THE
AUK:
A QUARTERLY
JOURNAL
OF
ORNITHOLOGY.
•7OL.'XXXIX. A STUDY
OF
OCTOBER,1922. THE
NESTING
OF
MOURNING
No. 4 DOVES.
BY MARGARET MORSE NICE.* Plate XVIII.
THE campusof the University of Oklahomais a particularly favorableplacefor the studyof the nestingof the WesternMourning Dove (Zenaiduramacrouramarginella),for great numbersof this bird breed here. In August and September1919, we found 37 nests, during the seasonof 1920 we located 124 nests, and in April, May and September1921, 122. This study deals not with intensive observation of individual birds, but with statistics
on thesenests,the numbersof whichwerelarge enoughto enable us to make averagesand draw somegeneralconclusions. Norman is situated almost in the center of Oklahoma, its eleva-
tion is 1170feet, andthe yearlyrainfallvariesfrom30 to 35 in&es. The countryis levelprairie,nowlargelyundercultivation,and almostthe onlyindigenous treesgrowalongthe creekbeds. Boththe townandthe campusof the Universityhave beenliberallyplanted with trees,mostlyelmsand locusts,few of whichare older than * I wish to acknowledge my indebtedness to my husband, Dr. I•. B. Nice, who went on many searches for Dove nests and to my daughter, Constance, who, with her unquencbable zeal for climbing the trees, was of indispensable assistance to
me.
457
458
N•cg,Nes•in# ofMournin# Doves.
[Auk toc;.
25 years,and most are younger. The Mourning Dovesevidently prefer the grove environmentof the campusto the same kind and sizesof treeson the streetsof the town,for, althoughwe have been on the lookout for nests of these birds wherever we have
been,in 1919,89 per cent of all nestsseenwereon the University grounds,and in both 1920 and 1921, 92 per cent were in this situation.
In orderto avoid confusionamongso many nests,I gradually evolvedan elaboratesystemof recordsdependingon a map of the campus, 10.5 X 14 inches in size, and a large notebook. I dividedthe campusinto 26 divisions,eachbeingdesignatedby a letter; then on the map I marked the locationof each nest by a nmnber, using a new-map each month and sometimesoftener. The notebook was divided into squares with columns for the number of the nest, its location on the earnpus,the kind of tree, heightfrom the ground,positionin a crotchor on a branch,and any peculiarity of the nestor parents. The rest of the columns were headedby the dates and hoursof visit, and under each date it was noted whether the parent was brooding,the contents of the nest, if examined,behaviorof the parents,size and position of the young, etc., or the fact of the destructionof the nest. 1. THE
NEST.
Building the Nest. Nest building as a rule takes place in the early morning. The male Mourning Dove gathersthe materials and eartiesthem to his mate who arrangesthem. He takes one pieceat a time, and if he happensto drop it, he doesnot stop but continueshis journeyto the tree and then starts over again. Dr. Chas.Whitman• says:"All pigeons,so far as I know',carry but onestrawat a time; the sparrow,on the other hand, loads itself up with as many piecesas it can hold in its mouth, and thus savestrips to the nest. * * * In this simpledifferenceof methodwe seea wide differencein intelligence." This laborious practiceof onestraw'at a timeisprobablyonereasonwhyDoves' nestsare suchpoor affairs. • Behavior of Pigeons III,
1919, p. 22.
Vol. XXXIX]
1922 J
NICE, Nestingof Mourning Doves.
459
Material. The nests of Mourning Doves are notoriouslyfrail structures,being simple platforms of dead grass,weeds,etc., and a few twigs. In three or four instancesonly, have the nestshere in Norman beenso scantythat the eggscouldbe seenthroughthe bottom.
I examined the materials in three typical nests that had been
deserted. Nest 7, found desertedApril 23, 1921, with one punctured eggin it, was situatedin a crotchof an ehn 12 feet from the ground. The materialsconsistedof 6 twigsfrom 1 to 6 inches long and 148 piecesof dried grass,4 of which were from 15 to 18 incheslong, 33 from 8 to 6 inches,27 about 6 inchesand 84 were smaller.
