ECOLOGY AND CONSERVATION OF GRASSLAND BIRDS OF THE WESTERN HEMISPHERE PETER D VICKERY AND JAMES R HERKERT, EDITORS Studies in Avian Biology No 19 A Publication of the Cooper Ornithological Society ECOLOGY AND CONSERVATION OF GRASSLAND BIRDS OF THE WESTERN HEMISPHERE Peter D Vickery and James R Herkert Editors Proceedings of a Conference Tulsa, Oklahoma October 1995 Sponsor: Association of Field Ornithologists Studies in Avian Biology No 19 A PUBLICATION Cover photograph of Greater OF THE Rheas (Rhea COOPER americana) ORNITHOLOGICAL in the Pampas of Argentina SOCIETY by Juan Carlos Rehoreda STUDIES IN AVIAN BIOLOGY Edited by John T Rotenberry Department of Biology University of California Riverside, California 92521 Studies in Avian Biology is a series of works too long for The Condor, published at irregular intervals by the Cooper Ornithological Society Manuscripts for consideration should be submitted to the editor Style and format should follow those of previous issues Price $25.00 for soft cover and $39.50 for hard cover including postage and handling All orders cash in advance; make checks payable to Cooper Ornithological Society Send orders to Cooper Ornithological Society, % Western Foundation of Vertebrate Zoology, 439 Calle San Pablo, Camarillo, CA 93010 ISBN: 1-891276-1 l-5 (cloth) ISBN: l-891276-08-5 (paper) Library of Congress Catalog Card Number: 99-74812 Printed at Allen Press, Inc., Lawrence, Kansas 66044 Issued: 10 September 1999 Copyright by the Cooper Ornitholigical Society 1999 CONTENTS LIST OF AUTHORS PREFACE _ Peter D Vickery and James R Herkert INTRODUCTION Conservation of grassland birds in the Western Hemisphere Peter D Vickery, Pablo L Tubaro, Jose Maria Cardosa da Silva, Bruce G Peterjohn, James R Herkert, and Roberto B Cavalcanti V ECOLOGY Population status of North American grassland birds from the North American Breeding Bird Survey, 1966-1996 Bruce G Peterjohn and John R Sauer 27 Linking continental climate, land use, and land patterns with grassland bird distribution across the conterminous United States Raymond J O’Connor, Malcolm T Jones, Randall B Boone, and T Bruce Lauber 45 History of grassland birds in eastern North America Robert A Askins 60 Grassland bird conservation in northeastern North America Jeffrey V Wells and Kenneth V Rosenberg 72 Use of cultivated fields by breeding Mountain Plovers in Colorado 81 Fritz L Knopf and Jeffery R Rupert Changes in bird populations on Canadian grasslands C Stuart Houston and Josef K Schmutz 87 Multiscale habitat associations of the Sage Sparrow: implications for conservation biology John I‘ Rotenberry and Steven Knick 95 Spatial distribution of breeding passerine bird habitats in a shrubsteppe region of southwestern Idaho Steven Knick and John T Rotenberry 104 BREEDING Habitat ECOLOGY Selection Habitat relations and breeding biology of grassland birds in New York Christopher J Norment, Charles D Ardizzone, and Kathleen Hartman Experimental analysis of nest predation in a New York grassland: effects of habitat and nest distribution Charles D Ardizzone and Christopher J Norment Satellite burrow use by Burrowing Owl chicks and its influence on nest fate Martha J Desmond and Julie A Savidge Songbird abundance in grasslands at a suburban interface on the Colorado High Plains Carl E Bock, Jane H Bock, and Barry C Bennett Thermal aspects of nest-site location for Vesper Sparrows and Homed Larks in British Columbia _ Kari J Nelson and Kathy Martin 112 122 128 131 137 Fire The effects of summer bums on breeding Florida Grasshopper and Bachman’s sparrows W Gregory Shriver, Peter D Vickery, and Dustin W Perkins 144 Effects of fire and herbicide treatment on habitat selection in grassland birds in southern Maine Peter D Vickery, Malcolm L Hunter, Jr., and Jeffrey V Wells Henslow’s Sparrow response to prescribed fire in an Illinois prairie remnant James R Herkert and William D Glass Effects of prescribed burning and grazing on nesting and reproductive success of three grassland passerine species in tallgrass prairie Ronald W Rohrbaugh, Jr., Dan L