,,united ,,states ,,department ,,of     
,,agriculture    ,,miscellaneous        
,,publication ,no4 #aae                 
,washington1 ,d4 ,c4        ,april1     
#aica        ,,information ,,for ,,the  
,,guidance ,,of ,,field ,,men ,,and     
,,cooperators ,,of ,,the ,,bureau  ,,of 
,,biological ,,survey ,,engaged ,,in    
,,the ,,control ,,of ,,injurious        
,,rodents ,,and  ,,predatory ,,animals  
,prepared under the direction of ,paul  
,g4 ,redington1 ,chief1  ,bureau of     
,biological ,survey1 in the ,division of
 ,predatory-,animal and                 
,rodent-,control1 ,stanley ,p4 ,young1  
,principal ,biologist1 in  ,charge      
,,contents                              
,page      ,introduction                
#a      ,necessity for control of       
wild-animal pests4                   #a 
,control functions of the ,bureau of    
,biological ,survey          #b         
,legal authorization for control work   
#b      ,instructions previously issued 
#c      ,animals on the control program 

#c      ,the injurious rodents          
#c      ,the predatory animals          
#c      ,other forms subject to control 
#d      ,instructions regarding field   
practices                          #d   
,the objective                          
#d      ,conservation1 ,state laws1 and 
cooperation                     #d      
,precautions in handling poisons        
#d      ,rodent-control operations      
#f      ,predatory-animal control       
#f          ,,introduction              
,,necessity ,,for ,,control ,,of        
,,wild-,,animal ,,pests    ,the demands 
made upon the ,federal ,government some 
years ago for aid in  suppressing those 
wild animals of the public domain that  
continually  spread out into areas that 
had been placed under cultivation or    
used  for grazing purposes produced the 
first ,federal cooperative efforts      
toward the control of predatory animals 
and injurious rodents4 ,the  settler who
 saw the profits of his early work wiped
 out by the  incursions of wolves1      

coyotes1 mountain lions1 and bobcats    
from the  public domain into his stock  
ranges1 and of prairie dogs1 ground     
squirrels1 pocket gophers1 jack rabbits1
 and other rodents into his  cultivated 
fields1 had no recourse other than to   
ask the aid of the  ,government whose   
lands served as breeding reservoirs from
 which these  predators and rodents     
came4 ,otherwise they would reinfest his
 stocked  and cultivated acres in spite 
of all that he could do to prevent them1
  either single handed or with the aid  
of his neighbors4      ,,control        
,,functions ,,of ,,the ,,bureau ,,of    
,,biological ,,survey    ,the           
administration of wild life by the      
,bureau of ,biological ,survey  involves
 not only research into the habits1     
distribution1 and  requirements of the  
varieties1 and the conservation of fur1 
game1  insectivorous1 and other valuable
 animals1 but also the regulation  of   
activities of a limited number of       
certain species that seriously          

interfere with the economic interests of
 man1 and1 in the case of some  of the  
larger predators1 prey upon valuable    
game species4    ,the leadership of the 
,biological ,survey in control          
operations during  the years since #aiae
 has been requested and encouraged by   
,state and  other cooperating agencies4 
,the funds made available from these    
sources  for expenditure under the      
direction of the district leaders of the
  bureau have been far in excess of     
those provided for the purpose from  the
 ,national ,treasury4 ,the              
investigations of the food and other    
habits1  the geographic distribution1   
and the relationships of the wild birds 
and mammals of the country 7including   
rodents and predators7 have been        
carried on for almost half a century and
 provide the basis for the  control work
 recommended and prosecuted4 ,research  
along these lines is  being continued by
 scientifically trained men and will be 
expanded as  funds permit4    ,it is    

well for the conservation of the wild   
life of the country that  leadership in 
the control of injurious species has    
been delegated to  a governmental       
organization that is concerned with the 
welfare of the  various forms and with  
the administration of wild-life refuges1
 one  that is charged with the          
enforcement of wild-life conservation   
laws1  and one that recognizes the      
desirability of preserving              
representatives  of all forms of wild   
life on suitable areas4    ,,legal      
,,authorization ,,for ,,control ,,work  
,the legal sanction for control work by 
the ,federal ,government is  contained  
in congressional direction in annual    
appropriation acts for  the ,department 
of ,agriculture and in a special        
enactment authorizing a  definite       
control program4 ,the appropriation acts
 making funds available  for the use of 
the ,bureau of ,biological ,survey since
 the year #aiae  have provided for      
investigations1 experiments1            

