This is a report on the status of our project that involves transferring prairie dogs from the Fort Niobrara National Wildlife Refuge to the 5,000-acre Hutton Niobrara Ranch Wildlife Sanctuary in order to establish a new colony.
Please be sure to view the extensive photo gallery with detailed descriptions on our website. Click here to visit the gallery.
We are hoping that the experience and information obtained will help to encourage and/or prove useful to other landowners and managers who want to establish new and/or maintain existing prairie dog colonies-and also benefit many of the associated wildlife species (including Burrowing Owls, Swift Foxes, Ferruginous Hawks, Golden Eagles and Ornate Box Turtles). In particular, success with fencing may prove useful for landowners who want to include it along with other techniques, such as vegetative barriers, to discourage dispersal from existing prairie dog colonies to adjacent areas where they are not wanted.
CAPTURING PRAIRE DOGS
On Saturday July 28, Fish and Wildlife Service staff and family members, and students working at the refuge for the summer, volunteered to lead the way in the capture of prairie dogs from the horse pasture behind the headquarters and residential facilities. The population there has been encroaching into that area beyond the level desired for other management purposes. Robert Bergersen-a student from Manhattan working with me at the sanctuary-and I also participated.
I had tried the previous week to capture prairie dogs with box traps acquired for the purpose and others loaned by Buffalo Bruce of Chadron, however that approach wasn't successful for several reasons. Success with box traps requires conditioning the prairie dogs to eating bait in and around the traps, sometimes over a period of week or more. In this location, the horses in the pasture discovered and responded to the "sweet feed" and oats more quickly and routinely turned the traps over to spill the bait. All I caught was a Kangaroo Rat, a cute little creature common in the Sandhills. (Refuge horses weren't being offered for translocation to the sanctuary, so use of extraordinarily larger traps wasn't an option!)
During the previous week, NWR staff had been in the field helping with the major effort to fight the devastating wild fires that had erupted from lightening along the Niobrara River valley, on constant call or patrolling to detect any additional fires. With the fires under control the refuge's fire engines were available for the prairie dog capture on Saturday, July 28. With a soapy substance added to the water in the tanks, water was flushed down prairie dog burrows to flood them out. Usually the suds would come up out of one or more additional burrows, suggesting a direct connection. Other long-established burrows seemed to be bottomless and could conceivably accept hundreds of gallons. The area has been exceedingly dry and the burrows and ground were really soaking it up. At first the task seemed to be about as difficult as trapping with box traps.
Then our luck changed and a few prairie dogs began emerging from most of the burrows flooded. We grabbed them with our gloved hands as they emerged soaking wet and rushed them over to water coolers with spigots where they were rinsed off. Then they were placed in holding cages kept in the shade since it was another of many days with a temperature over 100.
At the end of the afternoon, a fairly long day with a brief break for pizza and ice cream, we loaded them in the stock trailer acquired to be a mobile wildlife viewing blind at the sanctuary and headed 70 miles east (85 miles by road) to the relocation site designated to be a new prairie dog colony on the Niobrara Sanctuary <www.niobrarasanctuary.org>.
PURPOSES OF A NEW COLONY: ECOLOGICAL
The idea is to establish the new colony to serve several ecological, scientific and educational purposes. We have prepared a remarkably inviting place for their new home. Although prairie dogs were once common in Rock County, and occurred on the property now owned by Audubon of Kansas, the species has apparently been totally extirpated from the county. A couple small colonies have survived in Keya Paha County a few miles north, across the Niobrara River. Lewis and Clark first encountered prairie dogs about 50 miles northeast of the sanctuary, at a place called Baldy Knob.
Lewis and Clark described their first prairie dog "town" experience near the Nebraska/South Dakota state line, west of the Missouri River and north of the Niobrara River, where they captured their first prairie dog. A live prairie dog was among the specimens sent to President Thomas Jefferson from Fort Mandan in 1805.
From the Expedition Journals, September 7, 1804:
"Discovered a Village of Small animals that burrow in the grown (those animals are Called by the french Petite Chien) Killed one and Caught one a live by poreing a great quantity of Water in his ....
As a prairie keystone species that benefits many other wildlife species, the added presence of a prairie dog colony at the sanctuary should soon or eventually provide nesting habitat for Burrowing Owls, and become a part of the prey base for Ferruginous Hawks and Golden Eagles that fly that way. However, predation will be a factor that we will try to minimize until the colony is well established, reproducing sufficiently to sustain itself and occupying most of the available area within the 15 to 20-acre enclosure designed for this purpose.
The colony will help to fulfill our goal of making the sanctuary a place that will help to maintain grassland birds and other prairie wildlife native to the area. If prairie dogs cannot be sustained as part of the area's wildlife heritage within a wildlife sanctuary, where can they exit? As Aldo Leopold wrote, "A thing is right when it tends to preserve the integrity, stability and beauty of the biotic community. It is wrong when it tends otherwise."
