https://www.nature.com/articles/ncomms15469
Top predators constrain mesopredator distributions
- Nature Communications
- December, 15, 2016
Abstract
Top predators can suppress mesopredators by killing them, competing for resources and instilling fear, but it is unclear how suppression of mesopredators varies with the distribution and abundance of top predators at large spatial scales and among different ecological contexts.
Gray Wolf in Yellowstone Park keeping a Western Coyote
from it's Elk kill
Gray Wolf in Yellowstone Park keeping a Western Coyote
from it's Elk kill
We suggest that suppression of mesopredators will be strongest where top predators occur at high densities over large areas. These conditions are more likely to occur in the core than on the margins of top predator ranges.
We propose the Enemy Constraint Hypothesis, which predicts weakened top-down effects on mesopredators towards the edge of top predators’ ranges. Using bounty data from North America, Europe and Australia we show that the effects of top predators on mesopredators increase from the margin towards the core of their ranges, as predicted. Continuing global contraction of top predator ranges could promote further release of mesopredator populations, altering ecosystem structure and contributing to biodiversity loss.
a) On the edge of a top predator's range, mesopredator abundance should decline as top predator abundance increases. The breakpoint for the mesopredator indicates where their abundance starts to become close to zero. The breakpoint for the top predator indicates where their abundance starts to decline sharply on the edge of the range.
A breakpoint is not necessary for the ECH to hold, but it may be indicative of a key threshold where there is a sharp change in top predator or mesopredator abundance, and is therefore useful to assess. (b) The relationship in a should manifest where mesopredators overlap spatially with the edge of a top predator's range, with the relationship potentially applying more widely to other predator dyads that strongly interact and compete for similar resources, or even to any strongly interacting competitive species dyads (‘enemies’) including relationships involving parasites or pathogens.
Gray Wolves chasing and ultimately killing a Western Coyote
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JOURNALS OF THE LEWIS & CLARK EXPEDITION
Clark reporting:
thursday 11th Septr. 1806
a heavy Cloud and wind from the N W. detained us untill after Sunrise at which time we Set out and proceeded on very well, passed the nemahar [1] which was low and did not appear as wide as when we passed up. Wolf river [2] Scercely runs at all, at 3 P. M we halted a little above the Nadawa river [3] on the S. Side of the Missouri to kill Some meat that which we killed a fiew days past being all Spoiled. Sent out 6 hunters they killed and brought in two Deer only, we proceeded on a fiew miles below theNadawa Island and encamped on a Small Isld. near the N. E. Side, [4] haveing Came 40 Miles only to day, river rapid and in maney places Crouded with Snag's. I observe on the Shores much deer Sign—
Lewis & Clark encountered Gray Wolves
and Western Coyotes in the West and Gray Wolves
keeping Coyotes off their Elk and Pronghorn kills
the [mosquitoes?] are no longer troublesome on the river, from what cause they are noumerous above and not So on this part of the river I cannot account. Wolves were howling in different directions this evening after we had encamped, and the barking of the little prarie wolves resembled those of our Common Small Dogs that ¾ of the party believed them to be the dogs of Some boat assending which was yet below us. the barking of those little wolves I have frequently taken notice of on this as also the other Side of the Rocky mountains, and their Bark so much resembles or Sounds to me like our Common Small Cur dogs that I have frequently mistaken them for that Speces of dog— The papaws nearly
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