Assessing the ability of Conservation Reserve Program lands to provide habitat for lesser prairie-chickens (Tympanuchus pallidicinctus)

Assessing the ability of Conservation Reserve Program lands

to provide habitat for lesser prairie-chickens (Tympanuchus

pallidicinctus)

A Master’s Thesis

Presented to the Faculty of the

College of Science and Mathematics

Colorado State University-Pueblo

Pueblo, Colorado

In Partial Fulfillment

Of the Requirements for the Degree of

Master of Science in Applied Natural Science

By

Tyrel Shane Woodward

Colorado State University - Pueblo

December 2014

CERTIFICATE OF ACCEPTANCE

This Thesis Presented in Partial Fulfillment of the Requirements for the Degree

Master of Science in Applied Natural Science

By

Tyrel Shane Woodward

Has Been Accepted By the Graduate Faculty of the

College of Science and Mathematics

Colorado State University-Pueblo

APPROVAL OF THESIS COMMITTEE

Graduate Advisor (Dr. Brian Vanden Heuvel) Date

Committee Member (Dr. Annette Gabaldon) Date

Committee Member (Dr. Claire Ramos) Date

i

ACKNOWLEDGEMENTS

I would like to take this opportunity to express my sincere gratitude to all who have helped me in the completion of my master’s degree research and subsequent thesis. I’m extending a special thank you to Allison McGuire for her invaluable contribution volunteering as research assistance. This process would not have been possible if it were not for the assistance of my two advisors Dr. Brian Vanden Heuvel and Dr. Jack Seilheimer. Also, Dr. Annette Gabaldon and Dr. Claire Ramos for their time spent reviewing my final thesis report.

I am very grateful for the assistance provided to me from multiple biologists within Colorado Parks and Wildlife. Including Casey Cooley, Brian Dreher, Trent Verquer, Paul Foutz and Jonathan Reitz. Also from the NRCS, Frank Riggle; and from Kansas Department of Wildlife Parks and Tourism Kraig Schultz and Jim Pitman.

I would also like to thank the Aiken Audubon Society for a generous grant.

And finally and most of all I would like to thank my family. Without continued support from all of them I would not have been able to complete this program. Thank you to my wife, Kristin Woodward, my parents, and extended family for your continued support and encouragement. And of course my son Little Bear for his valuable input.

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TABLE OF CONTENTS

LIST OF EQUATIONS vii

INTRODUCTION 1

BACKGROUND 3

MATERIALS AND METHODS 28

RESULTS 34

DISCUSSION 52

APPENDICES 65

LITERATURE CITED 70

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Assessing the ability of Conservation Reserve Program enrolled

lands to provide habitat for lesser prairie-chickens (Tympanuchus

pallidicinctus)

Habitat loss is the single greatest factor leading to the continued decline of lesser prairie-chicken populations. The overall range of lesser prairie-chickens has decreased by more than 92% since the 1800’s, leading to a 98% overall population loss. The species was recently listed by the United States Fish and Wildlife Service as threatened under the Endangered Species Act of 1973. Much of the habitat degradation can be attributed to habitat loss and fragmentation by anthropogenic activities. Our study utilized rangeland sampling techniques to measure the benefits of habitat provisions within Conservation Reserve Program (CRP) lands. We employed modified daubenmire method, line intercept method, and Robel pole sampling techniques on 124 transects over 31 fields in southeast Colorado and southwest Kansas. Our data indicated CRP fields within both states fell far short of meeting recommended guidelines for lesser prairie-chicken nesting and brood rearing habitat. When comparing the two states it became apparent that fields within Kansas contained significantly greater communities of bunch grasses, and had greater diversity than those in Colorado. Both states met the minimum percent cover of grass for nesting habitat (>20%). However, only grasses within Kansas (75%) were within the minimum suggested percent of bunch grasses (>65%). When comparing data between counties once again we found that Morton County within Kansas had greater potential than any county sampled within Colorado. Both Morton (22.31% ± 1.41, 20,277 ± 3,578.91 plants/ha) county and Baca (29.76% ± 2.16, 33,750 ± 9815.71 plants/ha) county had increased cover and density of bunch grasses. Morton county boasted the greatest species diversity. In conclusion we found that both forbs and shrubs are greatly under-represented on CRP fields. The differences

iv

measured are largely reflective of species composition. We do believe there is still a potential for privately owned lands to offset habitat degradation through CRP. We would encourage that future CRP implementation consider a greater forb presence in seed mixes as well as a thorough investigation into the effectiveness of mid-contract management. Both of these practices may be valuable in increased species diversity, and encouraging the growth of beneficial species which will be of value to local lesser prairie-chicken populations.

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List of Figures

Figure 1: Diagram of year round habitat 14

Figure 2: Map of historic and current species range 26

Figure 3: Percent of transects meeting recommendations 38

Figure 4: Habitat attributes by county 39

Figure 5: Average species per transect by guild 45

Figure 6: Relative density of plants by guild (bunch grass, forbs, shrubs) 46

Figure 7: Relative density of sod grasses 47

Figure 8: Pie graph of average percent composition by species 49

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List of Tables

Table 1: Habitat recommendations for nesting and brood rearing habitat 35 Table 2: Colorado and Kansas parameters compared to nesting habitat 36 recommendations

Table 3: Colorado and Kansas parameters compared to brood rearing habitat 37

recommendations

Table 4: Mean number of species by guild 41

Table 5: Average density of plants by guild 42

Table 6: Average percent cover of plants by guild 43

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List of Equations

Equation 1: Percent Cover 33

Equation 2: Percent Composition 33

Equation 3: Relative Density 33

1

Introduction

As wildlife habitat is further threatened by encroaching land use and climate change,

it is becoming increasingly important to find new sources of suitable habitat for species

which may be on the brink of extinction. The lesser prairie-chicken (Tympanuchus

pallidicinctus) has lost approximately 92% of its native range since European settlement in

the 1800’s. Of this decrease, 78% has occurred since the 1960’s (Taylor and Guthery 1980).

This has attributed to a 98% decline in total population (Giesen 1998, Hagen et al. 2004). The

lesser prairie-chicken was first petitioned for listing under the endangered species act in

1995; currently, the lesser prairie-chicken is listed as a threatened species under the

Endangered Species Act of 1973 (USFWS 2014).

The lesser prairie-chicken is highly reliant upon specific habitat characters for

survival and reproduction. Due to this fact, habitat loss has been identified as the leading

cause of population declines (Hagen et al. 2004, Robb and Schroeder 2005, Ripper et al.

2008). Declines in lesser prairie-chicken populations in Kansas have coincided with the

development of center-pivot irrigation (Jamison 2000). Range-wide, species demography

surveys show a continual decline in the overall population. In 2004, a new survey method

was implemented, resulting in the discovery of new leks within Colorado and confirming the

use of land enrolled in the Conservation Reserve Program (CRP) by lesser prairie-chickens.