Reinking, Donald H Wolfe, Steve K Sherrod, and M Alan Jenkins Relationship of fire history to territory size, breeding density, and habitat of Baird’s Sparrow in North Dakota _ _ Maiken Winter 149 160 165 171 Conservation Reserve Program Le Conte’s Sparrows breeding in Conservation Reserve Program fields: precipitation and patterns of population change Lawrence D Igl and Douglas H Johnson 178 Density and fledging success of grassland birds in Conservation Reserve Program fields in North Dakota and west-central Minnesota Rolf R Koford 187 Management Nesting birds and grazing cattle: accommodating both on Midwestern pastures Stanley A Temple, Brick M Fevold, Laura K Paine, Daniel J Undersander, and David W Sample 196 Bird populations of seeded grasslands in the Aspen Parkland of Alberta David R C Prescott and Andrew J Murphy 203 Grassland songbird occurrence in native and crested wheatgrass pastures of southern Saskatchewan Stephen K Davis and David C Duncan 211 Data Collection and Analysis Monitoring grassland birds in nocturnal migration William R Evans and David K Mellinger 219 Design and duration of perturbation experiments: implications for data interpretation Kenneth L Petersen and Louis B Best 230 Sampling considerations for estimating density of passerines in grasslands Jay J Rotella, Elizabeth M Madden, and Andrew J Hansen 237 LATIN AMERICA Bird species richness and conservation in the Cerrado region of central Brazil Roberto B Cavalcanti The decline of the Pampas Meadowlark: difficulties of applying the IUCN criteria to neotropical grassland birds Pablo Luis Tubaro and Fabian Marcel0 Gabelli A preliminary assessment of distributions and conservation needs of grassland birds in Mexico _ A Townsend Peterson and Mark B Robbins Grassland birds in prairie-dog towns in northwestern Chihuahua, Mexico Patricia Manzano-Fischer, Rurik List, and Gerard0 Ceballos Seasonal movements and conservation of seedeaters of the genus Sporophila in South America Jose Maria Cardosa da Silva Demographic characteristics of Dickcissels in winter Gianfranco D Basili and Stanley A Temple Winter ecology, behavior, and conservation needs of Dickcissels in Venezuela Gianfranco D Basili and Stanley A Temple 244 250 258 263 272 281 289 LIST OF AUTHORS CHARLES D ARDIZZONE Department of Biological Sciences State University of New York College at Brockport Brockport, NY 14420 (present address: 1011 East Tudor Road Anchorage, AK 99503) ROBERT A ASKINS Department of Zoology Connecticut College New London, CT 06320 GIANFRANCOD BASILI Department of Wildlife Ecology University of Wisconsin Madison, WI 53706 (present address: Florida Audubon Society 133 Palmetto Avenue Winter Park, FL 32789) BARRY C BENNETT Department of Environmental, Organismic Biology University of Colorado Boulder, CO 80309-0334 Population, and LOUIS B BEST Department of Animal Ecology Iowa State University Ames, IA 50011 CARL E BOCK Department of Environmental, Organismic Biology University of Colorado Boulder, CO 80309-0334 Population, and JANE H BOCK Department of Environmental, Organismic Biology University of Colorado Boulder, CO 80309-0334 Population, and RANDALL B BOONE Department of Wildlife Ecology Nutting Hall University of Maine Orono, ME 04469 ROBERTOB CAVALCANTI Departamento de Zoologia Universidade de Brasilia 70910-900 Brasilia, D.E, Brazil GERARDO CEBALLOS Instituto de Ecologia Universidad National Aut6noma de MCxico, C.U Apartado Postal 70-275 MCxico, D.E, C.I? 04510 Mexico STEPHENK DAVIS Saskatchewan Wetland Conservation Corporation 202-2050 Cornwall Street Regina, SK S4P 2K5 Canada MARTHA J DESMOND Department of Forestry, Fisheries and Wildlife University of Nebraska Lincoln, NE 68583.0819 (present address: Caesar Kleberg Wildlife Research Institute Texas A&M University Kingsville, TX 78363) DAVID C DUNCAN Saskatchewan Wetland Conservation Corporation 202-2050 Cornwall Street Regina, SK S4P 2K5 Canada WILLIAM R EVANS Cornell Laboratory of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850 (present address: PO Box 46 Mecklenberg, NY 14863) BRICK M FEVOLD Department