BOSTON PUBLIC LIBRARY 3 9999 063 DOCUMtNTT^i-LEC i ION 7 738OURNING DOVE STATUS REPORT 1966 UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE BUREAU OF SPORT FISHERIES AND WILDLIFE Special Scientific Report - Wildlife No. 115 UNITED STATES DEPARTMENT OF THE INTERIOR, STEWART L. UDALL , SECRETARY Stanley A. Cain, Assistant Secretary for Fish and Wildlife and Parks Fish and Wildlife Service, Clarence F. Pautzke, Commissioner Bureau of Sport Fisheries and Wildlife, John S. Gottschalk, Director MOURNING DOVE STATUS REPORT, 1966 Compiled by James L. Ruos and Roy E. Tomlinson Migratory Bird Populations Station Division of Wildlife Research Bureau of Sport Fisheries and Wildlife Laurel, Maryland Special Scientific Report — Wildlife No. 115 Washington, D.C. • March 1968 For sale by the Superintendent ol Documents, U.S. Government Printing Office Washington, D.C. 20402 • Price 40 cents CONTENTS Page Abstract iv Introduction 1 PART I--Mourning Dove Breeding Population Status: 1966 Procedure 2 The Call-count Survey method 2 Quality checks of field data 3 Randomization of call-count routes 3 Physiographic stratification of call-count routes 4 Population Indexes 4 Determination of short-term population changes, 1965-1966 . 11 Determination of long-term population trends, 1954-1966 . . 11 Determination of population distribution, 1965-1966 .... 12 Findings 12 Population distribution by physiographic region, 1965-1966 12 Status of the 1966 mourning dove breeding population ... 14 Discussion 15 Relative numbers of doves by management unit, 1954-1966 . . 15 Relative density levels by management unit, 1954-1966 ... 18 Annual variability of densities by management unit, 1954-1966 18 Long-term dove population fluctuations, 1954-1966 21 Comparison of dove populations in hunting and nonhunting States, 1954-1966 24 Statistical significance of data 25 Quality of the 1966 call-count data 26 PART II--Mourning Dove Harvest Statistics Mourning dove harvest estimates: 1965 29 Procedure 29 Source 1 - Waterfowl Hunter Mail Questionnaire Survey . 29 Source 2 - Survey of mourning dove hunters reporting banded doves 29 Source 3 - Band recovery rate data 30 Source 4 - Personal interview survey 30 Determination of relative harvest by State 31 Findings 31 Proportionate harvest by State 31 Validity of mourning dove harvest statistics 32 Trends in numbers of mourning dove hunters, 1960-1965 .... 35 References 37 Appendix 39 in ABSTRACT Nationwide dove population indexes presented in the 1966 Mourning Dove Status Report were obtained, using several impor- tant refinements in data gathering and analysis. Changes in mourning dove breeding density indexes, obtained from call-count surveys conducted throughout the United States, are summarized by management unit as follows: Percent Change Management Unit 1965:1966 10-Yr. Mean:1966 Eastern + 4 +1 Central +10 - 6 Western +1 - 2 United States +6 - 3 Data analyses suggest that 1966 dove populations have fully recov- ered from the 1965 decline in the Eastern and Central Management Units, and partially recovered in the Western Management Unit. Present populations approximate those of the 1956-1965, 10-year means in all units. Long-term trends in population densities indicate that the Central Unit consistently maintains the highest dove densities, 31 percent greater than the Eastern Unit mean, and 49 percent greater than that of the Western Management Unit. The annual variability of populations composing the Central Unit is the greatest, while Eastern Unit populations are the most stable. Comparison of data from hunting and nonhunting States in the Eastern and Central Management Units reveals that hunting States typically contain dove densities at or above nonhunting State levels. When the all-hunt, low-density Western Unit States were included in the computation of the United States average density, slightly higher densities were determined for the com- bined nonhunting States. A special "quality-check" study of field data reveals that approximately 89 percent of the routes were run and recorded accurately in 1966, but only 74 percent were run and recorded accurately in both 1965 and 1966. Causes of route data inac- curacies are presented. This year, four sources of data were merged to obtain the best possible estimate of the 1965 nationwide mourning dove harvest. This study indicates that about 40.8 million doves were harvested by some 1.6 million hunters. The proportions of the total kill calculated for the management units were: Eastern - 41 percent, Central - 30 percent, and Western - 29 percent. State statistics are presented in tabular form. Procedures for obtaining these values are discussed. INTRODUCTION Management of mourning doves in the United States is confined essentially to the regulation of hunting for proper harvest. Wild- life administrators rely heavily upon population data gathered by the Call-count Survey to set annual regulations. The nationwide Call-count Survey has been conducted annually since 1953 by State, Federal, and independent observers on more than 800 prescribed routes. This report describes the methods employed to obtain and expand such data and presents the status of the 1966 mourning dove breeding population. Two dove status reports are prepared annually. In 1965 and 1966 the