against possible property damage or personal injury. If it is a fuel-wood pile, the wood can be
us ed before s pring, the bark can be peeled from the wood, or the wood can be s tored in a dry
place. In the cas e of dying or dead elm trees , the expens e of prompt removal to prevent Dutch
elm dis eas e s pread is us ually no greater than woul d be neces sary later, for mos t dead trees in
urban regions mus t be re moved eventually.’ The s ituation with regard to Dutch el m dis eas e is
theref ore not entirely hopeles s provided informe d and intelligent measures are taken. While it
cannot be e radicated by any means now known, once it has become es tablis hed in a
community, it can be s uppres s ed and contained within reas onable bounds by sanitation, and
without the us e of methods that are not only futile but involve tragic des truction of bird life.
Other possibilities lie within the field of forest genetics, where experiments offer hope of
developing a hybrid elm res is tant to Dutch elm dis eas e. The European elm is highly resis tant,
and many of them have been planted in Was hington, D.C. Even during a period when a high
percentage of the city’s elms were affected, no cas es of Dutch elm diseas e were found among
these trees. Replanting through an immediate tree nurs ery and fores try progra m is being urged
in communities that are losing large numbers of elms. This is important, and although s uch
prog rams might well include the res is tant Europea n elms , they should aim at a variety of
s pecies s o that no future epide mic could deprive a community of its trees. The key to a healthy
plant or animal community lies in what the British ecologist Charles Elton calls ‘the conservation
of variety’. What is happening now is in large part a result of the biological unsophistication of
pas t generations. Even a generation ago no one knew that to fill large areas with a single
s pecies of tree was to invite dis as ter. And s o whole towns lined thei r streets and dotted their
parks with elms , and today the elms die and s o do the birds....
Like the robin, anothe r A merican bird s eems to be on the ve rge of extinction. This is the
national symbol, the eagle. Its populations have dwindled alarmingly within the pas t decade.
The facts suggest that something is at work in the eagle’s environme nt which has virtually
des troye d its ability to reproduce. What this may be is not yet definitely known, but there is
some evidence that insecticides are respons ible.
The mos t intens ively s tudied eagles in North A me rica have been thos e nes ting along a s tretch
of coas t from Tampa to Fort Myers on the wes tern coas t of Florida. There a retire d banke r from
Winnipeg, Charles Broley, achieved ornithological fame by banding more than 1,000 young bald
eagles during the years 1939-49. (Only 166 eagles had been banded in all the earlier his tory of
birdba nding.) Mr. Broley banded eagles as young birds during the winter months before they
had left their nests. Later recoveries of bande d birds s howed that thes e Florida-born eagles
range north ward along the coas t into Canada as far as Prince Edward Is land, although they had
previous ly been cons idered nonmigratory. I n the fall they re turn to the South, their migration
being obs erved at s uch famous vantage points as Hawk Mountain in eastern Pennsylvania.
During the early years of his banding, Mr. Broley us ed to find 125 active nes ts a year on the
s tretch of coas t he had c hos en for his work. The numbe r of y oung ba nded each yea r was about
- In 1947 the production of young birds began to decline. Some nes ts contained no eggs ;
othe rs contained eggs that failed to hatch. Between 1 952 and 195 7, about 80 pe r cent of the
nes ts failed to produce young. In the las t year of this period only 43 nests were occupied. Seven
of them produced young (8 eaglets ); 23 contained eggs that failed to hatch; 13 were us ed
merely as feeding stations by adult eagles and contained no eggs. In 1958 Mr. Broley ranged
over 100 miles of coast before finding and banding one eaglet. Adult eagles , which had been