demonstrations1 and  cooperation for the
 control of wild animals injurious to   
agriculture1  horticulture1 forestry1   
animal husbandry1 and wild game1 and for
 the  suppression of rabies in predatory
 wild animals4 ,the special program  of 
control1 which was called for by the    
,seventieth ,congress1 was drawn  up by 
the ,department of ,agriculture to cover
 a #aj-year period1 and was  approved by
 the ,seventy-first ,congress 7,public  
,act ,no4 #ggf1 of ,march #b1  #aica74  
,,instructions ,,previously ,,issued    
,information regarding new developments 
and improved practices in  control      
procedure has been made available to the
 field personnel and  to cooperators of 
the bureau from time to time since the  
inception  of the cooperative work in   
#aiae1 in mimeographed and printed form1
  as well as by individual written      
instructions and personal contact4  ,it 
is now desirable to compile the more    
important of the statements  as to      
policy and specific directions in one   

publication4 ,all control  methods are  
based on fundamental research and give  
due consideration  to safeguarding the  
useful and harmless forms of wild life  
and the  public interests in general4   
,field methods have been adapted to meet
  varying local conditions as called for
 by research and the experience  of     
field forces4 ,investigations and       
experiments are being continued1  and as
 additional information becomes         
available1 field practices will  be     
subject to such modifications and       
improvements as the conditions  warrant4
          ,,animals ,,on ,,the ,,control
 ,,program      ,,the ,,injurious       
,,rodents    ,certain species of the    
rodents that in large numbers infest    
lands of  value for crop or forage      
production must be eradicated locally to
  meet the requirements of agriculture  
and forestry4 ,those that figure  most  
largely in the cooperative control      
operations in one part or  another of   
their ranges are the prairie dogs1      

ground squirrels1 pocket  gophers1 jack 
rabbits1 porcupines1 and native and     
introduced rats and  mice4 ,other groups
 that locally become unduly numerous and
 destructive  may also on occasion come 
within the control program4 ,it would be
  impossible to eradicate everywhere the
 ground squirrels1 prairie dogs1  and   
other rodents that range over vast areas
 of relatively worthless  lands1 and    
such action is not desirable1 even on   
the public domain4 ,in  areas of        
economic importance1 however1 definite  
tracts are established  where the       
rodents can be kept under thorough      
control1 and operations  are extended   
sufficiently to prevent reinfestation4  
,,the ,,predatory ,,animals    ,the     
control of such predatory wild animals  
as coyotes1 wolves1 mountain  lions1 and
 bobcats is concentrated on areas where 
serious damage is  being done to        
domestic stock1 poultry1 and game4      
,bears are not subject  to control      
except when individually injurious to   

livestock or property4      ,,other     
,,forms ,,subject ,,to ,,control        
,though the chief control work directed 
by the ,biological ,survey is  concerned
 with injurious rodents and predatory   
mammals1 it sometimes  becomes necessary
 to investigate cases of damage by other
 classes  of animal life1 including     
moles1 crawfishes1 and land crabs1 and  
to  recommend measures for their        
control4          ,,instructions        
,,regarding ,,field ,,practices         
,,the ,,objective    ,the underlying    
policy of the ,biological ,survey with  
regard to injurious  species of wild    
animals has been and will continue to be
 one of control  rather than complete   
eradication4 ,the bureau is not embarked
 upon a  general extermination program1 
but with every proper consideration  for
 conservation interests1 it has as its  
objective in this field the  adequate   
local control of injurious mammals1 so  
that the burdensome  losses suffered by 
farmers and stock raisers may be reduced

 to the  minimum and beneficial forms of
 wild life protected from undue         
destruction by their natural enemies4   
,though in some cases this may  mean    
local eradication of harmful forms1 it  
will not result in the  general         
extermination of any species4           
,,conservation1 ,,state ,,laws1 ,,and   
,,cooperation    ,the ,bureau of        
,biological ,survey is an organization  
primarily and  vitally interested in the
 conservation and protection of all     
forms of  wild life1 particularly where 
they are more beneficial than harmful4  
,those engaged under its direction in   
the control of predatory animals  and   
injurious rodents are instructed to     
cooperate closely with ,federal1        
,state1 and local officials intrusted   
with the administration of  wild-life   
protective laws4 ,they must also observe
 ,state and local laws  regarding the   
protection of life and property1 the    
exposing of poisons1  and the trapping  
or otherwise endangering of valuable    

