Evening star., 1932-03-17

to the special quality of the duck egg it
self. In those species where the greatest
feminist activity is shown. expert
ments show that this egg can be
Matched without much attention.
Whether this quality in the egg has de-
satisfaction of the mother with her sex
role or whether it came first and tended
to break down the mother instincts has
not been determined.
The egg of the ruddy duck can with
stand considerable variations in tenn
perature without apparent injury to the
embryo: 1t may be that it has special
heat-retalning and heat-resisting prop
critics, DR.. Friedman points out, or
even that there is some heat-producing
mechanism within the egg itself In
any event, it will hatch if incubated
only occasionally-as may be the case
when 1t is dropped in the nest of an
other bird.
The newly-hatched birds, however,
require some care. In the North Amer
lean rudy duck species this duty seems
TO nave been taken over by the father.
male may even give a mothers care
to neglected families other than his own.
He appears to have some pride in his
offspring, according to one observation
quoted by DR.. Friedman, and is seen
with the young broods until they are
one-third or half grown, behaving in a
most gallant fashion and rushing at
real or imaginary intruders with a great
show Of Jealousy"
How 1t All Started.
1t probably all started, DR.. Fried
mann explains, when ducks developed
the practice of dropping an occasional
egg in the nest of some other bird
Along with this went the thermal prop
critics of the eggs themselves and an
apparent diminution of the home
loving proclivities of the species. Thus,
the Smithsonian biologist says, in the
species where these traits are most de-
Veloped "the concept of territory Is
not well maintained, as the nests are
often close together. The mere fact
that females with nests of their own
lay in one another's nests shows how
poorly established are the territorial
limitations of the actions of the in
dividual birds.
The diminution of the territorial
and nest-building instincts are SEEM
ingly correlated with diminution of the
incubating activity on the part of the
female parent. If the bird comes to
the nest relatively little it follows that
it will not be apt to respect its terri
torial boundaries as much as a bird
with strong instructive attachment to
the nest.
I'm the case of the ducks the terri
tory, as such, vanishes after the eggs
hatch, as the parents take their off,
spring into the water and from then
on any place is home to them. Hence
the territory lasts only as long as the
incubation activity of the parents.
Thus it seems that the cause of the
diminution of the potency of terri
torialism is dependent on the lessen
ing of the incubation activities.
Territory Vanishes.
"Inasmuch as the lessening of incu-
baton is merely step on the path to
complete lack of incubation on the part
of the bird that laid the eggs, such as
in the case of those eggs laid in strange
nests, it follows that as this diminiSheS
approaching zero as a limit, so the ter
ritory itself becomes less and less real
and finally vanishes.
THE nest merely is something con-
Structed within territory as a recep-
tacle for the eggs that are to come.
Therefore, with the disappearance Of
the territory as such. there must in
evitably come the loss of the nest
building instinct.
1T is impossible to construct some
thing in non-existan, space Hence
it follows that the loss of the nest
building instinct is also dependent on
the decrease of incubation given the
eggs by the female parents. This in
turn is bound up in the heat adapta-
bility OF the eggs of the ruddy and
black headed ducks. Otherwise any
lessening of incubation would have re-
suited in destruction OF the species"