The Effect of Disturbance on Mourning Dove Nesting Success

THE EFFECT OF DISTURBANCE ON MOURNING DOVE NESTING SUCCESS

DAVID WESTMORELAND AND LOUIS B. BEST Departmentof Animal Ecology,Iowa State University,Ames, Iowa 50011 USA

ABSTRACT.--Disturbedand undisturbed Mourning Dove (Zenaidamacroura) nests were comparedfor differencesin daily survivalprobabilities and discrepanciesin the relationships between nest-sitefeatures and nesting outcome.At 3-day intervals, attending adults were flushed from disturbed nests(n = 51), whereas undisturbed nests(n = 50) were checkedfrom a distanceso that adultsdid not flush.Disturbed nests had significantly(P < 0.1) lower daily survival probabilities;this trend was evident during both the incubationand nestling stages, but was significantonly during the former. For disturbednests, two nest-sitefeatures (nest- bowl depth and nest support)were related to success(P < 0.1). In contrast,success of undisturbednests was relatedto four variables(substrate height abovenest level, relative light intensity above the nest, nest concealment,and nest width). These results indicate that standardnest-checking procedures influence nesting success and confoundinterpretation of relationshipsbetween nest-site features and nesting outcome. Received10 December1984, accepted30 April 1985.

MANY studies of the relationship between find nests, the value of concealment under nat- nesting successand nest-sitefeatures have re- ural conditions may be obscured.In the sum- suited in conflicting findings. For example, mer of 1983, we tested this hypothesiswith some authors (Meanley and Webb 1963, Hol- Mourning Dove nests.Any negative effect that comband Twist 1968) have reportedthat nest- nest checkshave on nestingsuccess should be ing successfor Red-winged Blackbirds (Age- particularlyevident for this speciesbecause the laius phoeniceus)is positively related to nest adults have noisy wingbeats [sometimes ac- height, whereas others have found a negative companiedby a distractiondisplay (Nice 1923)] relationship (Goddard and Board 1967, Ortego when flushed from the nest, and the eggsare and Hamilton 1978) or none at all (Francis 1971, noncryptic (white). The former could direct a Lenington 1980). Similar contradictoryresults predator's attention to the nest vicinity, and have been reported for Field Sparrows(Spizella the latter probably makes the nest more con- pusilla;Best 1978, Evans 1978) and Mourning spicuous.Under natural (undisturbed) condi- Doves (Zenaida macroura;Nice 1923, Schroeder tions, Mourning Doves attend the nest contin- 1970). Although researchershave studied sev- uously (Harris et al. 1963). eral bird speciesin diverse settings,most have Bart (1977) examined nest records for found no relationship between nest conceal- Mourning Doves and found evidence that ment and nestingsuccess (Roseberry and Klim- nesting successis reduced by researcherdis- stra 1970, Caccamise 1977, Best 1978, Gottfried turbance,but his results also can be explained and Thompson 1978, Best and Stauffer 1980, by reporting bias(Bart and Robson1982). Nich- Lenington 1980;but seeNolan 1978,Wray and ols et al. (1984) reported that daily vs. weekly Whitmore 1979, Murphy 1983). Becausepre- visits to Mourning Dove nests did not differ- dation often is the major causeof nest failure entially affectnesting success, but they did not in avian communities (Nolan 1963, Best and study undisturbed nests. Our objectiveswere Stauffer 1980), one would expect concealment to comparenesting successbetween disturbed to have a direct causal effect on nesting out- and undisturbed nests and to determine if dis- come. turbance obscuresrelationships between nest- The reason nest-site features often seem un- site featuresand nesting outcome. related to nesting successmay be that research- STUDY AREA AND METHODS er disturbance confounds the normal relationship between nest microhabitat and nesting The study was conductedfrom May through Au- outcome.If nest checksprovide additional cues gust 1983at Big Creek StatePark, Polk County, Iowa. or enhance existing cues that predatorsuse to A 110-ha sectionof the park containsseveral kilo-

