THE AUK- A QUARTERLY JOURNAL OF ORNITHOLOGY. VOL. XLIV. OCTOBER,1927. NO. 4. THE SNOWY OWL MIGRATION OF 1926-27. BY ALFRED O. GROSS. Plates XXII-XXVII T•r. SnowyOwl regularlymigrates from its breedingrange in the "Barrens" of North America to the southern provinces, especiallyof middle west Canada, but at more or less regular intervalsthe migrationextends much farther southwardincluding an area well into the United States. The most notable of these exceptionalflights which have occur-redduring the past fifty yearstook placein 1876-77,• 1882-83, 1889-90,1892-93, 1896-97, 1901-02, 1905-06, 1917-18 and the presentone 1926-27. A few SnowyOwls have foundtheir way into the United Statesnearly every year but they werenot accompaniedby a generalmigration except in the years indicatedabove. The causeof thesegreat invasionsfrom the north is not clearly understoodand constitutesa problem which deservesthe serious attention of ornithologists.Food, apparently,is one factor in- volved in causingthese movements,whereas weather conditions in the north are probably of minor importance. The amount of snowmay have an indirectbearing since it involvesthe acces- sibilityof the foodsupply of the Owls. With the accumulationof more data concerningthe life of the far north we may be able to correlatethe periodicmigrations of SnowyOwls with cyclesof Deane, R. 1872. Bull. Nutt. Ornith. Club, vol. 2, p. 9. 1902. Auk, vol. 19, p. 271. 1906. Auk, vol. 23, p. 101. 1907. Auk, vol. 24, p. 217. 479 T• Ave, VOL. XLIV. PLATE XXII. Photo by A. O. Gross CAr?•vr, SNowY OWLS--NOVr,MSEI• 21, 1926. 480 GRoss,The Snowy Owl Migration of1926-27. [oct.Auk abundanceof certain animalssuch as hares,rabbits and lemmings, the chief food of thesebirds. Accordingto reportsreceived from the Hudson Bay Company there was an unusual number of rabbits in the north in 1925 whereasthey were exceedinglyscarce duringthe latter part of 1926. In Bafiqnlandthere was an abund- anceof lemmingsin 1925 but as yet we have no reportsconcerning the abundanceof theserodents in that region in 1926. Reports from Alaska and northwestern Canada state the rabbits were common there in 1925 but were almost exterminated in certain regionsby diseasein 1926. It would be interestingto know just what part diseaseplayed in curtailing the food supply of the Owls as a whole, An abundance of food in 1925 would serve to bring about a successfulbreeding season for the Owls which in all probability would lead to an overproduction.When the food became scarce or difiqeult to obtain because of excessive snowsin 1926 the surplus Owls were forced to range far and wide to securea living. Diseaseby further reducingthe numbers of rabbits and possibly other rodents would thus serve to aid in eausingthis great migration into northeasternUnited States. When the Snowy Owls and Goshawksfirst' appearedin New England in the fall of 1926 the New England Ruffed Grouse Investigationunder the auspicesof the MassachusettsFish and Game Protective Association,turned its attention to the flight in an effort to determinethe effectof this migrationon the game birds especiallythe Ruffed Grouse. The committeeenlisted the aid of sportsmenwho were interestedin the problem and the variousNew England State Departmentsof Conservationvolun- teered to send in all informationwhich they receivedconcerning thesevisitors from th• north. Mr. ThorntonBurgess broad- casting our wants from radio station WBZ Springfield,Mass. received numerousreports and newspaperclippings from all parts of the range of migration especiallyNew England. Dr. Witmer Stone through 'The Auk' called the attention of the membersof the A. O. U. to the importanceof obtainingrecords of the occurrenceof the SnowyOwls and other speciesfrom the north. He also,x;ery obligingly agreed to combinehis records with those received by the Ruffed Grouse Investigation for a generalreport. We wish to acknowledgethe assistancegiven to Vol.1927 XLIV] J GROSS,TheSnowy Owl Miqration of1926-27. 481 us by numerous contributors. We are especially indebted to Mr. Ruthyen Deane of Chicagowho gave us all of his recordsand correspondencereceived in answer to numerousrequests for in- formation sent to light housestations, taxidermists and ornitho- logists. Mr. Edward H. Forbush,State Ornithologistof Massa: chusetts,permitted us to make use of the recordsand reportsof Snowy Owls and Goshawkscontained in his voluminouscorres- pondence. Dr. Arthur A. Allen of Cornell University sent us his personalrecords and a copy of all the reportsof thesebirds, receivedthrough a questionnairesent out by the generalRuffed GrouseInvestigation Committee. Mr. JosselynVanTyne and other membersof the staff of the Universityof Miehiga'nMuseum were chiefly responsiblefor the accumulationof the numerous