BOSTON PUBLIC LIBRARY 3 9999 06317 766 9 MOURNING DOVE STATUS REPORT, 1974 UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE Special Scientific Report— Wildlife No. 202 supurintendcnt oi Dc.caDicnfc JUN 24137?. Use of trade names does not imply U.S. Government endorsement of commercial products. MOURNING DOVE STATUS REPORT, 1974 By James L. Ruos, Compiler UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE Special Scientific Report-Wildlife No. 202 Washington, D.C. • 1977 Contents Page Abstract 1 Introduction 1 Procedures 1 The call-count survey 1 Quality checks of field data 2 Randomization of call-count routes 2 Breeding density index 2 Determination of population changes 16 Determination of changes in factors associated with the survey 16 Changes in the grouping of Central Management Unit States 16 Statistical evaluation of data 16 Determination of population distribution 16 Findings 16 Status of the United States dove population 16 1974 population distribution 19 1973 to 1974 population changes 19 1964 to 1974 long-term population trends 19 Status of the Eastern Management Unit population 22 1974 population distribution ' 22 1973 to 1974 population changes 23 1964 to 1974 long-term population trends 23 Status of the Central Management Unit population 24 1974 population distribution 24 1973 to 1974 population changes 24 1964 to 1974 long-term population trends 24 Status of the Western Management Unit population 24 1974 population distribution 24 1973 to 1974 population changes 25 1964 to 1974 long-term population trends 25 Statistical significance of data 25 1973 to 1974 population changes 25 1964 to 1974 long-term population trends 25 Acknowledgments 26 References 26 Mourning Dove Status Report, 1974 Compiled by James L. Ruos Office of Migratory Bird Management Patuxent Wildlife Research Center Laurel, Maryland 20811 Abstract Mourning dove population indices, as determined from the nationwide Call-Count Survey, decreased from 1973 to 1974 by 3% in theEasternManagementUnit, but increased by 2% in the Central Management Unit, and by 21% in the Western Management Unit. The change in the Western Unit was statistically significant {P<0.05). The 1974 indices were below the 10-year means (1964-73) by 1 1% in the Eastern Unit and 3% in the Central Unit, but 19% above the long- term mean in the Western Unit. Regression analyses of the call-count data for 1964-74 indicate a downward trend in dove breeding populations in all management units; mean rates of annual decline were 2% in the Eastern Unit, 1% in the Central, and 2% in the Western. The trends for the Eastern and Central Units were statistically significant (P<0.05). From 1971 to 1974, Western Unit population indices increased by 46%. Changes in population indices are described by State and physiographic region. The 1974 indices were higher than those in 1973 for over one half of the Nation, notably in the western States, the coastal plain of Texas and Louisiana, and several regions east of the Appalachian Mountains. Lower population indices occurred principally in portions of the north -central and southeastern States. Regression analyses of 11 years' data, 1964-74, showed statistically significant (P<0.05) upward population trends in seven States totaling 21% of the Nation's land area. Trends were significantly downward in 16 States that made up 35% of the land area. Management of mourning doves in the United States involves the regulation of hunting to achieve proper harvest. In setting annual regulations, wildlife administrators rely upon population index data provided by the Call-Count Survey, conducted annually since 1953 by Federal, State, and independ- ent observers. This report describes the methods employed to obtain and analyze these data and presents the status of the breeding population of mourning doves in 1974. Two versions of the dove status report, one preliminary and one final, are prepared annually. In 1974 the preliminary report was mailed to members of the Dove Regulations Committee a week before the June regulations meeting in Washington, D.C. This timely distribution was made possible because the cooperators sent their data directly to the Office of Migratory Bird Management at Laurel, Maryland, immediately after completing their surveys. The present report is the final version and contains additional analyses of survey data. Basic procedures for collecting and analyzing data in this report were similar to those used in 1973 (Ruos 19746). Data reflecting regulatory changes in the nonhunting and hunting status of South Dakota and Wyoming in 1973 are presented for the first time. Procedures The Call-Count Survey Field studies have demonstrated the feasibility of the Call-Count Survey as a method for detecting annual changes in mourning dove breeding pop- ulations (Foote and Peters 1952:1-3). Since 1953, these surveys have been conducted throughout the United States on more than 800 established routes. Each call-count route has twenty 3-min listening stations spaced at 1.6-km intervals; the routes are usually on lightly traveled secondary roads. A survey is conducted on each route once between 20 May and 10 June. Beginning in 1972, cooperators were instructed to run their routes between 20 May and 31 May. An extension to 10 June was provided to cooperators unable to complete their assignments during the desired period. Intensive studies in the eastern United States (Foote and Peters 1952:1-3) indicated that dove calling is relatively stable during the survey period. Call-count surveys are not made when wind velocities exceed 19.3 km/h or when it is raining. The numbers of doves heard calling during the 3- min listening periods are used for determining the population index. The number of calls per dove, and of doves seen, are not currently used in the index calculations, although they are recorded on the routes. These supplemental data are being analyzed. Routes on which no doves were heard or seen for two successive years are identified as Automatic Zero Routes and they continue to be included as zeros in the survey analysis. Once designated, these routes are no longer run annually; however, they are subject to periodic reexamination. Population indices derived from the Call-Count Survey are believed to be biologically and statistical- ly sound for detecting major year-to-year changes in