﻿SOCIAL 
  PARASITISM 
  IN 
  BIItDS 
  — 
  FRIEDMANN 
  379 
  

  

  arboreal 
  nests, 
  while 
  others 
  laid 
  only 
  in 
  domed 
  nests 
  either 
  in 
  low 
  

   trees, 
  or 
  on 
  the 
  ground. 
  The 
  ecological 
  factors 
  affecting 
  the 
  ranges 
  

   and 
  habitats 
  of 
  the 
  various 
  parasitic 
  cuckoos 
  necessarily 
  limit 
  the 
  

   number 
  of 
  host 
  species 
  available 
  to 
  each 
  species 
  of 
  cuckoo. 
  In 
  the 
  

   tropics 
  the 
  number 
  of 
  species 
  and 
  of 
  individual 
  birds 
  is 
  very 
  large 
  and 
  

   the 
  resulting 
  struggle 
  for 
  existence 
  more 
  intense 
  than 
  in 
  the 
  more 
  

   lenient 
  regions 
  to 
  the 
  north 
  and 
  south. 
  As 
  a 
  result 
  of 
  the 
  keeness 
  of 
  

   the 
  competition 
  we 
  find 
  that 
  similarity 
  in 
  habits 
  survives 
  side 
  by 
  side 
  

   where 
  those 
  habits 
  do 
  not 
  affect 
  the 
  same 
  species. 
  That 
  is, 
  a 
  habit 
  such 
  

   as 
  the 
  parasitic 
  one 
  could 
  survive 
  far 
  more 
  easily 
  in 
  many 
  species 
  in 
  

   the 
  same 
  region 
  if 
  they 
  did 
  not 
  conflict 
  with 
  each 
  other 
  than 
  if 
  all 
  

   were 
  parasitic 
  on 
  the 
  same 
  group 
  of 
  host 
  species. 
  So 
  then, 
  in 
  the 
  

   bushveldt 
  of 
  Africa 
  we 
  find 
  that 
  the 
  little 
  golden 
  cuckoos, 
  Lampro- 
  

   morpha, 
  victimize 
  weaver 
  birds, 
  grass 
  warblers, 
  and 
  a 
  few 
  other 
  

   types 
  of 
  birds, 
  chiefly 
  limiting 
  their 
  attention 
  to 
  the 
  weavers 
  and 
  

   Cisticolas. 
  Most 
  (almost 
  all) 
  of 
  their 
  victims 
  build 
  domed 
  or 
  covered 
  

   nests, 
  some 
  of 
  them 
  on 
  the 
  ground. 
  In 
  the 
  same 
  districts 
  we 
  find 
  

   that 
  the 
  crested 
  cuckoos, 
  Clamator, 
  confine 
  their 
  visitations 
  to 
  open, 
  

   arboreal 
  nests 
  such 
  as 
  the 
  golden 
  cuckoos 
  never 
  molest. 
  However, 
  

   with 
  a 
  fair 
  number 
  of 
  species 
  to 
  choose 
  from 
  there 
  is 
  no 
  environmental 
  

   reason 
  why 
  a 
  certain 
  individual 
  parasite 
  should 
  further 
  limit 
  its 
  range 
  

   of 
  activities 
  by 
  tending 
  toward 
  extreme 
  host 
  specificity. 
  It 
  is 
  not 
  

   of 
  any 
  particular 
  obvious 
  benefit 
  to 
  the 
  parasite 
  to 
  be 
  still 
  further 
  

   restricted 
  in 
  this 
  way. 
  

  

  The 
  only 
  way 
  to 
  arrive 
  at 
  a 
  proper 
  understanding 
  of 
  the 
  w&j 
  in 
  

   which 
  host 
  specificities 
  might 
  have 
  begun 
  is 
  to 
  study 
  individual 
  birds 
  

   as 
  well 
  as 
  species. 
  In 
  working 
  on 
  the 
  reproductive 
  habits 
  of 
  birds 
  one 
  

   of 
  the 
  first 
  things 
  to 
  be 
  determined 
  is 
  the 
  extent 
  and 
  definiteness 
  of 
  

   the 
  individual 
  breeding 
  territories. 
  Chance 
  and 
  others 
  have 
  done 
  

   this 
  for 
  the 
  European 
  cuckoo, 
  Cuculus 
  canorus 
  canorus, 
  with 
  splendid 
  

   results. 
  In 
  the 
  case 
  of 
  the 
  African 
  species 
  of 
  parasitic 
  cuckoos 
  I 
  

   found 
  that 
  all 
  of 
  them 
  establish 
  definite 
  breeding 
  territories 
  to 
  which 
  

   they 
  adhere 
  during 
  the 
  egg-laying 
  season. 
  The 
  males 
  of 
  some 
  species, 
  

   such 
  as 
  Lanipromorpha 
  caprius, 
  Chrysococcyx 
  cupreus, 
  and 
  Cuculus 
  

   solitarius, 
  are 
  very 
  faithful 
  to 
  their 
  territories. 
  The 
  breeding 
  territory 
  

   in 
  the 
  case 
  of 
  a 
  parasitic 
  bird 
  is 
  based 
  not 
  upon 
  a 
  sufficiency 
  of 
  food 
  

   for 
  the 
  young 
  but 
  upon 
  an 
  adequacy 
  of 
  nests 
  for 
  the 
  eggs. 
  As 
  stated 
  

   above 
  the 
  small 
  golden 
  cuckoos 
  parasitize 
  weaver 
  birds 
  {Ploceus, 
  

   Hyphantornis, 
  Otyphantes, 
  etc.) 
  very 
  frequently. 
  A 
  great 
  many 
  

   species 
  of 
  these 
  weavers 
  are 
  arboreal 
  and 
  build 
  their 
  nests 
  in 
  large 
  

   colonies, 
  often 
  as 
  many 
  as 
  a 
  hundred 
  or 
  more 
  nests 
  in 
  a 
  single 
  tree. 
  

   I 
  found 
  that 
  in 
  several 
  cases 
  a 
  pair 
  of 
  didric 
  cuckoos, 
  Lampromorpha 
  

   caprius, 
  had 
  established 
  their 
  territories 
  around 
  trees 
  containing 
  

   colonies 
  of 
  weavers 
  and 
  in 
  at 
  least 
  four 
  cases 
  the 
  territories 
  were 
  

   entirely 
  restricted 
  to 
  single 
  trees. 
  These 
  weaver 
  colonies 
  very 
  seldom 
  

  

  