Nest 33, on May 4, containedtwo eggs,while on May 9 it was empty. It wasin a crotchof an ehnon a very old Robin'snest,12 feetfromtheground. The materialswere3 twigs,1 to 2 incheslong, 10 weedstems,4 to 10 incheslong, and 145 piecesof dried grass,3 of which were about 12 incheslong, 28 varied from 6 to 10 inches, 34 were about 4 incheslong and 80 were smaller. Nest 41 was in processof constructionMay 9; containedtwo small youngMay 26, but wasemptythe next day. It wassituated on the branch of an ehn 10 feet from the ground. It was more substantial than the others and was made of 3 twigs about 8
incheslong, 1 tiny twig, 40 pleeesof dried grassstemsand grass roots,20 wild geraniumstems,40 pepper-grass stemsand 31 little piecesof weedand grass--135piecesin all. Many of the smallestpieceswere doubtlessfragments of the originalmaterialsgathered,althoughthe first two nestshad not been usedfor long. If we assumethat thesesmallestpiecesrepresenttwo or three times as many piecesas were carried to the nest, we would have from 87 to 115 piecescarried to the first two nests, that were placed in crotchesand from 115 to 120 to the last nest that was in a more exposedsituation. TreesChosen. In 1919,we found 22 Dove nestsin elms,10 in locusts,4 in osageorange,onein a box elderand onein a walnut; in 1920there were68 Dove nestsin elms,25 in locusts,14 in osage orange,4 in apples,3 eachin cedarsand box elders,2 in walnuts and one in a maple. In 1921 therewere79 in ehns,10 in locusts, 16 in osageorange,3 eachin maplesand walnuts,2 eachin eider
460
NicE,Nesting ofMourning Doves.
[Auk toct.
and Russianmulberry,and one eachin an appleand pine. The Doves seemto have nestedabout equally in all kinds of trees in proportion to their number except that silver maples (Acer saccharinurn) of whichtherearemanyonthe campus,are evidently not liked. Cottonwoods are avoided entirely so far as our experiencegoes. In 1921the Doves utilized elmsmore and locusts lessthan the year before,which was probablydue to a late frost that killed the locustbudsand delayedtheir leatingout for nearly a month. (In 1920 the first nest in a locustwas found April 18, but in 1921 none was seenuntil May 3, at which time thesetrees were in fairly full leaf.) Height of Nests. Only twice in Norman have we foundDove nestson the ground. One of these was located in a cornfieldin June 1917, while the other, which was on the campus,contained eggsJune 8, 1919. The following table gives the numbers and percentagesof nestsfound on the campusin 1920 and 1921 at different heights. TABLE I.
HEIGHT OF MOURNING DOVE NESTS FROM THE GROUND. 1920
1921
Height in feet Number of Nests Per Cent 3-6 8-10 12-20 25-30
12 31 72 7
9.9 25.4 59.0 5.7
122
100.0
Number of Nests Per Cent 0
0
36
30.4
80
68.0
2
1.6
118
100.0
In both yearsabout a third of the nestswereplacedat 10 feet or lower, and about two-thirds from 12 to 20 feet. In 1920 there
was more variationthan in 1921, more very low and very high nests. The averageof the two yearsis nearly the same,13.3 feet for 1920 and 14 feet for 1921.
Position of the Nests. Horizontal branches are more in favor
with Mourning Dovesfor placingtheir neststhan are the crotches of trees. The numbersthat choseeach positionin 1920 and 1921 are shown in Table II.
'Vol. XXXIX]
1922 J
NICE, Nesting ofMourning Doves. TABLE
II.
POStTtON. or MougN.IN.C
Dove
NESTS.
Branch Numbers
Year
461
Crotch Per Cent.
Numbers
Per Cent
1920
71
65.1
38
34.9
1921
75
63.6
43
36.4
In both years about two-thirds of the nests were found on branchesand onethird in crotches. Yet in early springa different. relationshipis shown;in April 1921 there were nearly as many crotch nestsas branch nests--12 in the former and 15 of the latter,
while the year beforein April there were even more in crotches15 nests--with only 12 on branches. This would look as if the Doves soughtprotectionin crotches when the leaves were small. Perhaps a shortage of suitable crotchesmay have somethingto do with the matter. Undoubtedly there are not enoughto go aroundin the heightof the nestingseason; but in July, August and September1920, when few Doves were nesting,only one-fifth of the 30 nestsfound were in crotches and in September 1921,.all four nestsseenwere on branches.This choiceof sitesin late summerand fall lendssupportto the theory that desirefor protectionis the reasonthat crotchesare preferred in April. That the Doves are not wise in their preferencefor horizontal branches rather
than crotches is shown in Table III. TABLE
III.
SUCCESSES*AN'D lq•AILURESIN' I•ELATION' TO POSITION. Branch Number Succes- Failses
ures
Nests
Crotch
Per Cent. Succes- Fail-
Number SuccesFailses
ures
Nests Per Cent. SuccesFail-
ses
ures
ses
ures
1920
6
16
27.3
72.7
8
12
40.0
60.0
1921
11
26
29.7
70.3
13
6
68.4
31.6
Total
17
42
28.8
71.2
21
18
53.8
46.2
ß * We knewthe outcomeof nearlyhalf the nestsfound. We co[lntedas "Successes" those nests that contained young large enough to fly when last inspected.
462
[Auk
raCE,Nesting ofMourning Doves.
[Oct.
