16 
EIGHTH REPORT. 
which have wintered farthest south, but before the first of March the 
vanguard has pushed into the deserted country north of the 42d parallel 
and our spring migration has begun. The Crow is a good example 
of what we may call our summer residents, or summer visitors, though 
in the southermost counties he may properly be called a permanent resi¬ 
dent, and from most of the State he is absent only about one-third of 
the year. 
Perhaps a better example of summer resident is found in the Purple 
Martin which usually arrives in southern Michigan from the 1st to the 
20th of April, nests during May and June, and again moves out of the 
State before the middle of September, thus spending only five of the 
twelve months with us. In 1884 the northward movement of these 
birds was noted from the time they entered the Mississippi Valley, the 
last of February, until a few arrived at Oak Point, Manitoba, on May 
23d. The distance from Few Orleans to Oak Point is about 1,440 
miles and apparently about ninety days was consumed in making the 
trip; an average of but sixteen miles a day. However, Prof. W. W. 
Cooke, who collected the data, was convinced that the forward move¬ 
ment was confined to twelve days (or rather nights), which would make 
the average about 120 miles per night for the twelve nights of travel.* 
This is a bird of such swift and powerful flight that it is perfectly 
possible for it to speed northward 150 or 200 miles with a warm 
southerly wind and yet retrace its course the next day in case the 
weather becomes inhospitable. It seems reluctant to retreat, however, 
and too frequently the early Martins which are caught by severe cold 
weather die from starvation. Their food consists almost entirely of 
insects caught on the wing, and when the temperature drops anywhere 
near the freezing point very few insects continue to fly. A few be¬ 
numbed stone flies may be picked from twigs and grass-tips, but not 
enough to supply heat and strength for these muscular and active birds. 
The Martin spends the winter entirely south of the United States, some 
lingering in Mexico and the West Indies, but more pushing far south 
into Central or even South America. 
Among the last birds to reach us in the spring is the Mghthawk, 
which is rarely seen in any part of the state before the second week 
in May, and often does not arrive until after the 20th. Fifty years 
ago, when weather prophets were held in greater esteem than now, the 
appearance of the Mghthawk was considered a sure sign that there 
would be no more cold weather. In a general way this may still be 
true, for it lives entirely on insects which are taken on the wing, and 
cold weather by preventing insect flight would bring starvation to the 
Mghthawk. But we know now that no bird is infallible as a weather 
forecaster, and doubtless each spring thousands of Mghthawks and 
countless numbers of other insect-eaters perish from starvation as the 
penalty of pushing north too recklessly. In August and September they 
pass south again, commonly in large straggling flocks, and by the last 
week in September all have disappeared from Michigan. A little later 
they pass out of the United States, visiting the West Indies, Central 
America and Brazil; and not a few winter far south of the Amazon 
Valley on the plains of Paraguay, Argentina and Patagonia. Probably 
* Birds of the Mississippi Valley, pp. 224-5. 