of Wildlife Ecology University of Wisconsin Madison, WI 53706 FABIAN MARCELO GABELLI Laboratorio de Biologia de1 Comportamiento Instituto de Biologia y Medicina Experimental Obligado 2490 1428 Buenos Aires, Argentina and Facultad de Psicologia Universidad de Buenos Aires Buenos Aires, Argentina WILLIAM D GLASS Illinois Department of Natural Resources Division of Natural Heritage P Box 88 Wilmington, IL 6048 ANDREW J HANSEN Fish & Wildlife Management Program Biology Department Montana State University Bozeman, MT 59717 KATHLEEN HARTMAN Department of Biological Sciences State University of New York College at Brockport Brockport, NY 14420 JAMESR HERKERT Illinois Endangered Species Protection Board 524 South Second Street Springfield, IL 62701 C STUART HOUSTON 853 University Drive Saskatoon, SK S7N 058 Canada MALCOLM L HUNTER, JR Department of Wildlife Ecology Nutting Hall University of Maine Orono, ME 04469 LAWRENCED IGL Northern Prairie Wildlife Research Center U.S Geological Survey, Biological Resources Division 8711 37th Street SE Jamestown, ND 58401 M ALAN JENKINS George M Sutton Avian Research Center PO Box 2007 Bartlesville, OK 74005.2007 DOUGLAS H JOHNSON Northern Prairie Wildlife Research Center U.S Geological Survey, Biological Resources Division 8711 37th Street SE Jamestown, ND 58401 MALCOLM T JONES Department of Wildlife Ecology Nutting Hall University of Maine Orono, ME 04469 STEVENT KNICK USGS Forest and Rangeland Ecosystem Science Center Snake River Field Station 970 Lusk Street Boise, ID 83706 FRITZ L KNOPF U.S Geological Survey, Biological Resources Division 4512 McMurry Avenue Fort Collins, CO 80525-3400 ROLF R KOFORD Northern Prairie Wildlife Research Center U.S Geological Survey, Biological Resources Division 8711 37th Street SE Jamestown, ND 58401 (present address: Iowa Cooperative Fish and Wildlife Research Unit Science Hall II Iowa State University Ames, IA 50011) T BRUCE LAUBER Department of Wildlife Ecology Nutting Hall University of Maine Orono, ME 04469 (present address: Department of Natural Resources Fernow Hall Cornell University Ithaca, NY 14853) RURIK LIST Department of Zoology, Oxford University South Parks Road Oxford OX1 3PS United Kingdom ELIZABETH M MADDEN Fish & Wildlife Management Program Biology Department Montana State University Bozeman, MT 59717 (present address: J Clark Salyer National Wildlife Refuge PO Box 66 Upham, ND 58789) PATRICIA MANZANO-FISCHER Department of Zoology, Oxford University South Parks Road Oxford OX1 3PS United Kingdom (present address: Apartado Postal 32-F Toluca, Mexico 50190 Mexico) KATHY MARTIN Centre for Applied Conservation Biology Department of Forest Sciences #270-2357 Main Mall University of British Columbia Vancouver, BC V6T 124 Canada (present address: Canadian Wildlife Service 5421 Robertson Road, R.R Delta, BC V4K 3N2 Canada) DAVID K MELLINGER Cornell Laboratory of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850 (present address: Monterey Bay Aquarium Research Institute 7700 Sandholdt Road Moss Landing, CA 95039-0628) ANDREW J MURPHY North American Waterfowl Management Plan c/o Ducks Unlimited Canada #8, 5580.45th Street Red Deer, AB T4N lL1 Canada KARI J NELSON Centre for Applied Conservation Biology Department of Forest Sciences #270-2357 Main Mall University of British Columbia Vancouver, BC V6T 124 Canada (present address: 1895 Sea Lion Crs Nanoose Bay, BC V9P 953 Canada) CHRISTOPHERJ NORMENT Department of Biological Sciences State University of New York College at Brockport Brockport, NY 14420 RAYMOND J O’CONNOR Department of Wildlife Ecology Nutting Hall University of Maine Orono, ME 04469 LAURA K PAINE Department of Agronomy University of Wisconsin Madison, WI 53706 DUSTIN W PERKINS Department of Forestry and Wildlife Conservation Holdsworth Natural Resource Center University of Massachusetts Amherst, MA 01003 JEFFERYR RUPERT U.S Geological Survey, Biological Resources Division 45 12 McMurry Avenue Fort Collins, CO 80525-3400 DAVID W SAMPLE Bureau of Research Wisconsin Department of Natural Resources Monona, WI 53716 BRUCE G