On an averagethe crotch nestsare almost twice as successful as thoseon branches,for slightlymorethan a fourth of the latter succeeded,while a little more than half of the former did. It is
interestinghowthe Dovespersistin preferringthe lesssafeposition. The Use of Other Nests. Mourning Doves sometimes save
themselves troubleby utilizingthe nestsof other birds. (In all but one of our cases,which was a new Robin's nest containing one Robin's egg, the doveshad added more or lessmatefta] of their own.) In 1920, twelve usedold Brown Thrashers' or Mockingbirds' nests, three Robins', two English Sparrows', one a Bronzed Grackle's and two old Doves' nests; in 1921, there were
eight old Thrashers'nestsused,five old Robins', three new Robin's and two old Doves'.
Table IV shows the numbers of these nests
and the percentagethey form of all the nestsfound in 1920 and 1921; the numbers of these nests that were built in April and finally the successes and failuresof thesenestsso far as they were known. TABLE
MOURNING
Year
IV.
DOVE NESTS BUILT
Number of
Per cent of
Nests
total nests
Number in
ON OTHERS.
Successes
Failures
April
1920
20
15.4
13
2
10
1921
18
15.1
12
8
4
There is a surprisinguniformityin the two yearsin the number of nests built on top of others--fifteen per cent each year. In 1920 thirteen of thesenestswere found in April, one in May, four in June,and two in September,while in 1921 twelvewere foundin April, three in May and three in September (we were not here during the summer). Thus two-thirds of these nestsoccurredin April in both years. Here again would seemto be evidenceof adaptation for greater protectionin early spring.* In 1921 it worked out this way for two-thirds
of the nests built on others were known to have suc-
ceededwhile only one-third of the others did. * It is possible •hat last year's Doves like to utilize these nests of other birds for their firsg attempts at nest building but with increasing experience grow mor• independeng later in the season.
Vol. XXXIX]
1922 •
NICE,Nesting ofMourning Doves.
463
But in 1920 the resultsare just the oppositefor then only onesixth of the nestsplacedon otherswereknownto have succeeded, whilethe sameproportionas in 1921--one-thlrdof the othersdid. An explanationof this lies in the fact of mostof the nestson top of others being built in April, for the fatalities in that month werefar greaterthan later in the season,due apparentlyto storms. These nests were neither
better
nor worse off than the others.
The chief advantageof buildingon anothernest lies in a larger, strongerplace for holdingthe young. Apparentlythere was no advantagewhen it came to weatheringa long cold rain. Of the two successful nestson top of othersin 1920,oneraisedonebird and the other raised two, and in 1921 all eight raisedtheir full quota, which was even threein one case, and of the sixteen other suc-
cessfulnestsnine raisedonly one bird apiece. (Howeverthree of thesehalf broodswere not due to fraility of the nests,two eggs being infertile, and one egg beingknockedto the groundby .the parent as he was frightened off the nest--the only caseof such
injury that occurredwith us.) Thus in 1920 no advantage accrued to the Doves that bui]t their nestson top of others,but in 1921.thesenestswere decidedly more successful,both as to percentagesof nests succeedingand to numbers of young raised. Sometimesa Dove's nest is used again the same season;we have noted five instancesof this. In 1919 a nest on August 16 contained one young bird and on August 26 two eggs. In 1920, one brood was observedto be in possession of a nest from April 22 to May 17, and on June 5 it was againoccupied;the other nest was in useMay 13 and 19, but wasempty May 31, on June16 a parent was again incubating. In 1921 one nest was used throughout April and wasempty May 4, on May 25 a parentwasincubating. In the other,one youngbird left the nest May 3 or 4, and on the 29th a parent was in possession.The natural assumptionis that the nest is usedagain by the pair of birds that built it, but we do not know whether
this is true.
Dr. •hitman
2 found a decided
tendencyamongall his pigeonsto selecta new site for eachnest. • Loc. cii. Ili,
p. 21.
464
NicE,Nesti•g of Mourning Doves.
[Auk
[Oct.
It may be that other Dovesutilize theseold nestsof their kind just as they do thoseof other birds. OccasionallyDovesmake surprisingchoicesof neststo buildon: squirrel's nestsare reported by two observers 3 4 but one of the most unexpectedis the use of a Baltimore Oriole's nest which was found in Kansas by Mr. A. J. Kirn. This habit of usingnestsof other birds occasionallyresultsin Dovesincubatingeggsof other species. Mr. F. Graham5reports of two Mourning Dove'seggsand three Boat-tailedGrackle'sin a Grackle nest; Mr. J. R. Pemberton6tellsof a Dove incubating two Brown Thrashereggsas well as her own two in a Thrasher nest; while Mr. J. L. Davison7 found a partly built Robin nest that had been finished by a Yellow-billed Cuckoo, and which containridoneRobin egg,two Cuckooeggsand two Mourning Dove eggs,the two latter birds being on the nest. What a pity this uniquefamily was not left to develop! Becauseof the Dore's methodof feedingyoungit seemsimpossible that any youngpasserincbird that happenedto hatch in a Dove nest could satvive. Cowbird'seggshave been reportedin Mourning Dove nestsby two authorss" We werehopingto watch developmentsin two nestswith alien eggsthis spring. The first casewasa Robin'snestfoundApril 15, with one Robin's eggin it; on April 23 a Dove was in possession and the nest containedtwo Dove eggsand one Robin's. On April 26 the situationwas unchanged,but on the 28th, to our disappointment,the Robin's egglay brokenon the ground. The Dore's eggshatchedMay 4, and the birds left May 19. The other instancewas an experimentwe made by placinga Cowbird's egg, taken from a Cardinal's nest, in a Dore's nest that containedoneeggon April 26. On April 30 the nestcontained two Dove eggsand the Cowbirdegg,but on May 4 and 5, only one Dove eggbesidethe Cowbirdegg,and on the 9th, the nestwas a Stoner, E. 1915. p. 76.
