﻿BIRDS 
  OF 
  N:n\' 
  YORK 
  67 
  

  

  more 
  and 
  more 
  difficult 
  to 
  add 
  a 
  new 
  bird 
  to 
  the 
  list. 
  The 
  observer 
  must 
  

   be 
  ubiquitous 
  in 
  migration 
  time. 
  

  

  The 
  time 
  of 
  arrival 
  is 
  several 
  days 
  earlier 
  in 
  the 
  southern 
  part 
  of 
  the 
  

   the 
  State 
  and 
  in 
  the 
  low^er 
  altitudes 
  than 
  it 
  is 
  in 
  the 
  Adirondack 
  district 
  

   and 
  the 
  Alleghari}^ 
  plateau. 
  The 
  variation 
  in 
  the 
  time 
  of 
  arrival, 
  both 
  at 
  

   different 
  stations 
  in 
  the 
  State, 
  and 
  in 
  different 
  years 
  at 
  the 
  same 
  station, 
  

   is 
  greatest 
  in 
  the 
  case 
  of 
  those 
  birds 
  which 
  arrive 
  during 
  February, 
  March 
  

   and 
  earlv 
  April, 
  the 
  difference 
  being 
  sometimes 
  three 
  or 
  four 
  weeks. 
  Birds 
  

   like 
  the 
  Bobolink 
  and 
  Baltimore 
  oriole, 
  which 
  come 
  early 
  in 
  May, 
  arrive 
  

   at 
  nearly 
  the 
  same 
  date 
  in 
  all 
  parts 
  of 
  the 
  State 
  [see 
  map, 
  p. 
  66], 
  and 
  

   their 
  time 
  of 
  appearance 
  varies 
  only 
  a 
  few 
  dcivs 
  at 
  each 
  station. 
  Sometimes 
  

   an 
  unusually 
  warm 
  wave, 
  early 
  in 
  the 
  season, 
  will 
  bring 
  bluebirds 
  and 
  

   redwings 
  on 
  the 
  same 
  date 
  to 
  nearly 
  every 
  station 
  in 
  the 
  middle 
  districts. 
  

   This 
  was 
  the 
  case 
  on 
  the 
  24th 
  of 
  February 
  1906, 
  when 
  these 
  birds 
  appeared 
  

   in 
  considerable 
  numbers 
  at 
  Ithaca, 
  Canandaigua, 
  Rochester 
  and 
  other 
  

   places. 
  These 
  facts 
  seem 
  to 
  indicate 
  that 
  our 
  birds 
  can 
  travel 
  the 
  whole 
  

   width 
  of 
  the 
  State 
  in 
  a 
  single 
  day 
  during 
  the 
  migration 
  if 
  weather 
  condi- 
  

   tions 
  are 
  favorable, 
  but 
  a 
  study 
  of 
  the 
  tables 
  following 
  page 
  74 
  will 
  show 
  

   that 
  the 
  average 
  date 
  of 
  arrival 
  is 
  several 
  days 
  later 
  for 
  the 
  more 
  northern 
  

   and 
  the 
  more 
  elevated 
  districts. 
  

  

  There 
  can 
  be 
  no 
  doubt 
  that 
  the 
  arrival 
  of 
  birds 
  with 
  us 
  depends 
  upon 
  

   the 
  temperature 
  and 
  probably 
  upon 
  the 
  winds. 
  With 
  the 
  advance 
  of 
  a 
  

   low 
  cyclonic 
  center 
  from 
  the 
  southwest, 
  bringing 
  high 
  temperature 
  to 
  

   western 
  New 
  York 
  in 
  March, 
  April 
  or 
  May, 
  there 
  is 
  sure 
  to 
  be 
  a 
  bird 
  wave 
  

   which 
  corresponds 
  in 
  magnitude 
  to 
  the 
  warm 
  weather 
  wave 
  which 
  undoubted- 
  

   ly 
  brought 
  it. 
  Man}' 
  facts 
  seem 
  to 
  show 
  that 
  the 
  birds 
  of 
  western 
  and 
  north- 
  

   ern 
  New 
  York 
  are 
  mostly 
  immigrants 
  from 
  the 
  southwest, 
  and 
  the 
  warm 
  

   weather 
  as 
  well 
  as 
  the 
  prevailing 
  winds 
  of 
  this 
  region 
  also 
  come 
  from 
  that 
  

   direction. 
  The 
  warm 
  weather 
  at 
  least 
  furnishes 
  the 
  favorable 
  conditions 
  

   which 
  induce 
  them 
  to 
  migrate. 
  These 
  are 
  no 
  more 
  an 
  agreeable 
  temperature 
  

   than 
  an 
  abundance 
  of 
  food 
  and 
  favoring 
  winds 
  to 
  aid 
  their 
  arduous 
  passage- 
  

  

  