Vol.59'] MARSHALLAND LEATHAM, Birds o[ GreatSalt Lake Islands 35 194 '• a

BIRDS OF THE GREAT SALT LAKE ISLANDS

BY WILLIAM H. MARSHALL AND LYNDON j. LF_•r•AM T•. nestingcolonies of birdson theislands of GreatSalt Lake, Utah, arejustly famous and havereceived considerable ornithological atten- tion. Suchpublications as those of Behle(1935), Woodbury and Behle (1933),Palmer (1916),and Cottamand Williams (1939),deal almost exclusivelywith theserookeries. Little hasbeen published on non- colonialbirds of the islandssince Ridgway (1877)visited certain of them in 1869. During the summerof 1938, field work for the U.S. Bureau of BiologicalSurvey provided an opportunityto obtain noteson birds of all the islands. Although the lists differ little from those for the mainland,they are of interestfrom severalpoints of view, as for comparisonwith Ridgway'slists of 1869,for the completecounts of individuals on certain small islands, and for the correlation of bird occurrenceswith certainhabitats. Most of the notesrepresent sight records,though, as indicatedin the lists,all birds of doubtful field identification were collected. Acknowledgmentsare due to Dr. D. I. Rasmussen,of the Biological Survey,and to Lee Kay, Utah Fish and GameCommission, for initiat- ing the seniorauthor's interest in the islandson the annual bird- colonycensus of 1937,when Bird and GunnisonIslands were visited; to ProfessorT. C. Adams,of the University of Utah, who provided the data on acreagesof the islands;and to A.D. Smith, of Utah StateAgricultural College, who identifiedmany of the plantsfound. Specimensprepared, as indicatedin the lists, were identifiedby Drs. H. C. Oberholserand ClarenceCottam in Washington,D. C. Text-figure1 indicatesthe placesand datesat which observations were made. Work in the field out of camp usmdlyamounted to at least eight hours,and, of course,all daylight hours spent in camp providedsome opportunities for taking notes. Marshall visitedall the islands except Gunnison in 1938, and was on that island in 1937. Leatham was on Stansbury,Carrington, and Bird Islands. E. O. Chatelain and R. J. Jansen,undergraduate students at Utah State College,were on Dolphin and Fremont Islands,respectively. A brief discussionof the islandsas bird habitats may be of value in presentingthe situation. It mustbe clearlystated that Gunnison is the only area that hasbeen an island,in a strictsense of the word, continuouslysince 1850 (Adams, 1938). This fact is probably of small significance,however, to birds other than colonial nesters. 36 MARSHALLAND LEnTSriM, Birds o[ GreatSalt Lake Islands ]'Auk I. Jan.

The habitatsagree somewhat with thosediscussed by Linsdale (1938). The geologicbasis of these,obvious in the field, suggeststhe follow- ing designationsthat are usedin the text. (1) Sand bars:-fringes of sand depositedaround each island to

0o!

TEXT-FIe.1.--Map of Great Salt Lake, Utah. the heightof about fifteenfeet abovethe salt flats. Theseare water depositsof recentyears. The abundantplants are Sarcobatusvermic- ulatus and Atriplex con[erti[olia, with ½hrysothamnusnauseosus, Oryzopsishymenoides, Artemisia spinescens,DistichIls stricta, and Donaliaspp. also found in scatteredspots. One area of high and apparentlywind-deposited sands on Stansburysupported a grove of Juniperusutahensis. Vol.59'] MARSHALLAND LEATHAM, Birds of GreatSalt Lake Islands 37 194• a