• Kirn
A. J.
April, 1920. • OOlogist,
A.
I•
Oologist,
,• letter.
XX]XII.
Condor, XXIII. 1921, p. 133. Auk, IV. 1887, p. 264. Coues, E., Auk. I. 1884, p. 293.
Tex•s,
Bendire, C., Sraithsonian ReD. 1893. XXXII.
1915, p. 211.
pp.
5S7-624.
Vol.
XXXIX] 1022 J
N•cr,Nesting ofMourning Doves.
465
empty. We hopeto carry out this experimentwitha Cowbirdegg another year. In thesetwo easesit looksas if the Doves did not wish to have more than two eggsin the nest as in each easeone disappearedand in the easeof the Robin's nest it was impossible for it to roll out. However, in two other nestsfound in 1921 three Dove eggswere incubated and hatehe& 2. THE
EGGs.
In.cubation period.Dr. Witman •øfoundthat thetimeof laying of the first egg of captive Mourning Doves occurredbetween 4 and 6 P.M., while in six casesthe secondeggwas laid early in the morningof the secondday after from 6.30 to 9.00 A.M. The incubationperiodwasfoundby him by observationon elevensets• of eggsto be 141• to 151• daysfor the first eggand 14 1/8 and'14 7/8 for the seeon& Dr. Whitman• noted that in the easeof all his pigeonsthe youngbirdsusuallyhatchedearly in the morning or between10 A.M. and noon. "If the eggdoesnot hatch by 3 P.M. one can be fairly certain that nothing will be done until next morning. It may be fully time for the bird to hatch, but for somereasonthe hatchingis not completed,and the bird goesto sleep,apparently rests, and then wakesup very early with the rest of the birds in the morningand concludesthe hatch." As a rule one or the other parent is continuouslyon the nest from the time the first egg is laid until the young are fairly well grown. Dr. Wallace Craigt• says,"Male and female take regular turns in sitting on the eggsor young: the female sitsfrom evening till morning,the male from morningtill evening,the exchanges taking'placeusuallyabout 8.30 A.M. and 4.30 P.M." As Mourning Doves will not e0me to their nestsif they see a personany where near, I have witnessed this exchange only when I was concealedfrom view. On May 11, 1921,a femalewas relieved by her mate at 8.17 A.M., and on September22, a male left the nest upon the return of the female at 4.25 P.M. •0Loc.
cid. II1.
p. 4,5.
"Loc. cit. 11I. p. 42.
•-*Loc. cid. Ill.
•Auk,
XXVIII.
p. 50.
1911. 19. 406.
466
[Auk
N•c•,Nesting ofMourning Doves.
[oct.
The Numberof Eggs. The numberof eggsin a set is almost alwaystwo, but one, three and four eggsin a nest have beenreported. Dr. Whitman's•4 Mourning Doves in two caseslaid only one
egg. Mr. J. G. Tyler•5founda heavilyincubated eggof thisspecies in an old nest of a Mockingbird,"the unusualdepth of the nest seeming"to precludethe possibilityof an egghavingrolledout. Capt. Bendire•6and Prof. Wm. S. Taylor•7say that "sometimes onlyone" is laid, whileMr. W. F. Henninger•ssaysthis "frequently happens." Setsof four eggshavebeenreporteda numberof times. In five suchcases •ø-•zno detailsare given. The four found in a Yellowbilled Cuckoo's nest by Messrs L. B. and L. I. Evans•4 were
all .equallyincubated. Mr. A. F. Ganier25statedthat "only one pair of birdswas in evidence"at his nest with "four perfectly fresheggs." Dr. LyndsJones 26reportedthat his setof four "was pretty clearlyoccupiedby two femalesamd one male." In a letter he says: "The eggswerepairedboth as to sizeand shape, anddegreeof incubation. •vo of them (whichwerealike in shape and size) were well advancedin incubation,while the other two were slightly add]ed." I have found reportsof over 40 casesof three eggsin a nest; most of the findersgive no detailsas to appearanceor stageof incubationof the eggs. Elevena7-a7 reportsinglecasesonly. •vo •4 •,oc. cit. III.
p. 43.
aaThe
25Pac. Coast Avifauna 9, 1918. p. 37. •6 Life Histories of North American Birds, I, 1892, p. 142.
