For the past couple of centuries, most hunters, scientists and naturalists assumed coyotes seldom targeted and killed moose. It made more sense that coyotes would concentrate on smaller animals like rodents and rabbits and simply supplement their diet when stumbling across the carcass of bigger animals that died naturally.

Given the right circumstances, David could certainly slay Goliath, but under normal conditions, it appeared coyotes had little to gain and much to lose by taking on moose. The energy such attacks would burn, and the risk they would incur from a kicking moose, would keep coyotes “honest” when they were eyeing a moose. Right?

Therefore, when biologists found moose hair in coyote scat, they assumed it came through scavenging moose carcasses. Or maybe they killed a moose calf — even though most research finds that calves become increasingly less vulnerable to predators by age 6 months.

In recent years, however, biologists began re-examining those assumptions as coyotes reclaimed more of the Eastern range they abandoned 500 years ago. Even though today’s Eastern coyotes aren’t as large as gray wolves, they are noticeably larger than their Western counterparts. Some of these new-age coyotes are direct wolf-coyote hybrids, and others are several generations removed from wolf-coyote pairings. Either way, or for whatever reason, Eastern coyotes are larger than their predecessors.

Size Matters

Therefore, given their large size and their eastward expansion in range and population densities, it seemed more conceivable that some Eastern coyotes would purposely take on moose. That’s especially logical for coyotes in areas with few whitetail deer.

Two researchers from central Ontario confirmed those suspicions by studying 10 coyote packs during the 2008 and 2009 winters after equipping 11 individual “dogs” with GPS-equipped collars. Researchers John F. Benson (Trent University, Peterborough, Ontario, Canada) and Brent R. Patterson (Ontario Ministry of Natural Resources, Peterborough) documented four different coyote packs of two to five animals killing adult moose.

The researchers aged the moose at 20 months (two), 4 1/2 to 8 1/2 years, and 20 1/2 years old. In two of the cases, the scientists recovered enough marrow from leg bones to look for signs of weakness, but found no evidence of severe malnutrition.

These are believed to be the first cases where scientists documented coyotes killing adult moose. They also documented five other cases where coyotes likely killed moose, but the evidence wasn’t conclusive.

Based on information Benson and Patterson had on the collared coyotes, they determined which coyote pack killed each moose. Also, they ruled out the possibility that wolves killed the moose, and that the coyotes were simply scavenging the carcass. That’s because wolves are relatively rare in the study area. Further, wolves, coyotes and wolf-coyote hybrids are so territorial that coyotes and hybrids do not establish home ranges where wolves live.

Identifying The Killer

Skeptics might wonder how researchers verify coyotes as a moose’s killer. It starts with GPS data transmitted from the collared coyotes every 90 minutes. When the researchers determined the coyotes were clustered within 200 meters of a spot for three hours or more, they investigated the site.

When they found moose remains, they looked for evidence of predation, such as vegetation broken off cleanly, which indicates a struggle. They also looked for blood sprayed on vegetation, rocks and snow; clumps of moose hair embedded in tree bark; ripped off legs, which indicated the legs weren’t frozen into the snow when the coyote “found” it; removed and shredded stomachs, which indicated they weren’t frozen when the coyote tore into them; and awkward body positions, which indicated the moose wasn’t resting while dying of natural causes.

Benson and Patterson also studied the surrounding area to determine how the coyotes killed the moose. They identified at least five factors that help coyotes and hybrids win such battles for survival.

First, snow conditions are important. Deep snow with a thick crust allows coyotes to run atop the surface while moose labor through it.

Second, steep hillsides of 40 to 45 degrees favor coyotes. While moose might struggle with their footing on steep terrain and labor uphill through deep snow, coyotes can move around longer without tiring.

Third, dense conifer stands can favor coyotes. Moose might be able to fit between tightly spaced trees, but they struggle to whirl around to face their aggressors — a tactic they generally use to fight off predators with their hoofs and/or antlers. Coyotes, meanwhile, generally attack large prey by biting their hind quarters, which is easier when moose can’t swing around.

Fourth, in the case of the 20 1/2-year-old moose, it was likely more susceptible to predation than younger moose. Older moose often develop osteoarthritis, which leaves them vulnerable to predators.

Fifth, if an area holds few deer, coyotes are more likely to hunt other animals for food. In the study area, the moose-killing coyotes occupied areas with lower proportions of winter deer habitat than did coyotes in areas where they didn’t attack moose. And make no mistake: Coyotes that kill moose are rewarded. Benson and Patterson documented coyotes spending up to 18 days feeding off one moose carcass.

Conclusion

Despite these findings, Benson and Patterson don’t think coyotes are a threat to moose populations in central Ontario. However, they suggest that researchers and wildlife managers in areas with declining moose populations consider the possible impacts of coyotes and coyote-wolf hybrids, writing:

“Recent studies found that the moose population in (our study area) was increasing, and that canid predation was apparently not a major cause of adult or calf mortality. Thus, it seems unlikely that predation by coyotes and hybrids is cause for conservation concern in central Ontario. Nonetheless, these smaller canids were more capable of killing large ungulates than previously believed. Given our results, it may be prudent for mangers of declining populations of moose, and threatened or endangered caribou populations, to investigate whether coyote predation occurs, and determine if it significantly adds to other sources of mortality.

“Alternatively, the situation in Ontario could be relatively unique because ongoing hybridization between coyotes and wolves coincides with a local moose population at relatively high density. We encourage other studies of Eastern coyotes and (or) coyote-wolf hybrids to investigate and quantify predation on ungulates to clarify the effects (where) wolves (are replaced by) these smaller canids across much of northeastern North America.”