Dawson EGGS OF HOUSE SPARROW 187

THE EGGS OF THE HOUSE SPARROW 11)' /) . c . J) ,j If 'S()N

I :-ITRODlICTION This pa per 'iU lIlIllari!)c!) Lhc

from ChrisLdwrch , New Zea la nd . (:h ;1 rancrisl ifs of Hou~c Sparrow C/{I{S

•

L.WII':G .I ' D INCU II.\TIO:-l EJ!;gs arc laid at dail y intcrval'i , h c twecn ciusk alld five a .lll .

Ill f uhaLioll n Oflll a ll)1 begins w ith thc pe llultim;n c tl{g-. hut som e h irds incubate sp0f<ld in tll y before [his. \OVitho ul \'is itin~ nes ts \'c r y frequc ntly ,In a( ('urate .. ill f ubatio ll period " ( :1 nnOl he d e termined . Thus the cxanly exprcs!lcd IIl cans a nd r:lIl gcs ill the l itc ra lUJ'e must he tr<..:alcd with sllsp i(·jOIl . The rang'c within whid1 the true incubation period II1USt lie was dc.' tcnnined for 68 dUldltS. These show the 11I t;::t n pe riod to be <loom 12 cl ays and the r:lIlge to be rrom IO~ to I (j days. ...\ poss ible vari;llion o nc clay ei the r s idc o f [hi ~ range must he m ClIlioncd . as da ily ·: i5it5. though fi xi ll ~ la y in~ time. allow the true hatchinJ{ l im e to he ;,(mos t o n e d ay less than the o hsen cd o lle. Eggs begi n to Hoat in wale r al bctwec 11 6 and J() da ),s of incubatio n : thi ~ can he used :i !oo a n approximate /{uide LO the tillle they have becn incuhated. SlIm mcrs-Sl11ith. 'luminA' Cramp's al1al ys is of Briti sh Trust for Ornilholog:y n ,:u)l'(ls, g:i\'cs Ihe iI\'era}!,c pe r iod as 12 da),s with a 1':ln}!,c of !J to l A.

CLUTC H SIZE HI!) cJ lIldl C~ \\I c re distrihmed as fo llo,,"s: 2 ( I), 3 (2~), ·1 (71 ), 5 (1 '1). The mc,,,, cl lltcl, ,izc is 3.!IIl

:..': O.utiR·. SUlHlIlc r:o.·Smilh ( 19(i~). ( IU O l eS Cramp's r esull of an avcrage (lul{h sizt: of ·1. 1 in Bri l;lin <111( 1 l11 el1ti o l1~ dUlch es or six and scvcn. a nd he writes lor th t United Stalcs: .. l h t averagc dlll( h silt li es in the range .1.:, lO rl. si,!{lIific lIHl y l.trp,tr thall IlIat in Briw ill." The ChrisLdlurdl lIIea ll wO llld sce l1 ~ sil4"l1iri C:lIlll y s lll a llt:r thal1 (' it he r.

COLOUR There apIH.::l rs 10 hc 110 dilrcrc ll ce.:: he tween the colo ur of N ew

l-c;!lalld c~}!,s illld LIl ;1 1 shown ill thc v'lriolls pl 'HCS and d tsniptiolls o f British cg-gs. The ntllllhcr, Si7C elml ('o lour of the spots is ('h araftc risti c for th e onc remale, c \'en ill SlK('css ivc (IUlc hes. Normally the last cf,;g has fewer spots ;Ind SOlllclillles the PClIlI ltilll atc e}!,}!, is intc rmediatc in (nlour.

SHAPE })ala rrolll :l2:; eggs.

T h e II1 t ; 1II hl'e.ullh is 15.3 ~ 0 .038 HIIII . ali(I thc ran);!,e i'i 13.R-Hi.7. Th e m C;1 1l leng th i'i 2 1.9 -<-: O. ()~n 111111 , and th e.:: ran~c is I H. j ·2:i.O. The shapc index o f the e~g:s (hrcadth ~x prcssccl "" a pcn c lltage

or Ic ll l{th) has a mean \'aluc or 69.R :t 0.2·1 al1d ranges rWIII :ifi to RO. SlIm1l1crs-Smith ( 1~lfi3) ~ i\'e~ the Hritish rangts il1 hrc<I (lLh alld lCIl g-tll as 1-t.:; · iti.OIHI11 ;1\1<119.7 · 25 .3 111111 . and g i\'cs th e m e; ln cgg' as 15.7 x 22 .:", 1lI1ll. These d ime lJs ions seem Sig llific lIltl y large r thal1 th e Christ· church on cs .

.. The ranges Quoted in Ihis paper are the s tandard er rors of the means . There is a 95% conr~nce Ihal Ihe mean of the whole populat ion lies w ilnin Iwice Ihis range .

188 NOTORNI S Vol. XI

Lc n)!.th, breadth, wc ig-hl ;lIId Sh;lPC show distin ct ly Si lll i l ;'11" him oda l distri but ions (scc Figs. 1 ·1). Kcndc igh. ({fa Iller a nd H <tlllcrstrom ( 1956) ha\'{.' foun d that the H o use ""n:n shows a n in crease ill egg'

we ight w ith bn.:cci in l{ a~c. whi le Coulson (1962) shows a cha nge i ll sha pe with hrcedin~ age i ll lll e Kiu iwakc. Pcrh;-,ps a s illl ila r pr()(.:css is a t work. ill Spar rows. wit h mod es reprCSe ll lil1~ d ifrcn.:lll age ~TO ll pS o f ureedin v; fe males. Thus first-yea T birds l'o uld la y cl4g-s averag ing 15.2 x 2 1.5 III Ill . 2.8 V;1lI , a nd a ~ha pc illdcx o f 67 . a lI(I o ld er o nes cgg!\ 3\,lTag in:.r IIl .II x 23.2, ~. ·1 g m a nd a sha pe illd ex or 73. I have ill ­suf!id cII l data as ye t to le\ l thi s.

o ~ C------.,-~-14 "

8 .. adlh (M .. )

60 60

3 No. 4 No.

of of .", .~"

o 0 ,. ao 3

, Shope Index Fi~Ure$

1,I.;~ht l~ ",)

WE IC H T .\ NIl VOL.U ~ I E

Da ta fro llt :l l i egw, weightd when fresh .

