LIFE HISTORIES OF NOETH AMERICAN" PETRELS AND PELICAXS. 205 



more or less regularity G to 8 feet from one another. As long as a bird' re- 

 mained within its own douiain, having a diameter of approximately 6 to 8 feet, 

 it was not molested ; but let it or its young advance beyond these limits and they 

 were promptly attacked. 



So closely, however, are the birds confined to their own little areas that dif- 

 ficulties of this kind are rare, and^ under normal conditions peace reigns in 

 the rookery. But when, as we walked tlirough the rookery, the birds, in escap- 

 ing from the larger evil, forgot the lesser one and inadvertently backed onto a 

 neighbors' territory, the unusual cause of the trespass was not accepted as an 

 excuse and they found the " frying-pan " worse than the " lirt'." as the enraged 

 owner, with bristling feathers, furiously assailed them with open bill, sometimes 

 taking hold. At these times and whenever the birds were alarmed, they gave 

 utterance to hoarse, raucous screams or screeches, though as a rule they were 

 comparatively silent. 



Young. — Kegarding the young birds he says : 



The young booby is born practically naked, and since exposure to the sun 

 before tl)e downy plumage is developed would result fatally, it is constantly 

 brooded, one parent immediately replacing the other when the brooding bird 

 is relieved. Brooding continues even when the white down is well developed 

 and the young bird, then too large to be wholly covered by the parent, lies flat 

 on the ground, the head exposed, the eyes closed, apparently dead. This relaxed 

 attitude is also taken by young which are not sheltered by the parent, and 

 we were not a little surprised on several occasions when about to examine 

 an evidently dead bird to have it jump up, and with a trumpeting call, blare 

 at us with open niouth. Nor do they rely only on the voice for defense, but 

 use the bill effectively, and, as has been remarked, they possess with the adult, 

 the somewhat ludicrous habit of venting their feelings by picking up bits of 

 stick and grass. 



Compared with other rookeries I have visited, the mortality among young 

 boobies on Cay A'erde — aside from the prenatal mortality already referred to — 

 was surprisingly small. This I attribute to the isolation of the cay, which 

 permits the birds to rear their young with little or no intrusion by man, whose 

 presence, even as a visitor, results in great confusion and consequent dteath 

 among the young of ground-nesting colonial birds. 



The young were fed on squids and fishes, which, in a more or less digested 

 condition, they obtained by thrusting their heads and necks down the parent's 

 throat, a manner of feeding common to all the Steganopodes with whose habits 

 I am familiar (including Pelccanus, Freyata, PhnUtcrovorax, and Anliinga). I 

 have not, however, seen Phaethon feeding its young, and it would be interesting 

 to know whether this tern-like member of the order has a similar method of 

 administering food. 



Evidently but one brood is reared, since approximately three months must 

 elapse after the egg is laid before the young can fly and care for itself. 



Plumages. — The young booby is hatched naked, but the down soon 

 begins to sprout in the various feather tracts and shortly clothes the 

 whole body, head, and neck, except the naked face, with a pure white, 

 soft, woolly covering. The juvenal, or first real plumage, appears 

 first on the wings, the primaries coming first ; the tail soon follows, 

 so that all the flight feathers are developed at an early age and con- 

 siderably in advance of the body plumage; the latter appears first 