774 The Auk 102:774-780. October1985 October1985] Disturbanceand Nesting Success 775 meters of windbreaks; each windbreak consists of a lesseggs or nestlingswere found on the groundbe- multiflora rose (Rosa multiflora) hedge flanked on one neath the nest. When the nest structure was dam- or both sidesby double rows of jack pine (Pinusbank- aged,we consideredmammals responsible. If the nest siana)or white pine (P. strobus).Most trees are less was intact, the failure was attributed to arian pred- than 6 m tall, and land use between windbreaks is ators. Snakesand chipmunks(Tamias striatus) were rotated between corn, alfalfa, oats, or nonuse. The rare in the study area, and we discountedthe impor- windbreaks are spacedat intervals of about 60 m. tanceof small nocturnal mammals(mice, shrews,etc.) Easternred cedar (Juniperusvirginiana) is a common becauseat least one adult dove was always present invader in perennially uncultivated areas. at the nest overnight. We located nestsby walking between pine rows To comparedifferences in nestingsuccess, we cal- and flushingnesting parents. All rowswere searched culatedthe daily nest survival probability (Mayfield weekly, and uncultivatedfield edgeswere searched 1975) and applied the statisticaltest developedby irregularly. When nests were discovered,we deter- Henslet and Nichols (1981). For these we used one- mined the age of eggsor nestlingsby using the de- tailed testsat a rejectionlevel of P < 0.1. This relaxed scriptionsin Hansonand Kossack(1963). We consid- rejectionlevel increasesthe power of the test (Hen- ered a nestingcycle initiated on the day the first egg sler and Nichols 1981) and has been the convention was laid. Nestswere randomly assignedto either dis- of previousresearchers (Coon et al. 1981,Nichols et turbed or undisturbed treatments. For the disturbed al. 1984). We used t-tests to compare nest-site vari- treatment,we approachednests directly, flushedthe ables between successful and unsuccessful nests attendingadult, and examinedthe nest contents.We within eachtreatment; a P < 0.05 rejectionlevel was checkedundisturbed nests from a distance(usually used for these analyses. >10 m) so that the attending adult did not flush. Mourning Dovescontinuously attend the nest until RESULTS the young are near fledRing age (Nice 1922),so pres- ence of an adult was taken as evidence that the nest Of the 150 nests found, 32 failed and 13 were wasstill active.In the latter half of the nestling stage, abandoned between initial discovery and the we often could see the nestlings directly. first revisit. We eliminated 4 additional nests Nestsin both treatmentswere checkedevery 3 days; from the undisturbed category becausethey when a nest failed, we assumed that it had survived could not be checkedwithout flushing the par- for 1.5 daysafter the previousvisit. Becauseall nests ent. The remaining 101 nests were used for were disturbed when discoveredinitially, we elimi- analyses.Median clutch age at discovery for natedfrom analysesall data for the interval between nest discoveryand the subsequentvisit. Nests that these nests was 5 days. failed during this periodwere not usedin analyses. Forty-three percent of all (101) nestssuccess- After a nest failed or the young fledged, we re- fully fledged at least one young; the daily s•r cordedthe speciesand height of the nest substrate, vival probability for all nests combined was nest height above the ground, nest width, depth of 0.946,yielding a nesting-successestimate of 21% the nest bowl, horizontal distance from the nest to for a 28-day nesting cycle. We attributed 79% the periphery of the substratecanopy, and, as an in- of the nest failures to avian predation. Doves dex of nest support, the total (sum) diameter of nested primarily in jack pine (61% of nests), branchessupporting the nest. Nest-bowl depth was multiflora rose (13%), and eastern red cedar measuredby placing a straightedgeacross the nest (8%). The remaining nestswere placed in elm and recordingthe perpendiculardistance from it to the center of the nest. The substrate height above (Ulmusspp.), mulberry (Morusspp.), and honey nest level was calculated from nest and substrate locust (Gleditsiatriacanthos) trees and in various height measurements.Visual concealment at nest shrubs.Daily nestsurvival probabilities did not level was rated aspoor, fair, good,or excellent(yield- differ (P > 0.1) among the three primary sub- ing valuesof 1-4, respectively).These estimates were strates(treatments pooled). made about 5 m from the nest in each of the four Effectsof disturbanceon nestingsuccess.--Thir- cardinal directions; the mean was used as an overall ty-sevenpercent of disturbednests and 50%of index of concealment around the nest. We estimated undisturbed nests were successful.Daily nest concealmentabove the nest by recordinglight inten- survival probabilitieswere significantlylower sity immediately above the nest and expressingit as for disturbed nests (P < 0.1); this trend was a percentageof ambient light intensity. We considereda nesting attempt successfulif the presentduring both the egg and nestlingstages, young survived to 10 days of age (Coon et al. 1981, but was significantonly during the former (Ta- Nichols et al. 1984). Nestlings usually remain in the ble 1). By Mayfield estimates,disturbed nests nest until age 13-14 days but will fledge at 10 days were about 50% as successful as undisturbed if disturbed.Failures were attributed to predatorsun- nests. 776 WESTMORELANDANDBEST [Auk,Vol. 102

TABLEi. Nesting successestimates for disturbedand undisturbedMourning Dove nests.