breeding population levels for management units and for determining long-term population trends for States and management units. However, additional field research is needed to more accurately relate changes in the survey index to changes in the population of mated doves. Specific relationships between calling doves and breeding pairs have been difficult to establish (Stone 1966). Quality Checks of Field Data As in previous years, all 1974 survey reports were examined for accuracy, completeness, and data comparability between identical routes run in both the current and preceding years. In this report, indices for years since 1967 have been derived from data meeting the 1972 standardized criteria for quality (Ruos 1974a). Randomization of Call-Count Routes The original Call-Count Survey routes, established between 1951 and 1956, were frequently selected in areas of high dove density. These were gradually replaced by more than 900 randomly selected routes between 1957 and 1970 in all 48 conterminous States (Ruos 1972). Breeding Density Index The Breeding Density Index (BDI) is the mean number of doves heard calling per route. Before 1966, State indices were represented by unadjusted values. Management unit (Fig. 1) indices, however, were adjusted by the proportional area of dove habitat that each State represented within a management unit. Beginning in 1966, State BDI's were determined from indices within each physiographic region (Fig. 2) weighted by the proportional land area that the region represented within a State. Management unit indices were then obtained from State BDI's adjusted for differences in land area that each State represented within the unit. Current weighting values for States and physiographic regions within management units appear in Tables 3 and 4. -Nonhunting States 1973 I I — Hunting States Fig. 1 . Mourning dove management units. Table 1. Changes in mourning dove breeding density indices on 20-stop call-count survey routes, 1973-74. States Routes Mean number of doves heard per routed Adjusted within year Adjusted to base year 1973 1974 1973 1974 Percent changeb Eastern Management Unit Hunting States Ala. 26 19.0 20.5 17.5 18.8 7.6 Del. 1 14.0 14.0 10.7 10.7 0.0 Fla. 19 10.8 11.3 6.8 7.1 5.1 Ga. 16 25.6 28.6 11.5 12.9 12.0 111. 14 20.6 18.2 27.5 24.3 -11.6 Ky. 15 24.7 23.5 27.0 25.7 -4.9 La. 17 5.9 6.4 6.2 6.6 6.8 Md. 7 14.8 15.6 23.8 25.1 5.4 Miss. 19 26.9 27.0 32.5 32.6 0.4 N.C. 17 24.1 16.4 14.8 10.1 -32.0 Pa. 15 7.1 7.1 5.6 5.5 -1.3 R.I. 2 10.0 12.0 2.0 2.4 20.0 S.C. 17 28.7 27.0 33.3 31.3 -6.0 Tenn. 19 22.4 21.7 28.6 27.7 -3.1 Va. 8 18.6 27.0 13.4 19.4 44.9c W. Va. 9 4.1 3.5 5.7 4.9 -14.4 Subtotal 221 Nonhunting States 17.6 17.5 -0.6 Conn. 1 1.0 5.0 5.5 27.5 400.0 Ind. 12 33.2 30.0 36.8 33.3 -9.5 Mass. 2 7.0 5.5 6.1 4.8 -21.4 Maine 4 0.0 0.0 0.0 0.0 0.0 Mich. 14 10.8 10.0 11.7 10.8 -7.4 N.H. 3 6.6 3.2 4.4 2.1 -51.9 N.J. 2 21.9 16.4 23.1 17.3 -25.1 N.Y. 11 12.7 10.9 5.7 4.9 -14.4 Ohio 10 25.1 23.3 22.0 20.4 -7.5 Vt. 2 0.0 0.0 0.0 0.0 0.0 Wise. 19 14.9 11.8 12.5 9.9 -21.1 Subtotal 80 13.6 12.3 -9.9^ Total 301 16.2 15.7 -3.1 Central Management Unit Hunting States Ark. 12 22.1 22.5 25.5 26.0 1.8 Colo. 14 13.2 17.2 19.7 25.6 30.0d Kans. 16 53.1 42.6 57.2 45.9 -19.7 Mo. 15 29.8 25.9 29.9 26.0 -12.9 N. Mex. 16 11.8 12.1 4.9 5.0 2.6 Okla. 5 37.2 40.6 42.2 46.1 9.2 Tex. 22 19.4 20.8 18.8 20.2 7.3 Wyo. 11 10.3 13.8 8.9 11.9 33.46 Subtotal 111 22.7 23.1 1.8 Table 1. Changes in mourning dove breeding density indices on 20-stop call-count survey routes, 1973-74- Continued. States Routes Mean number of doves heard per route^ Adjusted within year Adjusted to base-year 1973 1974 1973 1974 Percent changeb Nonhunting States Iowa 13 27.2 23.7 18.2 15.8 -13.2 Minn. 9 4.9 7.6 11.7 18.0 54.2 Mont. 10 7.9 6.0 3.8 2.9 -23.5 N. Dak. 18 28.1 28.0 23.2 23.1 -0.5 Nebr. 20 39.3 38.6 48.6 47.7 -1.9 S. Dak. 16 32.9 34.3 40.5 42.3 4.4 Subtotal 86 21.6 22.2 3.0 Total 197 22.3 22.8 2.2 Western Management Unit Ariz. Calif. Idaho Nev. Oreg. Utah Wash. Total 165 Hunting States 39 21.5 20.3 29.1 27.6 -5.2 53 12.6 16.3 11.1 14.3 29.0d 12 10.6 11.2 25.8 27.2 5.6 18 1.1 2.6 5.4 12.3 128.4 14 6.8 8.5 11.3 14.1 24.7 15 12.2 18.7 7.9 12.0 52.5 14 2.6 3.6 12.9 17.9 39.1 14.6 17.7 21.2^ United States Summary Hunting Nonhunting Total 497 166 663 18.6 18.6 18.6 19.8 18.5 19.4 6.4 -0.6 4.5 ^ Indices obtained from comparable, randomized route data adjusted for variation in the land area of each physiographic region area presented within year. State data adjusted to a base-year are shown here and in Table 3. Unit and subunit means are derived from State data adjusted to a base-year and weighted by total State land area values. " Significance levels for State and unit changes are determined fi-om analyses of data presented within year. •= P<0.01. ° P<0.10. ^ P*0.05. a c a be 0) c CO O lOOOCOaiMOIN'^OOC-lOOlOOO I I I rt I --I I I I I CO O lO TO IT) O ■^ ■ o i> CD o 06 c4 (3^ O 10 «C to O C-' o ^ to O 00 ■^' OOOCJ-*C3'T-iCOCD(MCOiOCDiOOqcO(M'3' O — I !>) !M 10 00-* 00 ^ ^ in bi c c« o XJ CJ T3 C) CJ OOO^^-Oi^CDlOOl'-HOqiniOlOCOO^ c^a;co^ai(N'-io6'^coc^»-3iriaio6f-< CO OCDOO-a'lOiniNOO'-' (N l010odOCO(NTtCO'-HC>0 -^ o eg 05 OOiOCJ^Tj-O^tr-CO-^CgiOCDOl'-HlO Oir~oocouooir-OOQO CO (33 3 o OS c c« X. o c (U s ca c cS CO ca w 03 CO be c c 05CDcocompi>oj^c -* oilO— <(N-*l>lOCOCOt-^lOU3<3Slrit^-* o CDLOC^CDlClCCDCDCDlOiO-^lOiOlOlO CD cDcD-t^LOt— C3i^^cvir-oooor~ ^ 00 O T3 OCOCOCg!NCOlOCO^COt~-.-HC^CqcDO to 0 ^__, 0 0 CN 0 in 03 ^ 0 i> 00 T— 1 0 in lO in 06 g 00 in in in ^ 0 in c6 in in S be 3 C o ^{Moqo(M(N(Nmoor~ co ^H T-t ^H ,— < CD MOMOoeqincocDOCo C8 > >>>.>>>>>>>.>1>>>>>V >>>>>>>.>>>, >> coacoaaaaacdccacdco^coa CS §ss§sssssss§sss§ s (Nr-cDincoocot^cgin (MC^(MrtC^C0(>aOQCM.-( O) cQcCCOcOcCcOcOcOCOcO*^ CO in >> CO CO Q CO ■*oco03inooa3cj3inin_, cocDcDt-HOi cgcotNMcq(M(MNcq;Ni^^,>,>,>, >^ >.>.>,>,>, '^ >.>,>,>.>> AC0cOaacOacOcOcO*^acOcOcOcO CO ^CScOraacOraCOcOcO^acOcOcOcO ra CO CO 5 ™ >. >. >. >, >> >^ >» >. CO CO CO CO CO CO CO CO CO o OS cDcO'5--*int^o>t~-'*'0)f-a3oor~ IM ^ ^ rtM(NO(N(NC.co2|"^aiHqgcd^ I ^or,rh-^jSSZ0.0SwH>5: m < Q E O J3 3 en o o C 05 Oi- m csj p i> o o Tt crj ^ (>i rH o III 1 CO CO 1 p oj p CO p in 00 lo ai CO ^ LO lO lo <6 00 r-; .