PURPOSES OF A NEW COLONY: EDUCATIONAL AND WILDLIFE APPRECIATION
One of the important goals of the Niobrara Sanctuary is to provide unique wildlife viewing opportunities to give visitors an opportunity to gain insight into the behavior of various wildlife species and interaction between species. The observation blind adjacent to the colony site will also be a good place for photography, especially once the colony is established and active. Among other things, prairie dog colonies attract a diversity of birds, including Upland Sandpipers, Western Meadowlarks, Horned Larks, and Sharp-tailed Grouse. A group of twelve Upland Sandpipers were residing on the refuge prairie dog colony as I was attempting to trap prairie dogs.
PURPOSES OF A NEW COLONY: SCIENTIFIC (Evaluating Fencing and Relocation Success)
The project will give us an excellent opportunity to evaluate the effectiveness of the fence I designed several years ago. We used it in western Kansas to discourage dispersal, but this will be an opportunity to observe its effectiveness as a complete enclose. In this case we can evaluate its effectiveness at keeping translocated prairie dogs on the site (within the fenced enclosure), and preventing badgers from invading the site and potentially decimating the new inhabitants. For the first few days, possibly weeks, prairie dogs translocated to new colony sites (without any recently occupied burrows available) are particularly vulnerable to predation by badgers.
In this instance, we dug "starter burrows" by auguring at an angle at least three feet deep into the ground with a 4- to 5-inch post hole auger. That is not nearly enough to provide security from the digging skills of a badger, but it provides a brief underground hiding place with some sense of security. The starter burrows can also be excavated more deeply by occupying prairie dogs and be transformed to more secure and complete burrow homes.
To make these starter burrows even more accommodating, and consistent with natural burrows, Bruce and Marge Kennedy brought their weed eater on a recent visit and cut the vegetation close in an area surrounding many of the starter burrows. We used a mower to accomplish the same around some of the other starter burrows. Prairie dogs prefer short vegetation adjacent to the burrows so they can see approaching predators and run unencumbered to their burrows when alarmed.
In addition to the larger enclosure, Robert Bergersen and I built a smaller fenced enclosure (about 50' by 50') inside the larger area to make it feasible to closely observe the prairie dogs released in it.
The stock trailer converted to a mobile wildlife viewing blind was parked adjacent to that enclosure. Sweet feed, oats and corn were placed two to three feet from each of the starter burrows inside the small enclosure and near many of the starter burrows in the larger area. This was done to make sure that they had nutritious food available, even though vegetation was relatively abundant. It was somewhat drought stricken and short throughout the site-consisting of Kentucky bluegrass and other plants that have naturally established in this old field.
A total of 65 prairie dogs were captured on July 28. Robert served as recorder as I sexed and aged each one as they were released. Throughout the day we were all aware of the disproportional number of young-of-the-year "pups", but the final tally was surprising. Fifty-eight were pups, and only six were adults (yearlings or older). Five of the six adult prairie dogs were females, and one was an aggressive "scar-face" male. He clamped down on my gloved finger and held on like a Snapping Turtle! The sex ratio on the pups was near 50/50. I treated each with flea powder prior to release and marked them in a way that provided near-term identity. Thick gloves designed for welders made it possible to handle them without being scratched or severely bitten.
One by one, they were released, generally head first into the starter burrows. They often turned upright and were ready to run out. A small quantity of hay was used to cover some burrows to provide an added sense of security for the prairie dogs, and it seemed to accomplish that objective. Within the smaller enclosure, a few sibling pups were released to run under the wooden pallets and stay together. We placed the pallets near burrows to provide additional aboveground cover for hiding purposes.
During the first day and into the second quite a few of the pups in the smaller enclosure ran around above ground trying to escape staying along the fence trying to get out. However, that strategy seemed to be totally unsuccessful. Sometimes they would try climbing up the poultry netting, stall out as they reached the overhanging netting extending inward, hesitate and then drop or climb back down to the ground two feet below. The electric wire on the inside of the enclosure was not turned on and it never seemed to be necessary to prevent their escape. Sometimes the pups simply laid flat on the ground next to the fence as if hoping to be overlooked by a person approaching. That wouldn't work well if the approaching intruder was a coyote, hawk or other predator. In a couple cases several pups piled into a single starter burrow that was not adequate to house them all and those on top were exposed. Adult prairie dogs did not linger above ground, and a couple within in the small enclosure excavated deeper burrows within the first day.
The inside electric wire could have been electrified with the solar electric fence charger as a means of potentially conditioning prairie dogs to avoid the fence entirely (as people often do with dogs around yards and livestock in fields), but I wanted to see if it was necessary to prevent escape. An electric charged wire might be a useful technique when first releasing prairie dogs in similar enclosures, especially for a few days, or add to the deterrence when one has a fence on less than all sides of an established colony and is concerned about dispersal in a particular direction.
By the third day it appeared that all of the prairie dogs were conditioned to run to a nearby burrow and disappear underground. They did not linger above ground.
Only one prairie dog was found dead; it was in the smaller enclosure. It may have succumbed to intra-species conflict, or a predator. It appeared to be a yearling (one of the six adults). It was partially disemboweled. A day later I saw three Red-tailed Hawks within a mile of the colony site as I drove to that field, and I recall seeing a Northern Harrier flying nearby sometime while working at the sanctuary that week. Along with Redtails, Northern Harriers and Rough-legged Hawks are abundant in the area in from fall into early spring-and I've observed Golden Eagles at he sanctuary on several occasions.