(2) Benchlands(Gilbert, 1890):--graveldeposits at variouslevels oœ ancient lakes that support chiefly Artemisia tridentata and (or) Bromustectorum, although a wide variety oœother plants alsooccurs; œromindications on CarringtonIsland such bunch grasses as Or•zopsis hymenoides,stipa comata,and Agropyron•_picatum may have been more abundantbeœore recent fires and heavywinter useby domestic sheep. (3) Original islands:-areason Stansburyand AntelopeIslands that wereabove the highestlevel oœLake Bonneville. Theseareas support extensivegroves oœ the mountain mahoganies(Cercocarpus montanus and C. ledi[olius)as well as someJuniperus utahensis and a few Pseu- dotsugataxi[olia (one small ravine on Stansbury). Rhus trilobata, Agropyronspicatum, and Astragalusspp. were also commonon the highestareas. (4) Springs:--œresh-watersprings are foundonly on AntelopeIsland, whereAcer negundo,Populus nigra vat. italica,Salix spp.,and a five- acre field oœalfalfa are maintainedby irrigation. This is the only permanenthuman habitation on the islands,and was usedas a base by Ridgwayin 1869,as well as by the seniorauthor in 1938. Acer glabrum, Salix spp., Rumex crispus,Urtica spp., and other plants grow in the non-utilizedspring areas. Brackishsprings on the shores oœAntelope, Stansbury, and Fremont Islandssupport dense growths oœDistichlis stricta and Scirpuspaludosus. AntelopeIsland is the only one havingall oœthese habitats; Stans- bury and Fremont lack fresh-watersprings; Carrington until recent yearshad a brackishspring, but now, like Dolphin, Gunnison,and Bird Islands,it hasonly sandbars and benchlands. BadgerIsland (aslocally known) is merelya large sandbar about midway betweenCarrington and StansburyIslands. Both the original islandsand benchlandareas have cliffs and talus slopesthat are oœsignificance to bird life. For convenience,bird lists by islands,with commentswhere sig- nificant,will be presented.For the smallislands, the total numbers oœbirds are estimatedbut no quantitative data were obtainedfor the larger islands. DOLPHIN ISLAND This northernmostand probablydriest island is about fiœtyacres in extent. It was visited June 4 to 6, 1938. PACIFICNIGHTHAWK, Chordeiles minor hesperis.--Twobirds were seen over the island in the evening. They might easily have come from the mainland, though there was suitable nesting habitat on the island. 38 MARSHALLAND LEATHAM, Birds of GreatSalt Lake Islands I'Auk L Jan.

AMERICANRAVEN, COr'ilUS corax sinuatus.--Onedried-up body of an immature bird was found on the sand bar. UTAH HORNEDLARK, Otocoris a. utahensis.--A nest of four eggs was found in DistichIis stricta, and from six to eight adults were often seen feeding about the sand bars of the island. SAGETHRASHER, Oreoscoptes montanus.--One pair with a nest (four eggs)in an •ltriplex confettirolla bush was observed. DESERTSPARROW, •lrnphispiza b. deserticoIa.--Twopairs noted in •ltripIex con- fertifoIia. BREWER'SSPARROW, Spizella b. breweri.--Twoor three breedingpairs wereon the island,nearly alwaysseen in ,'1triplexconfertifolia. On this small island, which was completelycovered during two days,we found the following nestingdensities.

TABLE 1

Speciesand Acreageof Acreageof numberof Totalacres nesting Acresper feeding Acresper nests per nest• cover• nest• caver• nesf:

Distiehlis Horned Lark DistichIls and flats 2 25 ){ • 100 s0

Sage Thrasher Atriplex Brushy 1 50 5 2.5 40 40

Desert Sparrow Atriplex Brushy 2 50 5 2.5 40 40

Brewer's Sparrow Atriplex Brushy 3 16 5 1.6 40 13 Authors' estimates based on observationsof nesting and feeding activities of this species on all islands. 1Zesult of dividing number of nests into estimated acreages.