species4 ,control  operations on ,state 
and private lands must be conducted in  
close  cooperation with ,state officials
 and with property owners and tenants4  
,,precautions ,,in ,,handling ,,poisons 
,since poison may be dangerous in the   
hands of inexperienced and  incompetent 
persons1 every possible precaution must 
be taken when it is  used in control    
operations1 to safeguard persons1       
domestic stock1 and  harmless and       
beneficial wild life4    ,poisons should
 not be exposed on private lands without
 the consent of  the owners4    ,control
 workers should familiarize themselves  
with appropriate  antidotes for poisons 
used and be in a position to administer 
them  promptly should the necessity     
arise4      ,,rodent-,,control          
,,operations    ,extreme care should be 
exercised in handling poisons in        
rodent-control  work4 ,prepared poisons 
should be placed in strong1 properly    
labeled  containers and should be       
distributed only to assistants working  

under  the direct supervision of bureau 
leaders or to responsible cooperators4  
,strychnine 7in the alkaloid form7 is   
the poison most largely used in         
rodent-control1 its speedy action making
 it one of the most humane4  ,moreover1 
numerous tests have shown that in the   
quantities employed  in control         
operations strychnine is relatively     
harmless to such  gallinaceous birds as 
quail1 pheasants1 grouse1 and domestic  
chickens4  ,the smaller birds also are  
safeguarded because of the fact that the
  grains used in poisoned baits are of  
the large-kerneled kinds1 such  as oats1
 and contain a minimum of weed seeds and
 cracked kernels4  ,furthermore1 in a   
large portion of the baits used the     
kernels are  steamed1 rolled1 and       
flattened so that their increased size  
lessens  their attractiveness to the    
smaller birds4    ,the use of red squill
 in the control of house rats and mice  
is  recommended1 as it is an effective  
and specific poison for these  rodents  

and relatively harmless to other forms  
of animal life4    ,the use of thallium 
in rodent-control will in some places   
succeed where  strychnine alone fails4  
,it should not be used1 however1 except 
to a  very limited extent in follow-up  
operations against ground squirrels1    
prairie dogs1 and rats4 ,such limited   
use of thallium should be guarded  with 
the greatest care under close and fully 
competent supervision1  as it is        
extremely dangerous to all life4 ,though
 thallium is highly  effective in       
destroying rodents1 it can not be       
overemphasized that this  poison is not 
to be recommended for general use1      
except to supplement  strychnine in     
follow-up work4 ,it should never be     
handled without  careful consideration  
in each particular case of all the      
potential  dangers involved4            
,arsenic1 cyanides1 and phosphorus      
should not be used or recommended  for  
rodent-control1 as they are not now     
known to have any special  advantages1  

and furthermore they may be a menace to 
other forms of  animal life4 ,not only  
is phosphorus dangerous to beneficial   
wild life1  but it is particularly      
unsafe because it sometimes causes fire4
    ,poisonous gases1 which are         
efficient in the fumigation of burrows1 
grain bins1 and garbage dumps1 should be
 used only by trained and  experienced  
workers in rodent-control4              
,,predatory-,,animal ,,control          
,poisoning operations for the control of
 predatory animals should be  limited   
strictly to areas where there is urgent 
need4 ,they will not  be undertaken     
under the direction of the ,biological  
,survey where  trapping or other means  
of control are practicable and the cost 
is not  prohibitive4    ,the handling of
 poisons should be intrusted only to    
properly trained  men working under the 
supervision of the ,bureau of           
,biological ,survey4    ,poison stations
 set for coyotes and wolves should be   
placed away from  the timbered and      

well-watered areas that are frequented  
by foxes1  raccoons1 skunks1 minks1 and 
other valuable forms of carnivorous     
animals4    ,in many agricultural       
sections poisons should not be used at  
all because  of the obvious risks4      
,the methods of handling poisons        
developed and used by the ,biological   
,survey can be employed most effectively
 and economically in controlling        
predatory animals at proper seasons in  
regions where conditions are  favorable4
 ,poison is especially suitable for     
winter use against  predators on some of
 the great stock ranges of the ,west1 as
 it can then  be employed with little or
 no danger to useful life4 ,the cost of 
the  same measure of control by any     
other known means would be practically  
prohibitive4    ,the control of         
predatory animals is an exceedingly     
difficult and  costly task1 and the use 
of poisons in this work1 particularly   
under  experienced supervision1         
materially reduces the expense4 ,when   

