228 



THE OOLOGIST. 



also mauy eggs which wei'o found in 

 June. They may be tal<en as late as 

 the middle of July. 



The Hades-Plunger is rarely seen 

 running about its nest, and if it is ob- 

 served on the same sheet of wafer, it 

 quickly becomes aware of our presence 

 and conceals itself. A careless collec- 

 tor may visit a lake or pond and think 

 that there are no birds there, when 

 there are ten to twenty pairs of birds 

 within a short distance, and as many 

 nests about the margin of the water 

 which we think uninhabited. 



Coming suddenly upon a Hell-Diver 

 in nestiug season it will be seen to dis' 

 appear; after which it will rize tu the 

 surface once or twice, and then appar- 

 antlj leave for good. Where it goes to, 

 we can only conjecture, but it is 

 reasonable to suppose that it seeks the 

 reedy edges, from which secure posi- 

 tion it is undoubtedly watching our 

 movements. Its nest is probably close 

 at hand, but unless one has had experi- 

 ence or information on the subject, it 

 is absolutely unless to search for the 

 eggs, for I assure yo . that there are no 

 eggs in sight. 



For a great mauy j'ears I looked for 

 the Grebe's thick shelled eggs in vain. 

 I knew, in a vague way, that the nests 

 were about, but I failed to fiml them, 

 try as I would. Finally I learned from 

 some professional frog-catchers for the 

 city markets, that the birds left their 

 nests during the warm days and cover- 

 ed them over to screen them from in- 

 spection and possible spoliation. All 

 complete sets of eggs that had been 

 found, were thus concealed, but in two 

 cases where the sets were incomplete, 

 namely, one and three eggs, the eggs 

 were left unprotected of covering. It 

 may be that the covering of the eggs 

 signities an effort on the part of the 

 reasoning birds, to assist incubation, 

 while temporarily absents. At least it 

 is not proven that the covering to the 

 pet is solely for purposes of concealment. 



Then again, if this habit of covering 

 the eggs does answer a purpose in 

 maintaining a proper degree of heat, 

 why does not the Loon also cover its 

 eggs, which are equally exposed and in 

 a correspondingly low situation. 



Thinking to satisfy myself partially 

 in regard to the matter I took the tem- 

 perature of the surface water near a 

 Grebe's nest at the edge of a pond. 

 The mercurjf indicated 74 degrees Fht. 

 while the atmosphere sun tempera- 

 ture was 107 degrees. The debris 

 which covered the eggs felt warm and 

 moist to the hands. In fact I tried to 

 convince myself that a degree of heat 

 was generated by a seeming fermenta- 

 tion, or a possible chemical action pro- 

 duced by decaying vegetation. We are 

 told that the eggs of the Mound-build- 

 ing Megapodins are hatched often in 

 this manner of incubation. 



Then again 1 have felt that the Gre- 

 bes cover their eggs to protect them 

 from the tierce rays of the sun, and this 

 explanation may meet the views of some 

 of the readers. Certain it is, that of 

 all the nests I bave heard of, not one of 

 the complete sets of eggs w^as left com- 

 pletely uncovered. As referred to above 

 some incomplete oets are founri which 

 are left uncovered. It may be that in 

 these casts the birds were surprised, 

 and driven away while about to deposit 

 additions to the sets of eggs, but it may 

 seem reasonable to think that the birds 

 cover the effgs for other purposes than 

 that of concealment. If concealment 

 was alone intended then it appears to 

 me that the birds would cover the eggs 

 before the set was complete. 



Two frog-catchers told me that they 

 found over tifty nests in a couple of 

 days alioutthe tdges of lakes and ponds. 

 This appears to be a rather big account 

 but I cannot dispute it. as I am aware 

 that the birds breed commonly, and 

 too, in places where their presence is 

 not suspected. 



But notwithstanding that this Grebe 

 is so proiitic a Ia3er and although it can 

 so carefully conceal its nest, still the 

 species does not seem to increase in 

 numbers, and (his circumstance, like 

 many another exami)le of similar char- 

 acter among our birds, affords me food 

 for reflection and wonderment .^ 