GUNNISON ISLAND While Dr. D. I. Rasmussen,Lee Kay, and the seniorauthor were on this islandon June 23, 1937,one family of Rock Wrens,$alpinctes o. obsoletus,was observed,and one pair of Prairie Falcons,Falco mexicanus, was noted. On June 18 to 19, 1935,Dr. Rasmussenfound two Prairie Falcons' (Falcomexicanus) nests and severalpairs of RockWrens (Salpinctes o. obsoletus)which may be considerednesting birds. In addition sevenAmerican Ravens (Corvusc. sinuatus)and a small flock of Black-neckedStilts (Himantopusmexicanus) visited the island. Vol.59'[ MARSHALLAND LEATHAM, Birds of GreatSalt Lake Islands 39 •94• a

Dr. Alfred M. Bailey,Director of the ColoradoMuseum of Natural History, Denver, Colorado, has very kindly made available to the authorsthe following additional noteson the bird life of this island. On May 28, 1937: AMERICANRAVEN, Cor•us corax sinuatus.--Anest with five young found. YE•OW-HEADm)BLACKmRD, Xanthocephalus xanthocephalus.--Six females observed. Cowram),Molothrus ater subsp.--Onepair observed. On June 8, 1937: (?) WRmHT'SFLYCATCHER, Ernpidonax wrighti.--One pair collected. BLaCK-HEADEDGROSBEAK, Hedyrneles rnelanocephalus papago.--A female bird col- lected. EASTERNYELLOW WARBLER,Dendroica aestiva aestiva.--One female collected. WmT•N CroPraNGSt'Am•OW, Spizella passerina arizonae.--One female collected. Dr. Bailey's expedition was on this island during a very stormy periodwhich may well explain the occurrenceof thesespecies on this, the most desert-like of the islands.

BIRD ISLAND Area twenty-twoacres; visited in the evening of June 30, 1938. One Prairie Falcon (Falcomexicanus) in the air and five Utah Horned Larks (Otocorisa. utahensis)on the sandbar to the southwere seen. It is probable that the falcon was the sameone seenon Carrington Island, and that the larks were visitors also. There is little, if any, suitablenesting area for thesebirds on this tiny islandas the pelican, gull and heron colonyutilizes most of the acreage.

CARRINGTON ISLAND Carrington Island, with an area of 1,740 acres,was visited from June 29 to July 2, 1938,with the exceptionof the eveningof June 30. The entire islandwas well coveredduring this period. WF•TERN I?•_,D-TAILEDHAWK, Buteo borealis calurus. MARSH HAWK, Circus hudsonius. PRAIRIE FALCON, Falco mexicanus. One individual of each of these birds was noted, but no hawk nest was found. WESTERNMOVamNg DOVE, Zenaidura macrouramarginella.--Four mourning doves were seen. SHORT-RAgr•OWL, .4SiO [. fiammeus.--Twobirds were often seenforaging during the evenings. They may well have nestedon the island. NUTTALL'SPOOR-WILL, Phalaenoptilus n. nuttalli.--Onebird wasseen and collected. UTAH HORNre>LAgK, Otocorisa. utahensis.--Thesebirds were frequently seen on the sand bars; at least severalfamilies were represented. ROCKWm•N, Salpinctes o. obsoletus.--Onepair wasobserved among the rocksat the west side of the island. <}0 MARSHALLANDLEATI•AM, Birds of GreatSalt Lake Islands I.I'Auk Jan.

WESTERNMOCKXNOBm•, Mimus polyglottosleucopterus.--One family group of sevenor eight birdswas noted feeding over the Sarcobatusareas on the sandbars of this island. SAgETIaRASHER, Oreoscoptes montanus.--Two nests (containing four and five eggs)were found in Sarcobatusbushes. Several other pairs were noted. CALXVORNXASI•VaKE, Lanius ludovicianusgambeli.--One family group of five was seen. DESERTSPARROW, .4mphispiza b. deserticola.--Common. BREWER'SSPARROW, Spizella b. breweri.--Abundant in the .4rtemisia areas. It is of interestthat membersof Ridgway'sparty (Ridgway, 1877: 371) visited this island on June 17, 1869. They brought back eggs of Avocet,Canada Goose, and CaliforniaGulls and reported"various other waterfowlas breedingupon this island and a smallerone near by." Accordingto sheepmena spring flowedupon this island until 1925.