preliminary version of this report was mailed to members of the Dove Regulations Committee one week prior to the regulations meeting, which is held in June of each year at Washington, D. C. This timely distribution has been made possible by the promptness of individual cooperators who sent their data directly to the Migratory Bird Populations Station immediately after they had completed their surveys. The final version, constituting this report, is published later in the survey year. It is distributed to all cooperators and is available to interested organizations and individuals. Prior to 1960, the Mourning Dove Newsletter reported on mourning dove research activities throughout the country, and on the annual status of the breeding population. The publication was discontinued after 1960 and was replaced by the Mourning Dove Status Report. In recent years, the Status Report has been con- cerned almost entirely with the results of the Call-count Survey. This report, utilizing more precise data, presents a more comprehensive analysis of mourning dove populations than has been possible in the past. Randomization of call-count routes, first begun in 1957, has been completed in 44 of the 48 contiguous States. Survey data were analyzed for the first time by physio- graphic regions, and, with the aid of automatic data processing equipment, a study of mourning dove kill statistics has been made this year. PART I— MOURNING DOVE BREEDING POPULATION STATUS: 1966 PROCEDURE The Call-count Survey method Field studies have demonstrated the feasibility of the Call- count Survey as a method for detecting annual changes in mourning dove breeding populations (Foote, et al, 1952). Since 1953, these surveys have been conducted throughout the United States over a system of more than 800 established routes. Each call-count route consists of twenty 3-minute listening stations, spaced at 1-mile intervals, usually on lightly traveled secondary roads. Counts are made once per route during the period May 20 through June 10. Intensive studies in the eastern United States (Foote, et_ al_, 1952) have indicated that dove calling is relatively stable during this time. Call-count surveys are not made when wind velocities exceed 12 miles per hour, or when it is raining. Records are kept of all doves seen or heard calling along the routes. The numbers heard calling during 3 minutes at each station are totaled for each route to provide the basis for determining the population index. The numbers of calls per dove and of doves seen are not currently used, although they are recorded, and a later examination of these data is planned to determine if a more precise population index can be found. The Call-count Survey has limitations and possible biases which require further study. One important limitation is that the Survey does not measure the current year's production. This factor may be especially significant since a high percentage of the fall population is normally composed of young -of-the-year. Recent studies (Frankel and Baskett, 1961; Jackson and Baskett, 19 64) have shown that unmated males call at a greater rate than mated males. This suggests that the reliability of the annual call- count census is reduced by the variability in the ratios of mated to unmated males. However, Wight (1964) observed that variations in the ratio of mated to unmated males, where the adult sex ratio approached equality, did not significantly alter the capability of the dove call-count for measuring annual trends of breeding mourn- ing doves. Irby (1964) also found no evidence on his study area in Arizona that the numbers of unmated males could materially affect call-count results. Quality checks of field data Field reports received at the Migratory Bird Populations Station were examined to judge some aspects of the accuracy with which the routes were run and data recorded. Records obtained from routes run under unacceptable conditions were deleted from analysis. Those routes completed under the prescribed conditions, but containing discrepancies, errors, or missing data, were studied to ascertain whether parts of the report were acceptable. If parts were, they were used in analyses for which they were applicable. Where an observer change occurred on the same route from one year to the next, the data were critically examined to determine if an unexpected population change was apparent. When such differences were detected, they were attributed to variation in observer efficiency and the data were deleted from th%e current analysis. Randomization of call-count routes The original call-count routes (established between 1951 and 1956 hereafter designated as "management routes") were, in many instances, selected in areas of high-density dove populations. Thus, they were not representative of populations over the entire State or management unit. Randomly located call-count routes were first employed in seven southeastern States in 1957 (Foote, et_ al . , 1958). A com- parative study of the random and management route data from these States confirmed earlier assumptions that a revision of the nation- wide call-count survey routes should be undertaken if representative dove population indexes were to be obtained. This recommendation prompted the gradual selection and establishment