Daily nest survival Estimated Nests No. of failures probability success' Incubation Disturbed 43 15 0.943 + 0.014 *• 44% Undisturbed 42 9 0.966 + 0.01! 62% Nestling period Disturbed 36 17 0.926 + 0.017 34% Undisturbed 41 16 0.947 + 0.013 47%

Combined Disturbed 5! 32 0.935 + 0.0!!* !5% Undisturbed 50 25 0.956 + 0.0! 29% Basedon incubationand nestlingperiods of !4 dayseach. * = significantdifference between disturbed and undisturbednests at P < 0.!.

Daily nest survival probabilities were lower tions were comparable.Also, there was no dif- during the nestling stage than the egg stage ference (P = 0.68) between treatments in the (Table 1). The data are biased, however, be- mean age of clutcheswhen nests were discov- cause we did not include nests that failed be- ered. Treatments did differ, however, with re- tween initial discoveryand the first revisit; most spect to which variables were related to nest- of these failures occurred during incubation. ing success(Table 2). For undisturbed nests, Other researchershave shown that Mourning four variables were significantly (P < 0.05; Dove clutchesare more likely to survive the substrateheight above nest level, nest width) nestling period than the incubation period or nearly significantly (P < 0.1; relative light (Harris et al. 1963, Caldwell 1964, Schroeder intensity, nest concealment)related to success. 1970, Best and Stauffer 1980). In contrast, two other variables were signifi- Nest reuse.--About 13% of the nests had been cantly (nest-bowldepth) or nearly significantly used in previous nesting attempts; 5 were (nest support) related to outcomeof disturbed reused dove nests and 8 were nests of Common nests. Grackles (Quiscalusquiscula), American Robins (Turdusmigratorius), or Red-wingedBlackbirds. DISCUSSION Nest reusedid not increasenesting success(see also Woolfenden and Rohwer 1969); the daily Effectsof disturbanceon nestingsuccess.--Wil- survival probability was 0.963 for reusednests lis's (1973) study of BicoloredAntbirds (Gym- and 0.956 for new nests (P = 0.68, treatments nopithysleucaspis bicolor) is frequently cited as pooled). Nest reuse probably is a time-conserv- evidencethat nest checksdo not affectnesting ing adaptation for this multibrooded species outcome, but researchers should be aware that (Woolfenden and Rohwer 1969). speciesseem to differ in their responseto vis- Reused nests that had been built by other itation. Among solitary-nesting species, nest species were significantly (P < 0.05) wider visitation has been reported to have no effect (147 + 9 mm; compare with values in Table 2), (e.g. Evans and Wolfe 1967, Roseberry and deeper (25 + 3 mm), and had more branch sup- Klimstra 1970), negative effects (e.g. Bowen et port (74 + 18 mm) than new nests.In the fol- al. 1976, Macinnes and Misra 1972), or even lowing analyses,we eliminated data for inter- positive effects (Osborne and Osborne 1980). specificnest reusesfrom nest width, nest-bowl Our results conflict with those of Nichols et al. depth, and nest support becausethey caused (1984), who found that daily vs. weekly visits skewed distributions for these variables. did not differentially affect Mourning Dove Relationshipbetween nest-site features and nest- nesting successin Maryland. These contrasting ing success.--Mourning Dove pairs in each resultsmay have arisen becausethe two study treatment used similar nesting sites; no mea- siteshad different predatorcommunities. At Big suredvariables differed significantly(P > 0.05) Creek State Park, avian predatorscaused most between treatments, and the standard devia- nest failures; in contrast,the Maryland study October1985] Disturbanceand Nesting Success 777

T^I•I•E2. Relationship between nest-site features and outcome for disturbed and undisturbed Mourning Dove nests.Values representmeans + SE.

