l86 maine agricultural experiment station. i9ii. 



On the Accuracy oi*' Trap Nest Records.* 



All experimental studies of any magnitude on fecundity in 

 the domestic fowl must rest ultimately upon trap nest records. 

 In spite of the fact that so much trap nesting work has been 

 done in the various Experiment Stations there has never been 

 any careful study, so far as the writer is aware, of what may 

 be called the residual error of trap nest records. By "residual 

 error" is meant that error which remains after all instrumental 

 sources of error, such as, for example, failure of a nest to 

 operate owing to its being out of repair, have been eliminated. 

 It will always be tlie case that some birds will at some times 

 lay outside the trap nest. The important point to anyone con- 

 cerned in the accuracy of the records relates to the amount of 

 this error. It is proposed here to present some data collected 

 at the Station regarding this matter. Prior to the fall of 1908, 

 what was known as the Maine Station type of trap nest * was in 

 use over the whole plant. A very slight study of the matter 

 convinced one that the instrumental error involved in the use 

 of this nest was too large, both absolutely and relatively. This 

 resulted from several factors but the following defects were 

 most serious. ( i ) The hens would lay in the front compart- 

 ment of the nest and not get trapped. (2) The door would 

 fail to lock when the nest was sprung, and thus while the hen 

 inside could not get out, another ofie (or more) could get 

 inside. (3) In general the nests very easily got out of repair, 

 and then failed to work properly. While in theory it ought to 

 be easy to repair immediately all such nests, in practice it was 

 impossible to prevent there being constantly on the plant a few 

 nests not working properly and needing repairs. 



It was believed that with a more efficient trap nest the num- 

 ber of unrecorded eggs could be reduced. Accordingly a new 

 trap nest was devised. This has been described elsewhere.* 

 These nests were installed in the fall of 1908, so that the pul- 

 lets put into the house that year had nests of the new pat- 



* Papers from the Biological Laboratory of the Maine Agricultitral 

 Experiment Station, No. 30. 



* For original description see Me. Agr. Expt. Stat. Ann. Rept. for 

 1898, pp. 141-143- 



* U. S. Dept. Agr. Farmer's Bulletin 357, pp. 36-39, 1909. 