2

cover and food availability coupled with severe winter storms resulted in a decrease from 296

birds observed to just 74 (Verquer 2007). The CRP continues to play a pivotal role in

Colorado, especially within the population in Prowers County (USFWS 2010). For this

reason it is essential to evaluate programs such as the CRP, and its potential as a management

tool in providing new lesser prairie-chicken habitat.

The CRP was instituted in the 1980’s and previously barren lands in Kansas were

enrolled in the program. By 1998, lesser prairie-chickens had expanded into 16 historically

occupied counties north of the Arkansas River (USFWS 2002). The population increase is

primarily attributed to CRP practices within those counties creating favorable habitat

conditions. The USDA Farm Service Agency reports that in Colorado alone there are

1,293,564 acres of land actively enrolled in the CRP; the total acres enrolled in Kansas is

1,654,170 acres. Specifically, within lesser prairie-chicken’s overall range there are an

estimated 3.4 million acres in the CRP (Ripper et al. 2008, Figure 4). Lesser prairie-chicken

use of CRP land has been documented in both states. The Colorado Parks and Wildlife

species profile for lesser prairie-chickens highlights the birds association with CRP land

within the state, especially in Prowers County. One third of the land in Baca County,

Colorado is enrolled in the CRP, although there are no documented leks on CRP fields.

There have been no studies documenting active leks on CRP land in Colorado.

3

fields enrolled in the CRP. Recent studies documented an expansion of lesser prairie-chicken

range to historically occupied land north of the Arkansas River in Kansas. It was postulated

that the presence and quality of CRP habitat was largely responsible for this range expansion.

Nesting success was relatively high within the associated CRP fields (Fields 2004, Rogers et

al. 2000). Taylor and Guthery (1980) highlighted the need for future research to be focused

on habitat and further understanding management of existing habitat. The potential of the

CRP to provide suitable habitat which facilitates the circannual cycle of lesser

prairie-chickens is evident. However, aside from Kansas, the use of CRP lands by the birds is

largely un-documented. There is a lack of data quantifying the benefits of the CRP to lesser

prairie-chickens and its potential to offset lost habitat (Jamison 2002, Rob et al. 2005, Ripper

2008). This study will utilize rangeland sampling techniques in an effort to better understand

the potential habitat provisions for lesser prairie-chickens within CRP lands.

Background

Life History

The lesser prairie-chicken is a member of the grouse family (Phasianidae) in the

order Galliformes. It is a ground dwelling species which was first recognized as a distinct

species by the American Ornithologists Union in 1957 (Taylor and Guthery 1980). The lesser

prairie-chicken is a medium sized grouse with a body length between 38 and 41 cm (Giesen

4

upper body being darker than the breast and abdomen area (Giesen 1998b). Body weight

varies between seasons, age classes, sex, and region. Male lesser prairie-chickens are larger

and typically weigh an average of 752 g compared to 712 g for females. Sexual dimorphism

is present within the species with characters expressed for mate selection during courtship

displays at leks. Male lesser prairie-chickens will have longer pinnae or feather tufts on their

heads. Males are also identified by the yellow eye combs and red esophageal air sacs which

are exhibited during courtship (Robb and Schroeder 2005).

Populations of lesser prairie-chickens are found within xeric mixed grass/shrub

ecosystems within the southwestern Great Plains (Robb and Schroeder 2005, Taylor and

Guthery 1980). Lesser prairie-chicken habitat is a mosaic of natural habitat types and plant

communities. Habitat selection is largely driven by the circannual cycle and the phenological

availability of foods and coverts (Jones 1963) as well as seasonal weather variations.

Lek attendance by females begins to grow during the early spring as male lesser

prairie-chickens vie for the best territories within a lek. In Colorado, greatest lek attendance

by female lesser prairie-chickens was mid-April (Giesen 1998a). Lek attendance continues to

be high through late April and early May, subsiding in mid-June (Hoffman 1963, Crawford

1974). Lekking will occur in spring and fall, although there is less data available on fall

5

In general male lesser prairie-chickens display smaller home ranges than do females.

Giesen (1998a) found the average home range of males to be 2.11 ± 1.54 km² versus 5.96 ±

8.18 km² for female birds. Females were found to travel a greater distance from the lek to

nesting sites (1.8 km) than the inter-lek distance within the study site. This led to speculation

that females may attend more than one lek during the breeding season. During breeding

season ranges decrease, male lesser prairie-chickens show greater decreases in daily

movements and will spend much of their time resting and preening near the lek location

(Taylor and Guthery 1980). More birds are typically on leks in the morning and evenings.

Median home ranges for male lesser prairie-chickens in Kansas during April and May ranged

from 12 to 140 ha (Jamison 2000).

Females initiate nesting 1 to 2 weeks after copulation occurs at the lek site, with

nesting activity peaking in early May (Pittman 2006, Giesen 1998b). Lek to nest distance has

been found to vary within different lesser prairie-chicken populations. Sell (1979) found that

female birds travelled an average of 1.2 km, while Davis et al. (1979) recorded a distance of

3.4 km. In Colorado, female lesser prairie-chickens travelled an average of 1.8 km between

the lek and chosen nesting site (Giesen 1998a). One egg is laid per day up to a clutch size of

11 to 14 eggs (Bent 1932). Clutch sizes for yearling females are slightly less. Incubation

typically lasts 24 to 26 days and will ensue after all eggs have been laid (Giesen 1998b,

6

prairie-chickens will re-nest if the clutch is lost early in the incubation period or before

incubation occurs, with replacement clutches being laid within two weeks (Giesen 1998b).

However, clutch sizes in re-nests average only 7.6 eggs (Pitman 2006). In Kansas, peak

hatching occurred on June 1st for first nests, second attempt nests peaked on June 22 (Pitman 2006). The daily movements of female lesser prairie-chickens during incubation are greatly

decreased. Feeding outings occur in the morning or evening and are limited to a distance of .3

km from the nest and do not last longer than 30 minutes (Giesen 1998b, Sell 1979). The

young are born precocial and typically leave the nest within the first 24 hours (Robb and

Schroeder 2005).

Giesen (1998) suggested that larger home range sizes for females are needed for

brood rearing activities. Riley et al. (1994) found that females with broods averaged daily

movement of 280 m per day with a home range of 119 ha. Conversely, unsuccessful females

moved 220 m per day with an estimated home range of 73 ha. Home range of a brood

averaged 47 ha in New Mexico in a year of normal precipitation (Ahlborn 1980). During a

dry summer in Oklahoma one brood averaged a home range of 104 ha (Copelin 1963). Daily

movements of broods increased with age. Broods less than 14 days of age averaged a

movement of 248 m per day while broods of 14 to 60 days of age moved an average distance

of 320 m per day (Jamison 2000). At two weeks of age, chicks are able to make short flights.

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prairie-chickens will abandon broods between 8-10 weeks of age. By early fall juvenile lesser

prairie-chickens will associate in flocks and begin lek attendance in September (Taylor and

Guthery 1980). There is very little data available on brood break-up.