PETERJOHN U.S Geological Survey, Biological Resources Division Patuxent Wildlife Research Center 12100 Beech Forest Road Laurel, MD 20708 JOHN R SAUER U.S Geological Survey, Biological Resources Division Patuxent Wildlife Research Center 12100 Beech Forest Road Laurel, MD 20708 KENNETH L PETERSEN Department of Environmental Dordt College Sioux Center, IA 51250 JULIE A SAVIDGE Department of Forestry, Fisheries and Wildlife University of Nebraska Lincoln, NE 68583-0819 Studies A TOWNSENDPETERSON Natural History Museum University of Kansas Lawrence, KS 66045 DAVID R C PRESCOTT Land Stewardship Centre of Canada 13 Mission Avenue St Albert, AB TEN lH6 Canada (present address: Alberta Conservation Association P.O Box 40027, Baker Centre Postal Outlet Edmonton, AB TSJ 4M9 Canada) DAN L REINKINC George M Sutton Avian Research Center p.0 Box 2007 Bartlesville, OK 74005-2007 MARK B ROBBINS Natural History Museum University of Kansas Lawrence, KS 66045 RONALD W ROHRBAUGH,JR George M Sutton Avian Research Center P.O Box 2007 Bartlesville, OK 74005-2007 (present address: Cornell Laboratory of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850) KENNETH V ROSENBERG Cornell Laboratory of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850 JOSEFK SCHMUTZ Department of Biology University of Saskatchewan 112 Science Place Saskatoon, SK S7N 5E2 Canada STEVE K SHERROD George M Sutton Avian Research Center PO Box 2007 Bartlesville, OK 74005-2007 W GREGORY SHRIVER Department of Forestry and Wildlife Conservation Holdsworth Natural Resource Center University of Massachusetts Amherst, MA 01003 (present address: College of Environmental Science and Forestry State University of New York Forestry Drive Syracuse, NY 13210) Jose MARIA CARDOSODA SILVA Universidade Federal de Pernambuco Centro de Ci&ncias Biologicas Departamento de Zoologia Av Prof Morais Rego, 1235 50670-420 Recife, PE Brazil STANLEY A TEMPLE Department of Wildlife Ecology University of Wisconsin Madison, WI 53706 JAY J ROTELLA Fish & Wildlife Management Program Biology Department Montana State University Bozeman, MT 59717 PABLO LUIS TUBARO Laboratorio de Biologia de1 Comportamiento Instituto de Biologia y Medicina Experimental Obligado 2490 1428 Buenos Aires Argentina JOHN T ROTENBERRY Natural Reserve System and Department of Biology University of California Riverside, CA 92521 DANIEL J UNDERSANDER Department of Agronomy University of Wisconsin Madison, WI 53706 PETER D VICKERY Department of Wildlife Ecology Nutting Hall University of Maine Orono, ME 04469 (present address: Center for Biological Conservation Massachusetts Audubon Society Lincoln, MA 01773 and Department of Forestry and Wildlife Conservation University of Massachusetts Amherst, MA 01003) JEFFREYV WELLS Cornell Laboratory of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850 (present address: National Audubon Society Cornell Laboratory of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850) MAIKEN WINTER Department of Behavioral Physiology University-Tiibingen 72072 Tiibingen Germany (present address: 611 Winston Court, Apt #4 Ithaca, NY 14850-1953) DONALD H WOLFE George M Sutton Avian Research Center PO Box 2007 Bartlesville OK 74005-2007 Studies in Avian Biology No 19:1, 1999 PREFACE This book had its genesis in 1994, when the Council of the Association of Field Ornithologists and the staff of the George M Sutton Avian Research Center recognized the need to convene a conference on the ecology, status, and conservation of grassland birds in the Western Hemisphere This two-day conference, convened in Tulsa, Oklahoma, in October 1995, reflected the deep concern held by many avian biologists that populations of many grassland bird species are declining throughout the Western Hernsphere Generous support from the U.S Fish and Wildlife Service, the Association of Field Ornithologists, the Sutton Avian Research Center, and the National Fish and Wildlife Foundation made it possible to invite a broad international contingent, especially from South America Steve Sherrod and the Sutton Avian Research Center