Michiganrecords. Mr. H. F. Witherby,editor 'British Birds', con- tributed many of the recordsof SnowyOwls observedon ships at sea. Of the many taxidermistswho contributedrecords, Angell and Cash of Providence,Rhode Island deservespecial mentionfor their excellentreport which containednot only dates and localities of the 135 Owls received but also detailed deter- minationsof the stomachcontents. It is impracticableto mention all the individualreports and recordsin this paper and we shall attempt to give merely a generalsummary of the 1926-27 Snowy Owl migration. We hope this report will assist the reader in visualizingthe extent and distributionof the flight and trust that it will behelpful in makingcomparisons with similarmigrations which occurredin the past and with otherswhich may take place in the future. The one regrettable thing concerningthis migration is the receptionthe birds received. The number of thesebeautiful and interestingbirds which were killed is appalling. They came at a time when there was a maximum number of gunners in the field and every Owl that appearedseemed to be an invitation to shoot. There are few hunters in the far north and hence the Owls especiallythe young birds which were in the majority, had but little fear of man. Their habit of feedingin the open also made them conspicuousand easytargets. Many hunterskilled them thinking it their duty to protect the game birds but too often the Owls were killed merely to satisfy a desire to kill or a 482 Gaoss,The Snowy Owl Migration of19•6-•7. [Oc•.Auk curiosity to examine the strange bird at close range. A large number of the Owls were thrown aside and wasted and of course were never reported. From estimates made of conditionsin Maine and from reportsreceived from elsewhereI feel that 5,000 is a conservativeestimate of the number of Snowy Owls killed in the United States and Canada during the 1926-27 flight. It would be most interestingto know how many Snowy Owls suc- ceededin returningto the northlandto breedafter havingpassed this gauntlet of fire arms on their visit to civilized America. THE EXTENT OF THE MIGRATION. Canada. Most of the correspondencereceived from Canadianobservers was of a very general nature and comparatively few reports included records of dates and localities of the birds killed and observed. Therefore tabulations of the numbers for the different provinceswould be of little valuefor comparativepurposes. The generalreports from Canada,however, are excellentand have en- abled us to trace very well the extent and volume of the migra- tion in that part of the continent. No SnowyOwls were reported from British Columbiaalthough Goshawkswere much above their normal numbers throughout that province. In Alberta the Snowy Owls, accordingto Frank L. Farley, are generallypresent in constantnumbers each winter and the past year (1926-27) has not been an exception. I-Ie statesthe Goshawkswere unusually common. As we go eastward we have a report from Mr. C. L. Broley of Winnipegwho states that therewere many SnowyOwls in Manitoba. Mr. C. G. I-Iarrold alsoof Winnipegwriting January9, 1927 statesthat therewas a markedSnowy Owl migrationin the fall but later the birdsseemed to have moved elsewhere. Continuing on to the east in our cross sectionof the migration in southernCanada we have numerous general reports indicating a very unusual flight throughout Ontario and Quebec. Harrison F. Lewis of Ottawa, states that twenty-sixtaxidermists in the Provinceof Ontario received517 SnowyOwls and twelvetaxidermlsts in the Provinceof Quebecre- ceived271 specimens.Mr. Lewisestimates that 1500Snowy Owls THE AUK, VOL. XLIV. PLATE XXIII. SHADED AREA SHOWS THE EXTE•T• AND DENSITY OF THE SNOWY OWL MIGRATION oF 1926-27. CROSS-HATCl•EV AREA THE APPROXIMATE BREEoma RANGE. Vol.1927 XLIV] J GROSS,TheSnowy Owl Migration of1926-œ7. z•83 were killed in thesetwo provincesalone which gives us a vivid impressionof the magnitudeof the migrationin that regionwhich is in the direct line of flight from the breedinggrounds to the Great Lakes and southeastwardto the New England coastline, the center of the presentmigration. The migration was general in the easternsections of Canada through New Brunswickand Nova Scotia to Newfoundland. In New Brunswick the Owls were abundanton the islandslying off the southerncoast. They were especiallyabundant on the islandof GrandManan and at Maehias SealIsland the keeper of thelight house station saw sixty of the Owls and killed twenty-four of them. Mr. Harry Piers of the ProvincialMuseum, Nova Scotia,reports a large number about Halifax and states there was an abnormally large flight. Mr. J. L. DeVany of AnnapolisRoyal, and R. W. Tufts of Wolfville, also state that there was a very large migration of Snowy Owls throughout the province. Mr. DeVany ineidently