BADGER ISLAND Badger Island is the local name for a sand bar about six acresin extent that lies midway betweenCarrington and StansburyIslands. Its chief ornithological interest is as being the site of a previously unreportednesting colony of Treganza'sHeron (Ardea h. treganzai). During the years 1871 to 1873 this bar was probably under water. From 1874 to 1902 and from 1907 to 1931, it has been surrounded by salt water. Two groupsof heron nest platformswere found. One, numbering105, wasin a goodstate of preservation;while six obviouslyolder platforms were found a shortdistance away. Sheep- men reportedthat heronsand gulls nestedhere in the 1920's. It is thought that the well-preservedgroup of platformsrepresents thisperiod, while the oldergroup may be nestsof the earlierperiod, 1879-1902. There were no occupiednests of heronsor gulls on this island in 1938. Birds noted here on the eveningof June 29 and the early morning of June 30 were: SHORT-EAREDOWL, Asio f. fiammeus.--Onebird foragingover the entire island. SAGETHRASHER, Oreoscoptes montanus.--Three birds noted, representingap- parentlytwo pairs at oppositeends of the island. DESERTSPARROW, Amphispiza b. deserticola.--Nineadult birds noted, which may well haverepresented four or five nestson the area. BREWER'SSPAPROW, Spizella b. breweri.--Abouttwenty birds noted, which ap- parently representedseveral 'family' groups. On this island with an estimatedfive acresof exceptionallyhigh and densebushes of Sarcobatusvermiculatus and Atriplex confetti- rolla two pairsof SageThrashers, four or five pairsof DesertSpar- rows,and probablyfour pairs of Brewer'sSparrows were found. Vol.1942•9] -• MARShtALLAnD L•AT•iAr•, Birds of GreatSalt Lake Islands 4 l

Thus a nestingdensity of 1 to 2.5 acres,1 to 1 acre, and 1 to 1.25 acresrespectively is recorded. These estimatescoincide closely with those for Dolphin when the suitable nesting cover is considered (Table 1). The use of the feedingarea is much more intense,pos- siblybecause the plant growthis muchmore dense on BadgerIsland.

STANSBURY ISLAND Intensivefield work from June 20 to 26, 1938,was carried on at the south and north ends of this large (19,305acres) island. The listsare divided by 'habitats,'since these were apparentlysignificant, although,of course,some birds overlapped.

Sand Bars UarA•{ HORNED LARr,, Otocoris a. utahensis.--Common; one bird collected. WEsTEanMOCKInGBn•, Mimus polyglottosleucopterus.--One bird was seena few times and frequently heard near the camp. CALIFORS•AS•mIKE, Lanius l. gambeli.--Onefamily of four youngand two adults fed for two or three daysnear the camp. Two spedmenswere taken. This species and the mockingbirdwere seenonly in the small groveof Juniperusat the north end of the island. Benchlands WESTERnMOURninG DOVE, Zenaidura macroura marginella.--Common. PAGIFIGNIG•iar•iAWK, ½hordeiles minor hesperis.--One nest with two eggs was found under an Artemisia tridentata bush. The adults were commonly seen in the evenings. AMERIGAnRAvEn, Corvus corax sinuatus.--A few adult birds were observed. SAGETHRAS•iER, Oreoscoptes montanus.--Common in the Artemisiaareas. WESTERnM•t•OWLARK, Sturnella neglecta.--Commonin the Artemisia areas. WESTERnI•RK SPARROW,½hondestes grammacus strigatus.--Rare in Artemisia areas; one bird was collected. DESERarSPARROW, Amphispiza bilineata deserticola.--Commonin the Artemisia areas. BREWER'SSPARROW, spizella b. breweri.--One bird collected; this specieswas abundant in the .4rtemisia areas.