-1 ;o o oi iM p T3 O O O O 00 N t> t— 1 3 1 o oioJD-'^cocot^ ai XI be CO i>coaot^tr-QOOc^odoiri(NCT>io CD rH p f-j p cq } (O ai -^ ■^ (^ OJ ^ CD ppppt>po CO COf- 3 O OCO'*uOCO-*OOiO CD 00 CTl lO -^ ^ _i ^ f- CO C^ T-H OJ O T-t 00 CO CO rt ,-1 ,-1 -D e bo c a O t> CO 05 3 O bo d o D a CD nj bj) CI Cl "cB W is C 0»— 'i— lOOOOi— IICCO lO NCDioodocd^T-! o looooocopcjpp p ■*oa5ir-^od"a"coi-i CD CO-*lOtDTfcDCD'* in lO^DCDin-^'-Hf-Hp c^o-^odciodoocD ;D-*ininTi"incD-^ (NcocDinioincNco ._g ^ ^ ^ ^ ^ M C a bo 1=1 o >-l(NCOCOOCOOCO i-H p ;>q p !> •* p CD CO CO -^ in -^ p -^ .-H p p (N r-5 iri f-H CO -^ CO in in ■* ■^ in ■* p (N CD O i-H I-H p ^ )■ ■* CO in i> 00 o CD Oi T3 T3 CO o o ■^ in (T> ■* 3) 00 I-H (M (N CO CO O CO IM in (N CO Tf 00 f— 1 00 in a in in •* ■* •* ■* •"J" Tj- I-H -tj s CD (D d in S m tlB a CO in in ■* ■* ■* ■* ^ in CO « *-+j in Oi I—* (M O CO 00 00 00 c 3 CO 00 rH rH »-H r-H CO O (M O IM (M i-l in C3 cocDi>ininco(Nt- in (N>>.>> >1 >. >. cd ^ cd cd cd A 03 ssssss s s CO Q CO 05 inooooointDCMO co >>>>>>1>1>.>.>. >> coco^rtcocdrtifl C3 ssssssss s 00 CD o in CD r~ (N CDC0OrH t^ ,>,>,>,>,>>>, >. A A ^ A ^ ^ ^ CD sssssss s 5 3 o iMcotDinininNcD rH ^H »-l .— I I-H C 00 o CD .-I ^ (M -H 05 CO 00 CO CO S s "^ o ca H ^ ^OfctJSZOH^ m 4J ^ CO ;ai ^-5 ' luSZO^^ o be C a o o eg C Tf 00 to 00 00 .-; ^ •S e a 05 k. e 3 o u o o o he ^ o o o CO CO Q IN 3 O be C CO 02 3 O oi bs C a! XI O OS CO Q 3 -4-> CO 00 00 0 in in 05 o C CO LO OJ CO s lO tP lO CO be 1 >1 o >> US CO r~ 00 3 6 lO oi CO ft 0 6 in ^ lO "C J3 01 3 o oi CO 03 CO CJ C 0 ■*-3 m «4-l V j3 CO c^ lO o CO 0) 0) 3 0 C 01 -f^ Tj< rr 00 l~l 03 Tj" .-1 in .a CO "3 3 a -s 3 ■3 1 lO t^ CD OJ 01 'oJ eq cq (M w bl > >. >, >. 3 C3 CO ^ CO C3 CO ^ j3 a> S2 2 CO CO O C o ■4-a V V V (N i >i >. 'e -0 I- .«-) ,^ ~t-> CO !fl CO c CO 0 'c bo CO 3 CO CO m SS s o •T3 £3 CO a; " a bo 0 S 6 C CO 0 3 -♦J G a 0 S c CO 0 s 2 S oq e G c CO CO CO bjj bs ho a:, CO (N t! CO -- (0 CO *M o3 "^ -^ Oi CO rr ^ in a be CO ^ 0) y y S C C-.2 bc bo ho CO 0 'O C a c 8 3 " c CO J3 a X! CO x: S o -g "o S 0 CJ u be c C 3 ■-3 J3 •a ^ 0) a> 0 0 0 1 re > OJ "3 > 0) 'q3 > 1) C C 3 O Q a cux J J J d: z CO XI 0 -a 0) CO ^ > o bo C8 c CO C8 -a CO ■^ r? ■=> r/ 'Z* O -^ CL, CL, PU PL, Pl, PM di PU P^ Ph Oh d. c c -S bo cfi S s Co -rt ~ ~ o PL, ^odiriirioM^iriood^'-O'-JcDod I II II I I I i-H I I ^ coc4'-ioiOOo6o6i>ii>'^i-H(NLO (>) Tt CD I lO CO t> I ■* 00 M oqi>— i05cr3t— cD-Hto— OOiOlOO(MOOiOOOfX) ot»«}a)cn2c«ScocOo ■;5ZZ^i 'z 'zz ■ PL, PL, pL, Ph c^^COCviTJ-f-il>CO ooc^t^r~oqti3 CO coca-* o't~cx5oiotooicocDt>o ocoiniOi-i'*(Nco.-iooco t-H II (Nil II iocopooo0'--fco(7i'^oa^ i>coo-*cDoJt^-*ooai (M CO rt r-H cq oqcqpcooo-*coor~OCT5mu30jai oi-*i>oi>ododt£!iri^t^^iood'-CD(NC000t> CO co' irj (m' ■^ c^ f-^ oi Ti" c^ lo c4 r-< (N 00 lo t-H .-IIM(M .-ICO.-I COCOi-H .-HT)"ooa>QOO'-icO'-iiM-*t:- 05 CO CO OJ CO lO t> "^ '^Tfcot^-^tr^oiooioc^ooo oqio.-;^a;c35r-;i>Tra5cDca5o6cDC--i-Hi-JlC"^'>3COlO ^ -HIMIN (NCNIM.-I COIMN inoqTi;r-;pcot~;(NcO'3;i-;-*'*-*'-t!NmcO'*CO>-H^05(NCO.-I^O-* ^Tr^oj-^ococDio-Ht^io-lO^ COtNOOOOOO-— 'LOCOlOOCOppP'^ CO^LOt>lOCD'-HcdOt>JG300^t^COLO CO cocococjco coca(M ^(Noq.-< >> cc m O H O c« > lOCOO'^Tj'rHLO-^lOOCSI ooor~cDa5cDa5c0'-!lNT-i'*t-:cDO'-< CO t-H i-H r- -" 05 CM a^(MlOt^p05l>t-HrH»-H^ •-HOOt>od'-Hirit>oiocD Tj'i>oi>oq.-i-^ooo.-HC] cMc-^ocDcdr-Jot-^cooio CM rt CO .-I ^ COCDtO^OOO'-'CJ^CMLOC^ CMCOQOCO^OOOi-^^pp cocoaSiot^io-^ocbicco CM .-H CO CO CM CO a; <; Q fc O s t!j J S S Z PL, PS cfi E-i > ^ en 3 C Ph '5 c O O o --i CO t> CM ili p p CO p ^ P-; p lOOOp-Hl^-^r-Jf-pOlO CD CM lO CM CO 00 CO lO CO CM ^ i-H LocdcDcd^^coiocMcdcM CO ^ IM CM .-H CO 1— t CD I—, CO ■* o ioc~pco-*oqcOTi;ppp .— t o CD CM lOodcJiooo^iOTfcDod t„ CO ^ CM CO T-H 00 I-H P be l> p Tl; lO r-; r- p p p ^_ p I-H p 00 r-t C3 r-^ r-, ^ CO r-i c) c-' lO o CD ci r-H .-H CO -H f— I l> c 3 O c o p lO p p .-H 00 p p O ^ lO ^ p I — 1 Z ■^ T-H ,-, -^ oi o oi CO i>^ CD ^ 1 — 1 1 — 1 CD lOCDOlOOiO^r^OOlOCMiO 00 Ol ai »-H ■^odcJ-^jj^odr-'iotico "^ r-H _ _ -^ OC) CM T~^ ,-1 r~i ^ 00 OO 00 CM 00 t> CM in p 00 i> rf in CD c5£SSSZZZO>^ M o 13 •S e a 05 e ■4-d CO ■3 05 3 o s 03 c CO CO IB e > o ■a V be a > CO 3 < C8 3 C c < o CD C a; DC CO c p C CO CO M s bo cS be c 3 (M ^ CD CO looqooco-^cooooi cd-*'r4aJo6CTii>iri 10 CD O CO IT-" ^ OJ ^ coi>cDa:)CqCT505NCX)a5 I-H lO CD Oi CD CO 0 lO CO CD oi 00 CO CO aj CO cocoi>inoocDC~io a2ioiq-*co-*oqiO oioo^odcDodoi (N CDCO 2 Z2 ^ in o o CL, Oi Oh M 0 -^ CD ^ •«?• 00 CD 06 -^ d M C3 ci 1 1 M 1 1 O CD 05 O (N ■ 00 00 o C35 r- ^ CO cq 10 00 !N 0 CO IM IM M .-1 ^ ^ (N ^ cq (M M c~ 00 CD oq in 06 ^ CO 00 co' d CD .-< C- 00 ct; [> <=> CO ai CO T-H "a- t> ?^ CJ 00 0 10 CO r—i 10 05 00 g CO CD 10 i-H CD CO d CD ^ C~ O C^ 00 10 b£ a c o Z 00 0 CD CO CO r~ t- (N in d CD d 00 eg CD CN 0 a> l> 0 t^ M 0 CD Tf CD od CO «— 1 -— 1 ^ s 00 iri eg CO e) I> ^H in i> CO CO 0 CO CO oci [> 00 d eg in 00 CO in CD 00 in oa CD CO CD ^ J—t !> 0 CD t> CD "^ ^ CO CT> en ^ ^ 00 CD cri ^ CD ^ .-1 ^ CO .-H CO ^ eg eg d 06 iri lO CO iri eg ^ rt in o] CO CO e) oO'-i.-icgcDt>--*oo cDcocoddc-^i>d .-I rH in -^ (N CO ^ r-oocooooococo CO^'^^CTlTt-pcO ■*t-^e)irit>Trdeg' COCOin-*I>'*t~CD CO Oi in It rH eg 0 (N CT) CO ej Tt d CO eg iri CD d d rf CO eg CO ^ ^ C30 in (35 r- O! r-; p ^ CD in eq •^ s CO in in CO •* -qJ d CO in en ■* in d CO ei en 0) 15 ^ CO o . j4 s >> a u C u =5 C " ui a > o T3 v be CO '5' < CO T3 C a CO CO c»gSoo«Jtn en Oh Oi Oh Oh cc-^cDinoooco o II i-H I I I OCCCD'^CCJoil^ 00 iM;oiOCT>(Nro^ ^ II I-H I I I CO CO OJ CO 1-H O Oi I> Tji C-^ C4 "^ CQ l> eg r-l IM ^ —I ,-1 .-I ^ I-H 00 "^ CO C^ 05 oi i-i lO iri ^ t> cj c^ rt oa ^ •-! C P -♦J Sj CO 0^ O) to be C C HI O 05 00 t- CO CX) CO O lO O CO o ■^ ^ oa 05 o c^ (N CO in Ti' rH 00 00 CO ei o CM T— I T-H ^ ^ »-l CO ej 00 -^ CT5 CM_ Tf [> TT t-^ -^ C^ C4 T-H C^I T-H ,-t .— I CM rH 0< OL, rH CD in ^ CM ^ lO 00 TT CD CM CM O CD I-H I-H Oi CD ^ Oi CM CM ^ ^ CO 00 in ai 00 CD CD 00 00 cn CT> oi 00 ^H^t^COOSOO-^ t-H COi-icMCOi-icCCM CM ^H T-t CM I-H I-H ^H I-H in CM C8 6 B 3 CO 0) coco-^c^^c^i-H ^ CO'HOJCM-^COcd CO CM CM ^ ,-1 .-H rf -H CD O CD 05 t-i 05 CM_ t-^ CM O CM 00 CM CO in oi IM CO CM —1 .-H ,-1 ^ 0) bt in .-H t:~ lr~ t> ■* c^ CD t> CO CM CM CO 00 00 S| CM .-H Tf ^ CM CO CO [> o in i> CO in -^ oi in I ^ -^ (-1 ^ fer f!:; o 05 05 00 05 CM 00 00 O 00 05 05 Tf CO ;D p O 00 CO CO 05 CO g^ 00 ^ ■«< ?