# Pumas as Ecosystem Engineers: Ungulate Carcasses Support Beetle Assemblages in the Greater Yellowstone Ecosystem

> What does a puma leave behind besides tracks? In the Greater Yellowstone Ecosystem, researchers trapped more than 24,000 beetles of 215 species at puma kills and nearby control sites. Each puma left about 38 kg of carrion a week, and the carcasses became busy beetle habitat for about two months, leading the authors to call pumas ecosystem engineers.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2019-barry-elbroch-pumas-ecosystem-engineers-ungulate/

## Citation and access

- **Authors:** Joshua M. Barry, L. Mark Elbroch, Matthew E. Aiello-Lammens, Ronald J. Sarno, Lisa Seelye, Anna Kusler, Howard B. Quigley and Melissa M. Grigione
- **Year published:** 2019
- **Journal or source:** Oecologia
- **Full citation:** Barry, J. M., Elbroch, L. M., Aiello-Lammens, M. E., Sarno, R. J., Seelye, L., Kusler, A., Quigley, H. B. and Grigione, M. M. 2019. Pumas as ecosystem engineers: ungulate carcasses support beetle assemblages in the Greater Yellowstone Ecosystem. Oecologia 189(3): 577–586.
- **DOI:** 10.1007/s00442-018-4315-z
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.1007/s00442-018-4315-z

## Tags

- **Species:** Invertebrates > Beetle; Mammals > Mountain lion
- **Region:** North America > United States
- **Tracking:** Blood; Caches; Feeding signs; Kill sites; Tracking; Tracks and signs identification; Trailing
- **Behaviour and ecology:** Behaviour; Feeding; Food caching; Predation; Scavenging
- **Methods and technology:** Chi-square test; CyberTracker; CyberTracker Tracker Certification; Geographic Information System (GIS); Global Positioning System (GPS) collars; GPS cluster analysis
- **Data type:** New field data
- **Observer qualification:** Certified trackers
- **Discipline:** Behaviour and ecology; Wildlife tracking
- **Year published:** 2019

## Detailed keywords

- **Species:** Studied: puma (Puma concolor) and the beetles (Coleoptera) using their kills: 24,209 beetles of 215 species in 33 families, identified to species. Most abundant: northern carrion beetle (Thanatophilus lapponicus). Families with significantly more beetles at carcasses: carrion and burying beetles (Silphidae), Carabidae, Curculionidae (mainly plant feeders), Staphylinidae, Histeridae, Scarabaeidae, hide beetles (Dermestidae) and Cleridae. Rarer carrion users noted: the family Trogidae (four beetles) and three species of the genus Omosita (Nitidulidae). Prey at the 18 sampled carcasses: elk (Cervus elaphus), deer (mule deer, Odocoileus hemionus, named in the results) and one bighorn sheep (Ovis canadensis). One carcass was taken over by coyotes (Canis latrans). In the study area but not studied: wolves (Canis lupus), black bears (Ursus americanus), grizzly bears (Ursus arctos), coyotes, red foxes (Vulpes vulpes), moose (Alces alces), bison (Bison bison), pronghorn antelope (Antilocapra americana) and white-tailed deer (Odocoileus virginianus). Other ecosystem engineers mentioned: North American beavers, Arctic foxes, African bush elephants and termites.
- **Location and habitat:** About 2000 km² of the southern Greater Yellowstone Ecosystem, north of Jackson, Wyoming, United States (43.51330, -110.34419); pumas captured in the Bridger-Teton National Forest. Elevations 1800 m to over 3600 m; short cool summers and long winters. Sagebrush (Artemisia spp.) and cottonwood (Populus angustifolia) at lower elevations; Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) higher up. Control sites 20 m from each carcass in the same habitat type and similar vegetation.
- **Topics:** ecosystem engineers; keystone species; carrion as habitat; predator-provided carrion; carrion provisioning; kill rates; carrion production; invertebrate scavengers and decomposers; beetle life history on carcasses (breeding, brooding, larval refuge); succession and decay stages; competition between vertebrate and invertebrate scavengers; puma caching; elk versus deer carcasses; consequences of predator removal.
- **Statistics or models:** Pearson’s Chi-squared tests with Bonferroni correction (P < 0.0026) by beetle family; generalized linear mixed models with negative binomial distributions and log link (R package MASS) for abundance and species richness; linear mixed-effects models (R package lmerTest) for Simpson’s Index of Diversity (1-D), logit transformed (R package gtools); fixed effects of group, time, group by time, caching and prey species, with carcass and control as random effects; marginal means and effect size (Cohen’s d); piecewise regression (R package segmented) to find when diversity levelled off (8 weeks); kill rates and carrion production per puma, following Elbroch and Wittmer (2012), with edible portions of 68% (ungulates) and 95% (small vertebrates) and captive puma feeding rates. GPS clusters: 2 or more locations within 150 m where a puma spent 4 hours or more, mapped in ArcGIS 10.0. Inconsistencies in the paper: (1) the results say the northern carrion beetle made up 60.6% of all beetles, but the counts given (14,674 at carcasses plus 254 at controls) come to about 61.7% of 24,209; (2) Table 1 gives carcass 9 as “76-10” percent utilized, presumably a typo for 76 to 100; (3) the abstract gives sampling as 4 May to 4 October 2016, while Table 1 lists kills from 31 March and the paper says sampling began on average 15 days after a kill.
- **Data type:** New field data: GPS clusters of six collared pumas investigated from 31 March to 3 September 2016; beetles sampled weekly from 4 May to 4 October 2016 (19 weekly periods). Part of a larger long-term puma study.