Within their home range lesser prairie-chickens are year round residents (Jamison

2002). Lesser prairie-chickens are predominantly ground dwelling birds which only make

short flights to evade predation. Flights are less than 1 km and typically occur between

breeding, foraging, loafing/roosting, and water areas (Giesen 1998b). During the winter lesser

prairie-chicken individuals will form flocks. Flock sizes have been related to weather

severity. During mild winters flock numbers tend to be smaller than during harsh winters

(Schwilling 1955, Copelin 1963).

Conservation

Overall range of the lesser prairie-chicken is limited to Colorado, Kansas,

Oklahoma, Texas, and New Mexico. In Colorado the species is listed threatened, while as

recently as 2005, lesser prairie-chickens were considered a game species in Kansas, New

Mexico, Texas, and Oklahoma (Robb and Schroeder 2005). Much of the decrease in the

occupied range is attributed to anthropogenic activities which produce negative impacts on

habitat quality. These activities include conversion of native rangeland to cropland, declines

in habitat quality due to herbicide use, excessive grazing by livestock, mineral and natural

8

regimes, and habitat fragmentation by roads, fences, towers, turbines, and utility corridors

(Fish and Wildlife pamphlet 1999, Robb and Schroeder 2005). Survival of female and

juvenile birds during the nesting and brood rearing periods has been identified as the greatest

limiting factor in maintaining a minimum viable population for lesser prairie-chickens. There

is a marked increase in predation during these seasons (Hagen 2005).

Species Distribution

Determining the historic distribution of lesser prairie-chickens can be difficult due to

the species not being officially recognized until the mid-1900’s. The lesser prairie-chicken

was recognized as a distinct species in 1957 by the American Ornithologists Union, although

early accounts by Ridgway 1873 described the lesser prairie-chicken as a variety of the

greater prairie-chicken, Cupidonia cupido (Taylor and Guthery 1980). Regardless, researches

have determined that early populations inhabited the eastern Great Plains from southwestern

Kansas to southeast Colorado, south through western Oklahoma and eastern New Mexico to

west-central Texas (Figure 2, Taylor and Guthery 1980). Aldrich (1963) composed a map by

which he estimated that the historic distribution of lesser prairie-chickens during the 1800’s

encompassed 358,000 km². The area decreased to 125,000 km² by 1969, and by 1980 the area

had decreased to 27,300 km². Thus in 1980, the distribution of the lesser prairie-chicken had

decreased by 78%; this decrease is equivalent to 92% overall decrease from historical times

9

numbers have declined to 97% of pre-European settlement numbers (Geisen 1998, Hagen et

al. 2004). The lesser prairie-chicken’s total population size in 1980 was estimated to be

between 44,000 and 53,000 birds (Rob and Schroeder 2005). For the purposes of this study

we will focus on occupied range within southeast Colorado and southwest Kansas.

Colorado

In 2002, population estimates for Colorado were between 800 to 1,000 birds while in

Kansas estimates ranged between 20,000 and 31,100 (US Fish and Wildlife Service 2002). In

2004, Rich et al. estimated the range wide population to be 32,000. In Colorado, the first

account of a lesser prairie-chicken was in Baca County in May of 1914. Populations were

concentrated south of the Arkansas River in the counties of Prowers and Baca, although there

are historic reports of lesser prairie-chicken in Kiowa, Cheyenne, and Lincoln counties as

well. Flocks were reported to have numbered in the hundreds. The farthest west report came

from a resident of Las Animas in Bent County (Hoffman 1963).

It is widely believed that, along with the aforementioned negative influences on

lesser prairie-chicken habitat, the drought of 1930 significantly reduced lesser prairie-chicken

populations within Colorado. Lek counts between the years of 1959 and 1963 showed an

increase in the number of attending male lesser prairie-chicken (Taylor and Guthery 1980). The breeding population peaked during the 1980’s during which time survey efforts by Colorado Parks and Wildlife yielded a population estimate of 1,000 to 2,000 birds. Giesen

10

(2000) reported that 1,500 breeding individuals were located in Prowers, Baca, Cheyenne,

and Kiowa counties.

Currently, the core population is located in Baca County east of the town of Campo,

largely within the Comanche National Grassland (Giesen 1994). The populations in Kiowa

and Cheyenne Counties were believed to be isolated from the rest of the Colorado

populations and believed to be comprised of 100 or fewer individuals (Giesen 2000). In 2009,

a total of 75 birds were counted within the state of Colorado, a decrease from the total of 116

observed in 2008. There were a total of 13 active leks detected in 2009; 6 in Baca County, 6

in Prowers County, and 1 in Cheyenne County. Preliminary results from lek counts in 2013

yielded a total of 105 male lesser prairie-chickens observed. Assuming a one-to-one ratio of

males and females there are an estimated minimum of 210 lesser prairie-chickens in Colorado

(Personal Correspondence, Trent Verquer Colorado Parks and Wildlife).

Concurrent to the surveys conducted by Colorado Parks and Wildlife, the USDA

Forest Service conducted surveys on the Comanche National Grassland (Figure 3). Over the

past 20 years, it is estimated the lesser prairie-chicken occupied approximately 27,373 ha on

the Comanche National Grassland (Augustine 2005). There have been a total of 53 active

leks on or immediately adjacent to the Comanche National Grassland between the years of

1984 and 2005 (USFWS 2010). Counts on the Comanche National Grassland were highest in

11

of males per lek declined from 174 birds in 1988 to just 34 birds in 2005 a decrease of over

80% (Augustine 2005).

Kansas

Like in Colorado, the historical distribution of lesser prairie-chickens in Kansas is

hard to determine due to the tendency to confuse them with the greater Prairie-chicken. The

original range in Kansas is thought to have included 39 counties in the southwest part of the

state. The occupied range spanned from the Oklahoma border in the south, north to the

Smoky Hill River, and east to Harper and Kingman counties (Schwilling 1955). Like in

Colorado, the neighboring Kansas population saw a drastic decline during the drought of the 1930’s. Heavy grazing and field cultivation coupled with severe drought nearly extirpated the species from Kansas. A survey conducted in 1950 by the Kansas Forestry, Fish, and Game

Commission found that only 14 of the original 39 counties were still occupied by lesser

prairie-chicken. These populations were concentrated around the Arkansas and Cimarron

Rivers (Baker 1953). Population numbers in the 1960’s were believed to be between 10,000

and 15,000 individuals (Sands 1968). During the 1970’s, the population expanded to a total

of 17 counties, and was estimated to be between 17,000 and 18,000 (Taylor and Guthery

1980, Crawford 1980).

As of 2010, lesser prairie-chickens occupied 35 of the historic 39 counties,

12

Wildlife and Parks estimated a density of 6.1 lesser prairie-chickens per square mile in 2006.

This number decreased by almost 50% in 2009 to approximately 3.7 birds per square mile.

Hunter harvest of lesser prairie-chicken in Kansas declined between 2010 and 2011, from a

total of 633 birds in 2010-2011 to just 378 in 2011-2012 seasons (Pitman et al. 2012).

