THE OOLOGIST, 



167 



after nestling down on them remain- 

 ed perfectly quiet, never having no- 

 ticed any change whatever. Her 

 whole manner was that of a bird in 

 perfectly confidence, not in the least 

 shy or suspicuous of any change 

 whatever; her first glance to see if 

 the eggs were there was enough to 

 place her at ease. She continued to 

 set on the eggs till within a few days 

 of their hatching, when some animal, 

 possibly a skunk, broke up the nest. 



In the case of Hawks and screech 

 owls, the hawks in particular, I am 

 not sure that they can either distin- 

 guish color, size or their own egg. I 

 have tried them in a number of ways 

 even having had Red-shouldered 

 hawks hatch, but not rear, eggs of a 

 totally different species. 



Now these cases are instances of 

 where the birds do not know their 

 eggs or those of another color, but 

 let us pass on to the Canada goose. 



A few years ago I had several pairs 

 of Canada geese (branta canadensis) 

 in capticity, some of them being 

 birds wingtiped and caught, the rest 

 were raised in captivity. Every year 

 while I kept these birds I had very 

 good chances to watch them building 

 their nests and hatching the young. 

 These birds' I am absolutely convinc- 

 ed knew not only their own goslings 

 from the time they hatched but each 

 egg. And what is more I could not 

 come within a mile of fooling them 

 on the goslings, and unless the egg 

 was a good one they would not ac- 

 cept it and some times not even then. 



For instance in the case of a young 

 ■pair of birds that have never before 

 laid, after building a nest and depos- 

 iting one egg in it, they left it and 

 the next day started another nest. 

 This seemed strange to me and rath- 

 er than loose the egg I put it in the 

 new nest, and the bird laid her next 

 egg in the first nest. I could not 



understand why the birds did not 

 want this egg, but decided rather 

 than bother them again I would put 

 it under a hen. This was done, but 

 after two weeks incuhation the egg- 

 was found to be infertile. The same 

 bird laid five other eggs in the origin- 

 al nest and hatched them all. Now 

 she knew that that egg was no good 

 and knew it well enough net to be 

 fooled by seeing it in another nest; 

 yet this egg to me looked the same as 

 any other unsolled gcose egg. 



In one other case with the geese I 

 had reason to want to mix three eggs 

 among another setting so as to have 

 the geese rear them rather than a 

 hen. I marked the eggs with a lead 

 pencil; line so that I could tell them 

 in case the birds should push any of 

 the nine eggs' out of the nest and al- 

 so to be sure as to which eggs the 

 birds would reject, if any. 



After having placed them in the- 

 nest I went off some distance and 

 waited with a pair of glasses for de- 

 velopments. It was not long before 

 the goose came hack to resume her 

 duties of incubation. She stopped 

 when close to the nest and gave it a 

 good look and then leaned over and 

 'began gently pokeing at the eggs 

 with her beak, and so far as I could 

 see she was trying to work out the 

 foreign egsg and not her own. But 

 it might have been that she was 

 merely arranging them in new posi- 

 tions, it looked to me very much as 

 though she knew something was 

 wrong. The nest happened to be an 

 unusually deep one, having been built 

 in a depression in the ground, so she 

 was unable to roll out any of the 

 eggs even though she wished to and 

 after working sometime on them she 

 nestled down and finally hatched 

 eight goslings. In this case the old 

 bird certainly knew that something 

 was not right, possibly that there 



