BIRDS OF THE ST. CROIX RIVER VALLEY 



81 



Habitat: Primarily a species of large semipermanently and permanently 

 flooded wetlands, and open expanses of the St. Croix River. 



Ivory Gull (Pagophila eburnea) 

 Status: Hypothetical. 



Record: N. R. Stone observed three adults at the Crex Meadows Wildlife 

 Area, Burnett County, on 3 April 1959 (Stone 19596). 



Sabine's Gull {Xema sahini) 

 Status: Hypothetical. 



Record: A single immature was observed on 1 October 1944 along the St. 

 Croix River at Stillwater, Washington County (Longley 1947). 



Common Tern {Sterna hirundo) 



Status: Regular migrant and casual summer resident. 



Migration: Fairly common migrant near the St. Croix River, uncommon to 

 rare elsewhere in the Western Upland and Central Plain, and rare to absent 

 in the Northern Highland. Spring migrants arrive 20-25 April. Peak spring 

 abundance occurs 10-20 May and departure by 30 May. Fall migrants 

 return 25 August to 5 September and depart by 25 September. 



Nesting Season Distribution: A casual summer resident in St. Croix and 

 Washington counties; most summering birds are found along the St. Croix 

 River. Establishment of nesting common terns along the lower St. Croix is 

 seemingly possible, because a small group of common terns summer near the 

 confluence of the Minnesota and Mississippi rivers at Ft. SnelUng in the 

 Twin Cities. Excessive recreational use of exposed beaches and sandy 

 islands in the lower St. Croix is probably a major factor Limiting colony 

 establishment. If colonies are established at a future date, intensive restric- 

 tion of human use will be necessary. 



Habitat: Primarily a species of large permanently flooded wetlands and 

 sandy beaches and islands of the St. Croix River. 



Least Tern {Sterna alhifrons) 

 Status: Accidental, one record. 



Record: R. A. Knuth observed an adult on Phantom Lake, Crex Meadows 

 Wildlife Area, Burnett County, on 17 August 1971 (Roberts and Roberts 

 1972). This bird was observed by over 60 people during a Wisconsin Society 

 for Ornithology field trip. 