of the 868 ran- domly-located call-count routes now employed in 44 States. Selection of random routes in the remaining four States of Maine, New Hampshire, Rhode Island, and Vermont (now represented by a total of 12 management routes) will be made at a future date. Both types of routes were run during the year of transition from management to random routes. This procedure permitted a direct comparison of data (Foote, et al_, 1958). Randomized data have been obtained in 35 of the 44 States for 2 or more years. Routes in the nine remaining States of Connecticut, Delaware, Indiana, Massachusetts, Michigan, New Jersey, New York, Pennsylvania, and West Virginia were randomized in 1966. Physiographic stratification of call-count routes Biologists recognize the limitation of sampling wildlife populations by political units. Census data collected and ana- lyzed by ecological divisions represent better statistical design and would be expected to provide more precise information with the same effort. An ecological sampling design for the collection of dove population data, using physiographic regions as the basis for stratification, was suggested by Foote, et al, (1958). The 78 regions designated in this report (fig. 1) are based essentially on a map entitled "Physical Divisions of the United States" prepared by Fenneman(1931 ) . The boundaries of these divisions were modified in several instances following early examination of field data and more recent ecological studies. The combined use of physiographic stratification and random- ization of call-count routes was designed to permit detection of a true population change of 20 percent with 95 percent confidence for each management unit (fig. 2). Additional physiographic and ecologic studies, combined with an examination of regional dove data, are expected to improve the statistical precision of this analysis. Population Indexes Two indexes to numbers of doves have been calculated to pro- vide information on dove status and to compare population changes and trends. The Breeding Population Index (BPI ) is an index to the total number of doves in a State, management unit, or physio- graphic region. The Breeding Density Index (BDI) is an index to the numbers of doves per unit area. Both indexes derive from the average number of calling doves per route. To obtain as precise an average as possible for derivation of the indexes, the call- count data are weighted according to differences among land areas in each State and management unit. Previously, the BDI for each State represented the average number of birds heard calling per route within that State, thus weighting all routes equally. The State averages were then weighted in proportion to the estimated area of dove habitat in ■d c o 3 Cl 0 a 4) > 0 -d bO c • •H to a 0) (-i X3 3 0 O u E at Mn 4-> O nj lH 03 +J ■ H to to >> l-l H o nj '■H C ni O c •O ■H to •d 01 » a Pi, 1-1 3 -5- Physiographic Regions Used in Analysis of Mourning Dove Population Data, 1966 [Modified after Fenneman (1931)] Description Stratum Code Laurentian Upland Division Superior Upland Province 010 Atlantic Plain Division Coastal Plain Province Embayed section 031 Upper Coastal Plain 032 Floridian section 033 East Gulf Coastal Plain 034 Mississippi Alluvial Plain 035 West Gulf Coastal Plain 036 Lower Coastal Plain 037 Appalachian Highlands Division Piedmont Province Piedmont Uplands 041 Piedmont Lowlands 042 Blue Ridge Province Northern section 051 Southern section 052 Valley and Ridge Province Tennessee section 061 Middle and Hudson Valley section 062 St. Lawrence Valley Province Champlain and Northern section 070 Appalachian Plateaus Province Mohawk and Allegheny section 081 Catskill section 082 Kanawha section 085 Cumberland section 086 6- Physiographic Regions — Continued Description Stratum Code New England Province Northern New England section 090 Southern New England section 091 Taconic section 095 Adirondack Province 100 Interior Plains Division Interior Low Plateaus Province Highland Rim section 111 Lexington Plain 112 Nashville Basin 113 Central Lowland Province Eastern lake section 121 Western lake section 122 Wisconsin Driftless section 123 Till Plains 124 Dissected Till Plains 125 Osage Plains 126 Great Plains Province Central Texas section 130 Missouri Plateau, glaciated 131 Missouri Plateau, unglaciated 132 Black Hills 133 High Plains 134 Plains Border 135 Colorado Piedmont 136 Raton section 137 Pecos Valley 138 Edwards Plateau 139 Interior Highlands Division Ozark Plateaus Province Springf ield-Salem plateaus 141 Boston "Mountains" 142 Physiographic Regions — Continued Description Stratum Code Interior Highlands Division, (continued) Ouachita Province Arkansas Valley 151 Ouachita Mountains 152 Rocky Mountain Division Southern Rocky Mountains Province 160 Wyoming Basin Province 170 Middle Rocky Mountains Province 180 Northern Rocky Mountains Province 190 Intermontane Plateaus Division Columbia Plateaus Province Walla Walla Plateau 201 Blue Mountain section 202 Payette section 203 Snake River Plain 204 Harney section 205 Colorado Plateaus Province High Plateaus of Utah 211 Uinta Basin 212 Canyon Lands 213 Navajo section 214 Grand Canyon section 215 Datil section 216 Basin and Range Province Great Basin 221 Sonoran Desert 222 Salton Trough 223 