EFFECTS OF SHINNERY OAK CONTROL WITH TEBUTHIURON ON LESSER PRAIRIE-CHICKEN POPULATIONS by CRAIG DONALD OLAWSKY, B.S. in Bio. Sci. A THESIS IN WILDLIFE SCIENCE Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for I the Degree of I MASTER OF SCIENCE \ \, Approved I" ' i Chairperson of~tee Accepted Graduate School December, 1987 © 1987 Craig Donald Olawsky ACKNOWLEDGEMENTS I would like to thank my major advisor, Dr. Loren M. Smith for his assistance and advice throughout the study. I am grateful for the assistance and helpful suggestions of Drs. Russell D. Pettit, and M. Kent Rylander, who sacrificed their time to serve on my graduate committee. Sincere appreciation is extended to Dr. David B. Wester for invaluable guidance with statistical analysis. I wish to thank Paul Gray, Rosemary Heinen, Mike Davin, Susan Tsai, John Hunter, Dr. Brian Murphy, Tony Leif, Rich Casner, Denver McMurry, Jay Wipff, Martin Stein, James Jaspers, G. Allen Rasmussen, Gretchen Scott, Sheila Merrigan, Colleen Schreiber, Rich Reiner, Mary Candee, Val Sewell, David Stahlke, Ralph Godfrey, David Cook, David Price, Bill Wallace, Mark Miller, Tim Riojas, Robert Sites, David Lee, and Dan Lemkuil, all of whom contributed to the success of the project. For their friendship, encouragement, and help, I am especially indebted to Perry Grissom, Jim Bergan, David Haukos, Guy McPherson, Doug Sheeley, and Jeff Weigel. Financial support for this project was furnished by the Texas Noxious Brush and Weed Control line item. Dr. Henry A. Wright also provided financial assistance. Texas Parks and Wildlife Department, and the New Mexico Department of Game and Fish supplied permits to collect ii lesser prairie-chickens. Frequent help was provided throughout this study by several members of the Soil conservation Service. Special thanks are extended to all landowners who graciously allowed the use of their lands for this research, primarily Randy Beasley, who provided the use of field station facilities. Finally, and foremost, I wish to thank my parents, Donald and Margerine Olawsky for their love, support, and encouragement. Their faith in me, especially during troubled times, made the completion of this project possible. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS ...................................... ii ABSTRACT .............................................. vi LIST OF TABLES ........................................ ix LIST OF FIGURES ....................................... xi CHAPTER I. EFFECTS OF SHINNERY OAK CONTROL ON LESSER PRAIRIE-CHICKEN DENSITIES.. ................... 1 Introduction ............................... 1 Study Area ................................. 4 Methods .................................... 4 Weather ................................. 4 Study Plots ............................. 5 Vegetation Composition.. ................ 5 Density Estimates ....................... 6 Results ...............................•.... 9 Weather ................................. 9 Plant Composition....................... 9 Density • •••••••• 0 ••••••••••••••••••••••• 13 Discussion · ............................... 17 Management Implications. ................... 21 II. EFFECTS OF SHINNERY OAK CONTROL ON LESSER PRAIRIE-CHICKEN DIET AND GUT MORPHOLOGY ....... 22 Introduction .. , ........ , , ................. 22 Study Area • ••••••••••••••••• 0 •••••••••••••• 24 iv Methods · .................................. 24 Results · .................................. 27 Precipitation..... ... ....... ..... ... .... 27 Diet .................................... 29 Gut Morphology .......................... 34 Discussion ................................. 37 Conclusions ................................ 43 III. NUTRIENT RESERVES OF LESSER PRAIRIE-CHICKENS IN TREATED AND UNTREATED SHINNERY OAK RANGELAND ..................................... 45 Introduction ............................... 45 Study Area ................................. 47 Methods · .................................. 47 Results · .................................. 49 Body Weights ............................ 49 Carcass Components and Liver Weights. ... 49 Discussion 59 Conclusions ................................ 62 IV. MANAGEMENT RECOMMENDATIONS........... ......... 64 LITERATURE CITED ...................................... 66 APPENDICES A. VEGETATION OF THE STUDY AREA.................... 72 B. MORPHOLOGICAL MEASUREMENTS OF LESSER PRAIRIE-CHICKENS ................................ 