478 
Forest and Stream 
Dent’s 
A marvelous tonic for dogs that 
are out of sorts, run down, thin 
and unthrifty, with harsh staring 
coat, materated eyes and high 
colored urine. Thera is nothing 
to equal them for distemper, 
mange, eczema and debilitating 
diseases. You will notice the 
difference after a few doses. 
At druggists or by mail, fifty cejits 
The Dent Medicine Company 
Newburgh, New York Toronto, Canada 
practical treatise on dogs and their treatment, a 
Is This Worth the Price? 
Stop your dog breaking shot and wing. 
Teach him what whoa! means. No long 
trailing rope or spike collar. Our field 
dog control is not cruel. Can be carried 
in pocket and attached instantly to dog's 
collar. Dog can’t bolt. Fast dogs can be 
worked in close and young ones field 
broken in a week. Works automatically — 
principal South American Bolas. Sent 
postpaid with full directions for $2. Testi^ 
monials and booklet, Making a Meat Dog 
sent on request. 
MAPLE ROAD KENNELS 
English Setters, Pointers 
and 
Wire Haired Fox Terriers 
Puppies and grown dogs 
of the best of breeding 
FOR SALE 
Good dogs at stud 
GEO. W. LOVELL 
MIDDLEBORO, MASS. 
Tel. 29-M 
Winner of all-American 
Endurance Race. Litter 
brother to Champion 
Mary Montrose. Peer- 
less on the bench and 
in the field. Dogs 
trained and handled. 
Setter, pointers and 
Walker hounds for sale. 
20,000-acre game pre- 
serve. 
EDWARD D. GARR 
Lagrange, Kentucky 
DOG OWNERS. AMATEUR OR PROFESSIONAL. 
Here is your opportunity. New book “Care of Dogs” free, 
contains helpful instructive information on feeding, train- 
ing, diseases. Every dog owner needs it. Book mailed 
free with a 3 months' trial subscription to Sportsman’s Di- 
gest — America's popular illustrated Dog and Hunting 
Magazine. Send 25c today (coin or stamps). SPORTS- 
MAN’S DIGEST PUBLISHING CO.. 503 Butler Bldg., 
Cincinnati. O. 
POHIC 38976 
The Lion of His Tribe 
at Stnd. A Winner — A 
Producer Fee $40.00 
Raise Silver Foxes 
Easy to raise. Larger profit, 
than any other live stock rais* 
ing. Stands strictest investiga. 
tion. Recommended by Gov- 
ernment. 4 different plans. 
One will suit you. Complete 
description free. Send today. 
C.T.DRYZ, Box 1033, EAGLE RIVER, WIS. 
WE BUY ALL YOU CAN oaicc JJ 
; FREE INFORMATION OR SEND ONE DOUAR FOR BLUE PRINT ETC 
21J W.30thSt 1P.DUFFUS.SIIVER FOX STORE wE»nroRK.N.v. 
MIGRATION RELATIVE 
TO BIRD SIZE 
{Continued from page 445) 
beak and Siskin that visit us from the 
far north in winter have representatives 
that breed in mountain ranges much far- 
ther south where they find a climate and 
environment similar to that of the north- 
ern forests. The migrations of these 
southern forms are generally inconsid- 
erable, consisting mainly of descent to 
low’er levels. We find the Mexican 
Crossbill breeding in the high mountains 
from Arizona and New Mexico to Gua- 
temala, larger than the American Cross- 
bill ; the Rocky Mountain Pine Grosbeak 
breeding in the Rocky Mountains from 
Alberta to New Me.xico, larger than the 
Pine Grosbeak; the Mexican Pine Siskin 
of the mountains of southern Mexico 
larger than the Pine Siskin. In the 
same category are the Guatemalan Blue- 
bird compared with the Bluebird, the 
Carolina Junco compared with the slate- 
colored Junco, and the Mountain Soli- 
tary Vireo of the southern Alleghenies 
compared with the Solitary Vireo. 