Mexican Highland 224 Sacramento section 225 Physiographic Regions — Continued Description Stratum Code Pacific Mountain Division Cascade Sierra Mountains Province Northern Cascade Mountains 231 Middle Cascade Mountains 232 Southern Cascade Mountains 233 Sierra Nevada 234 Pacific Border Province Puget Trough 241 Olympic Mountains 242 Oregon Coast Range 243 Klamath Mountains 244 California Trough 245 California Coast Ranges 246 Los Angeles Ranges 247 Lower Californian Province 250 c 3 c CD e cd C ni E > O •a bo c •H C t-l 3 O u 3 ■H c< -10- each State of a management unit, to provide the BPI for each unit. These index figures indicate year-to-year changes and long-term trends in population levels. Data obtained by the 1966 survey for 35 States, "randomized" for 2 or more years, were the first to be weighted by physiographic region in calculating BDI . The average number of birds heard call- ing per route from each region within a specific State was weighted by the total land area percentage occupied by that region in the State to obtain each State's BDI. A BDI value was similarly deter- mined for each of the three management units. This weighting procedure recognizes differences in quality of dove habitat as manifested by physiographic regions in States and management units. Nine States provided randomized data in 1966 but not in 1965. Management route data from these States were weighted only on the management unit level (to obtain BDI values) using statewide averages and ignoring physiographic stratification. Thus, for comparative purposes, the 1965 and 1966 BDI values include random- ized route data that are stratified from 35 States and management route data from nine States. In 1967, BDI values will be derived from data obtained on randomly selected routes in 44 States. Average numbers of doves heard calling per management route have been determined for Maine, New Hampshire, Rhode Island and Vermont, where routes have not been randomized. These averages were not weighted by geographical area and thus were not included in management unit means. Determination of short-term population changes, 1965-1966 Changes in mourning dove population size between 1965 and 1966 are indicated by data from 671 comparable routes run during both years. The average, appropriately weighted BDI values for each year, are presented for each State and management unit (table 1). Differences in these BDI values, expressed as percent change, determined the magnitude of population changes. Determination of long-term population trends, 1954-1966 Relative abundance of breeding mourning doves has been esti- mated annually since 1954 to document long-term population trends -11- in States and management units. After the routes in a State were randomized, a Base Year Index (BYI), representing the appropriately weighted State BDI , was selected. The average State indexes for previous-to-randomization years were then adjusted annually accord- ing to the percent change from the preceding year in counts on comparable routes. This year, the BYI ' s were determined from data obtained on randomized routes in 44 States. These "randomized" indexes provide a direct comparison of relative dove densities between years and States. As discussed under the section on Population Indexes, the "randomized" State indexes were adjusted by the land area they represented for determining average manage- ment unit indexes. Long-term indexes of the four States not randomized are not directly comparable to the other States' data. New BDI's, adjusted for variations in land areas among States, have been calculated this year for all management and sub-manage- ment units. These BDI's estimate the relative importance of each State for dove production. The total land area values and the BDI values for States and management units by year are presented in table 2. Determination of population distribution, 1965-1966 All 1965 and 1966 quality-checked data representing the numbers of doves heard calling on randomized routes, regardless of route comparability, were combined by physiographic region. The regional sums divided by the total number of routes per region estimate the density-distribution of breeding mourning doves in the United States. An average of 22.8 routes was tallied for each of the regions represented. FINDINGS Population distribution by physiographic region, 1965-1966 Relative densities of breeding mourning doves by physiographic region are illustrated in figure 3. The legend indicates the 1965-66 combined average "numbers of doves heard calling" on randomized routes by physiographic regions. Although a more thorough examination of these data will be ■12- w c 0 ■H +-> ni .H 3 a 0 a o •d • vO kjj vO c o ■iH H C 1 In m 3 >£> 0 o E rH bo « c c •H o T) •H u &c OJ 0 •rH ■H W w c >< V £ ■d a u >* > n I u 3 &D •H -13- made at a later date, it is evident that mourning doves breed abundantly throughout most of the subhumid and humid regions of the United States. Highest densities of breeding doves are found in the grassland-forest ecotone of the Central Management Unit, and in the Upper Coastal Plain of the Eastern Management Unit. Lowest densities prevail in the areas of extensive forests, mountains, and deserts. Status of the 1966 mourning dove breeding population The adjusted, average