•? The Mourning Dove. Bull. Univ. Texas, No. 57, 1916. p. 6. •s Wilson ]3niletin, IX, 1902. p. 138.
Hummer.
• Wilson
Bullelin
Aug.
1899.
XXXI,
1909,
p
190.
aSBeaxd,
T.
R.
a• Densmore,
In
R.
a letter.
OOlogist,
p. 16.
•Barnes, R. M. OSlogist, XXX. 1913, p. 148. 20Duprey, H. F. OSlogis$, XXX. 1913. p. 148. • Gainer, A.F. In a letter; set found by friend at Nashville. 2• Ha•rris H. Birds of Kansas City
•0Evermann, B. W. Auk, V. 1885; p. 351; also Proc. Ind. Acad. Sci. 1920, p. 37.
Region, 1919, p. 258. e• Shepardson, D.I.
SSGrinnell, J., Bryant, H. C. •nd Storer, T. I. Game birds of ornia. 1918, p. 595.
1909.
p.
15•.
2• O51ogist Also
in
Also in a letter. OSlogist, XX¾I,
a letter.
XXXI.
1914.
p.
80.
SlGraham, 1915,
F.
OSlogist,
XXXII.
p. 211.
s• Graves, E.W.
O61ogist, XX¾1,
p.
56.
a4Harris, H. •,oc.cit.
Also in a letter.
57ol. XXXlX1
1922 J
NICE,Nesting ofMourning Doves.
such sets are illustrated?
3ø Three
467
men 4"4-øhave found two in-
stancesof these sets,Mr. H. C. Little4areports "several," Mr. H. P. Artwater
writes that on "two
or three occasions" he has
comeacrosssuchsetsand Mr. L. B. Evans writes that a neighbor has found two or three. Mr. Wm. S. Tf/ylor statesin a letter that he has found three suchsets,while the Evans brothershave found as many as six setsin Kansas,all of theseoccurringin May. Of the men who do describetheir sets,only one44saysthe size and shapeof the eggswere aboutthe same. In six sets45-4s differencesin sizeare mentioned;in four, one eggwas smallerthan the
others,in oneit waslarger,and in the other, two weresmallerand one the usual size. Mr. J. G. Tyler4sdescribesthe third egg as "somewhatsmaller,morepointed,and of a shadeso unlikethe othersthat there appearedto be a differencein shell texture." In three casesthere was a marked differencein the stage of incubationof the eggs,Mr. F. Stephens 49reportingthat in "two incubation had commenced,the third was fresh," Mr. A. S. Pearse;ø findingthat two "were hardly incubatedwhile the other wasperfectlyfresh" and Mr. J. W. Jacobs 5•statingthat "two of the eggswere pipped" while "the third was perfectlyfresh and to all appearances fertile." We have found three nests5'øthat
contained more than the
normal set. The first was seenMay 25, 1917, when it contained two small squabs and one egg; unfortunately as we were not particularly interestedin Mourning Doves at that time, we did not revisitthisnest. The othertwo caseswerefoundin the spring asSimmons, G. F. Auk, XXXII. 1915, p. 322. a• Stoner, E. A. OOlogist, XXXlI. 1915, p. 76. •7 Westbrook, D. CI. O51ogist, XXX. 1913, p. 51. a• I-Iundley. •. O. 4th, Rep. Forest, Game & Fish Warden, W. Va. 1916, p. 120. •Ritenbergh, J. O51ogist, XXIV. 1907, p. 9.
40Dooli•tle, E. A. 1919,
p. 281.
4•I-Iartrauft, C.W. p.
Auk, XXXV].
O51ogist,XXV.
85-7.
• Jones, L. Loc. cit.
4a051ogist, 11, 1885, p. 39. •4 Seroroes, T., Jr. O61ogist, XX1V. 1907,
p.
3 sets; in a letter. O51ogis9,V1, 1889,
193.
a* I-Iutchinson, W. •. 1889,
p.
OS]ogist, V1.
176.
•8Tyler, J. G.
4, •it•d
koc. cit. p. 36.
by Bendire. koc. cit. 1892,
p. 142.
a0Wilson B•filetin, 1V. 1897, p. 63. *xWilson Bulletin. IV. 1897, p. 71. • Nice, M. •M. •ondor, XX111. 192], pp.
Also in a letter.
p. 8.
•*Evans, k. B. • B., W. D. k.
145-7.
