ECONOMIC RELATIONS OF OUR BIRDS.


and there are few fields but what have at least a few treas standing in them.
In
the portion of Jefferson county where the notes were taken, the country is
nearly level, with gentle undulations, and is traversed by Rock and Bark
rivers.
These streams draw a sharp line between prairie and openings on one side,
and
heavy maple timber on the other. Marshes trend along the streams, and shallow,
reedy ponds are common. Compared with the vicinity of Ithaca, the farms are
larger, the houses less numerous, the orchards smaller, the woods larger,
and few
trees stand in the cultivated fields.
Route I led from a point about one-half a mile north from Bark river out
and
across cultivated fields, through two small groves, across a marsh near Cold-
spring Pond, and then again across cultivated fields. Routes II and III each
led
east from Rock river, north of Jefferson, alternately through pieces of heavy
timber, and across dry cultivated fields. Route IV led from the Crawfish
west,
upon the prairie southwest of Aztalan, traversing dry treeless fields, and
lead-
ing through two small oak groves. Route V extended from the buildings of
Cornell University west across the valley, leading through a pasture, through
the
north end of the city, through the swamp, and up the railroad, bordered by
cul-
tivated fields on one side and by tangled thickets on the other. Route VI
led
directly east from the campus to Varna, and then southwest along the line
of
the railroad. On this trip only cultivated fields were crossed and one small
piece of woods passed through. Route VII led up the valley from Ithaca along
the east side, and then across to Enfield Falls. On this tramp we passed
in turn
along the railroad, bordered with small scattered thickets on both sides,
across
the Inlet, through low fields, and then past cultivated fields and small
pieces of
woods. Route VIII lay ten miles east of Ithaca, and led from McLean off to
the southeast of Dryden, and then through Dryden to Freeville. A branch of
Fall Creek was crossed twice, and with the exception of a small marsh near
Freeville, only dry cultivated fields and small pieces of woods were passed.
It should be observed that the notes taken in Jefferson county were obtained
after the breeding season, while those taken at Ithaca were made during the
breeding season before the young birds had, to any extent,jleft the nests.
The
difference in the times of observation in the two localities will doubtless
com-
pensate largely for the difference in topographical features. For instance,
the
Bobolinks observed on trip VIII were, with two exceptions, all males, so
that
the figures probably show but about one-half the actual number of birds of
this
species which were there at the time.
The table, as it stands, indicates that notwithstanding the fact that the
vicinity
of Ithaca has been much longer under cultivation, and that it is more thickly
settled, its bird population is more than a third larger, so far as the number
of
individuals is concerned, than that of Jefferson county. Whether this greater
abundance is due more to the influence of man than to natural topographical
features, the table does not appear to prove, for it is deceptive in regard
to this
point in several respects.
(3) What birds, if left to themselves, are likely to become most abundant
as
the country grows older. Before we can safely interfere with the restraints
which nature has imposed upon bird-life, we must know the facts in regard
to
this point, because it can hardly be supposed that the different species
will con-
tinue to hold the same relative proportions to one another that they now
do if
their enemies should be removed. If the birds in the table to which we have
had occasion to refer are classified under the four heads, Fruit-eaters,
Fly-
catchers, Seed-eaters and Insect-eaters, the average number of individuals
ob-
served per mile during the eight trips, considered collectively, will be
found to
be approximately as follows:


459