staff facilitated conference arrangements and field trips for this productive meeting The Council of the Association of Field Ornithologists, notably presidents Greg Butcher, Elissa Landre, and Charles Duncan, provided leadership and support throughout this process The commitment of the AFO council to both the conference and the publication of this volume is warmly and gratefully acknowledged We also thank Steve Lewis and the Office of Migratory Bird Management of the U.S Fish and Wildlife Service for their financial support of this volume The Center for Biological Conservation of the Massachusetts Audubon Society, especially Christopher Leahy, and the Illinois Endangered Species Protection Board provided logistical support and encouragement to Vickery and Herkert, respectively We thank the more than 40 reviewers whose insights measurably improved the manuscripts in this volume We also thank Andrea Jones, Dustin Perkins, Jan Pierson, Vanessa Rule, and Greg Shriver for their help and suggestions on a variety of issues Elizabeth Pierson meticulously copyedited the entire manuscript and brought greater clarity to every manuscript herein; that she was able to this with wit and grace and without offending anyone seems remarkable We thank Eugenia Wheelwright, who translated all abstracts into Spanish, and Rosita Moore, who provided assistance with graphics We are immeasurably grateful to Barbara, Simon, and Gabriel Vickery and to Linda, Nathan, and Nicholas Herkert for their collective patience and support We especially thank John Rotenberry, editor of the Studies in Avian Biology series, for his cheerful guidance, encouragement, and good counsel throughout This volume is dedicated to John A Wiens, whose research on grassland and shrubsteppe birds has had a profound influence not only on both of us but on countless other ecologists of many different disciplines John’s ecological perspicacity and intellectual brilliance continue to inspire and serve as a model This volume is also dedicated to our children and their millions of cohorts throughout this hemisphere, that they may all have the opportunity to admire prairiechickens and buntings, or rheas, canasteros, and seedeaters, in wonder, joy, and we hope, curiosity Peter D Vickery Center for Biological Conservation Massachusetts Audubon Society Lincoln, Massachusetts James R Herkert Illinois Endangered Species Protection Board Springfield, Illinois DICKCISSEL D 90 F 80 70 + $ 60 50 F 40 WINTER DEMOGRAPHICS-Basili and Temple 285 population We did find, however, that age structure varied by region and time In February 1992 we found different proportions of juveniles in Portuguesa (19%) and Gutico (33%; G = 15.419, df = 1, P < 0.001) In addition, when plotting percent adults over time, it appears that in Trinidad adults arrived earlier than juveniles This pattern was not observed in Venezuela, however (Fig 2) ARE WINTER ROOSTSSUBSTRUCTURED BY BREEDINGLOCATION IN NORTH AMERICA? 30 DECEMBER JANUARY FEBRUARY Fretwell and Shane (1975) proposed that local populations of breeding Dickcissels may overwinter together in discrete subpopulations identifiable by variations in wing length; they presented evidence that birds breeding in Texas winter together in Guiuico Our comparisons of adult and juvenile wing lengths revealed significant age differences in both sexes (Table 2) When we compared adult wing lengths between regions, however, we found no regional differences (Table 2) DISCUSSION 1991 EVIDENCE 1992 30n DECEMBER JANUARY FEBRUARY FIGURE Seasonal change in the age ratios of Dickcisselsin Trinidad (N = 1,309; ffrench 1967) and Venezuela(N = 3,519) at the nocturnal roost (G = 2.59, df = 2, P = 0.11) ARE WINTER ROOSTS SUBSTRUCTURED BY AGE? We never found a roost in which the majority of birds were juveniles It appears, at least in Venezuela, that young Dickcissels arriving on the central wintering grounds for the first time not segregate themselves from the rest of the TABLE FOR DIFFERENTIAL MIGRATION Many species of nearctic and palearctic migratory passerines have differential migration