# Fisher Predation on Canada Lynx in the Northeastern United States

> Can a fisher, at about half its weight, kill a Canada lynx? In northern Maine, researchers following radio-collared lynx for 12 years read the story in the snow: fisher tracks leading to lynx beds, drag marks, caches and bite marks. In the first study to document fishers killing lynx, fishers killed 14 of them, mostly in winter and in mature conifer forest.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2018-mclellan-vashon-fisher-predation-canada-lynx/

## Citation and access

- **Authors:** Scott R. McLellan, Jennifer H. Vashon, Erica L. Johnson, Shannon M. Crowley and Adam D. Vashon
- **Year published:** 2018
- **Journal or source:** The Journal of Wildlife Management
- **Full citation:** McLellan, S. R., Vashon, J. H., Johnson, E. L., Crowley, S. M. and Vashon, A. D. 2018. Fisher predation on Canada lynx in the Northeastern United States. The Journal of Wildlife Management 82(8): 1775–1783.
- **DOI:** 10.1002/jwmg.21538
- **Access status:** Hosted (freely available elsewhere)
- **PDF:** https://www.originalwisdom.com/wp-content/uploads/2026/11/2018_McLellan_and_Vashon_etal_fisher-predation-on-canada-lynx.pdf

## Tags

- **Species:** Mammals > Canada lynx; Mammals > Fisher
- **Region:** North America > United States
- **Tracking:** Beds; Blood; Caches; Hair; Kill sites; Scat; Snow tracks; Track measurements; Tracking; Tracks; Tracks and signs identification
- **Behaviour and ecology:** Behaviour; Carnivore coexistence; Feeding; Food caching; Hunting; Intraguild interactions; Predation
- **Methods and technology:** Descriptive statistics; Geographic Information System (GIS); Global Positioning System (GPS) collars; Radio telemetry; Very high frequency (VHF) radio collars
- **Data type:** New field data
- **Observer qualification:** Not reported
- **Discipline:** Behaviour and ecology; Wildlife tracking
- **Year published:** 2018

## Detailed keywords

- **Species:** Studied: Canada lynx (Lynx canadensis) as prey and fisher (Martes pennanti) as predator. Other possible predators of lynx considered: coyote (Canis latrans), bobcat (Lynx rufus) and black bear (Ursus americanus); bobcats were rare (one captured in 12 years) and bears were hibernating, so their bite measurements were not compared. Main prey of lynx: snowshoe hare (Lepus americanus). Predators of lynx elsewhere (not in northern Maine): mountain lion (Puma concolor), wolverine (Gulo gulo) and gray wolf (Canis lupus). In the study area but not studied: moose (Alces alces), deer (Odocoileus virginianus), red fox (Vulpes vulpes), American marten (Martes americana), North American red squirrel (Tamiasciurus hudsonicus) and ruffed grouse (Bonasa umbellus). Porcupine (Erethizon dorsatum) and deer carrion are mentioned as large prey for fishers.
- **Location and habitat:** Four townships (386 km²) in the Musquacook Lakes region of northwestern Maine, USA, on privately owned commercial forest managed for timber. Elevation 250 to 550 m, rolling hills and wide valleys. Regenerating red spruce, white spruce and balsam fir (46% clear-cut in the 1980s after a spruce budworm outbreak), lowlands of black spruce, tamarack and northern white cedar, and ridges of sugar maple and birches. Mature conifer forest made up only 12% of the area, mostly along rivers and streams. Average monthly snow depth 64.8 cm (1999 to 2011).
- **Topics:** predation on lynx by fishers; first documented case of fishers killing lynx; causes of death (mortality sources); kill site investigation; reconstructing predation events from tracks and signs in snow; ambush of resting lynx in beds; chases; drag marks and caching of carcasses; bite marks (intercanine width of canine punctures) to identify the predator; necropsy and bone marrow condition; habitat at kill sites (mature conifer); snow and winter severity; snowshoe hare density and alternative prey; intraguild predation; threatened species; trapping regulations and incidental take of lynx in fisher traps.
- **Statistics or models:** Descriptive statistics only: counts, percentages, means and ranges. Predator identity was assigned by comparing bite measurements with published skull measurements (Elbroch 2006). Time of death was estimated as the midpoint between the last active and first mortality radio signal.
- **Data type:** New field data, 1999 to 2011: 187 lynx captured, 85 radio-collared, and 65 deaths investigated. Inconsistencies in the paper: (1) the text says fishers dragged and cached lynx on 7 occasions, but Table 4 marks drag marks to cached lynx for 9 lynx (8 fisher kills and 1 possible fisher kill); (2) the text says 12 mortality sites with 10 lynx killed in beds and 2 chased, but the mother and kitten (L6 and L8) were killed at the same site; (3) the text says pre-mortem hemorrhaging with canine punctures on the head, neck or throat of 9 of 18 lynx, but in Table 4 one of those 9 (L9) had punctures only on a hind leg, and 11 lynx had hemorrhaging on the neck and head; (4) Figure 1 gives the study area as 400 km², the text as 386 km²; (5) the text says 64% of fisher-killed lynx were healthy, while Table 5 lists 6 of 14 as healthy (7 including “healthy to fair”); (6) table titles say “1999 and 2011” where the study ran from 1999 to 2011.