Similar to the Comanche National Grasslands, the Cimarron National Grasslands in

Kansas supports a population of lesser prairie-chicken on native sand sagebrush rangeland

(Figure 3). Concurrent with the overall population declines in recent years, the lesser

prairie-chicken numbers on the Cimarron National Grassland have also decreased. Surveys

conducted between 1988 and 1997 identified a total of 44 leks; it was believed that all of the

National Grasslands south of the Cimarron River (64,387 acres) was occupied (Augustine

2005). Between 1995 and 1999 a total of 27 different leks were being used. Population

estimates ranged from 173 to 283 birds during this time period. A population estimate in

2005 yielded 249 birds. These numbers were believed to represent a stable population

(Augustine 2005). However since 2005 population numbers on the Cimarron National

Grassland appear to have declined, ranging from a high of 139 birds in 2006 to a low of just

53 birds in 2009 (Chappell 2009). In all years, the underlying factor resulting in low

population numbers is availability of quality habitat; fluctuations are often compounded by

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Habitat

General Habitat

A key step in conserving habitat and thus preserving a species is first identifying the

species habitat requirements (Cunningham and Johnson 2006). “Lesser prairie-chickens are

associated with various components of their overall habitat depending on phenological

changes in the availability of foods and coverts and seasonal weather” (Taylor and Guthery

1980, Figure 1). Being a year round resident, the winter and summer ranges of lesser

prairie-chickens are the same; this necessitates that all aspects of lesser prairie-chicken

habitat must be present for sustainable populations. Throughout their range lesser

prairie-chickens are strongly linked with native dwarf shrub/mixed grass plant communities.

The two plant communities which are most commonly associated with lesser prairie chickens

are sand sagebrush (Artemisia filifolia)-bluestem (Andropogon spp.) and havard oak

havardii)-bluestem (Jones 1963). The associations comprising the year round range of the

species can be thought of as a mosaic of diverse natural habitats.

Optimum habitat consists of mid to tall grass prairies for nesting interspersed with

lower seral stages for feeding and brood rearing (Taylor and Guthery 1980). The eco-region

of southeast Colorado and southwest Kansas is dominated by rolling plains and tablelands,

14

content. The dry climate allows for annual evaporation which often exceeds annual

precipitation, accounting for the dominant short grass prairie ecosystem (Rob 2005).

Figure 1. Diagram of year round lesser prairie-chicken habitat. Adapted from Knopf 1996

Lek Habitat

Display grounds for leks, are often found in open areas. These sites are comprised of

short herbaceous cover (mean 10.39 cm) and located in areas of greater visibility such as

ridge tops; plant cover averaged 64% (Jones 1963). However, Copelin (1963) observed leks

in short grass valleys when sand sage vegetation on ridge tops was too dense. Physiognomic

and growth structures are more important than plant species for lek sites (Jamison 2002;

Hagen 2004). Davis et al. (1979) also found that height and density of vegetation influenced

reproductive success regardless of species of vegetation. Cultivated fields can have either

negative or positive effects on lek sites; lesser prairie-chicken have been reported to lek on

cultivated fields. However, recent cultivation near active leks has rendered those leks

15

composition on leks in Colorado was composed of 20% buffalo grass (Buchloe dactyloides),

19% blue grama (Bouteloua gracilis), 16% sideoats grama (Bouteloua curtipendula), and

red threeawn (Aristida purpurea). Sand Sagebrush density at the same 9 lek locations

averaged a density of 310 plants per ha (Giesen 1991). At lek locations where vegetation

grew at an increased rate, birds tended to abandon the lek site earlier in the season

(Donaldson 1969). Lesser prairie-chickens have also been known to establish leks on

artificially formed sites such as oil pads, roads, herbicide treatment plots, and windmill sites

(Crawford and Bolen 1976, Taylor 1980, Locke 1992).

Nesting Habitat

Lesser prairie-chicken females choose either shinery oak, sand sagebrush, or CRP

mixed grass habitats for nesting (Fields 2004, Giesen 1998, Mote et al. 1998). Females

construct nests from dried plant material; these nests are located in shallow depressions or

bowls in the ground (Giesen 1998, Copelin 1963, Bent 1932). Bowls average 20 cm wide by

7 to 10 cm deep (Copelin 1963, Sell 1979, Haukos 1988). Nest sites are characterized by

areas with higher residual plant cover and increased horizontal cover (Giesen 1998, Pitman

2003).

In Colorado, lesser prairie-chickens predominantly chose to nest beneath either sand

sagebrush or yucca (Yucca glauca) although sand sagebrush composed only 3.1% (2,497

16

(Giesen 1991). Species which typify these associations in Colorado include little bluestem

(Schizachyrium scoparium), switchgrass (Panicum virgatum), sideoats grama, and threeawn.

The association of either shrub cover or bunch grass cover is common in observations at nest

sites throughout the range (Bent 1932, Copelin 1958, Donaldson 1969, Giesen 1991, Jones

1963, Sell 1979, Taylor and Guthery 1980).

Riley 1978 found that vegetation height above a nest averaged 61cm vs. 29 cm

within 9 m (n=18) from the bowl, this included grass heights of 67 cm (n=10) at successful

nests vs. 35 cm (n=26) at unsuccessful nests. Giesen 1991 measured an average vegetation

height of 51 cm in Colorado for 29 different nest locations. In shinery oak grassland habitat

Wilson 1982 measured greater vegetation height (average or =34 cm), percent litter

( =39%), and canopy cover ( =37%) at commonly used nest locations. On the Comanche

National Grassland in Colorado, 69% of 29 nests were located in shrub cover; bunch grasses

provided cover for the remaining 9 sites. Similar tendencies have been documented in

neighboring southwest Kansas. In Colorado, average height of vegetation above nest bowls

was 50.7 ± 14.7 cm (range=29-81) with 69 % of nests (n=29) under vegetation of heights ≥40

cm. Overall height of shrubs, grasses, and forbs was greater (P‹ 0.001) over nests than paired

dependent site. Sand sagebrush density was 3,471 plants per ha. Percent cover of sand

sagebrush was 7.2%, grasses 29.4 %, forbs 1.4%, and bare ground 69.5% at 29 nest sites

17

than adjacent rangeland. Average sand sagebrush height was greater at nest sites (43.8 ± 1.4

cm) than paired random sites (39 ± 1.5 cm). Height-density of nest sites averaged 3.2 dm,

greater than the 2 dm average for adjacent areas. And overall lesser prairie-chicken nest sites in

Kansas averaged greater grass cover (37%), forb cover (8%), sagebrush cover (15%) with an

estimated density of 5,064 plants per ha, and less bare ground (38%), than reported in Colorado

(Giesen 1994).

Brood Rearing

Within sand sagebrush habitat, lesser prairie-chicken brood use of shrubby cover is

greater than use of grassy cover. This preference is believed to reflect the greater invertebrate

biomass within shrub/forb communities than grass (Davis et al. 1980). Taylor (1980) found

that diets of immature birds consisted of 85-90% invertebrates. Habitat selection for brood

rearing is a direct reflection of increased invertebrate foraging activity.

