The Repository @ St. Cloud State

Open Access Knowledge and Scholarship

Date of Award


Culminating Project Type


Degree Name

Biological Sciences - Ecology and Natural Resources: M.S.




College of Science and Engineering

First Advisor

Alfred Grewe

Second Advisor

John McCue

Third Advisor

Anthony Marcattilio

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

Northern Shrike, Lanius Excubitor, Wintering Biology, Central Minnesota, Sciences


Northern Shrikes (Lanius excubitor invictus Grinnell) wintering in central Minnesota were observed from 3 January 1991 to 10 April 1993. Wintering shrikes were monitored to determine: population size, density and age structure, territory size, extent of daily and seasonal movements, habitat preferences, hunting behaviors, diet composition, intra and interspecific interactions, vocalizations, night roost site locations, arrival and departure dates, and effective trapping methods.

Shrikes began to arrive in central Minnesota from sub-arctic breeding areas in early October. Density of birds continued to increase into late November when the population leveled out at an estimated 110 - 140 birds in the 750 square mile study area. Most of the birds sighted were adults, three of which had been captured on the same territory the previous winter. Of 54 birds captured, only 11 (20.4%) were in their first-winter plumage.

Territory size varied from one to two square miles where suitable habitat existed. Prey availability was a major factor in territory selection. Shrikes spent most of their time in the scattered frozen marshes, meadows, and brushlands. where small mammals and birds were concentrated. Unharvested agricultural fields and road ditches were important hunting areas as well. Hunting accounted for much of a shrike's daily activity.

Small mammals formed 90.1 % of a shrike's winter diet. Meadow voles accounted for 64.5% of mammalian prey followed by deer/white-footed mice at 25.5% and masked shrews at 6.7%. Small birds made up 6.6% of the diet while insects accounted for 3.3%.

The night roost sites of nine shrikes were located. Each bird alternated between several roost trees. Size, shape and species of tree and its proximity to other woody vegetation was important in roost selection.

Fifty-four shrikes were banded and marked with colored leg bands. Eight of th~se birds were fitted with radio transmitters. Shrikes were captured with a variety of trap designs and bait items. These were tested in various combinations to determine the m~ successful capture technique. A remotecontrolled bow-net trap baited with a house sparrow was the most effective.

Warmer days in late winter and early spring triggered some shrikes to break a long winter silence. Vocalizatio~s were highly variable and often elaborate. Departure from the study area, for breeding grounds in the far north, began in late March and most birds were gone by the first week of April.


The first field season of this stti&y was undertaken as a cooperative effort between myself and two other St. Cloud State University (SCSU) graduate students; M. A. Carroll and R. P. Marinan. The insight gained during this initial year and the input of these fellow researchers provided essential background data on which much of the subsequent research was based.

Partial funding for this study was provided by three George W. Friedrich Memorial Scholarships. SCSO Department of Biological Sciences provided miscellaneous field and laboratory equipment, office space, and computer access. Sherburne National Wildlife Refuge staff (especially J. M. Johnson) provided valuable sighting locations as well as access to refuge service roads.

Dr. R. D. Price, Professor Emeritus of Entomology at the University of Minnesota, identified lice specimens. Dr. R. Gunderson offered encouragement and assisted with preparation of lice specimens. Analysis of a portion of the pellet sample was completed by M. G. Lee. Valuable advice and field assistance were provided by K. Sundseth and R. Mockenhaupt. E. Thrune provided colored leg bands., and housed bait animals. S. Thrune was helpful in locating equipment. T. C. Flynn offered computer time and advice, assisted with graphics production, and· donated three original drawings. T. Klein and S. Stapleton assisted with graphics.

Many others provided a variety of forms of assistance, advice, donations, and encouragement throughout my graduate studies. Included among these were W. Brininger, C. Converse, B. Delaney, H. Dunevitz, D. Evans, B. J. Farley, J. Galli, B. L. Hill, M. Jansen, S. Kittelson, H.J. Lande, S. Lande, M. J. Lee, M. S. Lee, E. Rosenquist, S. Stapleton, J. Skarohlid, S. Stucker, S. Wilmore, S. Zager, and the staff at Advanced Telemet y Systems.

I thank J. McCue and T. Marcattilio for their input while serving on my graduate committee.

To my advisor, A.H. Grewe, Jr., is owed an unrepayable debt of gratitude for guidance and encouragement far exceeding expectations, and for being a true friend.

I owe a great deal to my family, especially my mother, B. J. Lee, for continued encouragement and unwavering support. K. R. Mierau kept me focused and honest through thick and thin with her own uncanny way of putting things into perspective. My daughter, B. J. Lee, was my inspiration.

Included in

Biology Commons



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