## Synopsis

### 1. What they did

Canada lynx are protected as a threatened species in the United States, but little was known about what limits them at the southern edge of their range. From 1999 to 2011, the Maine Department of Inland Fisheries and Wildlife ran a radio-tracking study of lynx in northern Maine. The authors expected lynx there to die of the same causes as in Canada’s boreal forests. This short paper (a “Note”) reports a cause of death that had never been documented before: lynx being killed by fishers.

- Collaring lynx. They captured 187 lynx and fitted 85 with very high frequency (VHF) or Global Positioning System (GPS) collars. Each collar had a mortality sensor that changed its signal when the animal had not moved for 4 hours. They checked the collars from a small plane about twice a week, weather permitting.

- Investigating deaths. When a collar gave a mortality signal, they found the dead lynx, photographed the site, and collected remains and data.

- Necropsies. Lynx without visible injuries went to a pathologist to find the cause of death (for example, starvation). Those with injuries were examined by the team, and thigh bone marrow was checked for body condition.

- Identifying the predator from bite marks. They measured the distance between canine tooth punctures on the carcasses and compared them with published skull measurements of fishers, lynx and coyotes.

- Identifying the predator from tracks and signs. In snow, they counted a death as predation when predator tracks led to a resting lynx, or when the tracks of a lynx being chased ended at a kill site. They identified the predator from track features, measurements and trail pattern.

- Habitat. They described the forest stand at each kill site from landowners’ stand maps and their own notes at the site.

### 2. What they found

Causes of death

- Of 65 dead lynx, 18 were killed by predators, 17 starved, 17 died of unknown causes, 12 died from human causes (legal harvest in Canada, illegal killing and vehicle collisions), and 1 from disease.

- Fishers killed 14 lynx (9 females, 5 males) and probably killed 2 more. The predator of the last 2 could not be identified.

- Thirteen of the 14 lynx killed by fishers were adults with established home ranges. The other was an 8-month-old kitten, killed and cached at the same site as its mother. Most were healthy or in fair condition.

What the tracks and signs showed

- Most deaths happened in winter, when tracks and signs in the snow let the team reconstruct what had happened.

- Ten lynx had been resting in a bed when a fisher ambushed and killed them. Two had been chased by a fisher and killed.

- The only predator tracks at these sites were fishers’. Other predator tracks and signs were absent.

- Fishers often dragged the lynx (drag marks from 1 m to 201 m long, often with bright red drops of blood along them) and cached them in tree cavities, root masses, hollow logs, under fallen trees or dense conifers, or buried in the snow.

