﻿Yerrill 
  — 
  Coloration 
  in 
  Mammals, 
  Birds, 
  Fishes, 
  etc. 
  133 
  

  

  many 
  colors 
  that 
  are 
  not 
  in 
  the 
  least 
  protective 
  by 
  day, 
  yet 
  are 
  

   eminently 
  so 
  by 
  night. 
  In 
  general, 
  the 
  black 
  and 
  very 
  dark 
  

   colors, 
  common 
  in 
  mammals, 
  birds, 
  and 
  insects, 
  are 
  protective 
  

   at 
  night 
  and 
  not 
  by 
  day. 
  One 
  of 
  the 
  most 
  obvious 
  effects 
  of 
  

   moonlight 
  is 
  to 
  give 
  very 
  strong 
  or 
  black 
  shadows, 
  in 
  which 
  

   black 
  or 
  dark 
  animals 
  become 
  invisible, 
  or 
  nearly 
  so. 
  This 
  

   invisibility 
  is 
  often 
  increased 
  by 
  sharply 
  contrasted 
  stripes 
  or 
  

   patches 
  of 
  white 
  or 
  light 
  yellow, 
  which 
  look 
  like 
  patches 
  of 
  

   moonlight 
  falling 
  across 
  a 
  dark 
  shadow, 
  and 
  thus 
  serve 
  to 
  

   break 
  up 
  the 
  outlines 
  of 
  bird 
  or 
  beast 
  that 
  might 
  otherwise 
  be 
  

   recognized. 
  Transverse 
  black 
  or 
  dark 
  brown 
  bands 
  on 
  fishes 
  

   that 
  rest 
  among 
  eel 
  grass 
  or 
  sea 
  weeds, 
  tend 
  to 
  render 
  the 
  out- 
  

   lines 
  of 
  the 
  h'sh 
  indistinct, 
  because 
  they 
  look 
  like 
  the 
  shadows 
  

   and 
  shaded 
  surfaces 
  of 
  the 
  weeds. 
  Black 
  tins 
  and 
  tails 
  have 
  

   a 
  similar 
  effect, 
  in 
  concealing 
  or 
  destroying 
  the 
  outline 
  of 
  

   fishes. 
  The 
  striped 
  colors 
  of 
  the 
  tiger 
  have 
  the 
  same 
  effect 
  

   when 
  it 
  lives 
  among 
  the 
  stalks 
  of 
  reeds, 
  etc., 
  and 
  is 
  probably 
  

   much 
  more 
  effective 
  in 
  twilight 
  or 
  moonlight 
  than 
  by 
  day. 
  

   The 
  same 
  is 
  true 
  of 
  the 
  spotted- 
  pattern 
  of 
  the 
  leopard, 
  pan- 
  

   ther, 
  and 
  jaguar. 
  

  

  A 
  great 
  number 
  of 
  small 
  nocturnal 
  mammals, 
  belonging 
  to 
  

   diverse 
  groups, 
  have 
  dark 
  gray 
  and 
  grayish-brown 
  colors 
  

   (mouse-colors) 
  which 
  are 
  highly 
  protective 
  at 
  night, 
  but 
  are 
  

   usually 
  not 
  at 
  all 
  so 
  in 
  the 
  daytime, 
  for 
  such 
  colors 
  are 
  con- 
  

   spicuous 
  among 
  the 
  green 
  herbage 
  which 
  they 
  frequent, 
  and 
  on 
  

   which 
  most 
  of 
  them 
  feed. 
  Moreover, 
  nearly 
  all 
  such 
  mam- 
  

   mals 
  hide 
  away 
  in 
  holes 
  in 
  the 
  daytime. 
  I 
  have 
  noticed 
  

   that 
  our 
  common 
  meadow 
  mouse 
  (Armcold) 
  which 
  is 
  very 
  

   dark 
  gray, 
  is 
  scarcely 
  to 
  be 
  seen 
  even 
  in 
  a 
  moonlight 
  night, 
  in 
  

   localities 
  where 
  it 
  is 
  very 
  abundant 
  among 
  grass, 
  and 
  when 
  

   large 
  numbers 
  are 
  so 
  near 
  that 
  the 
  sound 
  made 
  by 
  their 
  teeth 
  

   in 
  feeding 
  is 
  very 
  evident. 
  Among 
  insects 
  there 
  are 
  multi- 
  

   tudes 
  of 
  instances 
  of 
  colors 
  that 
  are 
  evidently 
  nocturnally 
  pro- 
  

   tective 
  and 
  which 
  can 
  be 
  explained 
  only 
  on 
  the 
  basis 
  of 
  natural 
  

   selection, 
  favoring 
  the 
  variations 
  in 
  color 
  that 
  are 
  in 
  this 
  way 
  

   most 
  useful. 
  Such 
  colors 
  may 
  or 
  may 
  not 
  be 
  more 
  or 
  less 
  pro- 
  

   tective 
  in 
  the 
  daytime. 
  Frequently 
  they 
  appear 
  to 
  be 
  just 
  the 
  

   opposite 
  of 
  protective 
  in 
  the 
  daytime. 
  Thus 
  many 
  butterflies 
  

   have 
  bright 
  colors 
  that 
  are 
  very 
  conspicuous 
  by 
  daylight 
  and 
  

   which 
  do 
  not 
  in 
  any 
  way 
  match 
  their 
  customary 
  surroundings. 
  

   This 
  applies 
  to 
  those 
  species 
  that 
  are 
  black 
  or 
  dark 
  blue, 
  striped 
  

   or 
  blotched 
  with 
  white, 
  yellow, 
  or 
  orange, 
  and 
  to 
  many 
  species 
  

   that 
  are 
  spotted 
  or 
  striped 
  with 
  red, 
  orange, 
  and 
  black 
  on 
  the 
  

   upper 
  surface 
  of 
  the 
  wings, 
  and 
  often 
  also 
  beneath, 
  so 
  that 
  

   they 
  are 
  conspicuous 
  whether 
  flying 
  or 
  at 
  rest. 
  Their 
  active 
  

   habits 
  and 
  acute 
  senses 
  probably 
  give 
  them 
  fair 
  protection 
  by 
  

   day. 
  At 
  night, 
  when 
  resting 
  with 
  the 
  wings 
  folded, 
  the 
  colors 
  

  

  