'Original Islands' WESarER•RE•-arAILFa• HAW•, Buteo borealiscalurus.--One pair of adults was ob- servedat the north end of the island,where an old nestwas found in a juniper tree. PP•IRmFALCOn, Falco mexicanus.--Anest of thesebirds with young was found on the face of an inaccessible cliff at the north end of the island. An adult, which dropped a recently killed ground squirrel (½itellus townsendimollis), was flushed on the south end of the island. NU•rALL'S POOR-W•L•,Phalaenoptilus n. nuttalli.--One bird seen and heard at dusk on the north end of the island. Pock WeEn, Salpincteso. obsoletus.--Common. AS•i-a•ROAa'•a•FL¾½AarC•iEa, Myiarchus c. cinerascens.--Severaladults seenand one spedmen taken. 42 MARSHALLANDLEATHAM, Birds of GreatSalt Lake Islands L[Auk Jan.

WESTERNGNATCATCHER, Polioptila c. amoenissima.--Onefamily groupseen and one bird collected. MONTANATOW•EE, Pipilo maculatus montanus.--One nesting pair wasnoted of which a specimenwas taken. HouseF•NCIt, Carpodacus mexicanus frontalis.--One adult bird wasseen several times. BrackishSprings An interestingactivity of the California Gull (Larus calffornicus) was noted at the large brackishspring on the northeastshore of the island. Throughout daylight there was a more or lesscontinuous streamof birds going both north and south along the east shore, apparentlyto and from the nestingcolony of Bird Island and the mainland. Many of them usedthese springs for a wateringplace; there were usuallyabout one hundredand fifty birds on the water drinking,and individualswere flyingin and out of the area almost constantly.About fifteenhundred birds rested on a nearbysand spit for mostof the day. One MarshHawk (Circushudsonius) was seen foraging over thesesprings. Two earlier records of birds on this island have been found: Ridgwayon June 12, 1869,reported the Catbird,Galeoscoptes (now Dumetella)carolinensis, and Stansbury(1852) mentions hearing the songof the Mockingbird. FREMONT ISLAND CaptainJohn C. Fremont(1850) writes briefly of the birdsseen on this islandin September1843, stating (p. 206) "a magpieand one largerbird... werethe only living things" seen on theisland. This apparentlycomprises the first recordedobservation of animallife on any of the islands.The men in the partyhad dreamedof a gameparadise on these isolated areas and were so bitterly disheartened that theynamed it DisappointmentIsland. This island,with an area of 2,940 acres,was visited August 6 and 7, 1938,when only the westernhalf wascovered. Sand Bars MARSHHAWK, Circus hudsonius.--Five individuals were seenhunting over the extensivebar area at the westend of the island. These apparentlywere one adult female and four young. S•ORT-E•amDOWL, Asio f. flammeus.--Onebird wasnoted several times hunting over the same area. UTA• HORNEDLARK, Otocoris a. utahensis.--Onegroup of sevenbirds was ob- servedat the westernextremity. Benchlands PRAIRIEI•ALCON, Fal½o mexicanus.--A recently used nest was found in the low cliffs at the north end of the island. One adult bird was seen. Vol.59'] MARSHALLAND LEATHAM, Birds o! GreatSalt Lake Islands •94• .•

MONTANAHORNED OWL, Bubo virginianus occidentalis.--Oneindividual was flushed several times from the low cliffs on the north side of the island. PACIFICNIGHTHAWK, ½hordeiles minor hesperis.--Atleast four adults were seen flying over the westernextremity of the island. ROCKWREN, Salpinctes o. obsoletus.--Twosmall groupsof thesebirds were ob- servedalong the rocky cliffsof the north shore. CALIFORNIASHRIKE, Lanius l. gambeli.--Onegroup of five birds, four immature, was noted in the sagebrushareas. BREWER'SSPAImOW, Spizella b. breweri.--Commonin the .4rtemisiaareas.