Disturbed nests Undisturbed nests

Successful Failed Successful Failed Nest-site variable (n = 19) (n = 32) pa (n = 25) (n = 25) Nest height (m) 1.4 + 0.I 1.6 + 0.2 0.28 1.6 + 0. I 1.5 + 0.I 0.47 Substrateheight above nest level (m) 1.8 + 0.2 2.3 + 0.3 0.16 3.0 + 0.4 2.0 + 0. I 0.04 Distanceto substrateperimeter (cm) 85 + 5 99 + 11 0.28 96 + 9 96 + 6 0.99 Relative light intensity (%) 20 + 3 21 + 4 0.86 15 + 2 20 + 2 0.08 Nest concealment 2.7 + 0. I 2.8 + 0.2 0.90 2.9 + 0.I 2.6 + 0.I 0.09 Nest width (ram)b 124 + 4 118 + 3 0.23 128 + 4 113 + 3 0.005 N•st-bowl depth (ram)b 12 + 2 17 + 1 0.08 16 + I 16 + I 0.89 Nest support (ram)b 30 + 4 46 + 7 0.05 49 + 9 37 + 5 0.24 Probabilities based on Student's t-tests. Does not include 8 reusednests of other species. site had avian, mammalian,and reptilian nest failures.The height of substrateabove nest level predators. Exposed Mourning Dove clutches was not related to the success of disturbed nests. probably would be more susceptiblein areas We believe this was becausepredators often where avian predationis dominant,simply be- saw us flush adults from nests. Once the nest causebirds rely heavily on sight to locateprey. vicinity was located,vegetation above the nest Mammals, especiallynocturnal species,rely to probably would have had little effect on the some extent on olfaction, and reptiles seem to nest being discovered. be opportunistic(Best 1978). Two variablesrepresenting nest visibility-- If researcher-induced nest failures are com- relative light intensity and nest concealment-- mon in Mourning Dove studies,some reported were significantly correlated to one another productivityestimates for this speciesprobably (Table 3) and may have been relatedto the out- are unrealisticallylow. In our study,productiv- come of undisturbed nests, but were not relat- ity of undisturbednests, based on Mayfield es- ed to the outcome of disturbed nests (Table 2). timates, was almost twice that for disturbed Undisturbed nests that failed were less con- nests.When estimatesare based on the per- cealedand more openly exposedto light than centage of nests that are successful,however, successful nests. These relationships ap- at least part of this bias may be compensated proachedstatistical significance and probably for becausesuch estimatesare likely to be ar- are biologicallymeaningful. tificially high (Miller and Johnson1978). In both treatments, successful nests were Relationshipbetween nest-site features and nest- wider than those that failed; the difference was ing success.--Undisturbed,successful nests had significant,however, only for undisturbednests significantly more substrateabove nest level (Table 2). Nest width was not correlated with than those that failed. This variable was not nest support or any other nest-sitefeature (Ta- correlatedwith relative light intensity (Table ble 3). One explanationof the greaterwidth of 3), so it evidently was not an index of visual successfulnests may be related to the duration obstructionby canopy vegetation above the of nest construction. Some columbids continue nest.Nests with more substrateabove them may to add material to the nest late into the nesting have been more successfulbecause they were cycle (White 1975).If Mourning Doves do also, positionedat a greaterdistance from predators or if nestsare flattened by the continued pres- that moved through the upper canopyor that ence of adults, successful nests would be wider flew over nest trees. On our study area, the simply becausethey were attended longer. We most frequently observed predators were testedthis by regressingnest width on the age American Crows (Corvusbrachyrhynchos), which (as determinedby egg or nestling•ievelop- are known to prey on Mourning Dove clutches ment) of nests that failed. [Becausesuccessful (Grau 1979). Red-winged Blackbirdsand Com- nestswere larger and alwaysat the upper limit mon Grackleswere abundanton the studyarea of the nest age distribution (24 days old), in- and might have been responsiblefor somenest cluding them would have caused an a priori 778 WESTMORELANDAND BEST [Auk, Vol. 102