Brood rearing habitat generally consisted of more sparsely vegetated areas with

lower overall cover. This includes areas of vegetation in early seral stages. Shrub and forb

communities may also provide for greater bare ground which helps to facilitate the movement

of juveniles within cover (Giesen 1998, Taylor and Guthery 1980). In New Mexico, brood

habitat was classified as having an open canopy (25% cover), an average vegetation height of

30 cm, relatively high percent basal cover of both shrubs and forbs, while maintaining less

18

areas based in the abundance of invertebrates; these areas also had increased presence of forb

species. In Kansas, invertebrate abundance was strongly associated with areas of moderate

sand sagebrush densities which facilities thermal and escape cover. Results from Hagen et al.

(2005) concurred with other studies finding strong relationships between invertebrates and

vegetation cover. Broods were found to have used areas of greater invertebrate biomass,

increased visual obstruction readings (VOR) and less grass cover. Management

recommendations included >15% forb cover. Lesser prairie-chicken broods in western

Oklahoma consistently select areas of greater forb cover. Forb presence was much higher in

areas used by broods than those used by male lesser prairie-chicken or unsuccessful females

(Jones 1963). Broods have been documented to use areas of greater canopy cover during

periods of hot weather (Copelin 1963, Donaldson 1969). Jones 1963 observed broods using

areas composed of 7.8% sand dropseed (Sporobolus cryptandrus), 22.8% sand sagebrush,

17.2 % skunkbrush sumac(Rhus trilobata), 15.7% western ragweed(Ambrosia psilostachya),

and <3% other perennial plants. Lesser prairie-chicken broods exhibit a greater reliance upon

invertebrate biomass for subsistence forage than adult birds without broods.

Loafing and Foraging

Lesser prairie-chicken use of greater cover for thermoregulation and predation

avoidance has been documented for loafing and foraging habitat. Seeds, leaves, insects, buds,

19

Guthery 1980, Schwilling 1955, Jones 1963, Donaldson 1969, Riley et al. 1993). In

southwest Kansas, the four most common food types were small grains, short-horned

grasshoppers (Acrididae), beetles (Coleoptera), and green wheat (Schwilling 1955).

In Oklahoma, lesser prairie-chicken forage largely concentrated within mixed grass

species 25-80 cm in height. During the spring, foraging activity was concentrated among

shrubs <80 cm tall. During the Summer and Fall, foraging shifted to grasses and forbs

25-80 cm tall, and in the winter, lesser prairie-chicken were found most often foraging in

grasses >80 cm tall (Jones 1963). In New Mexico, shrubs were of greater importance in

winter months than autumn. Seeds accounted for the greatest percentage of fall diets (43%),

followed by vegetative material (39%), and insects (15%). During the winter diets shifted to

largely incorporate acorns (69%) and wild buckwheat (Eriogonum annuum, 14%, Riley et al.

1993, Davis et al. 1979). At 23 autumn foraging locations total ground cover was 37.4%

litter, 37.4% bare ground, and 25.2% live plants. Total ground cover for 51 winter foraging

locations was 46% litter, 44.3% bare ground, and 9.7% live plants. Researchers found that

lesser prairie-chicken foraging sites were similar to overall habitat (Davis et al. 1979). In

Colorado Giesen (1991) also concluded that there were not significant vegetation differences

between foraging locations and paired dependent sites within sand sagebrush habitat.

Lesser prairie-chickens have also been documented to use cultivated grain crops

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Jones 1963, Donaldson 1969, Crawford 1974, Ahlborn 1980, Applegate and Riley 1998,

Giesen 1998, and Jamison 2000). Lesser prairie-chickens rely on cultivated crops more

during the winter than any other season; this is a shift from historic winter habitat which

included riparian areas with deciduous shrubs and young trees in sand sagebrush habitat

(Schwilling 1955, Giesen 1998). The shift does not negate the importance of native rangeland

for roosting and loafing habitat (Taylor and Guthery 1980, Jamison 2000).

Importance of Nesting and Brood Rearing Habitats

Robel et al. (2004) postulated that poor nest success and low chick survival were the

result of a shortage of suitable nesting habitat. These factors were determined to be the

leading contributors to population declines in Kansas between 1980 and 2000. In managing

for lesser prairie-chicken habitat efforts are often focused on adequate cover for nesting and

brood rearing. Success during these pivotal periods of a lesser prairie-chickens life cycle

often determines the success and failure of populations (Hagen 2005). Nest success is a

critical constraint in the demography of lesser prairie-chickens. Fluctuations in annual

recruitment success are dependent upon success during the nesting season. In Kansas,

two-week mortality was greatest during the nesting period; during a 7 year study >30% of all

female mortalities occurred during nesting and brood rearing periods (Pitman 2005, Hagen

2005). Researchers have found that nesting success is significantly greater in areas with

21

sagebrush in particular was a direct indicator of nest success in Southwestern Kansas

(Jamison 2002, Pitman 2005). Riley (1992) found that greater nest concealment resulted in

less nest abandonment. In a population study between 1997 and 2002 in southwest Kansas,

the recruitment rate from hatchling to first breeding was only 12%. When predicting winter

survival of chicks, body mass was the most important covariate. Results indicated that a 7.1%

population decline corresponded with a low recruitment rate. This outcome correlated with

homogenous vegetative communities, indicative of poor nesting and brood rearing habitats.

The present plant communities may have created difficulties for brood ground movements as

well as decreased invertebrate biomass (Pitman 2006).

Anthropogenic Influences

Since settlement by Europeans in the 1800’s lesser prairie-chicken habitat has

decreased in quantity and quality through degradation and fragmentation. In recent times

populations continue to decline although there has been a noted decrease in the rate of habitat

change in the last 20 years. This suggests that quality of habitat is a driving factor in the

continued suppression of population numbers (Hagen et al. 2004). Jamison (2002) noted that

declining populations were linearly associated with rates of landscape change; in particular,

landscapes with declining populations lost shrub land habitat at greater rates. Human

disturbance is known to be a leading cause in the continued loss of suitable habitat, directly

22

species cannot tolerate areas with greater than 37% habitat conversion (Crawford and Bowlen

1976). Declining trends are associated with extensive grazing and conversion of native

rangeland to center–pivot irrigated crops contributing to the loss of native range (Leslie et al.

1999, Woodward et al. 2001).

In a population study in southwest Kansas success of lesser prairie-chicken nests

was studied in relation to anthropogenic factors. Success was directly linked to grass height,

sagebrush plant density, and sagebrush height. Although there were no direct links between

anthropogenic features and nest success, lesser prairie-chicken females did avoid habitat

within 80 (wellheads) to 1000 meters (buildings) of all features except unimproved roads

(Pitman et al. 2005). This fact results in decreased habitat as well as increased fragmentation.

In an effort to identify mechanisms effecting population persistence, Patten et al. (2005)

determined infrastructure such as fences, power lines, and roads caused an increase in female

mortality.

Although many development practices by humans are harmful to lesser

prairie-chickens there are limited reports of some benefits. Lesser prairie-chickens have been

documented foraging on grain in cultivated fields. This is often a supplemental food source

during winter foraging periods. Use of fields relies on type of crop, juxtaposition to occupied

23

provide an additional food source the negative effects of destruction of native rangeland may

greatly outweigh benefits.