— 1 I— 1 ■«• CO T— t t— 1 CO d CO CM CM in ^ c ca ™ 0) c -M ™ <:o2 ZOD5= d ■a -^ p a ■s o CD 00 I> r~ cq I—i CM CO CM CM CM » ri I,'" « 13 CO O em S > ^o a !h ™ (Si a) -O ^ -^ rH ^ — T— I CJ c T3 sic o- °= -w bn CO bo.S o •S c ^ %H CO -PH O 0) CJ IH *j es a) '^ >- ^-"H cQ ^ c OJ ca CO >. K . OJ '*' I— i CS « ci -^i r O * K^ -" -O i'^ >, 1) S o S cS ^ .g ^ dj cd Cms CO CO -• *^ -n i— t jj C CO )H 03 O) CO 0) 0) r-- > '6 0 (S - '^ s s ra o J- S oj (U O _Q S S S S o CO c ^ & « S 01 a> g be >, g S C C CO "S T3 s i s E-i P.XI CO 5 6 o CO o I- CO u s X o o -4^ 1-H u a QQ 0) d A CO _3 Oh u ■« CO > -*J p< a o CJ CO to (0 o C o -s S IH O ■a ^ bo o s „ i M * z 01 c 3 XI 3 CO a ■So™—. S rt c to CO 11 G D a 6 cB C C8 c en CB W III p. C > o -a v bn ff! > < OhOh CUCUCIiCLiOh Oh Oh Oi CU Ph 05 (M 00 O lO OJ O O -H N TO ^ CO rr 1-H I I I I yj CO ^ . -H •OOJoicOCS-^COO.INCO'^OONO'H ICDllr-.CO 5'tOIII II eDCO'^tNCTSTl'-^Oa ■* j^ «3 O lO O 00 «>Z 7 ot^iooq^Or^pioai(Mcoioo^a5t>io tN-^tNodoJodc^to-^ 0[^oaoooQOoO'Xiina>o cd.odirii>iot>o-(NpiopcO'^i:~oiooocOT>iQoo>.-(0-* co^o^-^aj^'■q■^^-^c-Hi-i^t-iopoooc^;DaiOOOo-^C^lOC-;lOr£;COOOOOOOO'-H.-HCOCOOOOOO^'<^cOjjoqpTi;opoc~;iq(Mir-oa>Ortt^iO^O'-ir~ eq-^aii--i^'*jDt~-'tDr~'.'-4coTi!ot--^ocoa500ocdoiot>t--^cdcDOo C^ICOf-HCNCOi— li-Hi-HCN^i-HCOf-l T— I CO*-l'-Hi-<^'^CO oqiqini-fTfD-^coppTf csii-i-<3ioodto 1^ r- r-H 00 o CO o ™ t> oj CO ci oJ ci i-H »— I r-H CO Z i-H ^H ^t~.i---^piop<£>oq(Ncoco^oo CO C-) rt .-H rH CO c^a p M p 1-1 CO 00 t-^ oi _ _ MTr rtCN.-H.-lCvlCOZ.-l'-H.-lZ'-l ■*CDlC00Ir~„-(N'*«O 'cDoejio.cdcoiri ^ t- o CO ;o cocococsjai-^ccic^t-HT-i '^oa^oc4odaicN'-HTiH COCOr-((Naa50iM(Nc^t^ooooq'*^.-iot>coo5i>t-- ^COTj«C^C^lOp'-HCOinpppp'0>-lr-4i-((M(N(N->a" 3 c a o o CO CO CO o 00 OS C35 00 z o 0) 12 c S ID c CO "3 c O & CO u C > o he CO CO p c < o "2 03 X C a> be CO «l e o ■& ■2 'ZZ • -z 'zz 'Z ■ 'ZZ ■ -zzzzzz 'Z 'ZZ & CL, Oh P-, Ph O, CL, cu o, CJ5CT>0!NI><:OCT1C£)OCJ5 ci CO ■* O j^;qMiqc^inc~;r-;0)LqiNiqtDXio050'3<(Nt»co oc^oJcSc^iai.O(Ncoc£5o6^rHC£icd"i^*i-Hr-H^rHico- in i^(MN (XJ'^'^o^T-iiocoaso'^c^ W ■*.-l(Mt-it>oi CO o^.-i a> a cc cja6r-^cD-*oaico--iobcq ^ (M lO cq lO CO (N CO .-1 CO IM ■* - r-; CO C) lO 00 O^ 00 CO CO cx5 c^IcocO'H,-^pl^^aqoqcooqo05CO■-; co-*.-adcoiointN^oooiiDcioS COIMCO.-iCOC0-*C]IMCO(NCD— 1-* (MC~->*COoq!N.-ICOC3N'-l05IMOO)r-l 'a6-*ci-ciicoi>05-*od COtNCOi-HCOCOCOCOlMC-aeaOQCD'-i 00 OQOCO'-iOT-icq.-ilOCD-*^CJ5t>C^'-iCOOr-COaiCOCNCT>-*(>l-*^QOO^tNCO c-3^'c£)lOcDococo.-^o^o6r-^(^j^o--^c~^t^oc-4Loco^ol>^-•c3dldo6Q6t>co^^i CO^tNrH'*CO^-*t-(,-HC-(NCDCgrHT-(.-HC0 i— I i-H l-Hr-tt-H oo[>co'*coi-c-5-*(>]co(^io^ C^CX)C£jl>lO'*C^r^iO-*^T-JcO-*CTJt>-*C^t^CO'-H-*I>COt>t>-*CDOOlOCD 0].-i(N.-iCOCOCO-*(NCcdoi'*c3^cDioco ^co^coio-*-*c) (M 05 CO r- ^z a> 00 00 O 00 -* 00 CO QOr-iotDOco.-ico-*CT>rHooir-t^(Mr-iosDOOcococ3'-;t>oqc^ cocTJodcocou:Jcocor~^c^r~^oo.-<-*-q'od-^oiiricoco(Nt-^i:Dir-^io-*r-^odtDcsi (N^COIMCO-S-'J'CO^CO OJCD.-I (MC^CO "-i --H IC OJr-l C0^C£)OCDajl0O00C-OOO^-*OO^CN^(NOrHl0CDaiC-;-*aiCDt>CD -*cx)c^r-^o6(N^c£it>iou:iioc4coio^io--*cDC-^c>coio (Mt-HCOt— ICO'^CO^'-'-* (Minr-H^HCD (M C-] QO--t^f-Ht-oia5'*aiio^^oioootDcocoooco-*t^c3aio^ oc5i>^cc-*c-jododiricDod'-iir5t>ojDcio cg^coiNNcocoini-i-* csiio^ ^ co-h --h zzzzzzzzzzzzzzzzzzzzzzzzzzzz'zzzz i>omootc>]oooioi---*cj)c:5ooo-a'ioiom^ooococoooooooiMo>c~'-<3^»O(NlO^CDC0 ocDi>-*c^u:jeDc5o^c^i>co'*cDo6-*coco-*corHC^T-HO C0^t>CO IOC^T-H-*00 O^C-q.— i^^(M(N C'*l0 .-HC0COIMC^(N(N(NC0C0C0COCOCOCOCOCOC0-*-*lOlOC0l>00O5i-li-l.-<^(N(N z 1-H IN (N > "3 c CO C 13 "3 ;:> -§ e 3 C c a 6 be cS C CS c u a m i-a 1 -" Hs ?; 5 c a 0) u „ u C3 V 3 be C C C to < j= CJ -t-» B OJ o a >: -^ S o CU H a be C > o bu ca -d <: 00 -a C « 1-1 ScoggmgcogSwmcoggcnaJH zz -z ■ • -zz 'ZZ 'Z " z z ZZZ " 'ZZ Z in 05 ca X. Qj be •& I -r: oo (N 00 c- I ,-l05i>ocot-^odoJt>^Qt5odd^ooa^oooin^in-^ □ocoi3>iot>'-it--*'Oiooqqr-;'-;'*q^ iooait~^cNooio ,- T— I M T-H i-H T— I rH Oi "^ Ol 00 05 "^ o ■"TLno500oi>ooq(N ■'I' 00 O O *^ 00 - --H CO T-H CO w -*(NCOlOtO«3I>;r-;'*'-;00 I~^o6o6t>odcqo6toioo6co-*r-- T-H C^ CN T-H T— t T-H (N (N T-H T--: | t,N T— 1 __, r-^CTiod;DCO.-Hl- ^ ^ CO 5 ^ (N Z t~ca-HCj>co^cooxroaco(Mco(NtDqiniNq|jj , — (,-H^ I — ( I — ICNCNi I l-^ T— I ^ cooooocoiOooq cjiocDi?4t^cOT-HCD H r^^HC^T^Tto^qqqc^ r-^CDi-Ho6cOOO»C<75'^ T-l T-H (N CO OOl000T-Hin[^CT>'0O(N00C0in00j^ tjjcricDco^odirieq^-ooQogotDcocOT-H ^Tt^co^-H^ Z-- (N T-l (>) TT T-H O 00 T-H (N 00 coc--ci»OT-ic^a^a^io (M (N CO lO i^t>,o-Hi^t~r^oq^. oqqioqqinqqqqoqco — . - - H ir-^cood^coeNcD.-Hinai^csiO'T^c^c^^- cr.a5a5(NococoMr--i'cnooc£.>nioqc^-:-Hq(Nqq-|^c^Nc>qj^ r-cv)minoo(Moor-i?J05co05i>-;qrriqqqqqinqJ;2H COodoOCDcdoicaC^oddodcDJJi-Og^O^t-CD^OOOO^DOj-l:-^ T-l 05 00 z zzzzzzzzzzzzzzzzzzzzzzzzzzzzz SS2ggg^§SSSS^gS§SSS^S5SgS^SS2S Sc^t^°o;T-^CO0dLO^-< a; o > H < 14 o 25 scS: c CO c -s c S.fe '>^ a & -*^ "« ^ -a '53 a V c -« £. 03 O B -S S -o > bo H ^ 1 j3 c 'a 1 0! > a o c p. -a a V r ace able B B 3 a 3 QD •^ u C3 CJ "72 D a> X a c ^ 'b g o X c O E S 3 " .^ CO c o 02 r- ij ;^ 15 M u -Q C S ^ a o a g £ a -a i a c ly to he m () eat c 3 a> a; z "3 ■:= *^ c .B^ 3 c (U S _S a ^ = 1 " 'c 3 ^ X .^^ A C8 C B o Oh a 0) 5r . 0; ij c ji "t^ t. * i, T3 s 3 3 X " ^ it o i£ o _B 3 ^ ^ C 'a C3 >, c = 2 & 'S St x 'a > ■3 §-g g -§ O X a o rr O .1^ C O ^ r- >. k< X ^ o . — r -J £ St ^- a. ; ^ -S fc a = e-g 2 c = H a c X- 3^ a c __ S£ o a 5j 'x o ^ x u a> _x a a 01 c 0^ -^ K VJ J 15 Determination of Population Changes Year-to-year changes in breeding population levels were determined from comparable data (Table 1). Routes run under acceptable conditions by the same observer in successive years were deemed com- parable, and data from different observers were accepted when changes in number of doves heard did not exceed predetermined, expected values between years (Ruos 1972). Long-term population trends were determined by applying the percentage change in the BDI between successive years to a Base Year (BY) index. The year 1967 was selected as the BY for all States except Maine, New Hampshire, Rhode Island, and Vermont. The BDI's for this BY represented the mean number of doves heard on comparable routes run in 1966 and 1967 (Tables 1, 3). The four excepted States were assigned a 1971 BY index, representing the mean BDI of comparable routes run in 1970 and 1971 (Table 3). Long-term trend data have also been determined for each physiographic region. Yearly BDI's for regions were adjusted to a 1969 BY index represent- ing the mean BDI for routes accepted in 1968, 1969, and 1970 (Table 4). Determination of Changes in Factors Associated With the Survey Annual