Vol. XI 
1894 
] 
Chapman on the Origin of Bird Migration. 
/ 
Their case seems to me to be closely parallel to that of tWsea- 
birds previously cited. It is probable that in both cases these 
cdlonies owe their origin to the instinct which guides / bird to 
return to the place of its birth. Those individuals which selected 
the most favorable breeding ground would rear their young in safety 
and the young returning would aid in forming a future colony. 
On the other hand, the progeny of those birds which did not 
select so s^fe a home would be less likely to survive. 
Of this wonderful ‘homing instinct’ which plays so important a 
part in the migration of birds I have no explanation to offer. W e 
know, however, that it exists, not only in birds, but in many other 
animals. It is this instinct, aided by the ‘heredity of habit,’ which 
guides a bird to its nesting ground. The Carrier Pigeon is taught 
its lines of flight by gradually extending its journeys ; a species 
learns its routes of migration by gradually extending its range. 
As for the desertion of the breeding grounds and consequent 
fall migration, there seems to be no question that it is due mainly 
to the failure of the food-supply. Nevertheless, many species of 
birds migrate long before Wafere is apparently any reason for then- 
doing so. Early in July the Snipes and Plovers begin to appear 
from their nesting groqnds in the north. The first of August 
finds numbers of our land-birds crossing the Gulf of Mexico en 
route to their southern homes. Now, it has been frequently asked, 
if failure of the food-supply is the cause of the fall migration, why 
do these birds leave their breeding grounds at so early a date ? 
In reply I would ask, why should they remain? The object for 
which they came is accomplished, and unless they are offered 
some sjrecial inducement to stay, why should they not return to 
the regions in which — and I would emphasize this — many of 
them pass two-thirds of the year ? 
The sea-birds I have mentioned desert their barren homes as 
soon as (heir young are on the wing. The Arctic-nesting Snipe 
and Plover hasten from the north to more fruitful feeding grounds 
furthe/ south. In fact, as soon as the cares of the nesting season 
are over, the summer home seems to possess few attractions. 
So fire birds at once hurry back to their southern resorts, while 
others wander at will around the country, pausing wherever food 
is abundant, and do not retreat southward until they ar^ actually 
forced to do so. 
3 
I 9 
Vol. XI 
1894 
Mackay, Habits of the Double-crested Cormorant. 
It was during my recent trip to Seconnet Point, April, 1892, 
that I determined to visit the Cormorant Rocks, should the 
weather and sea be sufficiently favorable for making the trip, it 
requiring a calm sea and off shore wind in order to effect a land- 
ing. When other conditions prevail it is a most forbidding and 
dangerous place to attempt a landing, surrounded as it is with 
an impassable collar of surging surf and foam, while rising from 
the centre are the black jagged rocks surrounded by a nearly 
flat mesa-like apex crowned with a cap of Fusiyama whiteness 
as it glistens in the sunlight, but not, however, composed like 
it, of immaculate snow, but of lime. Such a day as I had 
wished and waited for was April 19, 1892, and as I rode at 
anchor in my little boat off the seaward side of West Island 
(which lies off’ the extreme point of Seconnet Point) shooting 
Scoters, the sea was calm, as it had been for the two days pre- 
viously, and a gentle breeze blowing from the northwest com- 
pleted the desired requirements. Perceiving a large cat-boat 
belonging to two Swedish lobster-men coming towards me, I 
motioned to them to come up in the wind, as I wished to board 
and speak with them. This they did, and I soon arranged for 
them and their boat to carry me to the rocks, to remain all day 
and return to West Island at night. Wishing to go on shore 
to secure a few things before starting I instructed them to stand 
off and on near the island and I would wave for them to come 
for me in their small boat when I was ready to start. We filled 
away about nine o’clock a. m., and just before ten o’clock, we 
were off the rocks. Putting my things into the small boat, one 
of the men rowed me to the rocks near at hand. After wait- 
ing awhile for a favorable opportunity to land, for it was break- 
ing all around, in we went through the surf without taking in 
scarcely any water and landed on the rocks where I remained 
until sunset. 
These low lying black rocks have been in the past, and are 
still, the resort and roosting place of all the Cormorants living in 
and around these waters, and as they undoubtedly received their 
name many years ago from such occupancy it may be interesting 
to know that on a map dated July 20, 1776, which is in an atlas 
called the ‘American Neptune,’ published in London in 177 6, 
and surveyed by Des Barres, that these identical rocks are cor- 
