Maggie Brandenburg
Conservation Biology
Research Project
March 29, 2011
Ecological Status and Conservation Plan for the Iowa White-Tailed
Jackrabbit (Lepus Townsendii)
Background
During my undergraduate career, I was involved in a project working on the disappearing white-tailed jackrabbit (Lepus townsendii) populations of Iowa. We studied this species of greatest conservation need mainly on the Iowa State University research farm just west of Ames, but also looked into other potential populations especially in northwest Iowa, and took down called-in sightings and road-kill findings from around the state. We combined this data with Iowa DNR data from August roadside surveys and Iowa DNR small-game harvest surveys to get a more complete picture of the population numbers and trends over the past several decades. What we found was a distinct declining trend in the numbers of jackrabbits found in Iowa due to the highly agricultural landscape focused on tall crops. In order to conserve the existing populations remaining in Iowa, which contain important genetic diversity in relation to the more numerous South Dakota (and further west) populations, I have coordinated with members of the Boone extension of the IDNR, ISU professors, and concerned citizens to create a workable conservation plan.
White-tailed jackrabbits are one of the two species of lagomorphs found in the state of Iowa (Kaufman et al. 1998), the other being the eastern cottontail. It is recognized by having a larger body size than that of the eastern cottontail (around two feet in length) and having ears greater than three inches in length (Kaufman et al. 1998, Kline 1963, Lim 1987). Its ears are tipped with black, but its tail is white, which distinguishes it from the more western species, the black-tailed jackrabbit (Lepus californicus) (Lim 1987). The pelage of jackrabbits turns white in the winter, and their spring weights are 6.8 and 8.3 pounds for males and females respectively (Kline 1963). Their breeding season extends from late February to late July, with a maximum of four litters of four to five offspring in each (Kline 1963, Lim 1987).
Jackrabbits prefer to inhabit relatively short vegetation in open environments, as they rely on visual cues to spot, and speed to avoid predators (Rogowitz & Gessaman 1990). Out on the ISU Agronomy and Agricultural Engineering Research Farm, just west of Ames, Iowa, Tapia (2010) studied seasonal habitat preference and home range of the resident jackrabbits. By dividing the calendar year into crop related segments, Tapia (2010) was able to discover the pattern of movement and discern habitat preference of jackrabbits in a highly agricultural environment. She concluded that jackrabbits chose to live in oats and alfalfa significantly more than any other crop (included substrates: oats, grass, corn, soybeans, alfalfa, and other) and selected against living in corn fields while corn was present (Tapia 2010). Tapia (2010) found the seasonal home ranges of central Iowan jackrabbits to be from .32 km2 to 1.58 km2 during the pre-harvest and breeding seasons, respectively. In contrast, in South Dakota, Schaible (2007) found jackrabbit home ranges to be .61 km2 - .88 km2 in highly agricultural settings, compared to 2.00 km2 in a grassland setting. This is most likely due to the higher quality food and shelter available in the grassland habitat (Schaible 2007).
Historically, the white-tailed jackrabbit was found mostly in western states such as South Dakota, Nebraska, Wyoming, and Montana, as far north as Manitoba, and as far south as Colorado (Figure 1) (Lin 1987). A small portion of the northwest corner of Iowa was also included in their historic distribution, but they moved down into the remainder of the state and further east into Illinois, Missouri, and Wisconsin when settlers began to break up the tall grass prairie for cultivation over 150 years ago (Lin 1987). Hare populations have been declining in many areas across the world (Dingerkus and Montgomery 2002), including the alpine hare (Newey et al. 2007), the European hare (Smith et al. 2005), the snowshoe hare (Keith et al. 1993, Keith et al. 1984), and the white-tailed jackrabbit (Kline 1963, Tapia 2010). These declines have largely been attributed to disease, predation, and habitat destruction. Disease in Iowan jackrabbits has been understudied, and so cannot contribute to this discussion. White-tailed jackrabbits are prey for coyotes, weasels, and bobcats, and their offspring fall prey to avian predators (Lin 1987). In the study by Tapia (2010), all but one of her subjects was killed by predation by coyotes, which lead her to believe that small, isolated populations of jackrabbits may come under higher pressures from predation. However, the IDNR does not believe predation by coyotes is a significant factor in the decline of jackrabbit populations (Todd Bogenschutz, personal communication). Despite this belief, the IDNR has closed the hunting season on white-tailed jackrabbits for 2011, to minimize potential negative effects any mortality may cause to isolated populations (Bogenschutz 2011).