changes in the mean survey date, temperature at the start of the sur\'ey , and percentage of route listening stations with high disturbance are presented in Table 2. Analyses of these factors were similar to methods described for determining year-to- year changes in the BDI (Ruos 1972). Changes in the Grouping of Central Management Unit States Change in status of Wyoming from a nonhunting to a hunting State, and of South Dakota from a hunting to a nonhunting State, occurred in 1973. As a result, their current status is reflected in the revised groupings of States within the Central and U.S. Units. The long-term trend data presented in "Find- ings" include these States as if they had been in their current groups for the entire period ( 1964-74). Subunit indices for these groups of States differ from previous reports. However, management unit and the U.S. indices are not affected by this restructuring. Statistical Evaluation of Data The Call-Count Survey was designed to detect major year-to-year changes in the breeding popula- tion index for each management unit (Foote 1959). In recent years, analysis of data revealed that observed differences of about 8, 9, and 13% between years within the Eastern, Central, and Western Manage- ment Units, respectively, would be statisticaJly significant at the 5% level. Although the survey was not designed to detect a change between years in the BDFs of States or physiographic regions, data from these areas were also subjected to statistical analysis. Long-term BDI's, adjusted to a BY for all physiographic regions. States, and management units, were examined to determine whether signifi- cant frends were present. Trends were determined by linear regression analysis. Determination of Population Distribution The geographic distribution of dove densities has been determined from a study of BDI values adjusted to a BY for each physiographic region and State. For graphic presentation, the 1974 data have been assigned to one of five density classes (Figs. 3, 4). Changes in the adjusted BDI's greater than 10% between 1973 and 1974 within physiographic region and State also were determined (Figs. 5, 6). Findings The further recovery of the Western Management Unit population index from the 1971 low and the further decline of Eastern Management Unit indices in 1974 highlight this report. From 1973 to 1974, population indices decreased by 3% in the Eastern Management Unit, but increased by 2% in the Central Management Unit and by 21^0. in the Western Management Unit. All management unit indices for the 11-year period 1964-74 are represented by downward frends. Since 1971, however, the trend in the Western Unit has been upward. The 1974 Eastern and Central Unit indices are below their preceding 10- 3'ear means, and the Eastern Unit index is at a 21- year low. The Western Unit index for 1974 is substantially above this long-term mean. Status of the United States Dove Population In 1973, dove hunnng was permitted in 31 of the 48 contiguous States, which represent 73% of the land area and 74% of the 1974 breeding population. In 1974, the mean breeding population index was 19.4 doves per route for the United States; for hunting States it was 19.8 doves per route and, for nonhunting States, 18.5 doves (Table 1). 16 ffiifc 205^ y^,li— 0^2 # ^y Baaed upon a a^p entitled "Physical DivLalona of the United Ststea" prepared by Pennemen (1931) Bcgions arc identified by numeral codes. Fig. 2. Physiographic regions used in analysis of mourning dove population data, revised 1970. Mean doves '..eard calling per route, 3.574, adjusted to a Base Year ^.0- ''•'5 iFffll no. 0-39. 9 0 .0-!9 .9 E^£^ hO .0 + 0 .0-29.9 Fig. 3. Relative densities of breeding mourning doves by State, 1 974. 3 a ^ CN CO -* o o o o CN CM CN CN — CM n Tf in -o CM CM CM CM CN CN ^ CN CO -^ CM CN CM CS CM CN CM CN .E o Q- o o o rs T3 01 3 S ^ B f. - S t C o O X .'±-0 ^ c — o '*■ -2 X 3 U Z O Q O 17 — CM CO -^ n CO CO CO CN CM CNJ CM ■— CNCO^iO-OKO CNCNCMCNCMCNCNCN s g s 0-50 b! o ii o " o c U c 6^0 01 o 8 s ?.^ =?; -c p ^ o o , o o a: .2 ti U ,« c .5 .5 ^ -2 Z < t/i t/> loo si dd 2 t o -o c o 3 a. -^ o ~ Q. n ■D O u E 0000 •O fN. CX5 O E i O U. - o '11 M 4) C c i; = o ■o c .0 c "° 5: E - I" 5 Q_ ii> en "- o o 5: ^ .E -• — o c o E -o Q- o -g CD T3 n y ill — E .E _0 OJ 0) * 5 i; ■£ - ? ? P Q O HI U 6 0 .? o "5 S S CD I o- u < O S i 0) O 5 S :? Q. O w 0> ,0 a. ^ CM n -^ m o hv CO CO n CO CO CO n 0000000 ■— CM 10 O 00 00 CO 00 0000 •— CM CO in o o» o o- o* o 0000^ c .E .E S ° 2 c s- Q- °- 0) a :> 9 s .9 Q .E -5 -5 S ■Si w o o ^ 00^ ■> ^ Q- D D _ = 00 < U -5 — O °- ? - c J "g O c 3 c o -c -E o * i 2 ^ t 9 I i i-g> -^ o ^ (t o 0) i: 3 = i_ H) / 0 CQ > ^ -o i: < C ^ .y -SC a -c E ■■ <^ ?. ^ ^ tt) 4) Qj -^ i: n ^ ? O ^ f- r- 05.su.SuSJJzS -o < 18 Mean doves heard calling per roufe, adjusted to a ase Year ''•O "'•^f:::! 30.0-39.9 '0.0 19.9^^ 1*0.0^ 3 20 .0-29 .91 1 J ^ j I I no data Fig. 4. Relative densities of breeding mourning doves by physiographic region, 1974. Change in mean doves heard calling per route between 1973 and 1974 I — } Decrease ;>11%) n No Change ':<10%) Increase (>10%) Fig. 5. Changes in densities of breeding mourning doves by State between 1973 and 1974. / 19 Change In mean doves heard callin per route between 1?73 and r.'74 I 1 ""ecrease ;>10%) rn No Change (<10%) ^9 Increase (>10%) I I Insufficient Data Fig. 6. Changes in densities of breeding mourning doves by physiographic region between 1973 and 1974. 1974 Population Distribution The area of highest dove density was in South Dakota, Nebraska, Kansas, and Oklahoma (Fig. 3), especially in portions of the southern Great Plains and adjacent Central Lowlands (Regions 135 and 126, respectively. Fig. 2, 4). Low breeding population levels were widely distributed along the Continental Divide, throughout much of the northern Ap- palachian States, and in coastal regions of several southeastern States. 