78 v ABSTRACT The herbicide tebuthiuron has been used in recent years to control sand shinnery oak (Quercus havardii) in west Texas and eastern New Mexico. However, the effects of shinnery oak control upon lesser prairie-chicken (Tympanllcblls 12allidicinctus) populations are not known. The range occupied by these birds has decreased over 90% since the 1800's. Therefore, expanding our knowledge of prairie­ chicken requirements and the impacts of various land-use practices upon the species is a high priority. Without such information, proper management of these birds is difficult. To determine the effects of shinnery oak control on lesser prairie-chickens, we made several comparisons between tebuthiuron-treated and untreated shinnery oak rangelands including: (1) vegetation composition, (2) densities of lesser prairie-chickens, (3) early summer diets and gut morphology, and (4) body condition of prairie-chickens. Forb and grass composition was higher in treated plots than in untreated plots. Densities of lesser prairie­ chickens were slightly higher in tebuthiuron-treated sites than in untreated plots for both seasons. Summer densities were 0.51 birds/ha in treated plots and 0.41 birds/ha in untreated plots. Winter densities were 0.53 birds/ha and 0.35 birds/ha in treated and untreated sites, respectively. vi prairie-chickens were also more difficult to detect in treated pastures than in untreated shinnery aCrosS seasons. Foods eaten by lesser prairie-chickens in treated pastures were different than foods eaten by prairie-chickens in untreated pastures. Shinnery oak acorns represented the major portion of the diet for birds collected in untreated shinnery, but were absent from the diet of birds in treated areas. Foliage and flowers comprised the majority of foods eaten in treated plots, but were less important to the diet of birds in untreated pastures. Prairie-chickens in untreated shinnery ate more insects than birds in treated plots during 1984. However, in 1985, insect consumption was similar between treatments. Differences in the sizes of digestive organs corresponded to differences in diet. Small intestines and caeca were longer in prairie-chickens from tebuthiuron­ treated sites than in birds from untreated plots, presumably because of the increased consumption of foliage. Conversely, gizzard weights were higher among birds from untreated shinnery, possibly as a result of greater acorn consumption in that treatment type. Lesser prairie-chickens collected from untreated shinnery had higher lipid levels than birds in treated pastures, indicating that they were in better overall condition. Higher lipid levels appeared to be correlated with consumption of acorns, seeds, and fruits. Protein vii levels of prairie-chickens increased from 1984 to 1985. Higher protein levels corresponded to increased insect consumption. Lesser prairie-chickens could most likely benefit from an interspersion of both tebuthiuron-treated and untreated sand shinnery oak rangeland. viii LIST OF TABLES 1.1 Monthly precipitation (cm) and deviation from the 3D-year average (cm) for the study area, 1985-1986 ........................................ 10 1.2 Percent basal composition of vegetation in treated and untreated sand shinnery oak rangelands ....................................... 11 1.3 Density of lesser prairie-chickens in tebuthiuron-treated and untreated sand shinnery oak rangelands during summer (July-September) 1985 and winter (January-February) 1986 .......... 14 2.1 Monthly precipitation (cm) and deviation from the 3D-year average (cm and percent) for the study area ....................................... 28 2.2 Food items from lesser prairie-chickens (N=42) collected during summer (27 May-3 July) in tebuthiuron-treated and untreated sand shinnery oak rangelands of west Texas and eastern New Mexico ....................................... 30 2.3 F-values from 2-way analysis of variance (ANOVA) of lengths and weights of digestive tract parts of lesser prairie-chickens collected May-July, 1984-85 from tebuthiuron-treated and untreated sand shinnery oak rangelands........... .......... 35 2.4 Average weights (g) and lengths (cm) of the digestive tracts' of lesser prairie-chickens collected from tebuthiuron-treated and untreated sand shinnery oak rangelands............ ..... .... 36 3.1 F-values from 2-way analysis of variance (ANOVA) of body weight (BW) , liver weight, and carcass components of male lesser prairie-chickens collected from tebuthiuron-treated and untreated sand shinnery oak rangelands during summer 1984-85 .......................................... 50 3.2 Comparison of body weight, liver weight, and carcass components (g) of male lesser prairie­ chickens collected 27 May-3 July, 1984-1985 from tebuthiuron-treated and untreated sand shinnery oak rangelands of west Texas and eastern New Mexico ........................................... 51 ix F-values from 2-way analysis of variance (ANOVA) of body weight (BW), liver weight, and carcass components of female lesser prairie-chickens collected from tebuthiuron-treated