Oil and gas extraction sites provide pads, or areas of cleared land, which are

sometimes used as lek locations by lesser prairie-chickens (Taylor and Guthery 1980).

However, like cultivated fields, oil and gas extraction results in the loss of native rangeland

and therefor a reduction in suitable habitat. For each site 1.6 ha of habitat is cleared; also

associated with extraction activities is an increase in road construction. The roads encourage

an increase in predation activities, incursions of invasive weeds, vertical vegetative

structures, and noise, as well as off road vehicles (Crawford and Bolen 1976, Davis et al

1979). Vertical structures such as power lines provide increased perch locations for predatory

raptors, increasing frequency of predation (Hagen et al. 2004). A 32% variation in lesser

prairie-chicken activity between active and inactive leks was attributed to oil and gas

production with a significant decrease in activity in areas with greater development (Hunt

2004). Also in New Mexico, researchers have documented the extirpation of lesser

prairie-chickens from areas with the greatest oil and gas development (Bailey and Williams

2000, Massey 2001). In a pamphlet released by the USFWS in 1999, management

recommendations were made for increasing habitat quality or availability. One recommended

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CRP and Lesser prairie-chickens

The CRP is administered by the USDA Farm Service Agency (FSA); technical support is largely provided by the USDA’s Natural Resources Conservation Service (NRCS). The program encourages agricultural producers to enroll environmentally sensitive land for

the conversion to long-term, resource-conserving cover types. Land is enlisted under a

contracted period of 10-15 years in which FSA provides rental payments and cost-share

assistance. The primary benefit and purpose of the CRP is the reduction of topsoil erosion; a

secondary benefit is the conservation of vegetative covers which the FSA states increase

wildlife populations around the country. To be eligible land must have been planted to an

agricultural commodity for four of the previous six crop years, and be physically and legally

capable of being planted in a normal manner to agricultural commodity. Priority and

eligibility of land is determined using a ranking system or environmental benefit index (EBI).

The EBI uses factors for assessing the benefit of a field’s enrollment, one of the factors being

suitability for wildlife habitat (FSA Fact Sheet 2013).

The CRP is believed to provide increased residual cover for birds. The CRP in

Kansas focuses on increased native grass species and forb densities. Forb growth in grassland

prairie is encouraged by disturbance. This was historically facilitated by wildfire and grazing

by large herbivores. Modern forms of disturbance are grazing by domestic livestock, burning,

25

mid-contract management practices within CRP fields, however enforcement of this clause is

often not consistent. Mid-contract management may also entail disking and reseeding efforts.

The USFWS recommends disking near leks and nesting habitat in a four to five year rotation.

Other noteworthy practices which are encouraged are the restoration to native grass

communities, as well as incorporating forbs and shrubs into re-vegetation efforts. The

emphasis on forbs increases invertebrate biomass which as mentioned before is a staple in the

diet of juvenile lesser prairie-chickens (Jamison 2002). Grass seed mixes tend to vary across

CRP fields in Kansas. Fields dominated with little bluestem interspersed with sideoats grama

with overall heights of about 45 cm were preferred by lesser prairie-chickens (Jamison 2002).

In Texas, suggested seeding of CRP lands include warm-season bunch grasses, native

legumes, and shrubs (Litton et al. 1994).

Offsetting habitat degradation may be a key component in the preservation of the

lesser prairie-chicken. This study seeks to evaluate the potential of the CRP to provide and

sustain much needed quality habitat. In order to do so, this study will ascertain whether or not

CRP fields in southeast Colorado and southwest Kansas meet recommended habitat

guidelines. There is speculation that CRP fields in Kansas vary greatly compared to fields in

Colorado. Numbers of fields enrolled in CRP are proportionate between the two states in

lesser prairie-chicken home range (Rob et al. 2005). Early reseeding efforts in Colorado were

26

prairie-chicken home ranges in Colorado lack both diversity and abundance of grass and forb

species when compared to Kansas (Fields 2004, Ripper et al 2008). In a study comparing

CRP fields within the lesser prairie-chickens range wide distribution within CRP fields

consistently had greater forb components as well as greater overall grass height. However,

little other research has been done to distinguish notable differences in CRP fields between

the two states. This study will use rangeland sampling techniques to statistically compare

current vegetative communities within the two states.

Figure 2. Estimated historic (perimeter circle) and current (black polygons) occupied lesser prairie-chicken range in

Colorado, Kansas, New Mexico, Oklahoma, and Texas. 2007range map layer courtesy of Texas Parks and Wildlife Department.

27

Hypothesis 1: Land which has been previously enrolled in the CRP, lacks the necessary

community composition and/or plant structure to provide adequate lesser

prairie-chicken habitat.

Specific Aim 1a: To conduct a comprehensive vegetative analysis on lands that have

been enrolled in the CRP and lie within lesser prairie-chicken range in Southeast

Colorado.

Specific Aim 1b: To compare known requirements for Lesser Prairie Chicken habitat

with data collected within the sampled plots.

Hypothesis 2: Other habitat treatments/seed mixes which are currently in use support

plant communities which would benefit Lesser Prairie Chickens

Specific Aim 2a: Conduct the same vegetative surveys on CRP land in southwest

Kansas within Lesser Prairie Chicken range.

Specific Aim 2b: Compare the results from fields sampled in Kansas to those

sampled in Colorado.

Specific Aim 2C: Compare data between all counties sampled.

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Sample Area

Sampling work was focused within the states of Colorado and Kansas (Appendix A).

More specifically, we sampled in the southeast corner of Colorado in the counties of Kiowa,

Prowers, and Baca. Within Kansas, we selected adjacent counties with lek history data,

including Morton and Hamilton counties. The region is located within the current occupied

and historical range of the lesser prairie-chicken (Figure 2). Currently the dominant

ecosystem types are Great Plains short grass prairies intermixed with Great Plains sandhill

shrublands. The area is defined as having a semi-arid to arid climate. Vegetative communities

are largely driven by topographic and soil conditions which sometimes create a blended

matrix of shortgrass prairie and shrubland ecosystems near ecotones. The soils range from

well drained sandy soils to loamy and sometimes clayey soil types.

Historically this region also contained Great Plains tallgrass prairie and Great Plains

sand prairie; anthropogenic influences including overgrazing are believed to be contributing

factors to the loss of these two ecosystems in the region (Colorado National Heritage

Program 2013). The altered landscape currently contains a patchwork of agricultural

farmland and CRP lands. Common crops include wheat, alfalfa, millet, corn, and sunflowers

(Colorado.gov). CRP fields vary largely due to growth conditions and variation in seed mixes

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Sample Site Selection

Selection criteria for sample point locations included the following criteria: 1) first

the point must lie within 2.4 kilometers of a documented lek location; 2) the percentage of

fields enrolled in the CRP within the township is greater than 12% (Appendix B); 3) the field

selected for the point location is a minimum of 294 acres or composed of two or more

contiguous fields with at least 294 acres combined; and 4) the points are located at least 400ft

from one another. A 2.4 km buffer is identified by Colorado Parks and Wildlife as the active

production area for lesser prairie-chickens.

