The Much Maligned Coyote

Here in Nebraska, we’ve lost most of our largest predators.  Bears and wolves are gone (excepting rare long-distance wanderers).  Mountain lions are making a slow comeback in the northern and western parts of Nebraska, but the agricultural character and fragmented nature of our state makes it difficult to imagine a much stronger presence of large predators than we have right now.  That’s not a critique – it’s just reality.  It’s difficult to know what effect the absence of those predators has on our wildlife and natural landscapes, but based on what we know from research elsewhere, it’s surely significant.  Throughout the world, and across a wide range of habitat types, major predators stimulate complex cascades of impacts far beyond simply suppressing the populations of their favored prey species.  In fact, the diversity and abundance of many plant, invertebrate, and wildlife species have been shown to decline dramatically when dominant predators disappear.

Illustration by Kim Tri

Coyote illustration by Kim Tri, one of our Hubbard Fellows and, obviously, a talented artist.

Today, in the absence of wolves and bears, coyotes have stepped into the role of top mammalian predator across much of Nebraska.  It’s hard to know if they are as effective as their larger counterparts at maintaining ecosystem function, but there is strong scientific evidence for the strong and positive impacts coyotes have on a number of other grassland species.  Much of the research on this topic was published 15-20 years ago, but few people seem to be familiar with it.  In fact, rather than being celebrated for their importance, coyotes are widely reviled, and often shot on sight, by many (most?) rural citizens across much of prairie regions of North America.

There is much unfortunate irony in the vilification of coyotes.  One common coyote narrative is that coyotes are hard on nesting birds, especially game species like pheasants, quail, turkeys, grouse, and ducks.  In reality, coyotes feed mainly on rodents, and the major predators of birds and their nests tend to be smaller animals, including foxes, raccoons, and cats (especially feral house cats).  Coyotes are large and aggressive enough to intimidate or kill those “mesopredators”, keeping their numbers low and driving them into areas where coyotes spend the least time, such as wooded draws, farmsteads, and even surburbia.  In fact, numerous studies have documented detrimental impacts to bird populations ranging from songbirds to ducks and grouse when coyote numbers are suppressed and mesopredator populations swell.

One of the most dramatic studies of coyote impacts on the structure and function of ecological communities took place on 20,000 hectares of west Texas land back in the 1990’s.  Researchers halved the number of coyotes in one portion of the study area and left the population alone elsewhere.  Within a year of coyote control, the area with fewer coyotes experienced higher populations of bobcats, badgers, and gray foxes.  Perhaps as a result, 11 of the 12 rodent species in that area disappeared, leaving only a skyrocketing population of kangaroo rats.  Jackrabbits also tripled their numbers in the coyote control area, much to the chagrin of ranchers, since jackrabbits compete with livestock for forage.

Another great coyote illustration by Kim Tri.

Another great coyote illustration by Kim Tri.

Speaking of ranchers, many tend not to be coyote fans, in large part because coyotes are sometimes hard on livestock.  Sheep ranchers can suffer big losses to coyotes if they don’t actively protect sheep with dogs, overnight enclosures, and other strategies.  Cattle ranchers can also have trouble with coyotes killing livestock, especially just-born calves.  Coyotes are very good at killing young deer fawns – a great reason for prairie enthusiasts to be coyote fans, by the way – but some transfer that skill to calves as well.  While any self-respecting cow can protect her calf from coyotes under most circumstances, even the toughest mother is weakened enough by the process of giving birth that she is vulnerable to a quick sneak attack.

Unfortunately, the response to livestock losses is often the indiscriminate killing of whatever coyotes ranchers can find.  Research has shown that kind of “coyote control” to be largely ineffective, in part because it usually fails to kill the individuals actually causing problems.  For example, a fourteen year study showed that almost every sheep killed by coyotes was taken by the “alpha pair” in the pack’s social structure.  Those alpha animals are also the wiliest and most difficult to kill.  Furthermore, of course, in the unlikely event that coyote control efforts succeed at suppressing the population in an area, the results might not turn out in favor of the rancher.  Higher numbers of raccoons and foxes, not to mention jackrabbits, along with fewer ducks, grouse, and quail, might take the thrill out of the temporary victory.

Even if coyotes gain wider recognition for their positive effects on natural systems, however, the relationship between coyote and human is bound to be complicated.  As we continue to alter their habitat, coyotes will continue to adapt and survive as best they can.  At times, that will bring them into conflict with us.  It is understandable, for example, that a rancher needs to address livestock losses, and sometimes that could mean tracking down and killing the individual coyote(s) responsible.  However, that kind of careful, targeted response is much different (and more effective) than current broad, indiscriminate campaigns against an animal whose bad reputation is largely based on innuendo and misinformation.

Ideally, seeing coyote tracks on their property would be a positive experience for landowners.

Ideally, seeing coyote tracks on a property would be a positive experience for landowners.