TABLE 3. Correlation matrix of nest-site variables. a

NH SANL DTSP RLI NC NW NBD NS Nest height 1.00 Substrateheight above nest level 0.44* 1.00 Distance to substrate perimeter 0.37* 0.47* 1.00 Relative light intensity 0.21' 0.08 0.04 1.00 Nest concealment -0.17 -0.38* -0.35* -0.38* 1.00 Nest width b -0.04 0.05 -0.01 -0.01 0.04 1.00 Nest-bowl depthb 0.20* 0.02 0.11 0.09 0.03 0.18 1.00 Nest support• 0.17 0.33* 0.23* -0.14 -0.30* 0.01 0.04 1.00 '*=P<0.05. Does not include 8 reusednests of other species. significant relationship between nest age and tween studies or have not been detected pre- width. We reasoned that if nests become wider viously. Nice (1922) noted that nestsbuilt in by continued use or through the addition of crotches of trees were twice as successful as twigs, a trend of increasing nest width with those farther out on branches, but Schroeder nest age should be discernable even for nests (1970) found that nestsin crotcheswere subject that failed.] Although there was a good distri- to rain-soaking.In Minnesota farmsteadshel- bution of ages for nests that failed (n = 43, terbelts, Yahnet (1983) found no relationship range 5.5-24 days),the regressionwas nonsig- between Mourning Dove nesting successand nificant (r2< 0.01, P = 0.89), indicating that five nest-site variables similar to those we mea- nestsdid not increasein width during the nest- sured. ing cycle. We do not understandwhy wider We know of only one other study of the ef- nests are more successful, but the trend has oc- fect of disturbanceon the importance of nest- curred again in data from the 1984 field season. site features, and the results were similar to In addition to obscuringthe relationship be- ours. In England, Osborneand Osborne (1980) tween nest microhabitatand nesting outcome, comparedEurasian Blackbird (Turdusmerula) researcherdisturbance may accentuatethe im- nestsplaced near areasheavily visited by hu- portance of nest-site features that otherwise mans with those away from frequent human would be unrelated to nesting success.Dis- contact.Nest height and relative light intensity turbed, successfulnests had less branch sup- were related to outcome of nests away from port than disturbed nests that failed, and the disturbance, but no nest-site features affected relationship between nest-bowl depth and successof nests near human activity. In con- nesting successapproached significance (Table trast to our results,they found that nestsnear 2). We cannot explain why these variables human activity had greater success,probably would be related to the outcome of disturbed becausepredators avoided human contact. Thus, nests. No nests were lost due to severe weather, although disturbanceevidently has a different so variablespotentially influencingnest stabil- effecton nestingsuccess in EurasianBlackbirds ity probably were of minor importance. Also, and Mourning Doves, for both speciesit con- reduced nest support probably increasednest founds researchers'attempts to discern rela- visibility from below. Coon et al. (1981) found tionshipsbetween nest-site features and nest- that nest stability was positively related to ing success. Our understanding of the Mourning Dove nesting success;thus, their re- relationshipsbetween breeding success,nest- suitsseem to contradictour findings. Perhaps site selection,and predationmay be distorted the relationship between nest support and by too-frequentnest visitation. nesting successin our study is spurious;such a Type I error has a 56% probability of occur- ACKNOWLEDGMENTS ring in a series of 16 t-tests. We thank James Dinsmore, James Nichols, Linda Researcherdisturbance may be the reason Southern, and an anonymous reviewer for critical that nest-sitefeatures important to Mourning evaluationsof earlier drafts. Robert Thompson was Dove nesting successeither have differed be- an untiring field assistant,and we are grateful to the October1985] Disturbanceand Nesting Success 779 personnel at Big Creek State Park for allowing free estimators and simulation results. Wilson Bull. accessto the study area. The study was supportedby 93: 42-53. a grant from the Max MacGraw Wildlife Foundation. HOLCOMB,L. C., & G. TWIST. 