Sex and age composition of Great Gray Owls (Strix nebulosa), winter 1995/1996

Robert W. Nero; Herbert W. R. Copland

Treesearch

Sex and age composition of Great Gray Owls (Strix nebulosa), winter 1995/1996

Informally Refereed

Authors:

Robert W. Nero, Herbert W. R. Copland

Year:

1997

Type:

General Technical Report

Station:

Northern Research Station

Source:

In: Duncan, James R.; Johnson, David H.; Nicholls, Thomas H., eds. Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium. Gen. Tech. Rep. NC-190. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station. 587-590.

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Abstract

In winter 1995/1996, a nearly continent-wide movement of Great Gray Owls (Strix nebulosa) occurred. A sample of 126 owls examined during this period, mainly from northeast of Winnipeg, included a large number from the 1994 hatch-year. If our assumptions regarding molt are correct, 51 birds were from this age class. An inhibited molt condition found in this group suggests a state of inadequate nutrition prior to or during the normal 1995 molt period. We think that a large 1994 hatch and a subsequent food shortage may be factors partly accounting for the 1995/1996 irruption.

Parent Publication

Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium

Citation

Nero, Robert W.; Copland, Herbert W. R. 1997. Sex and age composition of Great Gray Owls (Strix nebulosa), winter 1995/1996. In: Duncan, James R.; Johnson, David H.; Nicholls, Thomas H., eds. Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium. Gen. Tech. Rep. NC-190. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station. 587-590.