1973 to 1974 Population Changes The United States BDI increased 4.5%, from 18.6 doves heard per route in 1973 to 19.4 doves heard per route in 1974 (Table 1). Population indices increased in physiographic regions (Fig. 2) totaling 50% of the U.S. land area, decreased in 47% of the land area, and showed no change in 3% of the land area. Regions in which the population indices increased had lower mean values than regions in which the population indices decreased. This phenomenon was also evi- dent in 1973 (Ruos 19746). Changes greater than 10% in the BDI are illustrated by State (Fig. 5) and physiographic region (Fig. 6). The index increased in many of the western States, in the coastal plain of Texas and Louisiana, and in several regions east of the Appalachians. Population indices decreased in widely scattered areas of the southeastern, north- central, and southwestern States. From 1973 to 1974, the combined hunting States index increased 6.4%, and the combined nonhunting States index decreased 0.6%. Analyses of several factors associated with the 1973 and 1974 surveys revealed no important yearly differences in mean survey date, temperature at the start of the survey, or the percentage of survey stops with disturbance great enough to jeopardize the audibihty of caUing doves (Table 2). In 1974 about 9% of the survey route stops were subject to high disturbance. 1964 to 1974 Long-term Population Trends The 1974 indices for the United States, the combined hunting States, and combined nonhunting States are above their record lows established in 1970 and 1971. The 1974 population index for the United States was 1.0% below its preceding 10-year mean of 19.6 doves heard per route (Fig. 7). The current 20 _J to UJ ^ as GI ^ en > 12 ■ UN.'TCO 3'imC5 ricnizcf.rpL LINES :f;njCRic lO-rtEfi (lasn laiji mc^ns 19S4 196S 1957 1963 1369 1970 1971 1972 1973 1974 tER=l OF CBLL COUNT Fig. 7. Population indices of breeding mourning doves by management unit, 1964-74. 3C 23 25 ■■ 24 ■• NCNMUNTJNO SIftTES —I irj ■• (r rieniicr.iaL ljncs ;r.nJC07t io-tc.^^ (isbh la^sj MtSN5 19614 196S 1966 1967 1969 1969 1970 1972 1973 1974 Fig YEBR OF CRLL COUNT 8. Population indices of breeding mourning doves in hunting and nonhunting States, 1964-74. 21 30 36 a: cr CCNTHBL CCNTnBL nUKTlNC 3TBTES JiiiTra SHHfo L 1967 1969 :969 1970 •TERR CF CBLL CCUN7 Fig. 9. Linear regression lines of mourning dove call-count data, 1964-74. "ov° reec'ing Population Trend.^ Oeterm-.ned from Linear ?,egressron Significant Decline vP<.05) ^iMo Significant Change (p>.05) I Significant Increase (p<.')5) Fig. 10. Trends in mourning dove breeding populations by State, 1964-74. 22 Dove "reeding Population Trends as Deteririned from Linear !legre"&ion Analysis I i Significant Decline 'p'^.lO) I jt!o Significant Change (p>.10) ^^a Significant Increase 'p<.l^') I I Insufficient Data Fig. 11 . Trends in mourning dove breeding populations by physiographic region, 1965-74. combined nonhunting States index was also below its mean by 8.0%, whereas the combined hunting States index was 1.5% above its long-term mean (Fig. 8). Adjusted BDFs plotted in Figs. 7 and 8 reflect the trend in population indices since 1964. Linear regression analyses of these data (Table 3) are shown in Fig. 9. The incides declined at an average annual rate of 1.5% in the United States, 1.1% in the hunting States, and 2.6% in the nonhunting States. This study reveals a significant overall decline in nationwide dove breeding population between 1964 and 1974. Regression analyses of State values for the 11-year period showed seven States (21% of the land area) with significant upward trends in the population index, compared with 16 States (35% of the land area) with downward trends (Table 3, Fig. 10). A similar study of physiographic region data from 1965 to 1974 is also presented in Table 4 and Fig. 11. Population indices have been increasing over a broad area from the southern Great Plains to the Gulf Coast of Texas and Louisiana. Declining trends were prevalent east of the Appalachians, in the northern Great Plains, and in several regions of the Pacific coastal States. Status of the Eastern Management Unit Population The Eastern ManagementUnitconsistsof 27of the 48 contiguous States, including 30% of the land area and 24% of the current dove breeding population in the country. In the Eastern Unit, dove hunting is permitted in 16 States representing 66% of the land area and 73% of the estimated dove population. In 1974 the mean breeding population index was 15.7 doves heard per route for the Unit, with 17.5 doves heard per route for the combined hunting States and 12.3 doves heard per route for the combined nonhunt- ing States (Table 1). 1974 Population Distribution Extensive areas of high dove densities were reported from the Interior Plains (Regions 111, 124), Mississippi Alluvial Plain (Region 035), and Upper Atlantic Coastal Plain (Region 032). States with a mean of 30 or more doves heard per route included Indiana, Mississippi, and South Carolina (Table 3, 23 Fig. 3). Densities were generally low in the Ap- palachian Highlands, northern uplands, and the lower Atlantic Coastal Plain (Table 4, Fig. 4). Two Gulf Coastal States and nine northern States had means of fewer than 10 doves heard calling per route in 1974. warmer than in the previous survey year. There was no important difference in the percentage of high disturbance recorded per route between 1973 and 1974. The Eastern Unit had the greatest proportion of survey route stops affected by high disturbance (11.4%) of any unit in 1974. 1973 to 1974 Population Changes The Eastern Unit BDI decreased 3.1% from 16.2 doves heard per route in 1973 to 15.7 doves heard per route in 1974 (Table 1). Population indices increased in those physiographic regions (Fig. 1) representing 25% of the total land area, decreased in 70% of the area, and showed no change in 5% of the area. The most extensive area of increase was in those regions east of the Appalachians, particularly in the States of Connecticut, Georgia, Rhode Island, and Virginia. Substantially lower population indices occurred in portions of the Gulf and Atlantic Coastal Plains, and in Wisconsin (Figs. 5, 6). From 1973 to 1974 the combined hunting States index decreased 0.6% and the combined nonhunting States index decreased 9.9% (Table 1). The mean survey date was 25 May in 1974 and 28 May in 1973 in the Eastern Unit (Table 2). In 1974 the mean temperature at the start of the survey was 1.1 C 1964 to 1974 Long-term Population Trends The 1974 population indices were the lowest in 21 years for both the Eastern Unit and the combined hunting States. The 1974 index for the combined nonhunting States was the lowest since 1965. All current indices were below their preceding 10-year means, the Eastern Unit index by 11%, the combined hunting States index by 11%, and the combined nonhunting States index by 12% (Table 3, Figs. 7, 12). The negative departure of the 1974 i'ndex from the long-term mean was greater in the Eastern Unit than in the Central or Western Unit. Regression analysis shows a significant downward trend in the Eastern Unit population index between 1964 and 1974; the mean rate of decline was 1.5% per year (Table 3, Fig. 9). During the same period the combined hunting States index declined at a mean annual rate of 2.3%, whereas the combined nonhunt- ing States index increased at 0.7% per year. Long- en 30 ■■ 2G -■ CPaiEftN NONHUNIJNC 5TflTC3 pCRJlCMflL LJKtS INOICRTC IC-TCP!