﻿368 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  192 
  9 
  

  

  and 
  inasmuch 
  as 
  these 
  two 
  are 
  intimately 
  bound 
  up 
  with 
  the 
  mode 
  of 
  

   reproduction, 
  we 
  may 
  profitably 
  examine 
  the 
  territorial 
  situation 
  in 
  

   the 
  cowbirds. 
  

  

  In 
  the 
  bay-winged 
  cowbird 
  the 
  problem 
  is 
  somewhat 
  simpler 
  than 
  

   in 
  the 
  others, 
  as 
  each 
  pair 
  has 
  its 
  nest 
  and 
  is 
  thereby 
  tied 
  down 
  to 
  a 
  

   definite 
  area. 
  However, 
  instead 
  of 
  the 
  usual 
  procedure, 
  we 
  find 
  the 
  

   reverse 
  is 
  followed. 
  The 
  wintering 
  flocks 
  break 
  up 
  into 
  pairs 
  in 
  the 
  

   spring, 
  and 
  the 
  pairs 
  of 
  birds 
  go 
  about 
  looking, 
  not 
  for 
  territories, 
  but 
  

   for 
  nests. 
  They 
  will 
  fight 
  with 
  the 
  builders, 
  if 
  need 
  be, 
  to 
  gain 
  posses- 
  

   sion 
  of 
  the 
  nest, 
  or 
  else 
  will 
  quietly 
  occupy 
  an 
  uncontested 
  one. 
  Then 
  

   the 
  territory 
  is 
  extended 
  radially 
  around 
  the 
  nest, 
  instead 
  of 
  the 
  nest 
  

   site 
  being 
  chosen 
  within 
  the 
  territory 
  as 
  in 
  normal 
  birds. 
  

  

  This 
  altered 
  conception 
  of 
  the 
  breeding 
  territory 
  manifests 
  itself 
  

   in 
  the 
  defense 
  of 
  that 
  territory. 
  Instead 
  of 
  being 
  the 
  basic 
  thing, 
  the 
  

   area 
  becomes 
  secondary 
  to 
  the 
  nest 
  and 
  its 
  defense 
  is 
  correspondingly 
  

   weakened 
  or 
  lessened. 
  This 
  weakening 
  of 
  the 
  defense 
  opens 
  an 
  easy 
  

   path 
  to 
  a 
  distorted 
  type 
  of 
  sexual 
  relations, 
  such 
  as 
  promiscuity 
  or 
  

   polyandry. 
  

  

  The 
  territorial 
  situation 
  in 
  the 
  case 
  of 
  the 
  next 
  species, 
  the 
  screaming 
  

   cowbird, 
  is 
  of 
  interest 
  in 
  that 
  it 
  presents 
  a 
  rather 
  unusual 
  state 
  of 
  

   affairs, 
  although 
  superficially 
  it 
  seems 
  quite 
  ordinary. 
  This 
  species, 
  

   as 
  already 
  noted, 
  pairs 
  off 
  early 
  in 
  the 
  season 
  but 
  does 
  not 
  begin 
  to 
  

   breed 
  until 
  nearly 
  midsummer 
  (January 
  and 
  February). 
  Neverthe- 
  

   less, 
  quite 
  early 
  in 
  the 
  spring 
  it 
  establishes 
  its 
  territories, 
  often 
  as 
  

   early 
  as 
  the 
  first 
  week 
  in 
  October. 
  Sometimes 
  the 
  period 
  elapsing 
  

   between 
  the 
  time 
  of 
  territorial 
  establishment 
  and 
  the 
  actual 
  inception 
  

   of 
  egg-laying 
  amounts 
  to 
  two 
  or 
  even 
  nearly 
  three 
  months. 
  Yet 
  

   during 
  all 
  this 
  time 
  each 
  pair 
  maintains 
  its 
  particular 
  sphere 
  of 
  influ- 
  

   ence. 
  Pairs 
  from 
  adjacent 
  territories 
  do 
  not 
  join 
  or 
  mix 
  promiscuously 
  

   although 
  they 
  do 
  sometimes 
  form 
  temporary 
  groups 
  of 
  four 
  to 
  six 
  

   birds 
  in 
  neutral 
  feeding 
  areas. 
  Having 
  no 
  nests 
  to 
  care 
  for 
  or 
  young 
  

   to 
  provide 
  with 
  food, 
  why 
  should 
  these 
  birds 
  establish 
  territories 
  and 
  

   stay 
  in 
  them 
  day 
  after 
  day, 
  sometimes 
  for 
  nearly 
  a 
  quarter 
  of 
  a 
  year, 
  

   without 
  making 
  any 
  use 
  of 
  them? 
  One 
  would 
  hardly 
  expect 
  a 
  non- 
  

   parasitic 
  species 
  endowed 
  with 
  strong, 
  fully 
  developed 
  parental 
  

   instincts 
  to 
  limit 
  its 
  individual 
  liberty 
  of 
  action 
  for 
  so 
  long 
  a 
  time 
  

   merely 
  in 
  anticipation 
  of, 
  and 
  preparation 
  for, 
  its 
  reproductive 
  

   activities. 
  The 
  goldfinch 
  of 
  North 
  America 
  (Astragalinus 
  tristis) 
  

   breeds 
  at 
  the 
  same 
  relative 
  season 
  (reversed) 
  as 
  the 
  screaming 
  cow- 
  

   bird, 
  but 
  the 
  flocks 
  of 
  the 
  former 
  do 
  not 
  break 
  up 
  for 
  pairing 
  and 
  

   breeding 
  purposes 
  until 
  about 
  a 
  month 
  before 
  egg-laying 
  commences. 
  

   Furthermore, 
  not 
  only 
  do 
  they 
  have 
  to 
  establish 
  territories 
  and 
  procure 
  

   mates 
  in 
  this 
  month 
  but 
  also 
  to 
  build 
  nests, 
  which 
  the 
  screaming 
  

   cowbird 
  never 
  does. 
  The 
  late 
  breeding 
  of 
  the 
  goldfinch 
  is 
  doubtless 
  

   an 
  adaptation 
  to 
  seasonal 
  food 
  supply 
  but 
  in 
  the 
  screaming 
  cowbird 
  

  

  