patterns, depending on sex and age (e.g., Heydweiller 1936, Lack 1944, Balph 1975) For some species, such as Dark-eyed Junco (Bunco hyemalis; Ketterson and Van Nolan 1976) and White-crowned Sparrow (Zonotrichia leucophrys; King et al 1965), winter populations are segregated by sex, with females wintering farther south than males Dickcissels appear to exhibit differential sex migration on both their north- and southbound journeys In both Venezuela and Trinidad, males were more numerous than females in the early stages of their “winter” residence (Fig 1) Although differential migration was discernible in these data, we lack samples of the earliest birds arriving in Venezuela To better understand this pattern, it would be useful to sample roosts in WING LENGTHS OF DICKCISSELS WINTERING IN THE VENEZULAN LLANOS, FEBRUARY 1992 Mean wing length (mm) ? SD (N) Males GFXC3 Females Adults Juveniles 81.86 79.64 ? 2.01 (504) ? 1.93 (200)” 74.16 72.75 r+ 1.98 (453) 1.61 (104)b Portuguesa adults Gu&rico adults 81.93 81.58 1.96(406) Z 2.22 (98)c 74.20 73.99 +- 1.96 (363) -c 1.98 (90)d a T-testfor b for T-testfor d T-testfor T-test c mean mean mean mean wing wing wmg wing length length length length between between between between adult adult adult adult and juvenile males (t,,021 = 13.39, P C 0.001) and juvenile females (t,sssl = 77, P < 0.001) males by region (trsozl = 1.54, P = 0.123) females by regmn (t,45t] = 0.90, P = 0.368) 286 STUDIES IN AVIAN Mexico and Central America during migration, and also in the fall in Venezuela, when birds first arrive on the wintering grounds The proportion of juveniles decreased in the Venezuela population in January and February (Fig 2) This change could have resulted either from differential mortality of adults and juveniles or from a movement of juveniles out of central Venezuela ffrench’s (1967) data from Trinidad revealed a complementary pattern, wherein the proportion of juveniles increased in January and February This pattern suggests that juveniles may be leaving the central Llanos during this period, with some movement to peripheral areas such as Trinidad POTENTIAL BIASES IN SEX- AND AGE-RATIO ESTIMATES Sex-ratio estimates of a species can be biased by the method, time, or location of samples (Welty 1962) Biases include different capture probabilities because males and females may (1) behave differently, (2) have different migration patterns (e.g., Howell 1953), or (3) have different geographic wintering areas (e.g., Ketterson and Van Nolan 1976) When possible, we systematically reduced biases in our sex-ratio estimate Because male and female Dickcissels exhibit differential migration, our estimates could be affected by time of sample We addressed this concern by excluding data that were obtained in December and April, when differential migration would be most apparent We think our sampling location was most appropriate for a population-level estimate of Dickcissel sex ratios Among neotropical migratory passerines, Dickcissels present a unique opportunity for study because most of the world’s population winters in a small geographic area (Basili and Temple this volume) Approximately million Dickcissels converge in this area and form huge roosting aggregations that not appear to be segregated by sex, age, or breeding location Because of large sample sizes, however, we did find statistically significant differences in sex ratios between some roosts, and we therefore think the best possible population estimate results from sampling many roosts and pooling information The method we employed to sample roosts reduced potential biases in two ways Mist nets were open from the time birds first arrived and were closed only after nearly all birds had returned to the roost This reduced potential biases resulting from differential return times for sexes or ages, as has been documented in other communally roosting passerines (Jenni 1992) Nets were also stationed to intercept birds as they BIOLOGY NO 19 moved within the roost If any substructuring among individuals occurred for preferred roost sites