FALL MIGRATION of HERRING GULLS from KNIFE ISLAND, MINNESOTA by P
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104] HOFSLUND,K,ni/e Island Herring Gulls l•ird-Bandin•April WOODBURY,A.M., W. H. BEHLE, and J. W. SUGDEN. 1946. .Color-banding California Gulls at Great Salt Lake, Utah. Bull. Univ. Utah, Biol. Ser. 10: 1-15. WOODBURY,A.M. and HOWARDKNXCH?. 1951. Results of the Pacific Gull color-bandingproject. Condor53: 57-77. WOODCOCI%A. H. 1940. Herring Gull soaring. Auk 57: 219-224. • 1942. Soaring ,over the open sea. Scientific Monthly 55: 226-232. Biological Laboratories, Harvard University, Cambridge 38, Mass. FALL MIGRATION OF HERRING GULLS FROM KNIFE ISLAND, MINNESOTA By P. B. HOFSLUND In June, 1950 the Duluth Bird Club began a banding study of a colonyof Herring Gulls (Larus argentatus).This studyhas continued eachsummer since, the summerof 1957 marking the eighth year. The presentpaper dealswith the recoveriesof bandedgulls up to May 15, 1958. 120 - I[0 • • • c.• )00 90 McKNIGHT 6, McKNIGHT, BLOOMINGTON, ILLINOIS .Map 1. Recoveriesof Herring Gulls banded as nestlings on Knife Island, Minnesota. 37ol.1959 XXX HOFSLUND,Knife Island Herring Gulls []05 / DRAINAGE NORTH AMERICA COPYRIGHT BY •1• & •KHIG•T,BL•mGTOH, •HOIS • •• 120 I10 • • • c• •D0 McKNiGHT •* McKNIGHT, BLOOMINGTON, ILLINOIS Map 2. Recoveriesof first-yearHerring Gulls. The breedingsite is a smallisland in Lake Superior,roughly 800 x 300 feet at its longestand widest spots. It lies less than a half mile from the mouth of Knife River in Lake County, Minnesota, and is known, at least locally, as Knife Island. Much of the island is covered with Mountain Ash (Sorbus americana) with a scatteringof Balsam Fir (Abies balsamea),Balsam Poplar (Populus balsami/era), and a tangle of undergrowth. The periphery, however,is largely bare rock, and it is here that most of the nestsare located. One notableexception was a nest placedapproximately 18 feet up in a BalsamFir. Censusreports (Hofslund, 1952:162) for the years 1948-'52 showed nest countsvarying between150 and 312. Though no actual counts have been made since 1952, it is likely that the island now supports in excessof 250 breeding pairs each year. In recent years the only other nestingbirds found on the island have been a pair of Red- breastedMergansers (Mergus serrator). Passerinebirds are con- spicuousby their absence. Banding operationshave been confinedto an afternoon,usually on the secondweekend in June. There has been an attemptto work 106] HOFS,.U•D,Knife Island Herring Gulls Bird-BandingApril •c DRAINAGE NOR'r'H AMERICA • i•4 •i co•m• BY ,• • 100 90 McKNIGHT•. McKNIGHT,BLOOMINGTON, ILLINO• Map. 3. Recoveriesof second-yearHerrir•g Gulls. as swiftly and efficientlyas possiblewith a general limit of 500 bandsso as to minimizethe disturbanceof the colony. Despitethis, someyoung birds have been killed by adults or have met death in other ways associatedwith the disturbance,and more than likely, most of the birds recoveredin June of the year they were banded never survivedthe day of banding. A total of 3,028 nestlinggulls have been bandedsince the project started. We have received81 reports of recoveriesor 2.67% of the total banded. While not a large number,the recoveriesreveal certain patternsin the movementsof the gulls after they leave Knife Island. Lincoln (1928:59) and Gross (1940:153) describedthe dispersal of gulls from their breedinggrounds as "explosive,"a conclusion well-foundedon the basisof recoveriesfrom bandingsites in Lake Michiganand at KentIsland. The presentstudy was started in partto determinewhether this explosivenature of the dispersalwas apparent only whereready access to largewaterways was available. The followingpoints are pertinentto the discussionof the results of the study: Vol. 1959XXX HOFSLUND,K,nije Island Herring Gulls [107 McKblIGHT•, McKblIGHT,BLOOMINGTON, ILUblOIS Map 4. Roeoveriesof adult Herring Gulls banded ,as nestlingson Knife Island. 1. The majority of the recoveriesof Knife Island Gulls come from the Great Lakes. Of the 81 recoveriesonly 12 have not been from areas intimately associatedwith the Great Lakes-St.Lawrence Water- way. 2. Only two of the 12 recordsare from areasnorth of this waterway, the rest are south. 3. Of the 10 southeilyrecords all but three are associatedwith the Atlantic, Gulf of Mexico, or Caribbean Sea coastlines. 4. The three records not associated with coastal waters are on or near major tributaries of the Mississippi River, and the dates of recovery (Table 1) suggestthat these birds were continuing their wanderingnorthward toward the breedinggrounds rather than having reachedthese points through a southerlydispersal over land. 5. If we now turn our attentionto the distributionmaps (Maps 2, 3, and 4), it is apparent that the wanderingtendency is lessenedas the gulls reach breedingage, a conclusionpreviously brought out by others (Gross,1940:136), and in the caseof Knife Island gulls their travels seemto be confinedlargely to the Great Lakes. 