Jackrabbits have in the more recent past been a common site in Iowa. Kline (1963) reported densities at the time of 3-9 per km2, with a maximum of 71, and harvests of nearly 26,000 jackrabbits during the 1956-1957 and 1957-1958 hunting seasons (December-February). IDNR small-game surveys estimate that jackrabbit harvests were as high as 133,000 in 1965 (Figure 2). However, they have declined in numbers over the last several decades (Bogenschutz et al. 2004 & 2010), and exist largely in only two areas of the state, one of which is central Iowa, especially concentrated on the ISU research farm between Ames and Boone, the other is in the northwest corner of Iowa, near Spencer (Kaufman et al. 1998, Tapia 2010). This trend of declination has been observed in IDNR August roadside surveys (Figure 3), and was brought into the concern of the IDNR partially by Mike Thalman, a concerned citizen who has been monitoring jackrabbit populations around the state decline over the last decade (Mike Thalman, personal contact). White-tailed jackrabbits are considered extirpated in Illinois and Missouri, and in decline in Minnesota (Bogenschutz 2011, Tapia 2010). Nebraska also closed their jackrabbit hunting season in the eastern half of the state in 2006, though jackrabbits are still common in the western portions of North and South Dakota (Schaible 2007). These long term trends of declination lead to the listing of the white-tailed jackrabbit by the IDNR as a Species of Greatest Conservation Need in Iowa in the Iowa Wildlife Action Plan (Zorher 2006).
It is important to the species Lepus townsendii that we take action to preserve the Iowan populations of jackrabbits. This species exhibits a metapopulation dynamic across the central United States, with the central Iowan populations being a remnant fragment population, more susceptible to demographic or environmental stochasticity (Frankham 2005, Laikre et al. 2009, Templeton et al. 1990). A remnant population may be “saved” by immigrants from the source population (Hanski and Gaggiotti 2004) but this depends on the organism’s willingness to cross the intervening space (Haddad et al. 2003), which in this case is unsuitable habitat. The central Iowan population (a periphery population) of white-tailed jackrabbits has significantly different genetics than that of the jackrabbits in northwest Iowa and South Dakota, based on eight microsatellite markers (Tapia 2010). This is likely due to the time these populations have been separated because of the large intervening space of >100 km of mainly corn fields separating the central Iowa populations from those of northwest Iowa (Tapia 2010). Although the northwest Iowa populations did not show significant genetic differences from the South Dakota population (considered the source population of this metapopulation landscape), the large amounts of corn separating the populations could potentially create a genetic rift between populations in the future (Tapia 2010). The extent to which the corn fields separating populations is able to be permeated by jackrabbits is currently unknown, though current data does not support long-distance migrations (Tapia 2010). As a vast majority of the state of Iowa is devoted to growing corn (Figure 4), it is important that we consider these issues before the white-tailed jackrabbit becomes inbred or potentially extirpated in Iowa.
Conservation Efforts
Because the white-tailed jackrabbit is not historically native to all of Iowa (Lin 1987), and to create a feasible conservation plan for the Iowan jackrabbits that remain, this project will focus conservation efforts on conserving those populations in northwest Iowa. These populations currently show evidence for continued gene flow with the South Dakota jackrabbit populations (Tapia 2010) and will benefit the most from the implementation of suitable habitat to better connect them with the South Dakota jackrabbits, due to proximity (compared to the proximity of central Iowa populations). The success of this plan is dependent on many factors including home range size, relative success rate of similar conservation plans, and the willingness of local agriculturists to incorporate conservation methods into their land use. The home range size of white-tailed jackrabbits in highly agricultural settings has been found to be approximately 1-2 km2 (Kline 1963, Schaible 2007, Tapia 2010). Natal dispersal also influences population range, and although this has not been studied in white-tailed jackrabbits, it has been found to be 1.6 km in a similar species, the European hare, Lepus europaeus (Bray et al. 2007).