- There were usually many fisher scats and a network of fisher trails to and from the carcass. Once, a fisher was found in a cavity with the remains of a lynx. Twice, dark brown guard hairs were found inside a dead lynx’s mouth.

Bite marks

- On 6 lynx, 19 of 20 canine puncture measurements fell within the range for fishers and outside the ranges for coyotes and lynx, confirming what the team had seen in the field.

- Measuring was often hard: tissue stretches, attacks involved repeated biting, and many fishers have broken or missing canines.

Where and when

- Twelve of the 14 lynx killed by fishers (86%) died in mature conifer forest, although this made up only 12% of the study area. Most of these stands were dominated by northern white cedar or black spruce.

- Twelve of the 14 (86%) were killed from January to March, when snow was deepest, and often during a snow event.

- Fishers killed more lynx after 2006, when snowshoe hare density in regenerating clear-cuts dropped from about 2 to about 1 hare per hectare. While hares were more plentiful, only female lynx were killed.

- The kills fell within the territories of several radio-collared fishers over 12 years.

### 3. What they concluded

- This is the first study to document fishers killing lynx.

- Fishers seem to be opportunistic predators of lynx, not a few individuals with a learned habit and not only targeting weak animals.

- Snow probably helps fishers approach resting lynx unseen and ambush them; the limited signs of struggle at kill sites support this. Mature conifer forest gives cover and resting places to both species, which may bring them together, and snow may be shallower there.

- In winter, especially when hares are scarce, a lynx may be the most profitable meal available to a fisher. Fishers average 4.6 kg, about half the weight of an adult lynx, but are aggressive predators.

- The absence of other lynx predators (wolverines, mountain lions, wolves) and the habitat conditions may have created a unique opportunity for fishers in northern Maine.

- There was no evidence that fishers were limiting lynx numbers or range, or excluding them from habitats.

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

Tracks and signs in snow were central to working out how each lynx died. The team identified predation when predator tracks led to a resting lynx’s bed, or when a chase trail ended at a kill site, a patch of disturbed snow with tracks, scratch marks, broken branches, blood and tufts of lynx hair. They identified the predator from track features, measurements and trail pattern, and recorded drag marks, caches, scats, fisher trails to and from carcasses, and hair in the lynx’s mouth. Where fresh snow or bare ground hid the tracks, the predator was identified from any signs present, from bite measurements, or recorded as unknown. Sites were visited 1 to 13 days after the estimated time of death.

### 5. Tracker or observer certification

Not reported. The paper does not say who read the tracks and signs at the kill sites or what experience they had, although the identification of fishers as the predator rests largely on this. Many field technicians and volunteers are thanked.

### 6. Other technologies, skills or innovations

- VHF and GPS collars with 4-hour mortality sensors, monitored from fixed-wing aircraft.

- Measuring the distance between canine punctures on carcasses and matching it to published skull measurements of possible predators.

- Necropsies and bone marrow condition to separate predation from starvation and to judge the health of killed lynx.

- Geographic Information System (GIS) stand maps to describe habitat at kill sites.

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

- Maine did not increase fisher trapping to help lynx, because Maine’s lynx population was growing with abundant habitat and prey.

- Fisher trapping rules have instead become stricter, to reduce the accidental catching of lynx. This has reduced fisher harvest, so predation may come to have a greater effect on lynx.

- Where lynx and fishers live together, the authors recommend monitoring both species, and say managers could consider changing fisher harvest if predation is holding back lynx population growth.

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

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

- The study shows how much tracks and signs in snow can reveal at a kill site: whether a lynx was ambushed in its bed or chased, which predator did it, and what happened to the carcass afterwards. Bite measurements confirmed the field reading in the cases where they could be taken.

- Bite measurements were often unreliable because of tissue trauma and broken teeth, so tracks and signs were often the main evidence for identifying the predator.

## Cite this summary

Lawrence, K. 2026. Summary of: Fisher Predation on Canada Lynx in the Northeastern United States (McLellan and Vashon et al., 2018). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2018-mclellan-vashon-fisher-predation-canada-lynx/