## Synopsis

### 1. What they did

Ecosystem engineers are animals that create or change habitat for other species, as beavers do with their dams. Predators are rarely thought of this way. But pumas often leave large parts of their kills behind, and for many beetles a carcass is more than food: it is where they find mates, lay eggs and raise their young. Carrion beetles need fresh carcasses in spring and summer, just when natural deaths are few. The authors asked whether pumas, by leaving carcasses on the landscape, act as ecosystem engineers for beetles.

The work was part of a long-term puma study in the southern Greater Yellowstone Ecosystem, Wyoming, United States:

- Finding kills. Pumas were caught with trailing hounds in winter and fitted with Global Positioning System (GPS) collars that took a location every 2 hours. The team visited places where a puma’s locations clustered, once the puma had left. At remains, they looked at signs of struggle, blood patterns, bite marks on the carcass and which body parts had been eaten, to decide whether the puma had killed the animal or was scavenging.

- Sampling beetles (May to October 2016). At 18 fresh puma kills (elk, deer and one bighorn sheep), they set three barrier pitfall traps around the carcass and the same set-up at a control site 20 m away in similar vegetation. They emptied the traps weekly, and beetles were identified to species at Montana State University.

- Measuring what pumas provide. CyberTracker-certified researchers investigated the kill sites and estimated the age of the prey. From prey weights, time the pumas spent at each kill and feeding rates of captive pumas, the team estimated how much meat each puma ate and left behind, and calculated each puma’s kill rate and weekly carrion production.

- Comparing carcasses and controls. They compared beetle numbers, number of species and diversity between carcasses and controls over time, and tested whether caching by the puma or the prey species (elk or deer) made a difference.

### 2. What they found

Pumas and carrion

- The team investigated 501 GPS clusters of six pumas and found 190 kill sites, 261 bed sites, 21 carcasses the pumas had scavenged rather than killed, and 29 sites with no clear evidence of behaviour.

- On average each puma killed 1.4 animals and produced 37.9 kg of carrion a week, with individuals ranging from 24.7 kg to 57.5 kg a week.

- Pumas cached (covered with debris) 11 of the 18 carcasses sampled for beetles.

- Beetle sampling started on average 15 days after a kill and lasted an average of 12 weeks.

Beetles

- 24,209 beetles of 215 species from 33 families were caught; 83% were at carcasses.

- The northern carrion beetle made up about 60% of all beetles, and 98% of them were caught at carcasses.