Corridors have been shown to be a successful way of maintaining populations of bird and rodent species in habitats that are highly fragmented by residential development (Bolger et al. 2001). In addition, Brinkerhoff et al. (2005) looked into the combined effects of connecting corridors and predation risk on prey behavior in several small mammal species, and found that behavior was not significantly correlated with either corridor presence nor manipulated predator levels. Jepsen et al. (2005) tested models evaluating the effects of corridors and landscape heterogeneity on dispersal probability and found that for habitat specialists with limited mobility (such as the white-tailed jackrabbit), a well-connected stepping stone landscape should see the greatest success rate. It is a stepping-stone spatial organization that this conservation plan is trying to achieve, to see the highest success rate and the greatest acceptance by Iowan agriculturalists.
Estimating the willingness of northwest Iowan farmers to agree to a conservation project that involves changing part of their profitable corn and soybean fields into jackrabbit-friendly habitat such as oats, wheat, and alfalfa, comes down to presentation and compensation. In Kansas, landowners have been found to be more likely to accept alternative land management strategies because of their effects on community quality of life (Schrader 1995). Some of the current pushes in Iowan agriculture are toward improving water quality, chemical use, and soil erosion. Very few farmers actually plant cover crops because most farmers believe that the disadvantages of doing so outweigh the advantages. However, cover crops such as wheat, alfalfa, and oats, when managed correctly, have many benefits, including reduced nutrient leaching, soil erosion protection, carbon sequestration, integrated pest management, and weed suppression (Hoorman 2009). The planting of cover crops can help trap soil moisture for use by future crops in dry years, as a single pound of the organic matter left in soil from cover crops can absorb 18-20 pounds of water (Hoorman 2009). No-till cover crops also increase the activity of mycorrhizal fungus within the soil, promoting a symbiotic relationship with plant roots that assists in water and nutrient uptake (Hoorman 2009). Furthermore, no-till cover crops are used in up to 95% of some areas in South America to promote weed suppression, and subsequently reduce pesticide usage (Hoorman 2009). In addition, the usage of cover crops has numerous other advantages, including increased water infiltration, increased soil organic carbon, improved soil physical properties, recycling of nutrients, promoting beneficial insects, and improving local wildlife habitat and landscape aesthetics (Hoorman 2009).
These significant increases in the quality of water runoff from fields planted with cover crops should be of special interest to farmers in the northwest region of Iowa. This area is well known for the tourism associated with the Okoboji and surrounding lakes. Tourism in Iowa is a $5.8 billion annual business, and in Dickinson County alone (the location of the Okoboji Lakes), tourist spending has seen a large increase recently, up from $170 million in 2005 to $183.6 million in 2006 (Tidemann 2008). For the protection and conservation of just one of the “Iowa Great Lakes”, the Storm Lake Watershed Protection Program was created in 1994. In seven years, this program invested over $216,000 in the watershed area (Kestel 2002). According to a project feasibility study by the IDNR in 1994, if something drastic is not done to improve the water quality of Storm Lake, a significant proportion of fish population will be lost, and recreational activities such as swimming will be hampered (Storm Lake Pilot Tribune 2001). Studies by Buena Vista University since 1991 showed that negligible amounts of nitrates and silt run into the Storm Lake and rest at the bottom, causing shallow waters and increased turbidity (Kestel 2002). It has also been suggested that a major dredging project that resulted in a mean depth of 12 feet (from 7 feet) could last as long as 300 years (Kestel 2002). In 1994, the IDNR figured the cost of such a project to be $53 million (Storm Lake Pilot Tribune 2001). In the Comprehensive Plan for Storm Lake Water Quality Project, three objectives are called for to implement the process of Sustainable Development:
“1. Diversify and improve development and improve owner management practices in the lake area.
