (Thylogale stigmatica). Also mentioned: Bennett’s tree-kangaroo (Dendrolagus bennettianus), Matschie’s tree-kangaroo (D. matschiei), koala (Phascolarctos cinereus), swamp wallaby (Wallabia bicolor), snowshoe hare (Lepus americanus), eastern grey kangaroo (Macropus giganteus) and red-necked wallaby (M. rufogriseus).
- **Location and habitat:** Far North Queensland, Australia (Wet Tropics). Captive animals at a licensed wildlife carer’s home on the Atherton Tablelands, at the Wildlife Habitat in Port Douglas and at another licensed carer on the Atherton Tablelands, in enclosures of 15 to 80 m². Laboratory trials used soil and leaf litter from a type 5a notophyll vine forest at 17°24’38”S, 145°31’21”E. Forest trial in a 64 ha complex notophyll vine forest fragment (type 5a) on the Atherton Tablelands at the same coordinates, at three sites: sunny regrowth forest (“sun”), shaded old growth forest (“dark”) and beside a waterway (“creek”).
- **Topics:** scat counts for abundance and distribution; scat production (defecation) rates; scat decay and decomposition; ageing scats; scat mass and circumference; scat pH; mould on scats; dung beetles and scat loss; false positive and false negative errors; misidentification of scats from sympatric species; seasonal timing of scat surveys; non-invasive methods for cryptic arboreal mammals.
- **Statistics or models:** Analysis of variance (ANOVA) in Microsoft Excel; post-hoc Tukey tests in PAST; Pearson correlation between scat mass and circumference; means with standard errors. Note on internal inconsistencies: the abstract says scats “showed an acidic pH” by Day 3, but the results say all scats tested at pH 7 (neutral, the top of the test kit’s range) from Day 3 onwards, and the discussion says scats with pH under 7 are likely less than three days old. The results give fresh scats a pH of about 6.12 and Day 2 scats about 5.38, while the discussion says fresh scats were “around five to six”. The text gives scat production of 0.01 to 0.028 g per gram of body weight per day, while Table 2 shows values up to 0.03. In the forest “sun” site, 100% of scats were lost by Day 3 but 89% on Day 4 (replacement scats were counted from Day 1 again). The 12-month-old male is called “juvenile” in the methods and “adolescent” in the discussion.
- **Data type:** New field data: scat collections from six captive animals over three or four 24-hour periods (dates not given), laboratory decomposition trials over ten days (dates not given), and a four-day forest trial with pitfall traps in November 2010.

## Synopsis

### 1. What they did

Lumholtz’s tree-kangaroos live high in the canopy of dense rainforest on the Atherton Tablelands of Far North Queensland, and are mostly active at night, dawn and dusk. They are hard to see, so counting their scats is one of the most promising ways to estimate how many there are and where they live. But scat counts can mislead: scats may vanish before anyone finds them (a false negative, wrongly concluding the animals are absent), old scats may linger (a false positive, wrongly concluding the animals are using the area now), and small tree-kangaroo scats can be mistaken for those of red-legged pademelons, which eat the same food.

The authors set out to find traits that tell fresh tree-kangaroo scats from old ones:

- Scat production. They collected and weighed every scat from six captive tree-kangaroos for three or four days. Vegetation in the enclosures was covered with cloth so no scat was missed.

- Laboratory decay. They kept fresh scats on leaf litter under four conditions (warm-wet, warm-dry, cool-wet, cool-dry) for ten days, and tracked mass, circumference (from photographs), pH and the first appearance of mould.

- Forest decay. In November 2010, they placed fresh scats in wire mesh cages on the forest floor at three sites (sunny regrowth, shaded old growth and beside a creek) for four days, and set pitfall traps baited with tree-kangaroo scats to catch dung beetles.

### 2. What they found

Scat production

- Each animal produced on average 60 to 128 scats a day, weighing 67.5 to 168.7 g in total.

- A single scat weighed on average 1.06 to 1.9 g.

- Production varied a great deal between animals, and animals given the same food did not produce consistently similar numbers or masses of scats.

Decay in the laboratory

- Scats kept wet gained mass until they levelled off at about 130% of their original mass.

- Scats kept dry lost mass: by Day 10, warm-dry scats had lost about 90% and cool-dry scats lost mass more slowly.

- Mass and circumference changed together (positive correlations in all four conditions), so scats grew when wet and shrank when dry.

- Fresh scats had a pH of about 6.1, and about 5.4 on Day 2. From Day 3 onwards every scat tested at pH 7, the highest reading the test kit could give.

- All scats grew mould. Most had some by Day 3, and all had visible mould by Day 4, with no difference between conditions.

Decay in the forest

- At the shaded old growth and creek sites, every scat disappeared within 24 hours on each of the four days.

- At the sunny site, 43% disappeared within 24 hours on Day 1, 78% on Day 2, 100% on Day 3 and 89% on Day 4.

- Because scats vanished so quickly, changes in mass and size in the forest could not be analysed.

- Pitfall traps caught on average 50.5 dung beetles at the shaded site, 38 at the creek site and 11.5 at the sunny site, which had the most variable humidity.

- No scats in the forest grew mould, though mouldy scats were often seen in two of the enclosures.

### 3. What they concluded

- Dung beetles likely ate most of the scats in the forest. This may be a rainforest problem: scat counts have worked well for eastern grey kangaroos in drier habitats, where few scats are lost.

- In the wet season, scats are likely to vanish quickly, raising the chance of false negatives. Wet scats also swell, which makes them less likely to be confused with pademelon scats.

- In the dry season, scats last longer, raising the chance of counting old scats (false positives), and dry scats shrink, which makes confusion with the smaller pademelon scats more likely.

- Scat surveys for this species should be done in dry periods, and only fresh scats of average size and acidic pH (and, under wet conditions, without mould) should be counted. Mouldy scats can be assumed to be at least three or four days old, and scats with pH under 7 are likely less than three days old, though weather and diet can affect both.

- Reliable estimates could come from measuring scat production, decay and dung beetle activity for each site and season at the time of the survey, or from occupancy models that account for false negative and false positive errors. More studies on traits specific to this species’ scats are needed.

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

The study is about scat, one of the main signs used to survey animals. No tracking was done in the field: scats came from captive animals, and the authors measured how scats change with age and weather (size, pH and mould) to help surveyors age scats and avoid confusing them with pademelon scats.

### 6. Other technologies, skills or innovations

- Scat circumference measured from photographs with the freehand tool in ImageJ software.

- Scat pH measured with a soil pH test kit and colour chart.

- Temperature and humidity data loggers at laboratory and forest sites.

- Pitfall traps made from PVC tubes, baited with fresh tree-kangaroo scats, to sample dung beetles.

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

- Lumholtz’s tree-kangaroos are listed as near threatened in Queensland, and a lack of reliable data on their numbers and habitat use makes conservation planning difficult.

- Better non-invasive methods, such as more accurate scat counts, could provide the knowledge needed to plan conservation for this species.

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

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

- The study shows how much a scat’s appearance depends on weather: the same scat can swell by a third in wet conditions or shrink to a tenth of its mass in dry, warm conditions. Size alone may mislead when telling similar species apart.

- In warm, wet rainforest, dung beetles can remove scats within a day, so the absence of scat may say little about whether an animal was there.

## Cite this summary

Lawrence, K. 2026. Summary of: Improving reliability of scat counts for abundance and distribution estimations of Lumholtz’s Tree-kangaroo (Dendrolagus lumholtzi) in its rainforest habitats (Heise-Pavlov and Meade, 2012). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2012-heise-pavlov-meade-improving-reliability-scat-counts/