﻿364 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  192 
  9 
  

  

  some 
  of 
  the 
  neotropical 
  cowbirds 
  were 
  likewise 
  parasitic, 
  and 
  observers 
  

   in 
  Africa 
  announced 
  that 
  the 
  habit 
  was 
  also 
  found 
  in 
  some 
  of 
  the 
  

   honey 
  guides. 
  Quite 
  recently 
  a 
  few 
  of 
  the 
  African 
  weaverbirds 
  were 
  

   shown 
  to 
  be 
  parasitic, 
  and 
  just 
  a 
  few 
  years 
  ago 
  a 
  South 
  American 
  

   duck, 
  Heteronetta 
  atricapilla, 
  was 
  found 
  to 
  possess 
  this 
  habit 
  as 
  well. 
  

   At 
  present, 
  this 
  manner 
  of 
  reproduction 
  is 
  known 
  to 
  occur 
  in 
  five 
  

   widely 
  separated 
  and 
  distantly 
  related 
  families 
  of 
  birds 
  — 
  the 
  cuckoos 
  

   (Cuculidae), 
  the 
  hang 
  nests 
  (Ideridae), 
  to 
  which 
  group 
  the 
  cowbirds 
  

   belong, 
  the 
  weaverbirds 
  (Ploceidae), 
  the 
  honey 
  guides 
  (Indicatoridae), 
  

   and 
  the 
  ducks 
  (Anatidae). 
  Of 
  the 
  cuckoos 
  about 
  70 
  species 
  are 
  

   known 
  to 
  be 
  parasitic; 
  of 
  the 
  hangnests, 
  only 
  the 
  cowbirds 
  and 
  the 
  

   rice 
  grackle, 
  half 
  a 
  dozen 
  species 
  in 
  all; 
  of 
  the 
  weavers, 
  only 
  3; 
  of 
  the 
  

   honey 
  guides, 
  all 
  the 
  species 
  of 
  whose 
  breeding 
  habits 
  we 
  have 
  any 
  

   knowledge, 
  less 
  than 
  half 
  a 
  dozen; 
  and 
  of 
  the 
  ducks, 
  a 
  single 
  species. 
  

   The 
  entire 
  number 
  of 
  parasitic 
  species 
  forms 
  but 
  a 
  mere 
  handful 
  out 
  

   of 
  the 
  thousands 
  of 
  kinds 
  of 
  birds 
  known 
  to 
  science. 
  

  

  As 
  the 
  number 
  of 
  birds 
  known 
  to 
  be 
  parasitic 
  increased, 
  interest 
  in 
  

   the 
  subject 
  increased 
  accordingly, 
  and 
  an 
  enormous 
  literature 
  grew 
  

   up 
  around 
  the 
  problem. 
  The 
  number 
  of 
  theories 
  brought 
  forth 
  to 
  

   account 
  for 
  the 
  origin 
  of 
  the 
  habit 
  became 
  almost 
  as 
  great 
  as 
  the 
  num- 
  

   ber 
  of 
  writers 
  on 
  the 
  subject. 
  Before 
  adding 
  still 
  another 
  to 
  the 
  long 
  

   list 
  of 
  theories, 
  we 
  may 
  at 
  this 
  point 
  examine 
  the 
  evidence 
  and 
  ma- 
  

   terial 
  available. 
  In 
  order 
  to 
  make 
  the 
  problem 
  more 
  approachable 
  

   we 
  may 
  limit 
  it 
  for 
  the 
  present 
  to 
  one 
  group 
  of 
  birds 
  — 
  the 
  cowbirds. 
  

  

  THE 
  COWBIRDS 
  

  

  The 
  term 
  cowbirds 
  as 
  used 
  in 
  this 
  paper 
  includes 
  the 
  true 
  cowbirds 
  

   fgenera 
  Agelaioides, 
  Molothrus, 
  and 
  Tangavius) 
  and 
  the 
  rice 
  grackle 
  

   (Cassidix). 
  The 
  latter 
  is 
  in 
  reality 
  nothing 
  but 
  a 
  large 
  edition 
  of 
  

   Tangavius, 
  although 
  it 
  is 
  not 
  generally 
  called 
  a 
  cowbird. 
  The 
  genus 
  

   Agelaioides, 
  restricted 
  to 
  Argentina, 
  Paraguay, 
  Uruguay, 
  and 
  Brazil, 
  

   is 
  the 
  oldest 
  and 
  most 
  primitive 
  of 
  the 
  cowbirds. 
  It 
  contains 
  two 
  

   closely 
  related 
  species, 
  A. 
  badius 
  of 
  Argentina, 
  Paraguay, 
  and 
  Uru- 
  

   guay, 
  and 
  A.fringillarius, 
  a 
  pale 
  representative 
  form 
  in 
  eastern 
  Brazil. 
  

   The 
  former 
  is 
  the 
  one 
  that 
  is 
  now 
  well 
  known 
  and 
  will 
  be 
  called 
  the 
  

   bay-winged 
  cowbird 
  in 
  this 
  paper. 
  The 
  genus 
  Molothrus 
  contains 
  the 
  

   most 
  typical 
  cowbirds 
  — 
  three 
  species 
  with 
  many 
  races 
  — 
  M. 
  rujo- 
  

   axillaris 
  of 
  Argentina, 
  Uruguay, 
  and 
  Paraguay; 
  M. 
  bonariensis 
  of 
  

   South 
  America 
  from 
  Patagonia 
  to 
  Panama; 
  and 
  M. 
  ater 
  of 
  North 
  

   America, 
  from 
  the 
  highlands 
  of 
  central 
  Mexico 
  to 
  the 
  region 
  of 
  Lake 
  

   Athabaska, 
  and 
  from 
  the 
  Atlantic 
  to 
  the 
  Pacific. 
  M. 
  rujo-axillaris 
  

   will 
  be 
  referred 
  to 
  as 
  the 
  screaming 
  cowbird, 
  M. 
  bonariensis 
  as 
  the 
  

   shiny 
  cowbird, 
  and 
  M. 
  ater 
  as 
  the 
  North 
  American 
  cowbird. 
  The 
  

   genus 
  Tangavius 
  contains 
  one 
  species 
  known 
  in 
  life 
  and 
  one 
  known 
  

   only 
  from 
  four 
  skins 
  preserved 
  in 
  the 
  American 
  Museum 
  of 
  Natural 
  

  

  