2. Sustain and enhance resource productivity and improve the environmental qualities and aesthetics of the Storm Lake Watershed.
3. Enhance the quality of life of each watershed resident and visitor.” (Kestel 2002)
In addition, the IDNR lists to “ensure significant improvement in water clarity, safety, and quality of Iowa lakes” in its Lake Restoration Program project goals (Leopold 2009). For this program, conserving 35 lakes and watersheds throughout the state of Iowa, they are asking in excess of $8.6 million per year to carry out their plans (in 2009 the project received $12.8 million), and the majority of the plans proposed does not involve the changing of farming practices (Kestel 2002, Leopold 2009). As of yet, the proposed plans for lake restoration mainly include the costly drudging of included, and highly polluted lakes. While I do not deny the necessity or wisdom of such an action, I can’t help but notice how these plans are mostly reactionary and contain very little proactive plans. By emphasizing the many beneficial effects that a change in crop growing habits would have on the soil quality and especially the water quality issues that concern Iowa farmers, this conservation plan will have an increased likelihood of being locally accepted.
Proposed Conservation Plan
I propose that in an effort to improve water quality, and create more viable habitat for the declining populations of native white-tailed jackrabbits, farmers in northwest Iowa should designate a portion of their farmland toward the planting of cover crops such as wheat, oats, and alfalfa. These three crops have been shown to be preferential habitat for Iowa jackrabbits (Tapia 2010) and the implementation of patchy suitable habitat would create a stepping-stone habitat that is the most likely habitat to successfully connect northwest Iowa and South Dakota jackrabbit populations (Jepsen et al. 2005). In addition to providing suitable habitat for jackrabbits, these crops fall into the definition of cover crops, of which we have previously discussed the many benefits toward water quality, soil quality, and soil erosion, which would greatly assist in the prevention of further damage to the lakes of northwest Iowa (Hoorman 2009). In addition, this change in land cover would assist in the fulfillment of the goals of both the Comprehensive Plan for Storm Lake Water Quality Project and the IDNR’s Lake Restoration Program, as listed above. However, in order to encourage participation, compensation should be offered to landowners who agree to partake in the conservation effort. These compensation values are calculated by finding the difference in monetary return of the original crop and the new crop (i.e. corn, changed to oats) and multiplying this by the amount of land that the landowner agrees to convert to the new crop. Actual monetary values can be found in Table 1. These values can be used to estimate a total cost for this project, based on the voluntary participation of local area farmers.
The USDA Natural Resource Conservation Service has a conservation program called the Conservation Stewardship Program (CSP) that could offer funds toward this project. Through CSP, the “NRCS provides financial and technical assistance to eligible producers to conserve and enhance soil, water, air, and related natural resources on their land” (CSP website). Participation in CSP is completely voluntary. The CSP provides payments to farmers per acre for being good environmental stewards; offering payments for following conservation plans, including practices like keeping no-till fields, managing manure and fertilizer, etc. CSP actually pays participants for conservation performance – in other words, the greater the performance, the higher the payment. In addition, there are two types of payments: an annual payment for installing new conservation practices and maintaining existing practices, as well as a supplemental payment for participants who adopt a resource-conserving crop rotation (such as that provided by planting cover crops). Through this plan, a farmer can earn up to $40,000 a year or $200,000 over five years for implementing conservation plans on his or her land. Working closely with the IDNR, this plan should be both presentable and appealing to the CSP, which would give the project the funding and attention it needs to get off the ground. If the CSP agrees to offer payments to farmers who include alfalfa and other small grains into their crop rotation, it will address many of the soil erosion and water quality concerns in northwest Iowa, and subsequently provide suitable jackrabbit habitat.