^ (13^^.1373) MtQN5 1964 196S laSS 1367 196'i 1969 1970 1971 1972 1973 1974 YEBR OF CBLL COUNT Fig. 12. Population indices for breeding mourning doves in the Eastern and Central Management Unit hunting and nonhunting States, 1964-74. 24 term trends by State and physiographic region are shown in Figs. 10 and 11. Only 2 States (2% of the Unit's land area) had statistically significant upward index trends, compared to 10 States (45% of the area) with downward trends. Population indices declined in all sections of the Eastern Management Unit. A significant increase in the index (48% from 1972 to 1974) occurred in the Piedmont Upland (Region 041) for the second consecutive year (Table 4). Status of the Central Management Unit Population The Central Management Unit consists of 14 of the 48 contiguous States, including 46% of the land area and 54% of the current breeding population in the country. Within the Central Unit, dove hunting is permitted in eight States representing 63% of the land area and 64% of the estimated dove population. In 1974 the mean breeding population index was 22.8 doves heard per route for the Unit; it was 23.1 doves heard per route for the combined hunting States and 22.2 doves for the combined nonhunting States (Table 1). 1974 Population Distribution Extensive areas of high dove densities were reported from the southern portion of the Great Plains and over much of the Central Lowlands (Regions 126, 135, 137). States represented by a mean of 30 or more doves heard per route included South Dakota, Nebraska, Kansas, and Oklahoma (Table 3, Fig. 3). Densities were generally low throughout much of the Rocky Mountain States (Table 4, Fig. 4). Montana and New Mexico had a mean lower than 10 doves heard per route in 1974 (Table 4, Fig. 4). 1973 to 1974 Population Changes The Central Unit population index increased 2.2% from 22.3 doves heard per route in 1973 to 22.8 doves heard per route in 1974 (Table 1). Changes greater than 10% in the breeding index are portrayed by State (Fig. 5) and physiographic region (Fig. 6). The index increased in extensive areas of the Gulf Coastal Plain of Texas and in the northwest along the Rocky Mountains and adjacent Great Plains. Areas show- ing index decreases greater than 10% include the east- central and southwestern portions of the Central Unit. From 1973 to 1974, the combined hunting States and combined nonhunting States indices increased by 1.8 and 3.0%, respectively. No important differences in survey dates and mean survey temperatures occurred between 1973 and 1974. The 1974 survey, however, was associated with less high-disturbance along survey routes than in the preceding year (Table 2). 1964 to 1974 Long-term Population Trends The Central Unit BDI increased in 2 of the last 3 years (Table 3, Fig. 7) for the first time since 1966. This evidence provides some support to the conten- tion that Unit populations may be recovering from the 11 -year decline ending in 1971. The current population index is 3% below its preceding 10-year mean of 23.4 doves heard per route (Fig. 7). Since 1964 the combined hunting States indices have remained nearly stable; the 1974 index was less than 1% below its long-term mean (Table 3, Fig. 12). The current combined nonhunting States index is 7% below the 1964-73 long-term mean, but, following four con- secutive years of increase, it is 19% above its lowest point in 1970. Regression analysis shows that a significant downward trend in breeding population indices occurred from 1964 to 1974 in the Central Unit. A similar downward trend was observed for the combined nonhunting States. No significant trend in the population indices was shown for the combined hunting States (Table 3, Fig. 9). Annual rates of change in the BDI's were determined as follows: Central Unit, down 1.3%; combined hunting States, up 0.2%; and combined nonhunting States, down 3.8%. The annual rate for nonhunting States represents the greatest rate of decline of any unit or subunit. Long-term trends by State and physiographic region are shown in Figs. 10 and 11. Three States (31% of the Unit's land area) have statistically significant upward population trends, compared with four States (29% of the area) with downward trends. Increasing trends were most prevalent in the central and southeastern portions of the Unit. A significant decrease in the index occurred in the Dissected Till Plains (Region 125) for the second consecutive year. This important region's index declined 34% from 1972 to 1974 (Table 4). Status of the Western Management Unit Population The Western Management Unit is composed of 7 of the 48 contiguous States, including 24% of the land area and 22% of the current breeding population in the country. All States in the Western Unit permit the hunting of doves. In 1974 the mean breeding population index was 17.7 doves heard per route (Table 1). 1974 Population Distribution The highest population indices of mourning doves in the Western Unit were generally restricted to the Sonoran-Mojave Desert and adjacent areas (Regions 222, 223). Two States, Arizona and Idaho, had a mean of 20 or more doves heard per route (Figs. 3, 4). Indices 25 were low throughout much of the Great Basin and Rocky Mountains. 1973 to 1974 Population Changes The Western Unit BDI increased 21.2% from 14.6 doves heard per route in 1973 to 17.7 doves heard per route in 1974 (Table 1). Population indices increased between 1973 and 1974 in physiographic regions (Fig. 2) representing 74% of the land area; they decreased in 19% of the area and did not change in the remaining 7% of the land area. The increases were important, if not spectacular, throughout most of the Unit (Figs. 5, 6). The current indices are above those of 1973 in all States except Arizona. Analyses show no important differences between 1973 and 1974 in the mean survey date or in the extent of high disturbance along routes (Table 2). The mean temperature at the start of the 1974 survey was 1.1 C cooler than in 1973. 