Using these criteria, fields were ordered by priority. Priority was given to fields

within townships composed of the greatest percent of CRP. Whether a given field was

sampled was largely influenced by ease of access. Not all fields sampled were of greatest

priority. Selection criteria began at the level of Township/Range/Section. We were able to

acquire data delineating Townships by density of CRP; the townships with the greatest

density of CRP lands overlapping known lesser prairie-chicken leks were given highest

priority. Leks were mapped within the townships using ArcGIS and a buffer of 2.4 km was

applied to each lek location (Appendix A). We did not discriminate between active and

inactive leks due to low overall numbers of leks and available records. Colorado Parks and

Wildlife identifies 2.4 km as the production area of an individual lesser prairie-chicken.

30

then ground truthed to provide certainty (Appendix C). Only fields with 294 contiguous acres

of CRP land were selected. This minimum was used because it is the average minimum home

range size of a female lesser prairie-chicken with brood (Riley et al. 1994). Fields were

deemed contiguous if they shared at least one common border. Within the buffer, all fields

were assigned a random number using ArcGIS; these numbers were randomized through the

use of Microsoft Excel. Care was taken to not sample the same field more than once;

however, to increase sample size, in some instances more than two fields from a lek were

sampled. After a field had been selected and access granted, four random points were

identified for sample transect locations. Random points were created using ArcGIS. In all, a

total of 124 transects were sampled in a total of 31 fields between the two states (Appendices

D and E).

Sampling Protocol

Site description

The site description was composed of the UTM’s for each transect as well as a site ID, transect direction, photo numbers from transect photographs, general comments, field

disturbance notes, and any plant species which were not detected using the modified

daubenmire sample frames. The direction in which the 100ft transect was run was randomly

determined based on the second hand of a watch identifying the direction from the starting

point. Also, at this point an overall picture of the 100ft transect was taken. Lastly we recorded

31

Modified Daubenmire Method

Modified daubenmire method was used to ascertain community descriptive metrics

by species. These metrics included percent cover, percent composition, frequency, and

density of plants. Other measurements recorded using this method included highest

vegetation at the corners of the sample frame, average grass height, percent litter, and percent

bare ground. A total of three 1m² sample frames were classified per transect. Sample frames

were laid out at distances of 33, 66, and 100 ft. A close-up photograph of each sample frame

was taken. Total count by species was recorded for each plant within the data frame. Each

species was then assigned a percent cover value based on a portion of 100% cover. Only

standing plants rooted within the sample frame were counted.

Robel Pole

VOR’s were measured at six points along the 100ft transects. The Robel pole method has been cited by many studies of lesser prairie-chicken habitat as an efficient

method for measuring nesting cover. We deployed this method to measure the height and

vertical density (height-density) of habitat within CRP fields. The height density provides a

representation of vertical biomass within a plant community. At each of the six points a 48”

robel pole was staked into the ground. Measurements were recorded using a reference stick

with I-bolt attached to the top; the stick was 39” tall and attached to a rope which was 157”

32

measurements taken at each point, one from each side of the transect. The highest

unobstructed point on the robel pole was recorded.

Line Intercept

In order to measure the habitat structure of bunch grasses and sparse shrubs on a

larger scale we utilized the line intercept method. Along the entire length of the 100ft transect

the beginning and end points of the intersection of a plant and the transect were recorded..

We identified the species of each individual plant which intersected the tape and recorded the

total foliar cover. Line intercept was used to estimate average percent cover and average

percent composition as well as relative density for bunch grasses and shrubs.

Data Calculations and Statistics

We used 1-way analysis of variance (ANOVA) to measure differences in average

vegetative parameters between counties. Five of the six counties sampled were included.

We excluded Hamilton County within Kansas due to low sample size. Statistics were

completed using SPSS 19 (SPSS Inc, Chicago, IL). We completed post-hoc analysis using a

bonferroni adjustment. Averages for multiple parameters were compared between each of the

counties yielding a comparison of habitat structure between each county (Appendix A).

Differences in means between Colorado and Kansas were examined using a t-test.

33

variance for each average. Data obtained from the applied rangeland field techniques were

run through calculations to provide the desired metrics for comparison.

Equations used are as follows:

Percent Cover (%) =

Percent Composition (%) =

Relative density =

Density (ha) =

The previous equations were used to calculate parameters using data collected via

modified daubenmire method and line intercept. VOR’s were totaled for each individual

transect. These totals were then averaged to obtain the average height-density for each

transect. For ease of comparison to previous research the measurements were converted from

inches to centimeters. Measurement of average percent cover by species, relative density, true

density, and percent composition were established using both the modified daubenmire

method and line intercept method.

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Habitat Recommendations

In total 31 fields were sampled between Colorado and Kansas. There were 124

transects in 5 different counties, three counties in Colorado and two in Kansas. Access and

positive identification of CRP fields was a major complication in both states, and limited the

number of total fields and number of counties which were represented. The table of

recommendations provided below (Table 1) is a conglomerate of advised habitat

characteristics reported in Rondeau et al. (2013). The characteristics were reported in various

research reports as well as the USFWS wildlife habitat management leaflet #6, published in

1999.

35

Habitat Factor Nesting Source

Shrub Cover (%) 5-30 Giesen (1994)

Forb Cover (%) 5-15 USFWS (1999)

Grass Cover (%) >20 Bidwell et al. (no date) 65% (Clumps) USFWS (1999)

Grass Height (cm) USFWS (1999)

Habitat Factor Brood Rearing Source

Shrub Density (plants/ha) 2000-7000 Hagen et al. (2005)

Shrub Cover (%) 40-45 USFWS (1999)

Forb Cover (%) 15-20 USFWS (1999)

Grass Cover (%) 40-45 USFWS (1999)

Grass Height Short-Medium USFWS (1999)

(Adapted from Rondeau et al. 2013)

20

The recommendations and associated statewide averages are divided based on life

cycle stages of the nesting and brood rearing seasons. When means are compared between

each individual state and the recommended habitat parameters neither state appears to

36

Table 2. This table illustrates the averages for habitat parameters measured in each state compared to the recommended parameters for quality lesser prairie chicken nesting habitat.

Parameter Colorado Kansas Recommended Shrub Cover (%) 0.19 0.35 5-30

Forb Cover (%) 1.33 1.11 5-15

Grass Cover (%) 33.94 27.95 >20 46.11% 75.00% 65% (Clumps) Grass Height (cm) 18.73 14.70 20

The current habitat conditions fall far short of providing adequate nesting habitat

(Table 2). The only recommendation which is met by CRP in both states is the percent of

ground which is covered by grass. Both states meet the required minimum grass cover (CO=33.94%, KS=27.95%, Rec.≥20%, Table 2). The recommendation is two-fold in that it not only identifies minimum cover but also what percent of that cover should be composed of

clumps or bunch grasses (65%). Kansas is the only one of the two states to meet this

recommendation with 75% of grasses measured in Kansas being bunch grasses. Colorado has

a greater average percent cover of grasses; however the percent of that cover which is

composed of bunch grasses is less than fields within Kansas.