6. There is a lack of uniformity in distancestravelled by gulls of ]lOS] HOFSLUND,K,nije Island Herring Gulls Bird-BandingApril IOO 2oo 3oo 40o 5oo 6oo 70o 8oo 9oo I ooo •oo • ,•oo i • 4o0 I$OO 1800 19oo 2ooo •,lOO 2 2o• 24oo 25oo 26oo 29oo 5 Ioo Figure 1. Scattergramshowing distancesfrom banding point to place of recoveryof 6rst-year birds. the sameage as is shownby the scattergrams(Figures 1, 2, and 3). An extreme examplewould be the two first-year birds recoveredin February,one of whichhad wanderedabout 450 mileswhile the other had coverednearly 2,950. 7. Gulls banded at Kent Island oi• the coast of New Brunswick (Gross, 1940:137) were largely recoveredalong the Atlantic coast. Only a very few were found away from coastalwaters. 8. Gullsbanded by Lyon an• •ilson (•ross, 1940:139) an• •hose •iscusse••y Lincoln (lP28) were •an•e• mostlyin Lake Michigan. Theseshowe• a •ispersalin all •irections. Vol. XXX 1959 HOFSLUND,Knife Island Herring Gulls [109 IOO 200 500 400 500 &o o 70 o 800 900 I ooo IlOO i zoo 1300 1400 1500 1600 I 7'00 I 8oo 1900 2000 2 I00 Figure 2. Scattergram showing distancesfrom banding point to place of recovery of second-yearbirds. 9. The report of the Pacific gull-bandingproject (Woodbury and Knight, 1951) showedalmost a strict adherenceof Pacific gulls to coastal waters. These points bring me to the conclusionthat the term "explosive dispersal" is not suitable to describethe fall migration of Herring Gulls, but rather shouldbe called a wanderingwhose directional ten- denciesare determinedby the availability of large waterways. The explosivequality is effectivelyblocked by the lack of shoreor coastlines. The tendency to move southward after the first of the year as suggestedby Lincoln (1928:56) and Gross (1940:153) also seems to me as not being an applicablegeneral assumption.From the dis- tribution of the recordsalong the coastlinesit appearsthat the only major southwardmovement comes from gulls that have reached the coastline.Once the coastlinewas reachedthe availability of food and the major water traffic would exert a positive force in a southerly direction.Major shippinglines might havesome effect on this and also might determineto some extent the distancesthat individual gulls might travel. The concentrationof recordsalong the southernshores of the Great Lakes indicatesthat there are factors favoring such a distribution,one of which might be that the major portsof call of the ]_]_0] HOFSLUND,Knije Island Herring Gulls Itircl-•ndingApril ioo • oo 300 400 5 oo 6 oo 7o O* • YEAR BIROS 0.4 YEAR BIRDS •.5 YEAR BIRDS Figure 3. Scattergramshowing distances from banding point to place of recovery of those birds that reached t'heir •hird, fourth, or fifth year of age. iron ore shipswould be in theseareas. An observeron Lake Superior can seeconcentrations of younggulls followingsome of theseships as they move away from and toward the shippingcenters at Duluth and Two Harborsin late August. Causesof deathand the mortalityrate are muchas havebeen found in othergull studies.At leasttwo-thirds of the mortality occursbefore the Herring Gull has reachedone year of age. The usualreport is that the bird was "found dead," but several more detailed records, such as "broughthome by the cat," "killed goingover Niagara Falls," "landed in an oil pit," etc., are given in Table 1. TABLE RECOVERIES OF GULLS BANDED ON KNIFE ISLAND Date Banded Recovered At How Found Date Recovered June 17, 1950 Burlington, Ontario Brought ,home by Dee. 9, 1950 cat mile from Duluth Found .dead on April 23, 1951 highway June 16, 1951 Marinette, Wisconsin Landed in oil pit Aug. 28, 1951 Big MuskegoLake, Brought to museum Wisc. for identification Nov. 23, 1951 Tampico, Tamaulipas, Captured alive April 5, 1952 Mexico Pneuforbee Creek, 8 Found dead M,ay 3, 1952 miles N. Tuskegee,Ala. Coatzacoalcos,Vera Found, probably Dec. 15, 1952 Cruz, Mexico dead West River, shore of Found dead in Feb. 8, 1953 Beaver Island State water Park, Grand Island, New York Lake Kagawong, Found dead, may Oct. 5• 1953 Manitoulin Island, •have been shot Lake Huron Duluth, Minnesota Forrod dead June 7,1954 Vol. XXX 1959 HOFSLUND,Knife Island Herring Gulls [ ] ] ] June 14,1952 Lake Superior,Duluth Found ,dead June 14, 1952 Duluth, Minnesota Drifted to shore June 24, 1952 Duluth, Minnesota Found dead• badly July 13, 1952 decomposed Knife River, Minn. Found dead Aug. 24, 1952 Manitoulin Island, Found Sept. 8, 1952 Meldrum Bay, Altoma, East County,Ontario M•assawippiLake, Killed Sept. 22, 1952 Ayer's Cliff, Start- stead County, Quebec Elmvale, Simcoe, Ont. White .diarrhea Oct. 9, 1952 Manistee,Michigan Found dead Oct. 18, 1952 West Twin River, Found dead Nov. 16, 1952 T.wo Rivers, Wisc. St. Maurice River, Caught in fox trap Blov.20, 1952 Laviolette County, Que. June 14,1952 Wilson, Niagara Found dead Mar. 31, 1953 County, New York Jay Township, Dunnell, Found with a April 24, 1953 Martin County, Minn. broken wing. Died Pentwater, Oceans Found dead July 10, 1953 County, Michigan Pur•gnivik, 10 rail.es Four•d Oct. 1953 So. of Nain, Labrador Marble Lake, Lake Found dead with May 15, 1954 County, M'innesota fishplug in mouth Mouth of Brule River, Found in fisher- May 28, 1954 Douglas County, Wisc.