﻿ACADEMY 
  OP 
  SCIENCES. 
  271 
  

  

  their 
  fluctuations 
  in 
  range. 
  On 
  reconsidering 
  the 
  matter, 
  I 
  have 
  become 
  con- 
  

   vinced 
  that 
  it 
  would 
  be 
  better 
  to 
  wait 
  as 
  long 
  as 
  possible 
  before 
  attempting 
  

   this 
  work, 
  and 
  until 
  I 
  have 
  finally 
  closed 
  the 
  investigations 
  now 
  in 
  progress. 
  

   Each 
  year 
  has 
  presented 
  new 
  facts, 
  and 
  modified 
  our 
  views 
  of 
  old 
  ones 
  ; 
  and, 
  as 
  

   our 
  field 
  may 
  be 
  still 
  further 
  enlarged, 
  and 
  our 
  observations 
  supplemented 
  to 
  a 
  

   considerable 
  extent, 
  a 
  reasonable 
  delay 
  may 
  add 
  a 
  good 
  deal 
  to 
  the 
  accuracy 
  

   and 
  value 
  of 
  the 
  tables 
  indicated. 
  

  

  I 
  would 
  call 
  special 
  attention 
  to 
  the 
  fact 
  that 
  no 
  intrusion 
  of 
  Asiatic 
  forms 
  

   occurs 
  toward 
  the 
  western 
  end 
  of 
  the 
  chain 
  ; 
  and 
  also, 
  that 
  the 
  birds 
  of 
  that 
  

   region 
  are 
  reinforced 
  by 
  several 
  arctic 
  forms, 
  not 
  included 
  in 
  that 
  part 
  of 
  the 
  

   archipelago 
  near 
  the 
  continent 
  to 
  the 
  eastward. 
  This 
  peculiarity 
  in 
  distribu- 
  

   tion 
  is 
  more 
  marked 
  when 
  we 
  regard 
  the 
  plants, 
  coleoptera, 
  and 
  marine 
  inver- 
  

   tebrates, 
  as 
  well 
  as 
  the 
  birds, 
  all 
  of 
  which 
  groups 
  present 
  the 
  same 
  peculiarity 
  

   in 
  a 
  more 
  striking 
  manner 
  than 
  the 
  '„irds 
  themselves. 
  This 
  may 
  be 
  due, 
  in 
  

   part, 
  to 
  the 
  temperature, 
  which 
  is 
  affected 
  by 
  the 
  Arctic 
  current 
  which 
  sweeps 
  

   down 
  the 
  Kamchatka 
  coast, 
  although 
  it 
  passes 
  some 
  distance 
  west 
  of 
  the 
  islands. 
  

  

  We 
  noted 
  that 
  on 
  those 
  islands, 
  such 
  as 
  Attn 
  and 
  Atka, 
  where 
  the 
  Arctic 
  

   fox 
  and 
  other 
  land 
  animals 
  have 
  been 
  introduced 
  by 
  the 
  Russians, 
  the 
  birds 
  

   preferred 
  to 
  build 
  on 
  islets 
  and 
  rocks 
  off 
  shore, 
  or 
  not 
  accessible 
  from 
  the 
  

   beaches. 
  But 
  on 
  those 
  islands 
  where 
  there 
  are 
  no 
  such 
  animals, 
  the 
  habits 
  of 
  

   the 
  same 
  species 
  are 
  quite 
  different. 
  They 
  build, 
  without 
  fear, 
  on 
  the 
  banks 
  

   and 
  hillsides 
  of 
  the 
  main 
  island, 
  and 
  are 
  not 
  found 
  on 
  the 
  rocky 
  islets 
  at 
  all. 
  

   This 
  indicates 
  not 
  only 
  a 
  change 
  in 
  habits 
  brought 
  about 
  within 
  historic 
  times, 
  

   by 
  the 
  struggle 
  for 
  existence, 
  but 
  also, 
  that 
  the 
  progeny 
  of 
  individuals 
  probably 
  

   continue 
  to 
  reside 
  on 
  the 
  same 
  islands 
  as 
  their 
  progenitors. 
  

  

  On 
  Amchitka,a 
  low 
  island, 
  which 
  was 
  abandoned 
  by 
  the 
  Russians 
  in 
  1849 
  — 
  

   and 
  which 
  has 
  not 
  been 
  visited 
  since, 
  except 
  by 
  our 
  party 
  — 
  the 
  birds 
  were 
  re- 
  

   markably 
  bold 
  and 
  fearless, 
  scarcely 
  stirring 
  at 
  our 
  approach, 
  and 
  confidently 
  

   disporting 
  in 
  the 
  water 
  close 
  to 
  the 
  vessel. 
  This 
  was 
  especially 
  noticeable 
  in 
  

   shy 
  and 
  timid 
  birds, 
  such 
  as 
  the 
  loons. 
  

  

  The 
  numerous 
  species 
  of 
  small 
  auks 
  and 
  puffins 
  for 
  which 
  this 
  region 
  is 
  

   famous, 
  are 
  peculiar 
  in 
  their 
  habits. 
  They 
  spend 
  the 
  larger 
  part 
  of 
  the 
  day, 
  at 
  

   a 
  distance 
  from 
  shore, 
  varyii% 
  from 
  two 
  to 
  fifteen 
  miles 
  ; 
  enormous 
  flocks 
  cover- 
  

   ing 
  acres 
  sociably 
  sitting 
  on 
  the 
  water 
  close 
  to 
  one 
  another, 
  feeding 
  or 
  sleep- 
  

   ing, 
  even 
  in 
  rough 
  weather. 
  They 
  prefer 
  places 
  where 
  the 
  currents 
  form 
  streaks 
  

   on 
  the 
  water, 
  or 
  narrow 
  eddies, 
  as 
  here 
  are 
  collected 
  much 
  of 
  the 
  wash 
  from 
  the 
  

   shores, 
  small 
  pieces 
  of 
  sea-weed, 
  and 
  the 
  small 
  Crustacea 
  feeding 
  on 
  the 
  decaying 
  

   sea-weed, 
  which 
  form 
  the 
  principal 
  food 
  of 
  the 
  birds. 
  The 
  birds 
  also 
  eat 
  a 
  

   good 
  deal 
  of 
  sea-weed, 
  their 
  stom^hs 
  always 
  containing 
  more 
  or 
  less 
  of 
  it 
  mixed 
  

   with 
  fragments 
  of 
  Crustacea. 
  The 
  auks, 
  pufiQns, 
  and 
  smaller 
  divers, 
  seem 
  to 
  sub- 
  

   sist 
  entirely 
  on 
  these 
  matters. 
  I 
  have 
  never 
  seen 
  them 
  eat 
  mollusks, 
  echini, 
  or 
  

   other 
  invertebrates, 
  even 
  when 
  the 
  shore 
  was 
  strewn 
  with 
  them. 
  The 
  murres, 
  

   pufBns, 
  and 
  larger 
  divers, 
  consume 
  a 
  great 
  many 
  small 
  fish, 
  but 
  never 
  any 
  dead 
  

   matter, 
  so 
  far 
  as 
  I 
  could 
  observe. 
  On 
  the 
  contrary, 
  the 
  gulls 
  and 
  crows 
  per- 
  

   ambulate 
  the 
  sand 
  with 
  fantastic 
  motions, 
  watching 
  the 
  ebb 
  of 
  the 
  tide, 
  and 
  

  

  