The 11 1ta ll egg wc iJ.{hl W;IS 2.88 -= 0.022 ~-1I 1 il nd t hc ra nV;c was 1.9·1 - 3.8:; gm . I have used fresh weight itS a ll illdex of egg volume. as the \'o iumc o f such SIll ,11I eggs ('<lIl1lO t he d etermined hy it (Iui( k. p ran icd lIIethod . As it will o ft c lI prove ill1p o~s ihl l' to weig hf fresh , eggs ;11 t" urald y a formula :

w -"

C III he used . weigh ts of 21i fo rmula is:

2 O . " · I ~h I

.. wh ere w - (rclih wcinlu - M

o b = hreadth

and I - le ng th Thi " w a"i dc ri \'~:d fro III kno wn dimensions (l l1 d eggs and is ;H,.lu r :Il C to the I1 C;, t rCs L 0. 1 Alii . The

fresh IIsual

..

Dawson EGGS OF HOUSE SPARROW 189

? -.... wh er e V = vo lu1I1e v -- kb I

fo r which SLOne ho use ( 1~)f13) J,;i\'ts a r<ln g'c o f k. O.!)()() . (1.5 1:") and a m e .. n of 0.;; 12. l 'hese \,;llues wer e d c te rmill cd ror la rger eggs than t1w~e o f the .sp a rrow. T o ('Oll\'c rt the first formula to the se( ond Ihc re!.ttio nship :

s.g-. --

w o

v i ~ used . Th e sp c('ifi (' g ra vity (s.g.) o f 12 eggs wa~ d etermin ed hy lIoata lion tes ts dllrin~ i1J <- uhalio n . The results o bta in ed g-ive a r; lIlgc with in whit h the true specifi c AT:I\'it)' must li e. Thus if an q !,g of fresh we iglll :S.Ot) g m is found to s ink whe n weighing 2.R214'J1) ilnd /l o al whe ll we ighing 2.RO g ill i1'\ s.g. (wh c lI fresh) is ill th e ra nge 3.00 3.00

A 11 th e n e n~cs d e term i ned iurl uded lhe \';11 u c 1.07 2.R2 2.HO. and three (r iti ra l on c~ lI1a y be r ited : I .Uti:) · 1.075. 1.07 · ) .(lS. I.cH · J .1l7 .

O. :,")<J ~ .,. .. k in g 1.07 as the s.g. th e (,(HlsLant (k) h~co lll es: -- O.o0H

1.07 whi(h falls illw the range g i\'(:n hy StolldwlIse fo r brger eggs. Liulr , ' 1'1'0 1' W O t! Id result in Wo. ing his 111 <:al1 \' :1 I ti C o f 0.5 12 for Sp a rro w eggs.

DAILY LOSS OF WEIGHT

l-'rolll '13 eggs we igh ed daily during il1 cuh:uio n. The eggs were weighed to the lI ea re~t 0.01 ~H\ :1I1() sho wed ;t

daily l o~s he tween ahOlH OJ)I ;m d n.o:) ~1I 1. This v .. ried as fo ll ows: be fo re ill Cul >a lio n a l ().~s of O . OI ~ -1-: 1I .00I Rgm, during ilH 'uhatiol l 0.032 I (1 .0011 g'l ll, and immediate ly hefo re:: hatching' (UliO ~ O.O() !):; gl ll.

The dillt:rclI (,cs he tween these mea ns .,re all statiMi c dl y sig nifi cant (p < 0 .0':;). The va ria tio n in we i1{ht lost wo uld be due to \'aria t ion 'i in the c \'<ll)()r a t in ),{ p o we r o f the :Iir (humidity. wind specd , te mper a ture). the imrc'lsc o n the o nse t o f ill (' ui>a tio n wou ld b e due to the in creased te lllp:;: ra ture. ;tnd the illffeasc wi t h the duratio n o f in cuhation could he dur to the respire" io n o f the emhryo (Ios'\ of C02) also in ('reasing. The porosi ty o f the II hcll is :I n 1Illkno\\,11 :lIId could a llio rt n'eeL liw loss in we ight if it , ·;t ri ed .

TH .\ ' I{S

T am indebtcd to Or. n. Sto n eho use ,lIld i\lr. G . A. T Ul1llicliffe for nd\'in', cr itic ism and encouragem e nt and to .lim HilwJ1 for <l lIowillR lIlC 10 use som c tlO egg- m('''SlIre IllCIIIS litke ll hy him .

REFERENCES

COULSON, J . C. (1962): E9iI ~ize imd shllpe in tho Kitt iwake and thoir u~e in ~s l imat i ng age compos ition of populations . Proc . Zool. Soc , Lond . 140: 211 · 227.

KENDE IGH , S. c. , KRAMER , T . C. and HAME RSTROM . F, ( 19~ ): V .. r il)l ions in egg characteri seics of the House Wren. Auk 73: 42 - 65 ,

STONEHOUSE. B. (1 963) : Eg; d imerosiOfls of some A\ccn\ion Island sea·birds . Ibil 1031'>: 474 · 479.

SUMMERS·SMITH, J . D. (1963) : Ths Hous* Spurow. Coli ins .