Conclusions
After an initial influx into the whole of the state of Iowa over 150 years ago, white-tailed jackrabbit (Lepus townsendii) populations have been steadily declining since the 1960s (IDNR data, Figures 2 & 3). This trend of declination is mainly due to loss of habitat (Kline 1963, Lim 1987, Tapia 2010), as most farmland in Iowa is corn and soybeans, as compared to the shorter crops such as alfalfa and oats preferred by jackrabbits (Tapia 2010). This loss of habitat has lead to a fragmentation of the jackrabbit metapopulation, leaving isolated populations vulnerable to extinction through predation, demographic stochasticity, and environmental variation (Frankham 2005, Laikre et al. 2009, Templeton et al. 1990). These fragmentary and isolated populations contain unique genetic material, the loss of which could be highly detrimental to the overall health of the white-tailed jackrabbit (Tapia 2010). Because of the importance of peripheral populations to the genetic make-up of a species (Frankham 2005, Laikre et al. 2009, Templeton et al. 1990), they have been listed as a Species of Greatest Conservation Need (Zorher et al. 2006), and our help is greatly needed.
This conservation plan will create a stepping-stone, mosaic habitat as suggested by Jepsen et al. (2005) in northwest Iowa that will help to connect the fragmentary jackrabbit populations in northwest Iowa to the more stable South Dakota populations. This can be accomplished through the monetary assistance of the USDA Natural Resource Conservation Service’s Conservation Stewardship Program (CSP) which pays individual land owners up to $40,000 a year to implement and maintain approved conservation practices on their land. This conservation plan will appeal to the CSP as well as the IDNR and the local communities because of the many highly beneficial effects of planting small grains on soil and water quality, both of which are of great concern in Iowa. Through this double-headed conservation plan, we can save both the northwest Iowa jackrabbits, as well as improve the water quality in a problematic area.
Works Cited
Bogenschutz, Todd. 2011. 2011-12 Upland Game Season Recommendations, Iowa Department of Natural Resources Memorandum, February 17, 2011.
Bogenschutz, Todd and Mark McInroy. 2004. Iowa August Roadside Survey, Iowa Department of Natural Resources.
Bolger, Douglas T., Thomas A. Scott and John T. Rotenberry. 2001. Use of corridor-like landscape structures by bird and small mammal species. Biological Conservation 102:213-224.
Bray, Y., S. Devillard, E. Marboutin, B. Mauvy and R. Péroux. 2007. Natal dispersal of European hare in France. Journal of Zoology 273:426-434.
Brinkerhoff, Robert Jory, Nick M. Haddad and John L. Orrock. 2005. Corridors and olfactory predator cues affect small mammal behavior. Journal of Mammalogy 86:662-669.
Conservation Stewardship Program. 2011. <http://www.ia.nrcs.usda.gov/programs/Conservation StewardshipProgram.html>.
Dingerkus, S.K. and W.I. Montgomery. 2002. A review of the status and decline in abundance of the Irish Hare (Lepus timidus hibernicus) in Northern Ireland. Mammal Review 32:1-11.
Frankham, R. 2005. Genetics and extinction. Biological Conservation 126:131-140.
Haddad, N.M., D.R. Bowne, A. Cunningham, B.J. Danielson, D.J. Levey, S. Sargent, and T. Spira. 2003. Corridor use by diverse taxa. Ecology 84:609-615.
Hanski, I. and O.E. Gaggiotti. 2004. Ecology, genetics and evolution of metapopulations. Academic Press, Amsterdam.
Hoorman, James, J. 2009. Using cover crops to improve soil and water quality. Fact Sheet, Agriculture and Natural Resources, The Ohio State University.
Jepsen, J.U., J.M. Baveco, C.J. Topping, J. Verboom and C.C. Vos. 2005. Evaluating the effect of corridors and landscape heterogeneity on dispersal probability: a comparison of three spatially explicit modeling approaches. Ecological Modelling 181:445-459.
Kaufman, Sharon, Mark Müller, and Dan Cohen. 1998. Iowa Mammals. Iowa Wildlife Series. Iowa Association of Naturalists.
Keith, L.B., S.E.M. Bloomer, and T. Willebrand.1993. Dynamics of a snowshoe hare population in fragmented habitat. Canadian Journal of Zoology-Revue Canadienne De Zoologie 71:1385-1392.