468
ofou,ig
Auk
[ot.
of 1921;in one,Nest 20, oneeggwasslightlysmallerthan the other two, but the three hatched just one day apart. In the other, Nest 29, the third egg lookedsomewhatyellowish,and it hatched five and six days after the other two. So in two of our easesthere was a differencein appearanceof the eggs,and in two a difference in. the age. The questionarisesas to whether Mourning Doves lay three
andfoureggsin a clutch. I think weareonsafegroundin assuming that whenfour eggsare found in one nest they are the productof two females. Whether suchcasesalwaysor usuallymean polygamy •vehave no meansof knowingat present. As to the matter of three eggs,I askedthe opinionof two men who have made a specialstudy of the life historyof pigeons,Dr. Wallace Craig and Dr. Oscar Riddle. Dr. Craig wrote: "The questionis partly a physiological one, as to whetherit would be possiblefor a femaleDove to lay three eggsin oneset. Asto the questionof behavior,I suppose it possible that a femalemightlay in another'snest. Or I suppose it possible that two femalesmight form a homosexualunion, as they sometimes do in captivity." Dr. Riddle answeredmy questionas follows: "I very much doubt that Mourning Doves ever lay three eggsin a clutch. It seemsto me probablethat where three Mourning Dove eggsare found in one nest they have one of the two followingorigins. "(1) The same female has laid eggsor an egg, and while ineubatlnghas againlaid in the samenest. (We have a very few ring-doveswho do this.) "(2) The eggsare laid by two different MourningDoves. If the latter happens,one conjecturewould be that the samemale had mated temporarilyor otherwisewith the two females. We have observedconsiderable lapsesof fidelity of male dovesto their mates."
Still anotherpossibility in someeasesmightbe the adoption of a desertedDore's nest which contained an egg. Beforeleavingthe considerationof three eggsin a nest, let us turn to the casesxvherethree young have been found. Besides our two instances,I can find four others5a-55 only one of which5* Fisher,
A.
K.
No.
Amer.
Fauna,
No. 7, 1893, p. 33.
Vol.
XXXIX]
1922
J
NICE, Nestit•gof Mourning Doves.
469
is in any way described:in this casethe three young were "al] of one size." Most of the findersof three eggsin a nest seemto - have collected these unusual sets or not to have revisited them.
Prof. Wm. S. Taylor, however, did return to thosehe found and in a letter he saysthat in eachof the three eases"when I visited the nest after the birds had hatched out I found two birds, and no trace of the third egg. Each of these nestswas built on the flat surfaceof a rail in a rail fence,the bird usinga flat depression in the rail for its nest. All of thesenestswerein Kentucky."
In the easeswe foundin 1921,we wereableto tracethe history of the nestsfrom the egg stageto the time the young left and at neithernestwasthereevermorethan onepair of birdsin evidence. The first of thesethree eggssets(Nest 20) wasfound in a new Rob-
-n's neston April 30; the eggshatchedMay 13, 14, and 15. Tile birds developedrapidly so far as feather developmentwent, but on May 19,uponweighingthem,wefoundthat the two younger weresmallerthan othersof their age;the five-day-oldweighing 21.8 grams, and the four-day-old 17 grmns, the average of two other five-day-oldbirdsbeing36 grams,and of two four-dayolds30.5 grams. It would t!lus appearas if the threewere not gettingquite enoughfood, yet, althoughwe did not disturbthem after May 21, they left the nestat the averageagefor Doveshere, when 13, 13 and 12 days old respectively. The other nest (No. 29) wasa fairly substantialonein a crotch of an ehn; on May 3, it containedtwo eggsand on May 9, three. TheseeggshatchedMay 16, 17 and 22, on the last of which dates the birds weighedrespectively40.3 grams,37.8 gramsand 4.4 grams. The belated squab could not compete for food with its
large nest-mates. The next day it had only gainedfour-tenthsof a gram, and the day after it was dead. Tile others left the nest when 12 and 13 days old.
Thesetwo nestsare of particularinterestin that their history andoutcomeweredifferent. The raisingof threebirdsto maturity in Nest 20 was dependenton two favoring circumstances, the roominess and depth of the new Robin's nest used,and the fact 24Semmes, T. Jr., Loc. cit. cases.
Two
• Wharram, S.K. p. 134.
O51ogist,XXXII,
470
[Auk
NICE,Nesting of Mourning Doves.
tOc•.
that the birdsdifferedonly a day in age. In Nest 29, the hatching of the last bird five and six days after its nest mates made its
survival impossible,as the others were eight and nine times its size,and it would be hopelessfor it to expectenoughfood. Moreover if the threehad hatchedonly a day apart the nest couldnot have held them whenthey werehalf grown. So herewe have two possibleexplanationsof the rarity of threeyoungMourningDoves beingfoundin one nest: first, the ordinary Dove nestis incapable of holdingthree youngbirdsto maturity, and secondly,the third bird may hatch so late that it cannot competefor nourishment with its large nest mates. 3. T•E
YOUNG.
