Evening star. [volume] (Washington, D.C.) 1854-1972, 1889-05-04
TIMING THE BIRDS.
The Speed at Which They Fly in Their
Annual AIigrations.

| INTERESTING OBSERVATIONS MADE UyDER THE
| DIRECTION OF THE DEPARTMENT OF AGRIcuI-
TURE-THE RATE OF FLIGHT CALCULATED
! FLYING BY NIGHT.
An interesting report on bird migration in
the Mississippi valley in the years 1884 and
| 1885, prepared by W. W. Cooke, under the
direction of DR.. C. Hart Merriam, has Just been
issued by the Department of Agriculture. The
| migrations of birds are treated as the result of
! inherited experience. The first migrations it
is held were doubtless. Mr. Cooke SAYS. limited
| in extent, and probably were intelligent move
ments which through repetition became ha-
bitual, and the habit was transmitted from
parent to offspring until it has become the
| governing impulse of the birds life 1t is I'M
| doubtedy true. the writer SAYS that love of the
nesting ground, which is to them their home,
is the foundation of the desire for migration.
and year after year they find their way
! thousands of miles back to the same
box or tree by the exercise of memory
not always the memory of the individual.
but the memory inherited from numberess
preceding generations which have passed aud
repasSed over the same route. Dr. Merriam in
a note added to this takes exception to the
statement that love of the nesting-ground is
the foundation of the desire for migration.
This explanation. he asserts, is forced and I'M
necessary. Birds desert their winter homes,
he holds. because the food supply fails: because
the climatic conditions become unsuitcd to their
needs; because the approach of the breeding sea-
son gives rise to physiological restlessness. and
because they inherit an irresistible impulse to
move at this particular time of the year.
THE RETURN SOUTHWARK.
Mr.. Cooke says the return movement of birds
southwark is obviously the result of two causes
! the approach of winter and the failure of the
food supply OF these two. the latter is prob
| ably by far the more powerful. since it is we'll
known that single individuals of species which
retire far to the south often remain behind.
and. favored by an abundance OF food, with
stand the most severe weather. Thus many
red-headed woodpeckers remain through the
winter in the cold climate of northeastern New
" rk, frequenting the heavy timber. where
there Is great quantity Of their favorite food;
| and 1t is not unusual for a few robins to spend
! the winter i'll north central Wisconsin. Shelf
cred In the thick pine forests; while ducks. and
| even wilson suipe, have been known to remain
! throughout the whole winter On Wyoming.
| near the hot springs. whose warmth keeps the
/ neIghboring waters and ground from freezing.
Nevertheless. 1t Is as yet unexplained why
| some birds, notably many of the warblers, re-
| tire III winter to such great distance south.
/ some even crossing the equator and passing
several hundred miles beyond. Certainly
/ neither cold nor hunger can be the cause OF
| such wanderings. 1t has been often noticed
| that during the fall migration many birds seem
| to be able to foretell the approach of storms
| from the north. and hurriedly depart south
ward, before human eyes can detect any signs
/ OF the coming change.
| SPEED AT WHICH BIRDS MIGRATE
In studying the speed at which birds pro-
| coed northward in their migrations Mr.. Cook
says. one is beset by many difficulties To de-
| termne the comparative speed of the several
| species Il easy enough, but to determine the
| absolute rate-the exact number of miles
| which "a particular bird makes during
| one days journev-is beyond our power
/ While In the fail migration the Younger birds
lead in the spring they loiter behind. and it is
| the Old birds. those in whom we may suppose
! the love OF home and the desire for procrea-
| ton are strongest which press forward so
| eagerly. Moreover, Of these old birds, those
which arrive first at given place, as a rule.
! are birds which lived there the previous
J summer and which will remain there to breed.
/ Thus the vanguard is constantly arresting it.
| self and the forward movement must await the
! arrival OF the next corps, which may be near at
| hand or far III the rear. The movement of mi
grafton, then, Is made up OF a series of constant
| OyeTlapplng5, aud the real speed is evidently
much greater than the apparent. OF this real
/ speed OF transit we take no account and our
/ calculated rates. therefore, are of value only in
50 far as they show the relative speed of mgra-
| ton Of the different species. In the accom-
paEyIng report the speed of migration is calcu-
| lated in the following manner The most south
! EN- reliable record ~ selected tor comparison
with the most northern record of the same
/ character: the distance in miles between these
/ two stations is divided by the number of DAYS
/ elapsiag from the time the species made its ap-
/ peardnce at the southern station to the date at
which it seen by the northern observer
/ The result gives the average daily rate of mi
grafton III miles for the species. For example ::
The Baltimore oriole was seen at Rodney Miss
&ht- 81. o.. }, April Z. 1t was not seen at Oak
Point Manitoba (lat. so 800, until May 70. 1t
was therefore As days il passing over the 1928
miles between the two stations, which gives an
average speed OF u miles day.
FASTENING THEIR FLIGHT.
The records of fifty-eight species for the
| spring Of 1888 give an average speed of %
miles day for an average distance of APO
| miles. A study of the records for 1888 led to
| the statement that in spring birds migrate
| more rapidly in the northern portion of their
routes OF travel than in the southern. In the
| spring of 1854 twenty-five species of we'll
known birds, concerning which we had full
| records, were selected for careful study The
result bears out the foregoing statement. The
J distance travelled was divided as nearly as pos
| sible into two equal portions, and the spec d
! was calculated for each. Some OF the records
( DO not admit of division; Others show an equal
speed throughout, while six show an increase
( OF II per cent in speed for the northern half,
aud three show decrease of AZ per cent. Thus
| II will be seen that the record is strongly in
/ favor of the increase. The same result may be
| reached by calculating the average speed of
/ these twenty-five species separately for each of
| the different months i'll which migration is per-
| formed; the average speed for March is 10
| miles, for April % miles, and for May 26 miles
/ per day. The record for 1884 also confirms the
statement that the later a bird migrates the
! higher average speed it will attain.
In all probability the same bird seldom mi
| CRATES for several nights in succession. but
stops to rest after flight of night or two so
| that the birds migrating one night are not the
I same individuals that were moving the night
| before.
| THE RELATIVE SPEED.
] In regard to the relative speed at which the
different species travel all that can be said at
/ present is that those which migrate later have,
as a rule, the highest rate. Thus the average
| speed of the robin, cowbird and golden-shafted
] flicker is about II miles day, while the aver
age of the summer redbird, Baltimore oriole,
ruby-throated hummer and nghthawk is %
| miles. If We try to calculate the relative
speed of the different families, we find
that some of the species in family mi
| CRATE early and slowly, others late and rapidly,
| bringing the average of most of the families
very close to the general average OF ALL which,
as already stated, is % miles day. Birds have
| seldom been seen while on their way in undis-
| turbed migration at night. 1t is known that