Using parts of spools from rolls of barbed wire used elsewhere on the sanctuary, I designed a metal extension that we stapled to the tops of all of the wood posts used for the prairie dog fences. They are intended and designed to discourage hawks and owls from perching on the posts and launching attacks on unsuspecting prairie dogs.
We are keeping the electric fence wire on the outside of the large enclosure electrified. It is the most vital defense against predation by Badgers during the first few weeks. It may also help deter Coyotes, although they would not be as effective at digging in the extremely hard, dry soil or even when it softens somewhat with rain. (Rain has been scarce in the area this summer.)
After we released the 65 prairie dogs, it was immediately apparent that the area within the fenced enclosure could readily accommodate many times that many.
We hope to capture 35 more in mid September if it works with the schedules of refuge staff and we bring a few more volunteers to help. Anyone interested in assisting is invited to contact me; it will probably be accomplished during the week, rather than on a weekend-when all of Nebraska stops to observe football games!
A POTENTIAL LIMITING FACTOR: The Vulnerability of Pups in Their First Year of Life
With starter burrows located throughout the large enclosed field, there are certainly a sufficient number of sites for released prairie dogs to establish new burrows now and later. However, young prairie dogs do not normally disperse from their natal burrow system until they are yearlings. Thus, it remains to be seen how successful they will be at sufficiently excavating new burrows and surviving all the challenges of their first year of life. Normally only about 50 percent survive this period--and that is in already established prairie dog colonies with many advantages.
For purposes of establishing a new breeding colony within a year, the additional challenge is the fact that only a small percentage of yearlings breed and raise young. One study suggested that as few as 6% of yearling males mate, and only 9% of yearling females produce emergent pups.
According to John Hoogland in his chapter on population dynamics of prairie dogs (in the book he edited entitled "Conservation of the Black-tailed Prairie Dog: Saving North America's Western Grasslands", most prairie dogs do not "become sexually mature and mate" until "in the second February or March, approximately 21 months following first emergence from the natal burrow." The reproductive success of yearlings "is low for both sexes." "Some individuals further delay sexual maturation until the third year."
Prospects for the colony will be enhanced if we can secure more yearlings and adult prairie dogs for relocation to the site. Beyond that, relocation of a greater total number of prairie dogs could help. We may also be able to achieve greater survival and reproduction with supplemental feeding--in much the same way that highly nutritious feed enhances reproduction with heifers and other livestock. We will probably use corn or oats.
Young wild animals learn survival skills from adult members of their species, usually mothers/parents but likely others as well in communal species. Because larger colonies confer safety against predators, colony size is an important consideration for conservation. After detecting a predator, adult and yearling prairie dogs often give alarm calls with considerable information. However, juveniles only rarely call. Learning the language of alarm calls signaling the type of predator (avian or mammalian), "all clear" and other forms of communal communication may be particularly critical to survival in this new colony comprised principally of young-of-the-year juveniles.
Considering the relatively large high-quality habitat available within the confines of the fenced area, it is unlikely that there will be much if any dispersal pressure in the foreseeable future. This summer, fall, and winter there will likely be almost no dispersal because of the fence, tall vegetation serving as a visual barrier surrounding the site just beyond the fence, and the fact that juveniles do not normally disperse.
The prairie dog colony is one of several wildlife conservation and habitat projects implemented within a 212-acre unit within the sanctuary designated as the Harold W. 'Andy' Andersen Wildlife Habitat Area. Most of that unit was previously cultivated. Native grasses and forbs planted on a 150-acre portion have become a brood-rearing habitat for Sharp-tailed Grouse, an area used by Northern Bobwhites, and a magnet for nesting Dickcissels and Grasshopper Sparrows.
We are grateful to everyone who has helped to make this conservation venture possible. First, we thank Harold W. 'Andy' Andersen of Omaha for his leadership as a member of the Audubon of Kansas Board of Trustees and as a distinguished conservation leader in Nebraska.
Second, we thank all of the Fish and Wildlife Service staff and family members who volunteered, and student employees at the Fort Niobrara National Wildlife Refuge for their leadership and "hands on" involvement in capturing prairie dogs on July 28, and for the planning that led to that marvelous day (pictured in the photo gallery). USFWS Staff who assisted included Alan Whited and his son Tracker Whited; Steve Hicks, his wife Jennifer and daughters Amanda and Heather; Brett Bowser; Billy Cumbow; Daniel Bloemer, a summer student from Kentucky; and Mallory Irvine, a summer student from western Nebraska. Refuge biologist Kathy McPeak also assisted with planning. Brice Krohn, a biologist with the Platte River Whooping Crane Trust, effectively employed his previous experience capturing prairie dogs.
Staff of the Nebraska Game and Parks Commission evaluated the reintroduction site, carefully considered the view of all stakeholders, approved the plan, and issued the necessary Scientific and Education Permit.
Manager, Hutton Niobrara Ranch Wildlife Sanctuary
Executive Director, Audubon of Kansas
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