ANTELOPE ISLAND This large island,area 26,056acres, has the only freshwater and human habitation of all the group. It is particularly interesting becauseof the fieldwork by Ridgwayon June4 to 8, 1869. He stayed at the ranch which was built in early pioneer times, the original buildingsof which are still in use. Through the courtesyof John R. Dooley,of Salt Lake City, the samebuildings were used as a base in 1938,from July 12 throughJuly 14. Ridgway (1877: 370) used nearly identical phrasesto describe habitatsas are usedin the presentpaper. Hence the listsare directly comparable. A combinationof the current lists for Stansburyand AntelopeIslands duplicates the list of sixty-nineyears ago exceptfor two habitats,as pointed out later.

Sand Bars Little time was spent in this habitat exceptat two previouslyun- reportedCalifornia Gull colonies,which as noted at Bird Island, are not suitablefor passefinebirds. One of the colonies,at the end of a sand bar about a mile north of the ranch, had an estimated 1,500young. The other,at thesouth end of the island,•ontained approximately300 young.

Benchlands BLACK-CROWNEDNIGHT HERON, Nycticorax n. hoactli.--One immature bird with a flock of California Gulls feeding on grasshoppers. WESTERNRED-TAiLED HAWK, Buteo borealis calurus.--Two adults seen. CALIFORNIAGtmL, Larus calffornicus.--Severallarge flocksseen feeding on grass- hoppers. 'Original Island' PRAIRIEFALCON, Falco mexicanus.--One adult seen. AMERICAN RAVEN, Corvus corax sinuatus.--Two adults seen. This list is quite incompleteand probablyshould be comparableto that for . the samehabitat on StansburyIsland. MARSHALLANDLEATHAM, Birds o[ GreatSalt Lake Islands lF Jan.Auk

BrackishSprings K•Lt•r•, Oxyechusv. voci[erus.--Common. SI•O•tX-ra•EDOwL, ,4sio[. flammeus.--Abundant. UTAH Ho•tN•) LA•, Otocoris a. utahensis.--Common. B•t•-w•t'sB•½•Bnm, Euphagus cyanocephalus.--One group of six birdsseen. Ridgway recordedobservations at the ranch, used as headquarters,separately from the other habitats. Since these notes representthe area of greatestamount of freshwater and plants dependenton it, they were comparedwith the 1938list for 'Springs--freshwater' which is as follows: CALIFORNIAQIaAIL, Lophortyx c. calffornica.--One coveyseen. RING-NECKEDPHEASANT, Phasianus c. torquatus.--Twomales noted. B^•trqSwA•tow, Hirundo erythrogaster.--Abundant. ErqGL•SHSeAr. sow, Passerd. domesticus.--Veryabundant. B•t•wr•'s BLnCKBr•,Euphagus cyanocephalus.--One small flock seen. A comparisonof the recent lists with those of Ridgway showed three striking points: (a) the number and kinds of waterfowlusing the islandshave been greatly reduced; i.e., Cartingtonnotes; (b) the speciesof birds found on the 'original-island'and benchland areas are practicallythe same; (c) a pronouncedreduction of native song- birds suchas Warbling Vireo, oriole, Redstart,and Catbird at the ranch headquartershas taken place. In their steadwere found an enormousnumber of EnglishSparrows that swarmedin large num- bers in the shadetrees and about buildings. A comparisonof theselists with that of Stanford (1932) indi- cated that most of the birds seen on the islands have also been reportedfrom areasto the north of the Great Salt Lake. Thus, as far as birds other than thosenesting in the rookeriesare concerned, the avifauna of the islands is consideredas typical of the desert areas of northwestern Utah. The lack of a permanentfresh-water supply on mostof the islands presentsan interestingproblem as to water requirementsof these nestingbirds. Weather Bureau recordsof ten years,1911-20 (Alter, 1926), show the followingconditions for the nestingseason at Midlake (seemap, Text-fig. 1). TABLE 2 Averagenumber Average dayswith .01 Average Highest monthly precipitation maximum recorded precipitation or more temperature temperature April 0.43 2 57.1 78 May 0.38 3 66.1 88 3une 0.5O 2 76.9 94 3uly 0.32 2 83.0 92 August 0.09 0 81.6 90 Vol.194250] J MARSHALLAN.Lr_AT•A•, Birds of GreatSalt •ke Islan• •

