i<\ri-. oi- i.v^iMi AM) i-,c.(i I'liODi ( rioN nn 



111. ('iin-> III' iiiit liil\ciiii .liininil I'.ilil I'liniil niiil .liiininl h'uli. 



Ill tlif coiicliKliiii; si'ction of' tlu->i- >lii(lirs, tlic (•(•rrrlal inn lu'twt't'ii ;mi- 

 !iii;il r.itf ;nul ;utmi;il protliict idii is ctuisidrrcd. Siicli studies will briiijf to 

 lirht soim-tliinj: of tin' iniixn-tanct- of iiitciisitv nuMsurfd over a long period 

 (tf tiiiii' as a t',uti)r in aiimial ejiji yield. In makiiin' ii)) the correlation 

 lal)li' tlie aniuiai recDrd of eacli individual \n as tal)nlatcd against her in- 

 tciisitv i-fc'Ofd. riif constants a])pear lit'low : 



NnniinT of liirds 2o(iO 



Mean annual produftiint 181.59 



Annual ])rodiiction standai-d deviation iJ'-i.SO 



.Mean annual rate 57.57 



Annual rate standard (h-viatinn ±9.57 



C'oeftieient correlation +.710() ±.00fi() 



The con-elatiiui l)et«een annual i-ate and annual i)roduction is po.sitivc 

 and dccidedl\ intimate. .\s ,i criterion of annual ])rodiiet ion, annual rate 

 is of outstandin.i: \alue. Only out other criterion of annual i)roduction, 

 namely, annu.il ])ersistency (llays and .Sanliorn. 192(i b), shows a .similar 

 dcfiree of correlation to yearly iiroductiiui. .\nnual intensity, therefore, 

 shoidd he ade<|u itel_\ stressed in a iiro^irani of hreedinp.' for fecundity. 



The Measures of Intensity Compared. 



In these studies four nieistM'cs of intensity have been considered in re- 

 lation to winter and annual eji'.ir ])roihiction. The measures of intensity 

 <-ini)loyed are: (a) first sixty-day record: (h) mean size of winter clutch; 

 (c) net winter rate of laying': and (d) annual rate of laying'. Ba.sed on the 

 intimacy of con-elation with \\inter )n-oductioii three criteria rank as fol- 

 lows: net winter rate, mean winter clutch size, and first sixty-day jirodnc- 

 tion. On t!ie intiniaty of cnrreiation with yearly ])roduction the rank is 

 annual rate, net w intei- rate, mean winter clutch si/.e, and first sixty-day 

 record. 



.Vs sho)-t-time measures ot intensity net winter rate and mean winter 

 clutch size are siijyerior to first sixty-day ejifi' record, .ludfied by the intimacy 

 of correlation with both winter and annual eji'K records, net winter rate is 

 somewhat siijjerior to mean clutch si/.e. Both show the same relation to 

 liatching date, a.ae at first egfi' and weijiht at first egg. Mean clutch 

 ^izc is more definite than is net winter rate because short ])ause intervals 

 atfect net winter rate and apparently do not aflt'ect clutch size. Mean 

 ( Intch size has been shown to behave as an inherited trait and to depend 

 upon two autosomal genes. From the breeding standjioint, therefore, 

 winter clutch size may be considered the best measure of intensity thus 

 far de\elo)-)ed. since annual rate is valueless for jirediction ])url10';^s and is 

 known onl\ after the first laying year closes. 