Keith, L.B., J.R. Cary, O.J. Rongstand, and M.C. Brittingham. 1984. Demography and ecology of a declining snowshoe hare population. Wildlife Monographs:1-43.
Kestel, Jeff. 2002. Conservation plan for Storm Lake Water Quality Project.
Kline, Paul D. 1963. Notes on the biology of the jackrabbit of Iowa. Iowa Academy of Science 70:196-204.
Laikre, L. T. Nilsson, C.R. Primmer, N. Ryman, and F.W. Allendorf. 2009. Importance of genetics in the interpretation of favourable conservation status. Conservation Biology 23:1378-1381.
Leopolod, Richard A. 2009. Lake restoration 2009 report and 2010 plan. Submitted to: Joint Appropriations Subcommittee on Transportation, Infrastructure, and Capitals and Legislative Services Agency.
Lim, Burton K. 1987. Lepus townsendii. Mammalian Species No. 288:1-6.
Newey, S., F. Dahl, T. Willebrand, and S. Thirgood. 2007. Unstable dynamics and population limitation in mountain hares. Biological Reviews 82:527-549.
Rogowitz, G. and J. Gessaman. 1990. Influence of air-temperature, wind, and irradiance on metabolism of white-tailed jackrabbits, Journal of Thermal Biology 15:125-131.
Schaible, Dustin J. 2007. South Dakota State University, Brookings. M.S. Thesis.
Schrader, Charles C. 1995. Rural greenway planning: the role of streamland perception in landowner acceptance of land management strategies. Landscape and Urban Planning 33:375-390.
Smith, R.K., N.V. Jennings, and S. Harris. 2005. A quantitative analysis of the abundance and demography of European hares Lepus europaeus in relation to habitat type, intensity of agriculture and climate. Mammal Review 35:1-24.
Storm Lake Pilot Tribune. 2001. The pilot editorial - digging in heels on dredging. March 8, 2001.
Tapia, Irma I. 2010. Iowa State University. M.S. Thesis.
Tidemann, Michael. February 14, 2008. Spirit Lake Council gets Okoboji tourism update. Estherville Daily News. <http://www.esthervilledailynews.com/page/content.detail/id/500043.html?nav=5003 &showlayout=0>.
Templeton, A.R., K. Shaw, E. Routman, and S.K.Davis. 1990. The genetic consequences of habitat fragmentation. Annals of the Missouri Botanical Garden 77:13-27.
Zorher, J.J. 2006. Iowa Wildlife Action Plan. Iowa Department of Natural Resources.
Figure 1. Historic (shaded) and present (broken-lined) distribution of Lepus townsendii (two subspecies: 1. L.t. campanius and 2. L.t. townsendii). From Lin 1987.
Figure 2. Jackrabbit harvest estimates from Iowa small-game surveys from 1963 to 2004. Source: IDNR.
Figure 3. Total number of jackrabbits counted during August roadside survey from 1980 to 2010. Source: IDNR.
Figure 4. Percentage of counties in Iowa planted as corn and soybeans; five year averages 1999-2003. Source: Iowa Agricultural Statistics, ISU Department of Agronomy, 2004.
Table 1. Compensation values for changing previously corn/soybean fields to cover crops, as called for in this conservation plan.
Yield/acre Price/unit Income/acre Price Diff/acre from Corn Price Diff/acre from Soybeans Corn CSP Payment Soybean CSP Payment
Corn 170 $5.00 $850.00
Soybeans 52 $12.00 $624.00
Wheat (all) 55 $7.00 $385.00 $465.00 $239.00 $46.50 $23.90
Oats 75 $3.00 $225.00 $625.00 $399.00 $62.50 $39.90
Hay (alfalfa)* 3.7 $120.00 $444.00 $406.00 $180.00 $40.60 $18.00
Yield/acre and price/acre based on personal communication with Todd Bogenschutz and Bruce Babcock
*Hay is ton/acre
Yellow values are price/acre that CSP would need to pay on the entire field to match corn or bean income lost by growing wheat, oats, and hay on 10% of the field