1968. Ecologicalfactors This is Journal Paper No. J-11691of the Iowa Agri- affecting nest building in Red-winged Black- culture and Home EconomicsExperiment Station, birds. Bird-Banding39: 14-22. Ames, Iowa, Project No. 2168. LININGTON,S. 1980. Female choice and polygyny in Red-wingedBlackbirds. Anim. Behav.28: 347- 361. LITERATURE CITED MACINNES, C. D., & R. K. MISRA. 1972. Predation on Canada Goose nests at McConnell River, North- BART,J. 1977. Impact of human visitationson avian west Territories. J. Wildl. Mgmt. 36: 414-422. nesting success.Living Bird 16: 187-192. MAYFIELD,H. F. 1975. Suggestionsfor calculating --, & D. S. ROBSON.1982. Estimating survivor- nesting success.Wilson Bull. 87: 456-466. ship when the subjectsare visited periodically. MEANLEY,B., & J. S. WEBB. 1963. Nesting ecology Ecology 63: 1078-1090. and reproductiverate of the Red-wingedBlack- BEST,L.B. 1978. Field Sparrow reproductive success bird in tidal marshesof the upper Chesapeake and nesting ecology. Auk 95: 9-22. Bay region. ChesapeakeSci. 4: 90-100. --, & D. F. STAUFFER.1980. Factors affecting MILLER,H. W., & D. H. JOHNSON.1978. Interpreting nesting successin riparian bird communities. the resultsof nestingstudies. J. Wildl. Mgmt. 42: Condor 82: 149-158. 471-476. BOWEN,D. E., R. J. ROBEL,& P. G. WATT. 1976. Hab- M•RPH¾,M.T. 1983. Nest successand nesting habitat and investigatorsinfluence artificial ground its of EasternKingbirds and other flycatchers. nest losses: Kansas. Trans. Kansas Acad. Sci. 79: Condor 85: 208-219. 141-148. NICE,M. M. 1922. A studyof the nestingof Mourn- CACCAMISE,D. F. 1977. Breeding successand nest ing Doves. Auk 39: 457-474. site characteristicsof the Red-winged Blackbird. Wilson Bull. 89: 396-403. 1923. A studyof the nestingof Mourning Doves. Auk 40: 37-58. CALDWELL,L. D. 1964. Dove production and nest NICHOLS,J. D., H. F. PERCIVAL,R. A. COON, M. J. site selection in southern Michigan. J. Wildl. CONROY,G. L. HENSLER,& J. E. HINES. 1984. Ob- Mgmt. 28: 732-738. 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Reproductive successof Red-winged Blackbirdsin north cen- OSBORNE,P., & L. OSBORNE. 1980. The contribution tral Oklahoma. Wilson Bull. 79: 283-289. of nestcharacteristics to breeding-successamong GOTTFRIED,B. M., & C. F. THOMPSON.1978. Experi- Blackbirds Turdus tnerula. Ibis 122: 512-517. mental analysisof nest predation in an old-field ROSEBERRY,J. L., & W. D. KLIMSTRA. 1970. The nest- habitat. Auk 95: 304-312. ing ecologyand reproductiveperformance of the GRAU, G. A. 1979. Crow predation on attended Eastern Meadowlark. Wilson Bull. 82: 243-267. Mourning Dove eggs.Jack-Pine Warbler 57: 169. SCHROEDER,M. H. 1970. Mourning Dove produc- HANSON, H. C., & C. W. KOSSACK. 1963. The Mourn- tion in a Kansasosage orange planting. J. Wildl. ing Dove in Illinois. Illinois Dept. Conserv.Tech. Mgmt. 34: 344-348. Bull. 2. WHITE,S.J. 1975. Effectsof stimuli emanatingfrom HARRIS, S. W., M. A. MORSE, & W. H. 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unvisited nests of Bicolored Antbirds. Auk 90: tation on nesting successof Vesper Sparrows. 263-267. Auk 96: 802-805. WOOLFENDEN,G. E., • S. A. ROHWER.1969. Breeding YAHNER,R. I-I. 1983. Site-relatednesting successof birds in a Florida suburb. Bull. Florida State Mus. Mourning Dovesand AmericanRobins in shel- 13: 1-83. terbelts. Wilson Bull. 95: 573-580. WRAY,T., & R. C. WHITMORE.1979. Effectsof vege-

The RaptorResearch Foundation is interestedin identifyingorganizations whose major purpose is to deal with someaspect of the life of raptors.It is RRF'sintent to compilethe resultsand provideeach responding organizationwith a copy of this documentto facilitate communication,and to make it available to other organizations(e.g. wildlife or conservationagencies, funding agencies). Officersof organizationsare asked to submit the following information for inclusion in A Directory of Raptor Organizationsof the World: officialorganization name, address (permanent address, if there is one), brief statementof purpose,approximate number of members,major area(s)of interest (e.g. basicresearch, captivebreeding, conservation, education, falconry, general aspects, raptor movementor rehabilitation),and name and official positionof respondingindividual. This information shouldbe forwarded (on an organi- zational letterhead,if one is available)to: Richard J. Clark, Vice President,Raptor ResearchFoundation, Inc., Departmentof Biology,York Collegeof Pennsylvania,York, Pennsylvania17403-3426 USA.