Growth. There is almostalwaysa differencein sizein a pair of MourningDove squabs,due to their usuallyhatchingoneor two days apart. In our experience,in six neststhe younghatchedon sacceedingdays, in t•vo neststwo days apart and in anotheron the sameday. With Dr. Whitman's5øcaptive iVIourningDoves one set hatched two days apart, two sets on the same day and nine on succeedingdays. In May 1921,we weighedthe nestlingsin onenestfrom the day they hatchedto the age of eight and nine days, we weighedtwo other youngfor four successive days and have singleweightsof five other squabsof whoseage we are certain. Table V. gives the weightsof six youngMourningDoves. (Unfortunatelythese birdswerenot alwaysweighedat the sametime eachday.) TABLE V. DAILY
When
WEIGHTS IN GRAMS OF YOUNG MOURNING
1
2
3
4
5
6
7
8
DOVES. 9 10
11
Hatched day days days days days days days days days days days 29a
8.1
10.2
15.3
22.2
28.8
34.3
40.3
44.1
52.2
55.8
29 b 25 a 25 b
6.2
11.5
19.0
23.5
32.2
37.8
44.4
52,1
77.6
49.7
69.8 55.0
71.0
45.0
56.3 62.3 53.0
41.0
43.0
42.7
47.2
60.2
71.0
77.6
48
57.7
20a
Aver.
7.2
10.8
Daily Gain 3.6 ** Lo½. ½i•. III,
17.2
6.7 p. 51.
22.8
5.6
30.5
7.7
36.1
5.6
6.6
4.5
56.3
9.1
3.910,8
6.6
Vol. XXXIX]
1922
J
NICE,Nesti•gof MourningDoves.
471
We neverweigheda youngbird beforeit had beenfed, except, perhaps in the caseof the third squabin Nest29, whichweighed 4.4 grains. An infertile egg weighed5.2 grams. The rapidgrowthof thesebirdsis apparent;29b increasing its weightninetimesby the eighthday, whilethe averageof all the birdsincreasedeleventimes by the eleventhday. There was considerable individual difference in the birds; 29b
growing fasterthan29a,sothat whentheformerwassevendaysold it weighedslightlymorethan its eightday nest mate. On the other hand 25a was decidedlyaheadof its nestmate evenat the satneages.Here therewasa twodaysdifference in ageand the olderoneapparentlygotmorethanits shareof food. No. 48 was alonein the nestbut did not weighquitesomuchas25aat the age of eightdays. No. 20a wasthe oldestin a nestof three;andis slightlybelowaverageweight,but thereis no markeddifference as with the youngerbirds. No. 20b weighedonly 21.8 and 26 gramsat fiveandsixdays,and20cweighed 17gramsat fourdays. I kepta fewnotesonthemoststrikingphases of featherdevelopment.
First hatched: covered with white down, blind.
One day old: appearance the same,but squabis larger. Two daysold: pin feathersof wingsappear;eyesopena little. Three days old: eyesopenwider. Four days old: pin feathersof tail appear.
Five daysold: in two birds;vingfeathershavebegunto unsheath,but in two birds they have not.
Six daysold: wingfeathersunsheathed in all four birds;tail feathersbegin to unsheathin two.
Seven daysold:tailfeathers moreorless unsheathed inallthebirds. Eightdaysold: pin feathersof headunsheath. Feeding.YoungMourningDovesarefed"pigeonmilk," which is regurgitated by bothparents,the youngputtingtheirbillsinsidethat of the parent. When they are smallthe parentfeeds bothat the sametime,pumpingthe foodup by a bowingmotion. • How longyoungDovesare fed after theyleavethe nestI do
notknow. A youngbirdwehadin captivity 57stillbegged frantia, Nice, M. M. Proc. okla. Ac•d. Sci. I. 1921, pp. 57-65.
472
NICE,Nesting ofMourning Doves.
[Auk
[Oct.
cally from an older Dove at the age of four weeks;after this I never saw him do it. Perhapshe would have persistedlongerif he had beenrewardedwith food insteadof cruel pecks. Positionin Nest. Mr. F. C. Willard•ssaysof youngMourning Dovesin Arizona that they "always face in the samedh'ection." Miss Althea Sherman59showedthat this was not tnle in Iowa, the
earliestdateat whichshereportsyoungDovesasfacingin opposite directionsoccurringwhen the oldestwas six days old. Our experiencehasbeenthat the moreusualpositionis for squabsto face in the samedirection,but that near the end of nestlife they often face in oppositedirections. At first the youngfacethe tail of the parent; the oldestbirdsin whichwe notedthis positionwereeightandninedaysold. Later they are moreapt to facein the samedirectionas the parent. Lengthof time theyoungare brooded.Mom'ningDovesusually broodtheir youngalmostconstantlyup to the age of about ten days;after this the squabsare apt to be left alonemoreor less.* In 26 easesparentswereseenbroodingwith largeyoungandwhere the agewasknownit variedfrom ten to thirteendays. In five of thesecasesthe young flew out when disturbed:Two broodswere replaced,oneof whichwasnotedunbrooded in the nesttwo days later, but in the other three casesthe birdsleft for goodand were thus broodedtill the very endof the nest life. (With suchlarge birds,the parentusuallysits besidethem.) In nine of the 26 cases,the parentsdid not broodconstantlytill the very end of the nest life, and seven other broods of large young were seen with no parent on the nest. A few casesin which the agesof the youngare knownwill be •iven. Nest 25: youngbroodedwhen 10 and 12 days old; but parentnot seenwhenyoungwere11 and 13 daysold; youngleft the nestnextday. Nest29: youngbroodedwhen10 and 11 days, but parentnot seenwhenyoungwere11 and 12 daysold; young left the next day. Nest 1: youngbroodedtill 10 and 11 daysold •SCondor, ** Condor,
X1V. X1V.