Sampling results from both states show similar results when compared with habitat

recommendations for brood rearing habitat (Table3). Means for different parameters still fall

short of the recommended requirements. Neither state had averages across all fields sampled

37

Table 3. This table illustrates the averages for habitat parameters measured in each state compared to the recommended parameters for quality lesser prairie chicken brood rearing habitat.

Parameter Colorado Kansas Recommended Shrub Density (plants/ha) 52.08 274.08 2000-7000

Shrub Cover (%) 0.06 0.35 40-45 Forb Cover (%) 1.56 1.11 15-20 Grass Cover (%) 34.16 27.00 40-45

Grass Height 18.73 14.70 Short-Medium

The classification of grasses into categories of short-medium is subjective. Using height

definitions provided on the US Geologic Surveys website we can assign the measured means

into the category of being short grass only (6-24 cm).

The aforementioned results were calculated from averages across all fields sampled

within each state. By identifying which individual transects met the habitat recommendations

we can quantitatively dissect where the majority of fields stand in relation to the

38

Figure 3. This graph shows the total percent of transects meeting 0-4 habitat recommendations

There were no transects which met more than four of the total recommendations

between brood rearing and nesting. The data shows that Colorado had a more even

distribution of percent of transects meeting recommendations with 6.25% meeting zero

recommendations and 9.38% meeting four recommendations. (F63, 59 = 2.52, P<.01) Kansas

had a distribution which was more heavily concentrated around one to three

recommendations met, with two being the greatest percentage (45%). There were no transects

within Kansas which met either zero or four recommendation. Overall the variances within

the two distributions were not equal, the number of recommendations met in Kansas is less

39

Kansas vs Colorado Habitat Attributes

Habitat variables which were measured were compared using statewide averages

between Colorado and Kansas. Using students T-test, I evaluated the means for each

parameter measured on CRP fields in Colorado in contrast to those measured in Kansas.

There were significant differences for eight of the twenty comparisons (Figure 4). As

expected fields within Kansas contained a greater number of bunch grass species on average

(t122 = -7.97, P < 0.001), and fewer sod grass species than Colorado (t116 = 5.69, P <.001).

Figure 4. Vegetation attributes by state. a) Average percent species composition categorized by plant guild. b) Average

plant density measured in plants/ha. c) Mean number of species per transect. d) Average percent cover categorized by plant guild. * Indicates statistically significant differences (P < 0.05)

40

There were no significant differences in the number of species recorded for either

forbs or shrubs (t116 = .65, P > .05). The average density of sod grasses within Colorado was

significantly greater than fields within Kansas with an average of 508,706 ± 57,027

individuals recorded (t120 = 4.08, P < .001). The average number of individual forbs within

each field in Kansas was determined to be 25,013 ± 4219 while in Colorado fields averaged

only 12,460 ± 3187 individual forbs (t122 = 2.39, P < .001). Similar results were found when

determining the percent cover and percent composition of fields within each state. Fields

within Colorado consistently had higher percentages of sod grass and lower percentages of

bunch grasses than fields within Kansas (t117 = 4.77, P < .001, Figure 2). The comparisons

between forbs and shrubs yielded only a significant difference when measuring density (t122

= 2.39, P < .001). Average bareground measured within Kansas was 16.39% while in

Colorado cover was composed of 15.40% bare ground, this was not a significant difference

(t122 = .265, P > .05). We also did not measure a significant difference in the visual

obstruction between the two states; measurements within Colorado yielded an average VOR

of 1.33 ± .78 dm, the Kansas average VOR was 1.26 ± .76 dm (t122 = .659, P > .05).

Comparisons between counties

The following data includes comparisons of vegetative parameters between counties.

There were no significant differences found when comparing measurements of bare ground

41

greater number of species of sod grass and fewer species of bunch grass than Morton and

Baca counties (F3, 116 = .535, P = .659 Table 4). Prowers County had the greatest number of

sod grass species ( = 1.69 ± 0.17 species/transect) while Morton County had the greatest

average number of bunch grass species ( = 2.82 ± 0.15 species/transect). There were no

significant differences measured in the number of forb or shrub species per transect (F3, 116 =

0.87, P = .460). Test P-Value Prowers vs Baca Bunch Grass 0.92 ± 0.12 1.92* ± 0.15 P<.05 Sod Grass 1.69* ± 0.17 0.92 ± 0.08 P<.05 Prowers vs Kiowa Sod Grass 1.69* ± 0.17 1.00 ± 0.09 P<.05 Prowers vs Morton Bunch Grass 0.92 ± 0.12 2.82* ± 0.15 P <.05 Sod Grass 1.69* ± 0.17 0.55 ± 0.08 P <.001 Baca vs Kiowa Bunch Grass 1.92* ± 0.15 1.13 ± 0.24 P<.05 Baca vs Morton Bunch Grass 1.92 ± 0.15 2.82* ± 0.15 P<.05 Kiowa vs Morton Bunch Grass 1.13 ± 0.24 2.82* ± 0.15 P<.001 Sod Grass 1.00* ± 0.09 0.55 ± 0.08 P<.001 Means

Prowers County had a significantly greater density of sod grass ( = 621,435 ± 68,172.38 plants/ha) than Baca County ( = 150,194 ± 50,488.23 plants/ha, P=.004). Statistically there were no differences recorded between Prowers and Kiowa, Baca and Kiowa,

or Baca and Morton Counties (F3, 116 = 1.383, P = .252). Counties for average plant densities.

Table 4. Statistically Different Mean Number of Species Present by Guild

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Prowers once again contained a greater average density of sod grasses than Morton County (

=621,435 ± 68,172.38 plants/ha, =156,517 ± 57,006.35 plants/ha, P<.001, Table 5).

Test P-Value Prowers vs Baca Sod Grass 621435.18* ± 68172.38 150194.44 ± 50488.23 P<.0001 Prowers vs Kiowa No Significant Differences Prowers vs Morton Sod Grass 621435.18* ± 68172.38 156517.87 ± 57006.35 P<.0001 Baca vs Kiowa No Significant Differences Baca vs Morton No Significant Differences Kiowa vs Morton Sod Grass 524270.83* ± 105202.62 156517.87 ± 57006.35 P<.01 Means

Baca County had an average of 29.76% ± 2.16 cover of bunch grasses. This was

significantly greater than Prowers County ( = 10.08% ± 2.51, P < .001). Morton County had a

significantly greater percent cover of bunch grasses than Prowers County (P < .001). Percent

cover of sod grasses was significantly larger in both Kiowa ( = 17.33% ± 3.27) and Prowers

( = 23.36% ± 2.28) than in Baca ( = 4.35% ± 1.14, P < .0001) or Morton ( = 5.08% ± 1.49,

P < .0001) Counties. Aside from grass cover there were no other measurable differences. We

did however detect trends in the forb guild; cover in Prowers County was greater than Kiowa

County and Baca County (F3, 116 = 1.905, P = .133). These differences however were not

significant.

Table 5. Statistically Different Average Plant Density by Guild