numbers of mourning doves heard call- ing on comparable call-count routes in 1965 and 1966 are tabulated by State and management unit (table 1). These figures adjusted to a base-year appear in table 2. Further summarization, shown in table 3, reveals the current status of populations by management unit. United States - The mourning dove Breeding Density Index increased 6.5 percent from 1955 to 1966. The adjusted mean number of doves heard calling per route was 23.2, a figure 3.1 percent below the 10-year average of 24.0 for 1956-65. Dove hunting States, representing 69 percent of the total United States land area, contained 69 percent of the total breed- ing population in 1966. The average, adjusted BDI for these States increased 5.4 percent from 21.7 in 1965 to 22.9 in 1966, while the BDI for all nonhunting States increased 9.0 percent from 22.2 in 1965 to 24.2 in 1966. The BDI for all hunting States was 3.8 per- cent below the 10-year mean and that for nonhunting States was 0.4 percent below this average. Eastern Management Unit - The Eastern Unit contains 30 percent of the land area of the United States, and 27 percent of the esti- mated 1966 dove breeding population. The BDI increased 3.8 percent between 1965 (20.8 doves heard calling per route) and 1966 (21.5). The 1966 BDI was calculated to be 0.7 percent above the 10-year mean of 21.4. Dove densities in hunting States (66 percent of the unit's land area) declined 2.2 percent between 1965 and 1966, while in the nonhunting States, the BDI increased 21.2 percent. Central Management Unit - The Central Unit contains 46 percent of the land area of the United States, 54 percent of the dove population, and the highest mean BDI, (26.7). The BDI increased -14- 9.7 percent between 1965 (24.4) and 1966 (26.7). The 1966 BDI , however, was 5.6 percent below the 10-year mean of 28.3. Hunting States (56 percent of the unit's land area) experienced the greater population increase of 13.0 percent, while the nonhunting States gained 5.4 percent between 1965 and 1966. Western Management Unit - The Western Unit represents 24 per- cent of the land area in the United States and contained 19.3 per- cent of the 1966 mourning dove breeding population. All States within this management unit provide dove hunting opportunities. BDI values increased from 18.1 to 18.3 between 1965 and 1966, an increase of 1.3 percent. The 1966 BDI was determined to be 2.0 percent below the 10-year mean of 18.7. DISCUSSION Two methods for comparing annual differences in breeding population size were used for the first time this year. As dis- cussed previously, statistically better sampling procedures were employed in 1966 to determine Breeding Population Indexes (BPI). These BPI's estimate the relative importance of dove breeding areas (see fig. 4). Dove densities, expressed by the average number of doves heard per route, were calculated from Breeding Density Index (BDI) values for States and Management Units. Changes in dove population between geographical areas and years were determined from these adjusted BDI values as presented in figure 5. Relative numbers of doves by management unit, 1954-1966 The 13-year average (1954-66) BPI values, in thousands, were determined as follows: Central Management Unit - 24.5, Eastern Unit - 11.5, and Western Unit - 8.5. These data, when expressed in percentages, reveal that the Central, Eastern, and Western Management Units contained an average of 55 percent, 26 percent, and 19 percent, respectively, of the total breeding population in the United States during this period. Long-term population trends by management unit and year are presented in figure 4. -15- NO on CO ON NO ON nO ON O NO ON ON m on CO m ON H in o (saNVsnoHi) xacmi Nonvmaoa-ONiaaraa -16- M3 u-l ^* CI CM r* O CM CM CM CM CM CM CM ainoH HHa dnitivo (wvaH saAoa aovnaAV -17- Relative density levels by management units, 1954-1966 A study of annual BDI ' s since 1954 reveals that, without exception, the Central Management Unit maintained the highest, the Eastern Management Unit the next highest, and the Western Management Unit the lowest average dove densities (fig. 5). Long-term average indexes for these units were 27.7, 21.2, and 18.6 doves heard per route, respectively. The Central Unit indexes averaged 31 percent greater than the Eastern Unit, and 49 percent greater than the Western Unit. Minimum differences between units of highest and lowest density were recorded in 1954 and again during the period between 1962 and 1966, when the Central Unit's indexes averaged 34 percent greater than those of the Western Unit. Maximum differences were observed during the intervening years between 1955 and 1966, when Central Unit levels exceeded those of the Western Unit by an average of 67 percent. Annual variability of densities by management unit, 1954-1966 The extent to which annual dove densities vary from long- term means has been calculated to determine the relative stability or variability of populations (fig. 6). Population density values between 1959 and 1966 in the Eastern Management Unit were remark- ably stable, while those in the other units were more variable. Figure 7 portrays graphically the degree of variability that annual population indexes for each management unit have shown during this 13-year