1912, p. 59. 1912. p. 153.
* Practically all our data are based on single visits, so if we recorded a nest unbrooded or brooded at one time, it would not necessarily be true of the whole
day.
Tnr. Aw, VOL. XXXIX.
PL.,CrF. XVIi[.
1 and 2. Portion•of the MortruingDove GroveFebruary,1921.
3. ThreeyoungDovesfromonene• 8ixjoneandsevendaysold. 4. Threeym•ngDov•z{n61dROBifi'•ne•t,eighi,sere, anti six •{•? old.
Vol. XXXIX]
1922 J
NICE, Nesting ofMo•omi•*g Doves.
473
at least,but parentsnot seenwhenyoungwere 13, 14 and 15 days old. Nest 118: youngbroodedtill 4.25 P.M. by male when 8 and 9 daysold; femalewaitedin the tree one-halfhourbeforeshe cameto the nest;no parent seenwhen nest was visited,when the youngwere 12 to 14 daysold. The earliestage at which we have found youngleft unbrooded was four andfive days. On September23, 1919,in nestA the male was on the nest at 4 P. •I.
No parent was there at 5 P. 3•I. al-
thoughthe femalewas near, but at 7.30 P.M. shewas on. On September27 the youngwerenot broodedat 7.15P. M.,but at 7.45 the female was on. Another brood--V--of
young that hatched
on the samedaysas broodA, wasfoundwith no parent on or near at 5 P.M. September23, althoughthe female was broodingat 7.30 P.M. Thesetwo nests were exceptionalas we have never foundany othernestlings unbeooded for evena shortwhileunderthe ageof ten days,exceptNest 118,for half an hourwhenthe young were eight and nine days old. The weatherwas not warm; the maximumand minimumon September23 being 73ø and 53ø and on the 27, 85øand 65ø. And althoughthe parentsof onenest--V-showedthemselves later to be indifferentto the fate of their young, thoseof the other provedthemselvesespeciallydevoted. Lengthof time the youngstay in thenest. •-Vfr.E. W. Gifford,6ø with captiveMourning Dovesin California,foundthat two young birdsin differentbroodsleft the nest at the end of twelvedays. Mr. Frank L. Burns6•givesthe periodof nestlinglife of this species, as ten to twelve days;basinghis statementon his own experience in Pennsylvaniaand on that of Mr. C. H. Rogersin New Jersey. In contrast to these short periods,Miss Shermanø2describeda broodthat did not leavetill 17 and 18 daysold. In answerto my questionabout thesebh'dsshewrote, "I have no theory why this brood staid in the nest longer than the average herewhich is at least fifteen days." We know the agesat which 16 young Mourning Doves left the nest of their own accord in 1921. 60 Condor
XI,
•Wilson
Bulletin,
p. 96.
•a Loc. ci;.
1909, p. 85.
XXXII],
1921,
474
B.ILE',An Arizona Feeding Table. TABLE
AGE AT WHICH MOURNING
Nest 1 11 34 20 48 25 29 118
Date of Leaving Apr. 19 & 20 May 19 May 23 & 25 May 26 & 27 May 27 May 28 May 29 Sept. 27
[-Auk
[Oct.
VI.
DOVES LEFT THE NEST.
Number in Brood 2 2 2 3 I 2 2 2
Age in Days 15 15 13 13, 13 & 12 12 12 & 14 12 & 13 13 & 14
Four birds left at 15 days, two at 14, six at 13 and four at 12,
makingan averageof 13.4 days. The averageageof the 12 birds leaving after May 23, is just 13 days. The young in the two earliestnestsstaid longerthan thoselateral5 days--whereasno later birds staid longer than 14 days.
YoungMourningDovesare easilyfrightenedout prematurely. The earliestage at which we have found this to occurwas eight days--the squabiu Nest 48. It was replacedand left of its own accordfour days later. In Nest 25 the older bird was frightened off the nest when 11 days old but wasput backand did not leave permanentlyuntil it was 14 days old. Norma•., Oklahoma.
(To t•econcluded)
AN
ARIZONA BY
FLORENCE
FEEDING MERRIAM
TABLE. BAILEY.
A FLOCK of Gambel'sSparrowswith their handsomeblack-andwhite striped crowns,spendingthe winter of 1920-21 like ourselvesamongthe mesquitesat the foot of the SantaRita Mountains in southern Arizona, made a bird table seem important; for if
they were kept around our tent duringthe winter, what other interestingmigrants might they not tempt to stop in passing duringthe spring. They werequickto respondto ourhospitality, and for five months,during which they were fed daily, made our