properly  used1 poison should not be    
more destructive to other species than  
the  use of traps1 and in some cases it 
has been found to be even less  harmful 
and more humane4    ,hunters should take
 every precaution to protect harmless   
and valuable  mammals and birds and     
should be familiar with the antidotes   
for each  poison used4    ,only         
strychnine as processed by the          
,biological ,survey should be used  in  
operations against predatory mammals1   
because it can be handled  safely1 is   
constant in effect1 and1 since it kills 
quickly1 its action  is humane4         
,baits made of small pieces of          
perishable fat should be used almost to 
the exclusion of others by field men and
 cooperators of the bureau4  ,they      
should be systematically placed about   
decoy stations consisting  of carcasses 
of worn-out horses or other useless     
animals or pieces of  meat4 ,wherever   
possible they should be placed in slight
 depressions and  covered with thin flat

 stones1 pieces of hide1 or other light 
material1  as coyotes and wolves can    
easily detect them under such cover1 but
 they  are thus made inaccessible to    
birds4    ,stations where poison is     
placed should be posted to warn owners  
of  stock or valuable dogs of the       
danger4 ,conspicuous warning signs such 
as  those furnished by the ,bureau of   
,biological ,survey in its cooperative  
work should be used for the purpose4    
,in dispensing poisons for the use of   
cooperators in predatory-animal         
control1 ,biological ,survey field      
leaders are instructed to exercise the  
greatest care to make sure of the       
integrity1 honesty1 and cooperative     
spirit of those requesting supplies4    
,when the leader has satisfied  himself 
as to the intent of the cooperator1 he  
should keep in close  touch with him and
 observe his methods1 to make sure that 
the poison  is being properly used and  
that no supplies are left in his        
possession  after cooperative work has  

been terminated4    ,studded stations1  
or those in which the poison is placed  
in parts of  the carcass instead of     
about it1 are to be used only under     
especially  favorable conditions4 ,their
 use is sometimes justified along the   
known  runways of predatory animals on  
high barren mountain ridges1 high       
benches1 or stock driveways that can not
 be visited by the hunter after  the    
first heavy snowfall4 ,such stations    
should be at some distance from  timber1
 to make remote the danger of poisoning 
fur bearers4 ,as soon  as trails are    
open in spring1 the hunter is directed  
to revisit such  stations and bury or   
burn all the baits4    ,all             
predatory-animal hunters must visit     
their poison stations as  frequently as 
possible1 and except under extraordinary
 conditions  should avoid making long   
poison lines4 ,baits that have become   
rancid  should be destroyed1 and on     
completion of the poisoning work a      
general  clean-up must be made1 and all 

baits possible destroyed4 ,the use of   
perishable fat baits is particularly    
recommended for the reason that  they   
are readily disposed of naturally1 for  
those that can not be  located usually  
disintegrate in warm weather and become 
harmless after  they have melted and    
soaked into the ground4    ,bears are   
ordinarily classed as game animals and  
are protected as  such4 ,only when they 
are doing material damage should they be
 taken1  and then by traps or by aid of 
dogs1 and not by poison4 ,state laws on 
the subject must be observed4 ,field men
 and cooperators must exercise  the     
greatest possible care to kill only     
those individuals responsible  for      
damage1 and must remove no more bears   
from a locality than it  is absolutely  
necessary to take in order to stop the  
destruction of  livestock4    ,in       
placing traps for the capture of        
injurious wild animals every  possible  
precaution is to be taken to avoid the  
accidental capture of  valuable game and

 fur-bearing animals and other harmless 
or beneficial  forms of wild life4      
,hunters working under the supervision  
of the  ,biological ,survey are         
instructed to visit their trap lines  as
 frequently as possible and to liberate 
game animals and  foxes1 badgers1       
skunks1 martens1 minks1 raccoons1 and   
other animals  accidentally caught1     
unless they are so injured that they can
 not  survive4 ,in occasional individual
 cases1 however1 where fur bearers do   
serious injury to livestock or poultry1 
it is permissible to trap and  kill them
 if in accordance with ,state laws4     
,the most nearly humane traps available 
should be used1 and trap lines  should  
be so placed that they can be visited at
 frequent intervals1 to  avoid any      
unnecessary suffering1 injury1 or loss  
of trapped animals4        ,u4 ,s4      
,,government ,,printing ,,office3 #aica 
,for sale by the ,superintendent of     
,documents1 ,washington1 ,d4 ,c4        
,price #e cents