period. The Eastern Unit would not be expected to vary more than 9 percent from its long-term mean at the .05 probability level. By contrast, the same probability levels for the low- density Western Unit and the high-density Central Unit were deter- mined to be within 19 percent and 24 percent of their means. The United States mean would not be expected to vary more than 16 percent. On the basis of the 1954-1966 data, the mean number of doves heard per route in the United States for a given year would not be expected to deviate from the long-term average of 23.6 by more than 3.7 unless one chance in 20 occurred. The expected maximum devia- tions from the long-term average by management unit at the same probability level are: Eastern, 21.2 - 1.8 doves; Central, 27.7 - 6.6 doves; and Western, 18.6 i 3.4 doves. ■18- + + ' NV3W woaj aaruavaaa tviinnv NO • NO (J ON at r-l e NO nO u-| kl On NO H H ON 3 1 -1 3 -3- u-i On r-l 2 u sf fl NO a ON ■4 r-i 11 U s o <1) M 3 NH en . (1) NO • .— t ; 3 O t-l ■v i u to <1> NO r. a ON r-l U -i bo B c ED •H r-l • r-1 nD 6) at U on «2 1— 1 ■d 3 v* M nt U a) a B o a vO Ed w ON 0 ■d w c ON 4-1 at m ^i i> ON 3 F r-l » T3 4-1 c D 0J u /) 14 3 m o U5 C o D a o a 60 c ■H •a a; 01 u £> V > o 60 c ■H c u 3 O e O u C/3 I r~ D l-l 3 60 ■H Uh AVERAGE DOVES HEARD CALLING PER ROUTE -20- Long-term dove population fluctuations, 1954-1966 As shown in figure 5, mourning dove populations in the United States have experienced periods of abundance in 1957 and again in 1960. Subnormal populations were evident in 1954, 1963, and 1965. The BDI ' s for the three management units fluctuated in unison 58 percent of the time between successive years. The probability that this degree of synchronization occurred by chance is 0.14 (14 times in 1000). Further study shows that the Eastern and Central Units fluctuated in the same direction 83 percent of the time (p = .04), while the Central and Western Units agreed 75 per- cent (p = .15), and the Eastern and Western Units agreed only 58 percent of the time (p>.50). These calculations suggest that (1) population fluctuations among management units are not due to sampling error, and (2) factors affecting population levels extend over larger areas than management units. Since management units represent more or less discrete populations, this latter suggestion is not explained by mobility of the species. Limited data suggest that changes i,n the numbers of doves in the Western Management Unit tend to precede, by 1 year, population changes in both the Central and Eastern Units. This relationship was evident during 64 percent of the years tested (p = .28). The Western Unit changes preceded those of the Eastern Unit 73 percent of the time (p = .23), while those in the Central Unit preceded Eastern Unit changes 64 percent of the years (p">.50). Further, an increase in Western- Unit populations preceded by 1 year an in- crease in Eastern populations 80 percent of the time (p = .19). It is evident that these correlations are statistically weaker than those relating to changes among management units within years. Comparison of dove populations in hunting and nonhunting States, 1954-1966. The mean BPI's, in thousands, for all hunting vs. all non- hunting States since 1954, are 31.1 and 13.4, respectively. Since the hunting States represent about 70 percent of the total land area in the nation and contain about 70 percent of the total dove breeding population, it is apparent that no significant differences occur between dove densities in hunting and nonhunting States. The long-term mean BPI of 14.0 for the hunting States in the Central -21- Management Unit represents 57 percent of that unit's total popula- tion, and that of 10.5 for the nonhunting States represents 43 percent. The Eastern Management Unit index of 8.6 for the hunting States was 75 percent of the unit's estimated total population; for nonhunting States it was 2.9 (25 percent). Annual trends of hunting and nonhunting State populations for the Eastern and Central Units are presented graphically in figure 8. The 13-year weighted average BDI for the combined nonhunting States (24.0 doves heard per route) was 2.5 percent greater than for the combined hunting States (23.4) (fig. 9). In both the Eastern and Central Units, greater dove densities are found in the hunting States than in the nonhunting States. In the Central Management Unit, the average BDI of 28.5 for the hunting States was 6 percent greater than that of 26.8 for the nonhunting States. An even greater departure was noted in the Eastern Unit, where hunting State densities averaged 30 percent greater than those of nonhunting States, with indexes of 22.8 and 17.5 doves, respectively, The expected annual variability of dove density indexes from their long-term means was similarly determined from a statistical analysis of BDI ' s since 1954. Annual indexes for the combined hunting States in the United States would not be expected to fluctuate more than 18.8 percent (.05 probability) from the 13- year mean, while indexes for nonhunting States vary about 20.5 percent. In the Eastern Management Unit, hunting States were more stable (mean - 11 percent) compared to nonhunting States (mean ± 13 percent). The variability of the Central Management Unit hunting States' population (mean - 26 percent), however, was greater than in the nonhunting States (mean ± 24 percent). Trends of dove densities within management units were also studied in hunting and nonhunting States. The most interesting observation was in the Central Management Unit, where only minor differences in densities between hunting and nonhunting States have been observed since 1959 (fig. 9). Prior to this year, the 1954-58 combined hunting States' BDI averaged 21 percent greater than in the nonhunting States. Thereafter, between 1959 and 1966, the nonhunting State indexes averaged 2 percent greater than in the hunting States. Figure 9 indicates how constant these dif- ferences have been. By comparison, the Eastern Management Unit -22- \ / \ \ / \ \ / \ V \ [ \ L_ 1 / / / / / t \ \ \ \ \ V \ to \ / 1 C 3 y •H X s 4J 1 * c c s 3 o s 3= S3 s 4 1 CO 1 0) 4J / / 4J / / co / 1 *n / \ C 1 \ 4J \ 1 c \ H ^v to 3 \ M \ ? \ g \i° \ a \ I hri v z J z / 00 / c s w / ■* s 1 o / ^ > < / 3 z M • 2 g • • H H • CO S • < | • w W ^ I o s \ < \ \ ' \ V \ ►J \ , \ s ) \ H / \ r_> i \ 1 V 1 L V \ N \ N V w ON £> c as n f— i c •o c CI ^D ac 0> n .-4 •H c 3 £1 CM vD l-i • ON r-t O o w H 0) 1 X T 1— ( c •H .-H C w 0 +j ■h ■ H o as C 3 r— t .H 3 ■M a C 0 dj a E 11 0£> M m c r3 0> •H C .— 1 •o cd 1) E M C X) •H 00 x: u-1 (U ■m <^ > •H 0 ? •a OJO c r^ •H to n a\ 3 O E C ■T-l * M s. J ac , « c= g ■ 1 C co 60 ro W 1 , ll B H lid ^ w H CO «: w Lnes indi Lines ind J% 7 / / / Lzontal 1 rizontal X. \ Solid hor Broken ho 1 1 1 . -J 1 1 1 1 1 'I 1 co n£> NO CU on •4-> i— i nS •i-> CO to) m C NO •H On ■4-> .— 1 c 3 si c 1 nj -3" r-H CO On t— l 3 ON a H O a - CO -H O o c T) 3 ON f— 1 bD +j C C •W ON U -H X) s NH O r^ CO u-i V ON •!-> •H CO C tu nO u-l T3 ON (1) > •H •t-i CtJ u-l u-i ON I I ON CU W 3 00 •H a, NO •* CnI o oo in «•■> tO <>*> CM -a- CN aiflo C 3 J3 1-1 a o •o W> C ■H c u 3 0 e > I I l-l 3 -33- ON CM ON CI CM I o CM O o •H e u J3 > o 73 bo c ■H c 3 o e > (LI I I u 3 •H -34- States. This factor may account for the exaggerated estimate for that State. The State kill estimates available for comparative study were combined by management unit. In the Eastern Management Unit, the Bureau's kill figure was found to be 1.5 percent less than the combined State estimates. With only two States available for com- parison in the Central Unit, the Bureau's figure was 23 percent below the combined State estimate. A more serious discrepancy occurred in the Western Management Unit where the Bureau's esti- mate was 79 percent greater than for the combined States' data. Closer examination revealed that the Bureau's adjusted average harvest per hunter was greater than the individual State agency estimates in all instances. The discrepancies were deter- mined by management unit as follows: Eastern - 54 percent, Central - 14 percent, and Western - 6 percent. The estimated numbers of hunters determined by the Bureau were 36 percent and 32 percent below the figures determined from the individual State estimates in the Eastern and Central Management Units. In the Western Unit, the Bureau's data were 58 percent greater than the combined State estimates for numbers of hunters. This comparative study reveals the need for precise kill survey information provided by a randomized, national survey of migratory upland game bird hunters. Until an economically feasible and statistically acceptable sampling can be obtained, the Bureau will attempt to provide the best estimate of mourning dove harvest possible. Acceptance of the data presented in table 6, and figures 10 and 11, should be made with discretion. TRENDS IN NUMBERS OF MOURNING DOVE HUNTERS, 1960-1965 A comparison between the 1960 and 1965 estimates produced by the National Surveys of Fishing and Hunting (U. S. Bureau of Sport Fisheries and Wildlife, 1961, 1966) suggests that mourning dove hunting increased in popularity while other forms of hunting decreased. Based upon the total number of persons 12 years old and older who hunted on any part of 3 different days or more, or spent $5 or more, the following data are presented: -35- Numbers of Persons Numbers (Thousands] Percent of Total 12 Yrs. Old & Over 1960 1965 % ChgJ 1960 1965 % Chg. Total U. S. Population 131,226 141,928 + 8.2 100.0 100.0 0 All Hunters 14,637 13,585 - 7.2 11.2 9.6 -14.2 Small Game Hunters 12,105 10,576 -12.6 9.2 7.5 -19.2 (incl. dove) Mourning Dove Hunters 1,357 1,629 +20.0 1.0 1.1 + 11.6 Big Game Hunters 6,277 6,566 + 4.6 4.8 4.6 - 3.1 Waterfowl Hunters 1,955 1,650 -15.6 1.5 1.2 -22.2 Examination of the data for all hunters in the above table suggests that sport hunting was less popular in 1965 than in 1960. The National Surveys also record that the combined number of days spent hunting by all hunters decreased 3 percent, even though the average hunter spent 4 percent more days hunting in 1965 than in 1960. In contrast to the general decline in hunting, numbers of mourning dove hunters increased at a greater rate (20 percent) than that for the total population (8 percent) between survey years. The mourning dove hunter estimates for both 1960 and 1965 have been derived from relatively small samples and, consequently, are less precise than those of the larger class estimates. Assuming these data to be reliable, the increasing popularity of dove hunting