Coyotes and other predators play critically important roles in grassland ecosystems.  It’s easy to understand how they directly suppress populations of their primary prey species.  However, as we continue to study predators, we find more and more of the kind of indirect impacts that ripple through ecological systems in ways that are difficult to predict.  While it seems unlikely that wolves and bears will ever return to prominence in Nebraska or most other prairie regions of North America, coyotes may be able to cover at least some of the ecological roles those larger predators once played.

But only if we let them.

 

Patches of Fire and Habitat

It’s been a difficult year for conducting prescribed fires so far – the wind seems to be blowing even harder and more consistently than in recent memory.  And that’s saying something, living in the Great Plains.

A couple of weeks ago, we were able to pull off one prairie management burn here in the Platte River Prairies.  The fire went well, and this week I took a quick walk through the burned area to see how the regrowth of vegetation was coming along.  It’s been a cold and dry spring, following a dry fall and winter, so plant growth has been slow, but things are finally starting to kick in.  Within the burned area, many plant species are a little behind their compatriots growing outside the burned area, but others are ahead.  Those that are behind are the species that were already starting to grow when the fire came through – those species had to start again, so are behind schedule.  The species that are further ahead in the burned area are those that are taking advantage of the warmer soil and have either germinated or emerged faster than those in the cooler soil of unburned areas.

Regrowth in sand prairie burned a couple weeks ago.  The wildflower in the foreground is shell-leaf penstemon (Penstemon grandflorus).

Regrowth in sand prairie burned a couple weeks ago. The wildflower in the foreground is shell-leaf penstemon (Penstemon grandflorus).

Regardless, plants are growing well in the burned area.  That’s good, because cattle will arrive within the next week or so, and we want the burned area to be particularly attractive to those grazers.  One of the major objectives of our fire was to concentrate grazing in one portion (the burned patch) of the prairie this season, leaving the remainder of the pasture with much less intensive grazing.  Hopefully, the result will support our efforts to create a variety of habitat patches across our prairies, and to shift the location of those patches from place to place each year.

The patch we burned this spring has had no fire and very little grazing over the last couple of years.  Last year, it had tall vegetation and abundant thatch – conditions that favor a certain set of plants and animals, but not others.  This year, it will have very little thatch and the vegetation will be short in stature because of season-long intensive grazing.  Next year, it will begin a multiple season recovery period from that fire and grazing until it is burned again sometime down the road.  (You can read more about patch-burn grazing here.)

Burning a different patch of prairie each year helps ensure that a mixture of habitat types is always available and most or all wildlife and invertebrate species can find the habitat they need.  Our prairies usually have a patch of very short habitat, several patches in some stage of recovery from intensive grazing, and some areas that are tall and very lightly grazed – or ungrazed.  Some animals will follow those habitat patches across the landscape.  Others will go through boom and bust periods within one portion of a prairie, depending upon what conditions they thrive best under.

Because we’re always changing the location of habitat patches, plant species also experience changing conditions from year to year.  This means that some species flourish one year, but may have to wait a few years before those favored conditions return.  In the meantime, other plant species will find success.  Constantly changing conditions help ensure that no group of species becomes too dominant, but that all species can survive and maintain a place in the plant community.  Our long-term data has shown the our plant communities have stable to increasing plant diversity under this kind of management, and we’re not seeing any plant species disappear.

This burned patch makes up between a third and a fourth of a 110 acre management unit in our Platte River Prairies.  Burning only a portion of each unit each year helps ensure good wildlife habitat and changing growth conditions for plants, but also helps avoid catastrophic impacts on species vulnerable to fire.

This burned patch makes up between a third and a fourth of a 110 acre management unit in our Platte River Prairies. Burning only a portion of each unit each year helps ensure good wildlife habitat and changing growth conditions for plants, but also helps avoid catastrophic impacts on species vulnerable to fire.

Another benefit of burning only a portion of our prairies each year is that it helps us avoid catastrophic impacts on plant and animal species that are negatively impacted by fire.  Invertebrates that overwinter above ground, for example, can be destroyed by an early season fire.  Growing season fires can kill animals (invertebrates and vertebrates) that are unable to escape by leaving the area or retreating underground.  These kinds of impacts are somewhat unavoidable, regardless of the season of fire, but by burning only a portion of our prairies, we can try to restrict impacts to a relatively small proportion of the population of each species, allowing the majority of individuals to survive and recolonize the burned patch over time.  Burning an entire prairie, especially in highly fragmented landscapes in which recolonization is unlikely, can result in completely and permanently obliterating vulnerable species from a site.

Hopefully, the wind will pause a few times during the remainder of the spring, and we’ll create a few more burned patches in our prairies.  If not, we’ll try to create patches of short habitat by haying or by temporarily fencing cattle into an area to knock vegetation height down.  We’ve found that all three methods (burning, haying, temporary enclosures) can create a patch that attracts livestock grazing afterward – and therefore pulls that grazing off of other portions of prairie.  There are lots of ways to create patchy habitats, and none are necessarily best.  As long as there is always a mixture of habitat types across our sites, we feel pretty good about our management.

Hopefully, the species living in our prairies feel pretty good about that management too.