102 THE CONDOR Vol. XXII 
these will have met their death, leaving again 20. Fifty per cent of the mini- 
mum annual population dies each year. 
Compare this with the run of land birds. To cite the song sparrow, which 
we will figure as rearing two broods of four each, and starting with 20 birds 
in April, there will be 100 birds by July. Eighty of these will have succumbed 
to the various exigencies of terrestrial existence by the following April, when 
the normal complement of 20 will again obtain. Here there has been a death 
rate of 400 percent of the minimum annual population. In other words the 
life expectation in the petrel when it hatches is eight times that of the song 
sparrow when 7 hatches. 
And what of the Brewer Blackbird and the Mudhen and the California 
Quail! 
It is clear, then, that even with the faster breeding sea birds, such as 
the gulls with their three-egg sets, no such annual mortality is suffered as 
with the great majority of land birds. Why is it, then, that the deaths of sea 
birds become so impressive? 
In the first place, as numerous naturalists have remarked before, the 
chances of a dead or dying land bird coming to the attention of the observer 
are relatively remote. Hosts of predatory animals of a variety of kinds are 
on the alert for any lagging bird. One that happens to drop onto open ground 
is quickly devoured, or carried away into concealment, or buried. But an 
oceanic water fowl which becomes decrepit or dies is rarely made way with. 
It floats on the surface of the water, for days and perhaps weeks, carried along 
by the currents and the winds. <A storm setting on-shore is bound to sweep 
everything towards the beach from miles of surface; the narrow winrow of 
debris there left is the concentration from great areas of adjacent sea surface. 
The visitor to the seashore at such times naturally gets an idea of the mor- 
tality among the bird species represented which is exaggerated far above 
the real state of affairs. 
I once experienced a five days’ northwester while returning to California 
from Bering Sea in a small sailing vessel. Part of the time hove to, and part 
of the time running before the gale with double-reefed jib and fore-sail, abun- 
dant opportunity was given me to watch the behavior of the sea birds, some of 
which were always in sight during the daylight hours. I was impressed be- 
yond all doubt, of the mastery of the albatrosses, petrels and fulmars over any 
ordinary stress of wind or wave. 
The annual mortality of sea birds, beginning with the moment of hatch- 
ing, probably pertains mostly to the early weeks of their lives before they have 
reached the full strength of their maturity, and to the period of advancing 
decrepitude in old age. Predacious enemies of sea birds, save of those that live 
close to shore within the domains of Duck Hawks, are rare. Accidents there 
must be, such as pertain to the processes of food capturing. But that wind or 
wave figure in any appreciable degree, per se, can hardly be considered for a 
moment. As above shown, life on the ocean wave, for those birds which are 
adapted to pelagic life, is by far the safest, as compared with the lives of the 
great majority of our terrestrial species. 
In this connection I wish to file a complaint against the custom which pre- 
vails, of basing local records of birds upon the finding of dead, or living but 
helpless, examples cast up on ocean beaches. Such ‘‘remains’’ may have 
drifted scores, even hundreds of miles from where the birds met their death 