- Eight families, with 113 species between them, were caught significantly more at carcasses than at controls. Most are known to use carcasses for courtship, mating, egg-laying, shelter or food for their young. Beetles of the family Curculionidae were a surprise, as they mostly eat plants; the authors suggest they came for the half-digested plants in the prey’s stomachs.

Carcasses versus controls (12 carcasses analysed)

- Six carcasses were left out of the models: five sampled late in the season, when cold sharply reduced beetles, and one taken over by coyotes after the second collection.

- In the first 8 weeks, carcasses had a large to very large effect on beetle numbers, number of species and diversity. Over the full 19 weeks the effect was medium.

- Beetle numbers and species were highest in the first collection week and then declined. The authors think they may have missed the first wave of beetles, because sampling began only after the puma left, and that scavenging mammals may have kept beetles away early on.

- Diversity was usually higher at controls, because the many northern carrion beetles at carcasses made the catch uneven.

- Caching made no difference to beetle numbers or species. Beetle numbers fell faster at deer carcasses than at the larger elk carcasses.

### 3. What they concluded

- Puma kills had a large to very large effect on beetle communities, which is strong evidence that pumas act as ecosystem engineers, creating habitat for beetles that depend on carrion.

- Carrion is an important but short-lived resource; the effects were strongest in the first 8 weeks and at the larger elk carcasses.

- By killing about 1.4 animals a week, pumas provide a steady supply of fresh carrion across the landscape in spring and summer, during key life stages for beetles and other species.

- Research on carrion left by predators has mostly looked at vertebrate scavengers. Understanding how predators shape the resources invertebrates depend on could help predict the knock-on effects of removing predators.

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

Tracks and signs were used to interpret what had happened at the puma GPS clusters. At each site with prey remains, the team read signs of struggle, blood patterns, bite marks on the carcass and which body parts had been eaten to tell a puma kill from scavenging, and recorded whether the puma had cached the carcass. They also told kill sites from bed sites. The prey’s age was judged from the remains. Pumas were caught for collaring with trailing hounds, which followed the pumas until they climbed a tree.

### 5. Tracker or observer certification

The authors used CyberTracker-certified researchers to investigate kill sites and estimate the approximate age of prey, citing Elbroch et al. (2011). The level of certification and which team members held it are not given. Co-author L. Mark Elbroch and Joshua M. Barry did the field work, with field help from others named in the acknowledgements.

### 6. Other technologies, skills or innovations

- GPS collars (Lotek Globalstar S or Iridium M; Vectronics Globalstar GPS Plus) uploading locations by satellite 1 to 6 times a day; locations shown in ArcGIS 10.0 and loaded onto handheld GPS units to find clusters in the field.

- Barrier pitfall traps: two plastic cups of odourless soapy water at each end of a 3-foot metal barrier, three per site, placed to leave corridors so some beetles could still reach the carcass.

- Beetle identification to species by an entomology laboratory (Marsh Laboratory, Montana State University).

- A study design that the authors say can be applied to predators anywhere.

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

- Where apex predators are few or have been wiped out, invertebrate communities that depend on carrion may suffer.

- Invertebrates are often overlooked but provide essential ecological services that people depend on.

- Predator-provided carrion may be more valuable to beetles than carrion from disease, starvation, road kill or hunters’ offal, because predators supply it all year and in many habitats, including in spring and summer when beetles need it.

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

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

- The study rests on reading kill sites: telling a kill from scavenging, a kill from a bed, and spotting caching. Certified trackers doing this work is what makes the kill rates, carrion estimates and choice of fresh carcasses trustworthy.

- A puma kill is a place where tracks and signs keep changing for weeks, as mammal scavengers and then waves of beetles move in. Knowing which beetles turn up when could help trackers judge how long ago an animal died.

## Cite this summary

Lawrence, K. 2026. Summary of: Pumas as Ecosystem Engineers: Ungulate Carcasses Support Beetle Assemblages in the Greater Yellowstone Ecosystem (Barry and Elbroch et al., 2019). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2019-barry-elbroch-pumas-ecosystem-engineers-ungulate/