may well be worth further consideration of research and management efforts. -36- REFERENCES Fenneman, Nevin M. 1931. Physiography of western United States. McGraw-Hill Book Company, N.Y. , N.Y. xiii and 534 pp. 1938. Physiography of eastern United States. McGraw-Hill Book Company, N.Y., N.Y. xiii and 714 pp. Foote, Leonard E. , and Harold S. Peters 1952. Introduction in investigations of methods of appraising the abundance of mourning doves. U. S. Fish and Wildlife Service, Special Scientific Report--Wildlife No. 17. , Harold S. Peters, and Alva L. Finkner 1958. Design tests for mourning dove call-count sampling in seven southeastern States. J. Wildl. Mgmt. 22(4) :402-403. Frankel, Arthur I., and Thomas S. Baskett 1961. The effect of pairing on cooing of penned mourning doves. J. Wildl. Mgmt. 25(4) :372-384. Irby, Harold D. 1964. The relationship of calling behavior to mourning dove populations and production in southern Arizona. Unpublished Ph.D. Dissertation. Univ. of Ariz. xii and 100 pp. Jackson, Gary L. , and Thomas S. Baskett 1964. Perch-cooing and other aspects of breeding behavior of mourning doves. J. Wildl. Mgmt. 28(2) :293-307 . McClure, H. Elliott 1944. Mourning dove management. J. Wildl. Mgmt. 8(2):129- 134. Peters, Harold S. 1956. 19 million doves. Southern Outdoors. 4(6):9 Nov. -Dec, 1956. Tomlinson, Roy E. 1968. Reward banding to determine reporting rate of recovered mourning dove bands. J. Wildl. Mgmt. 32(1):6-11. ■37- U. S. Bureau of the Census 1965. Statistical Abstract of the United States: 1965. (86th edition) Washington, D. C. , xii and 1047 pp. U. S. Bureau of Sport Fisheries and Wildlife 1956. National survey of fishing and hunting, 1955. kk. Washington, D. C. ii and 50 pp. Circular 1961. 120. National survey of fishing and hunting, 1960. Circular Washington, D. C. iv and 7 3 pp. 1966. National survey of fishing and hunting, 1965. Publication 27. Washington, D. C. iv and 76 pp. Resource Wight, Howard M. 1964. Matedness in the mourning dove and its effect on the nationwide dove-call census. Trans. 29th N. Am. Wildl. and Resources Conf. 270-281. •38- APPENDIX Table 1. --Changes in breeding mourning dove population density indexes, 1965-66. EASTERN MANAGEMENT UNIT - HUNTING STATES State Comparable routes Average doves hear d/route (weighted)J:/ 1965 1966 21.10 21.09 44.00 32.50 10.77 9.68 24.21 17.15 25.78 29.69 29.33 31.87 12.66 8.45 20.76 19.67 33.20 30.38 22.77 24.22 11.87 13.81 6.67 4.67 36.75 35.77 21.31 21.30 32.04 38.79 10.00 4.33 Percent change Ala. 28 Del. 2/ 2 Fla. 22 Ga. 19 111. 18 Ky. 15 La. 17 Md. 11 Miss. 22 N. C. 21 Pa. 2/ 16 R. 1.3/ 3 S. C. 19 Tenn. 18 Va. 11 W. Va.2/ 3 0.00 - 26.14 - 10.12 - 29.16 + 15.17 + 8.66 - 33.25 - 5.25 - 8.49 + 6.37 + 16.34 - 29.99 - 2.67 0.00 + 21.07 - 56.70 Sub- Total 245 22.32 + 9.7374/ 21.84 + 9.947, 2.15 EASTERN MANAGEMENT UNIT - NONHUNTING STATES Conn. 2/ 2 Ind.2/ 6 Me. 3/ 3 Mass. 2/ 22 Mich. 2/ 6 N. H.3/ 4 N. J. 2/ 7 N. Y.2/ 8 Ohio 11 Vt.3/ 2 Wise. 15 4.00 14.33 .33 5.27 13.50 8.50 24.57 21.50 18.12 1.00 19.13 6.00 26.33 1.33 7.55 20.67 6.00 23.14 24.00 24.87 5.00 13.18 + 50.00 + 83.74 +303.03 + 43.26 + 53.11 - 29.41 - 5.82 11.63 37.25 +400.00 - 31.10 + + Sub- Total 86 16.90 + 19.47% 20.49 + 22.047o + 21.21 Eastern Unit Total 331 20.65 + 8.44% 21.43 + 9.307o + 3.77 -39- Table 1. --Changes in breeding mourning dove population density indexes, 1965-66. (continued) CENTRAL MANAGEMENT UNIT - HUNTING STATES State Comparable routes Average doves heard/route (weighted).!/ 1965 1966 Percent change Ark. 15 Colo. 10 Kans. 14 Mo. 15 N. M. 7 Okla. 11 Tex. 27 17.48 11.46 41.89 35.05 23.38 34.85 21.16 19.48 14.81 45.07 38.81 34.47 29.55 22.97 + 11.44 + 29.23 + 7.59 + 9.30 + 47.43 - 15.21 + 8.55 Sub- Total 99 24.65 + 13.28% 27.85 + 12.94% + 12.97 Iowa 10 Minn. 10 Mont. 9 Nebr. 17 N. Dak. 18 S. Dak. 14 Wyo. 12 CENTRAL MANAGEMENT UNIT - NONHUNTING STATES 31.80 23.74 15.55 47.30 22.72 28.86 10.93 36.39 23.85 16.89 41.25 20.18 37.20 14.37 + 14.43 + 0.46 + 8.62 - 12.79 - 11.18 + 28.90 + 31.47 Sub- Total 90 24.00 + 21.67% 25.30 + 19.47% + 5.43 Central Unit Total 189 24.34 + 12.22% 26.68 + 11.26% + 9.66 WESTERN MANAGEMENT UNIT - HUNTING STATES Ariz. 34 Calif. 47 Idaho 9 Nev. 15 Oreg. 16 Utah 11 Wash. 19 24.52 15.46 11.81 3.42 14.64 13.86 20.31 27.99 12.36 11.38 5.00 14.50 14.97 20.64 + 14.15 - 20.05 - 3.64 + 46.20 - 0.96 + 8.01 + 1.62 Western Unit Total 151 14.76 t 19.61% 14.96 - 19.49% + 1. 34 -40- Table 1. --Changes in breeding mourning dove population density indexes, 1965-66. (continued) United States Comparable routes Average doves heard/route (weighted)-I' 1965 1966 Percent change Hunting States 495 20.57 21.68 + 5.43 Nonhunting States 176 21.88 23.86 + 9.05 United States Total 671 20.94 + 7.78% 22.31 + 7.46% + 6.54 1/ Except as noted , State and management unit indexes were obtained from comparable, randomized route data adjusted for variation in the land area of each physiographic region represented. 2/ State indexes obtained from comparable, non-randomized route data not weighted by physiographic region. State means adjusted to the percent of the total land area represented in the management unit average. 3/ State indexes obtained from comparable, non-randomized route data not weighted by physiographic region. 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