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Conditions Effecting the Distribution of Birds in Indiana.* 



By Amos W. Butlek. 



GEXEKAL CONr)ITION8. 



The rt'jiiiliir iiniu];il nu)vemeuts of liirds. their migrations, are 

 among- thi' most strilviug of the manifestations of Nature. With the 

 revivifying breath of spring, the aV)sent birds return. Last fall, when 

 the summer's work was done, they Avent to warmer climes. Now, they 

 seek anew their breeding grounds. Some make their homes with tis; 

 others go farther north to rear their young. The semi-annual ebb 

 and flow of these tides of bird-life, the breeding range and the food 

 supply are general factors that enter into the distribution of birds 

 everywhere. Our ancestors noted them as signs of the seasons. They 

 exist today, though we do not see them so readily because of our 

 changed conditions. 



ZOOLOGICAL AREAS. 



Indiana is a meeting-ground of various birds. Into it range typical 

 forms of different zoological regions. From the Avest, are prairie birds; 

 slightly tinging the north, are northern forms; wliile the dominating- 

 influence of the lower part of the State is southern. Indiana lies within 

 the eastern (Atlantic) fatinal province. According to Mr. Allen, it is 

 distinctively Carolinian (Bull. Mus. Comp. Zoc'il. II, No. .'5. pp. 39;j-.395), 

 yet the southwestern part is within the range of many birds char- 

 acteristic of the Lotiisianian Fatina (Austroriparian Province of Prof. 

 Cope, Bull. LT. S. Nat. Mus. No. 1. 187.5, pp. <i7-Tl». r>r. Merriam would 

 include the bulk of the State in the L'pper Austral Zone, the Lower 

 Austral Zone reaching into sotithwestern Indiana and the Transition 

 Zone intiuencing the northern part (Bull. No. 1<» Biol. Surv. U. S. Dept. 

 Agr. 1898). 



'•■'Contributions from the Zoological Laboratory of Indiana University, No. 37. 