The serieso[ recordsshows that three timesin June, twicein July and four times in August there was no recordableprecipitation. Evaporationfrom an open-watersurface has bccn between12 and 1• inchesduring July a• the Salt Lake airport. Theserecords, while not directly applicableto all the islands,indicate climatic conditions on the lake in generaland Dolphin, Gunnison,Bird, C•rin•on, and BadgerIslands in p•ticul•. Dolphin, Gunsson and B•d Islands arc fully fi[tccn miles from the nc•cst fresh water during thesemonths; while Ca•ington and Bird arc approximatelysix miles from the brackishsprings of Stans- b• Island. Thus thesebirds nestwithout a certainsupply o[ fresh water sinceflights of six and fi[tccn •lcs for water arc improbable for small passerincspecies.

(1) Environmental conditionson the islandsin the Great Salt Lake o[ Utah arc presentedbriefly and lists o[ birds •or ca• island •c discussed in relation to the 'habitats.' (2) For certain smallerislands complete counts of in•viduals •c presentedwith data as to nestingdensities. (•) One previouslyunrcportcd Trcganza's Heron colony and two recentlyestablished Call[orca Gull colonies•c noted as well as the possiblewater supply for the l•gc Call[orca Gull colonyof Bird Island. (4) Comprison of listswith thoseof Rid•ay for sixty ye•s pre- vious indicatesthe deleteriouseffect of recent •oughts and of the introduction of exotics upon birds of Ca•ington and Antelope Islands,although the lists of birds not directly dependenton fresh- water springs•e practicallyidentical. (5) Lists of non-colonialnesting birds are identicalwith thosefor northwesternUt•, exceptfor being lessvaried. (6) The severityof water conditionson the small isolatedislands indicates the tolerance of certain desert speciesto lack of water during the nestingand broodingseason. 46 MARSHALLANDLEATHAM, Birdsof Great Salt Lake Islands [Auk

LITERATURE CITED AVAMS, C. T. 1938. Personalletter on topographicaldata, August24. ALTER,J. C. 1926. Summaryof climatologicaldata for the U.S. by sections. U.S. Dept. Agr., Weather Bureau Section 11, Western Utah, 1911-20. BE•L•, W. H. 1935. A historyof the bird coloniesof the Great Salt Lake. Condor,37: 24-35, map. CO'I•AM, C. E., AND WILLIAMS, C. S. 1939. Food and habits of somebirds ncstlngon islandsin the Great Salt Lake. Wilson Bull., 51 (3): 150-155. FREMONT,J. C. 1850. The exploring expedition into the Rocky Mountains,Oregon, and Cali- fornia. Derby & Co., Buffalo,New York, 456 pp. GILBERT, G. K. 1890. Lake Bonneville. Monogr. U.S. Geol. Surv., 1: 1-425, illus. ][,INSDALE,J. s. 1938. Envlronmcntalresponses of vertebratesin the Great Basin. Amcr. Midland Nat., 19 (1): 1-206. PALMER, R. H. 1916. A visit to Hat and Egg Island, Great Salt Lake. Condor, 18: 113-123,5 figs. RIDGWAY, R. 1877. Ornithology,in 'Ornithologyand Palacontology,'U.S. Geol. Exp1.Fortlcth Parallel, 4, pt. 3, pp. 303--669. STANFORV,J. S. 1932. Birds of the desert, marsh, field, and mountains in northern Utah. Proc. Utah Acad. Sci., 9: 71-77. STANSBURY,H. 1852. Exploration and surveyof the valley of the Great Salt Lake of Utah. Lippincott, Grambe and Co., Philadelphia,487 pp., 23 plates, 35 figs., and 2 maps. WOODBURY, R. M., AND BEHLE, W. H. 1933. The bird rookeries of the islands of Great Salt Lake. Proc. Utah Acad. Sci., 10: 165. Fish and Wildlife Service Boise, Idaho and Utah State Agricultural College Logan, Utah