THE OOLOGIST. 79(f) 



123 



long it equally as long. 



Another important factor that has, 

 perhaps, to be taken into considera- 

 tion regarding the period of incuba- 

 tion of the birds' eggs is the peculiar- 

 ly constructed nest. The eggs repose 

 and are almost hidden in a thick, 

 warm, downy lining, and are never af- 

 fected by or exposed to the cold or 

 inclemency of the weather, as are the 

 majority of birds 'eggs, the Turdidae 

 for instance, and consequently incu- 

 bation will be assisted during the 

 bird's absence by the heat of the sun's 

 rays on the nest, etc. Be that as it 

 may, the temperature of the interior 

 of the nest seldom falls below 70 de- 

 grees I believe, but this is not the re- 

 sult of personal experiment, as I 

 could never procure the right kind 

 of a thermometer with which to ob- 

 tain the temperature, but I venture 

 to say that it will be found between 

 70 and 80 degrees Fahrenheit, ac- 

 cording to the hotness of the weather 

 when temperature is taken. 



If the sun's rays help to assist in- 

 cubation of covered grebes eggs, as 

 some authorities believe to be the 

 fact, during the bird's absence, why 

 should it not also assist those of the 

 Long-billed Marsh Wren? But I fear 

 some would say that the grebe's eggs 

 are covered with decayed vegetation, 

 which contains several degrees of 

 heat, which is lacking in the globular 

 Marsh Wren's nests, and accounts for 

 the assistance rendered incubation. 



True, but did I not say that the 

 Wren's eggs repose snugly in a soft, 

 warm, downy lining, protected by 

 thick walls and the interior with a 

 temperature of 70 to 80 degrees? But 

 I fear the incredulous will say that 

 these degrees ot heat are insufficient 

 to assist incubation, and quite rightly, 

 for I think that incubation is not as- 

 sisted by any artificial means. The 

 vegetation that covers grebes' eggs 



does not contain sufficient degrees of 

 heat necessary to assist incubation, 

 no more than does the downy lining 

 and thick walls of the Long-billed 

 requires 98degrees of heat, a contin- 

 uous supply, to hatch eggs, if I re- 

 member correctly, and — but this has 

 nothing to do with this paper; to re- 

 turn to the subject. 



The Long-billed Marsh Wren rears 

 two broods of young in a season, the 

 first brood in June and the second in 

 July or August, if the nests are un- 

 disturbed, but should the first and 

 second sets of eggs be taken, they will 

 lay a third; if these, a fourth; and 

 these, a fifth, which is the highest 

 number of clutches I have ever made 

 a bird lay to my knowledge. When 

 the first set is taken, the bird lays 

 her second complement generally in 

 one of her sham nests, with some ex- 

 ceptions, and while she is brooding 

 them the male constructs one or two 

 more, thus when a pair have been 

 robbed several times they will own 

 eight or nine false or sham nests. 



The earliest I have found fresh eggs 

 was May 22, 1906, and have seen 

 young barely capable of flight on 

 August 16, 1897. Wilson says that 

 "the young leave the nest about the 

 twentieth of June," speaking of the 

 Marsh Wren in Pennsylvania, which 

 a writer in Cassinia, Mrs. Clarence 

 J. Hunt, things exceptionally early, as 

 it undoubtedly is compared with his 

 incomplete observation of these birds' 

 habits. The young of the first brood 

 leave the nest between the twentieth 

 and thirtieth of June, rarely earlier, 

 the twenty-fifth of the month being 

 the minimum time, as far as I have 

 been able to ascertain. They are cared 

 for by their parents for about a week 

 longer, before being able to care for 

 themselves, but when fully capable 

 of shifting for themselves, the female 

 lays her second set. My experiences 