1964 to 1974 Long-term Population Trends The population index for the Unit in 1974 was 18.8% above its preceding 10-year mean of 14.9 doves heard per route (Fig. 7). Since the record low index was established in 1971, the Unit's population index has increased a total of 46.3% (Table 3). Linear regression analysis of data from 1964 to 1974 shows a downward population index trend, with an annual rate of decline of 2.0%. Study of these long-term data shows two distinct trends. From 1964 to 1971, Unit population indices fell during each of seven consecutive years at an average rate of 5.6% per year. From 1971 to 1974, the indices increased during each of the three consecutive years at an average annual rate of 13.2% This phenomenon has not received adequate study. From 1964 to 1974, the population indices showed a significant upward trend in Idaho and Nevada, which contain 27% of the Unit's land area; the trends were downward in California and Oregon, which make up 36% of the area (Table 3, Fig. 10). Statistical Significance of Data 1973 to 1974 Population Changes A significant (P <0.05) increase occurred in the BDI of the Western Management Unit between 1973 and 1974 (Table 1). None of the indices for the other units or their combined hunting States or combined nonhunting States differed significantly (P<0.05) between these years. Although not designed to detect population changes within States, the survey showed significant (P<0.05) increases in Virginia and Wyoming. Significant (i'<0.05) decreases did not occur in any State between 1973 and 1974. A study "f physiographic region data within management units revealed a significant (P<0.05) increase from 1973 to 1974 in the BDI of the Piedmont Uplands (Region 041) in the Eastern Unit (Fig. 1). From 1973 to 1974, significant decreases occurred in the Dissected Till Plains (125) and the Ouachita Mountains (152) in the Central Unit. In the Western Unit, the population index for Region 214 in northeastern Arizona decreased between 1973 and 1974. The analyses of several factors associated with the Call-Count Survey showed that the Survey was run significantly earlier and under significantly warmer conditions in 1974 than in 1973 in both the Eastern Unit and the combined hunting States of this Unit (Table 2). Surveys were conducted earlier in 1974 than in 1973 in the United States and in the combined hunting States of the United States. No other statistically significant (P<0.05)differences occurred between years for any unit or subunit in the analysis of mean survey date, temperature at start of survey, or percentage of high disturbance along survey routes. 1964 to 1974 Long-term Population Trends Linear regression analyses of the 1964-74 data revealed significant (P<0.05) downward trends in BDI's for the Eastern, Central, and U.S. Units, as well as for the combined hunting States of the Eastern Unit, combined nonhunting States of the Central Unit, and combined nonhunting States of the United States (Table 3). No significant trend was established for the Western Unit, the combined nonhunting States of the Eastern Unit, the combined hunting States of the Central Unit, or the combined hunting States of the United States. Although no 11- year trend was determined for the Western Unit, the data from 1964 to 1971 was represented by a significant (P< 0.05) downward trend, and data from 1971 to 1974 by a significant upward trend. Analyses of long-term data by State (Table 3) revealed that seven States representing 21% of the Nation's land area had significant (/'<0.05) upward population trends between 1964 and 1974. Sixteen States, totaling 35% of the land area, had significant long-term downward population trends (Table 3, Fig. 10). From 1965 to 1974, 13 of 79 physiographic regions, comprising 18% of the total land area, had significant (P<0.10) upward trends, and 19 regions, encompassing 23% of the land area, had significant (P<0.10) downward trends (Table 4, Fig. 11). For the second consecutive year, the population index for Region 041 increased significantly (P<0.05), and the index for Region 125 decreased. 26 Acknowledgments This report would not be possible without the cooperation of the State conservation departments and the many individuals who conscientiously assisted in collecting data. Preparation of this report represents a combined effort; special recognition is extended to F. R. Fiehrer for programming assistance, K. Munson for secretarial support, and to P. Hochman and C. E. Colgan for assistance in quality-checking field reports and for cartographic services. References Fenneman, N. M. 1931. Physiography of western United States. McGraw-Hill Book Co., New York. 534 pp. Foote, L. E. 1959. A sampling design for mourning dove call counts. A report to the Bureau of Sport Fisheries and Wildlife, U.S. Fish and Wildlife Service, from The Wildlife Management Institute. (Unpublished report.) December. 47 pp. + 24 tables + appendix. Foote, L. E., and H. S. Peters. 1952. Investigations of methods of appraising the abundance of mourning doves. U.S. Fish Wildl. Serv. Spec. Sci. Rep.— Wildl. 17. Spec. Sci. Rep.— Wildl. 17. Ruos, J. L. 1972. Mourning dove status report, 1971. U.S. Bur. Sport Fish. Wildl. Spec. Sci. Rep.— Wildl. 158. 40 pp. Ruos, J. L. 1974a. Mourning dove status report, 1972. U.S. Bur. Sport Fish. Wildl. Spec. Sci. Rep.— Wildl. 176. 35 pp. Ruos, J. L. 19746. Mourning dove status report, 1973. U.S. Fish Wildl. Serv. Spec. Sci. Rep. Wildl.— 186. 36 pp. Stone, C. P. 1966. A literature review on mourning dove song as related to the coo-count census. Colo. Dep. Game Fish Parks Spec. Rep. 11. 29 pp. As the Nation's principal conservation agency, the Department of the Interior has responsibiUty for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration. GPO 837 - 837 EDITORIAL OFFICE US. FISH AND WILDLIFE SERVICE AYLESWORTH HALL. CSU FORT COLLINS, COLORADO 80523 POSTAGE AND FEES PAID U S DEPARTMENT OF THE INTERIOR INT 423 NOTE: Mailing lists are computerized. Please return address label with change of address.