'T'HE Sonoran Yellow Warbler that 
breeds from Lower California, Ari- 
zona and New Mexico southward, and 
Duge’s Yellow Warbler of Central New 
Mexico, are both larger birds than the 
Yellow Warbler or the Alaskan Yellow 
Warbler that make the Canadian Zone 
in summer, and winter south of the 
United States. The Florida Yellow- 
throat breeding in the southern United 
States is larger than the Maryland 
Yellow-throat which reaches the Cana- 
dian zone in summer, and winters from 
the Gulf States south to Guatemala and 
Costa Rica. In the same way we may 
compare the Mourning Warbler and 
Macgillivray’s Warbler, the Myrtle War- 
bler and Audubon’s Warbler, the Water 
Thrush and Louisiana Water Thrush, 
Yellow-breasted and Long-tailed Chats, 
finding each time the smaller bird mak- 
ing the longer migration. Finally the 
Summer Tanager and Cooper’s Tanager 
and the Whippoorwill and Stephen’s 
Whippoorwill furnish further evidence 
of this law. 
This law does not apply to birds so 
highly developed for long - continued 
flight as Swallows, Swifts and Night- 
hawks, so although we have western 
forms of the Nighthawk, Purple Martin 
and Cliff Swallow whose migrations are 
considerably less, they are not larger. 
It will be noticed that this law applies 
without any regard to geographical lo- 
cation or climate. It is only necessary 
to compare birds in which the length of 
migration differs greatly. 
As a result, in all these e.xamples the 
smaller bird is the one breeding farther 
north. 
As for the well-known law that north- 
ern forms are larger, it applies to a large 
number of birds, but they all come under 
one head : they make short migrations, 
or to be more explicit, they generally 
winter within the limits of the United 
States. It seems that the two laws op- 
pose each other, and hence the most 
extreme cases in which the size of the 
northern birds are larger occur in the | 
Hairy and Downy Woodpeckers, which 
are among the least migratory of our i 
northern birds, the law of increase in 
size with increase in latitude meeting ' 
w'ith little opposition in these species. 
A S for the cause of endurance favor- 
ing the smaller animal, many ex- 
planations have been advanced, the 
greater weight of the larger being gen- 
erally one of the factors that are sup- 
posed to count in the running events. 
Such explanations would not help us in 
the case of the oarsmen. I will venture 
to propose one that will cover all cases. ' 
If we imagine two beasts or two men 
or two birds proportioned alike in all 
parts, one of which is twice the length 
of the other, the larger will have eight 
times the bulk of the smaller, which can 
be supplied by a heart of eight times the 
capacity. But the area of cross section 
of any artery or vein is but four times 
as great, hence the blood must be pumped 
through the vessels with twice the speed 
in the larger animal in order to renew 
the tissues in the same time. This, it 
seems, is not a matter for the anatomist 
or physiologist to decide, but a matter of 
simple calculation in elementary engi- 
neering. The bulk of the animal in- 
creases as the cube of any dimension 
while the amount of blood furnished to 
any part can increase only as the square. 
Bats do not generally migrate, but 
those that feed while flying, after the 
manner of swallows, are .smaller than 
the frugiverous kinds because they must 
have more endurance to sustain them- 
selves in the air for long-continued 
flights. The case is analogous to that of 
the swallows, which, subjected to every 
climate on the globe, have remained 
small ; nor is this due to their food, since 
a bird the size of the Nighthawk can 
feed in this way and, as the NighthawL 
does, make a living and enjoy a wide 
margin of leisure. The same principle 
applies to bat and bird; mechanical ad- 
vantage and endurance both favor the 
smaller in flight. 
Just as the smaller Rails make the 
longer migrations, so we find in the 
Sandpipers the very small Semipalmated 
Sandpiper migrating from Arctic shores 
to Patagonia; the Least Sandpiper from 
far north to Brazil, even crossing the 
sea to the Galapagos; Baird’s and 
White-rumped Sandpipers from Arctic 
coasts to Patagonia; while the great 
wanderings of the Phalaropes and 
Mother Cary’s Chickens also testify to 
the superiority of the small bird in en- 
durance. Among passerine birds the 
longest migrations are made by the 
Black-poll, Connecticut and Tennessee 
Warblers, all very small birds. Even 
the great tropical family of Humming 
Birds sends north to the glaciers of 
Alaska and to the Cape Breton Islands 
representatives of its smaller kinds. The 
Great Auk could not fly, but the Little 
Auk travels between Arctic shores and 
Southern New England every year. 
