22 NORTH AMERICAN FAUNA 70 



Frequency Scale 



Regular. Recorded every year. 



Irregular. Recorded less than once every year, but no less than 

 once in 5 yr, on the average. 



Occasional. Recorded less than once in 5 yr, but no less chan once in 

 10 yr, on the average. 



Sporadic. Recorded less than once in 10 yr, but no less than once 

 in 20 yr, on the average. 



Casual. Recorded less than once in 20 yr, on the average. 



Accidental. Recorded, but because of the species normal range it is 

 not expected to occur again. This term replaces the term "Exotic" 

 proposed in Arbib (1957:63-64). 



Seasonal Occurrence 



Resident. Breeding species, summer resident, winter resident, or 

 permanent resident. 



Visitant (= visitor). A nonbreeding species which occurs either as a 

 summer or a winter visitor. 



I apply the term migrant to those species that occur only during 

 migration. Records of migrants, and summer or winter residents are 

 listed with dates of arrival and departure where possible. 



Species that are considered definitely breeding are stated simply 

 as breeding species or summer residents. Where the breeding status 

 of certain species is in doubt I have used the terms ''probably" or 

 "possibly" breeds. The term "probably" refers to species that are 

 regular summer residents and are often observed singing, but no nest, 

 eggs, young, or food carrying by adults has been observed. "Possibly" 

 breeds refers to summer residents that, although within their normal 

 breeding range and habitat, have been observed infrequently and 

 may breed in small numbers; no breeding behavior has been observed. 



