Io BirDS oF MASSACHUSETTS 
of the “ islands ”’ of the Canadian zone to be mentioned later. The 
Transition zone is a region of nicely adjusted balance. Southern 
species endeavoring to extend their range to the north, here meet 
northern species pushing down towards the south. Since this re- 
gion, then, is one in which a large number of species are able to 
live, there is bound to be a more or less keen competition for. living- 
room among its inhabitants. If one species for any reason loses 
ground, another will sooner or later take its place. Interesting 
cases of this sort are recorded! in which Wood Thrushes have 
invaded the former ranges of the Hermit Thrush after the great 
mortality among the latter in 1895. A number of other instances 
of a species losing ground on the borders of its range may be ex- 
plicable by the fact that individuals habitually frequenting such 
outlying localities are cut off in numbers by some severe and unex- 
pected disturbance, so that their former habitat is left vacant for 
occupancy by others. Many other causes doubtless enter into 
the complexity of the problem. Cutting off of timber changes 
both the future plant life and climate of the spot and consequently 
the fauna. ‘Thus cutting away a spruce forest, with its coolness 
and dense shelter, gives rise toa growth of deciduous trees, whose 
open branches allow the sun to dry up the moisture formerly held 
by the denser trees, and thus a new fauna comes in. 
Following is a list of forty-five birds of the Austral zones 
which range north into the Transition zone of Massachusetts and 
here breed : 
Tympanuchus cupido, Bonasa umbellus umbellus, Colinus virginianus, 
Zenatdura macrura, Sterna dougalli, Sterna antillarum, Larus atrictlla, 
Egialitis voctfera, Figtalitis meloda, Bartramia longicauda, Butorides 
virescens, Ardetta extlis, Megascops asto, Antrostomus voctferus, Coccy,gus 
americanus, Sayornts phoebe, Mytarchus crinttus, Tyrannus tyrannus, 
Vireo flavifrons, Lanius ludovictanus migrans, Sitta carolinensis, Trog- 
lodytes aédon, Crstothorus stellarts, Cistothorus palustris, Galeoscoptes 
carolinensis, Harporrhynchus rufus, Stalia sialis, Hyloctchla mustelina, 
Dendreca discolor, Dendreca vigorstt, Dendreca esitva, Helmintho- 
phila chrysoptera, Prranga erythromelas, Icterus galbula, Sturnella 
magna, Ageleus pheniceus, Molothrus ater, Passertna cyanea, Pipilo 
erythrophthalmus, Sprzella soctalis, Spizella pusilla, Ammodramus cau- 
dacutus, Ammodramus henslowt?, Ammodramus savannarum passerinus, 
Poecetes gramineus. 
1Faxon, W., and R. Hoffmann; The Birds of Berkshire County, Massachu- 
setts, pp. 9, 10. Allen, F. H.; St. Johnsbury Caledonian, Sept. 11, 1896. 
