Distribution, Status, and Origin of Water Pipits Breeding in California ’
The Condor89:788-797 0 The CooperOrnithological Society 1987 DISTRIBUTION, STATUS, AND ORIGIN OF WATER PIPITS BREEDING IN CALIFORNIA ’ JON H. MILLER 1034 ShattuckAvenue, Berkeley, CA 94707 MICHAEL T. GREEN Department of Biology, Universityof North Carolina, Chapel Hill, NC 27514 Abstract. We investigatedthe racial identity, distribution, and abundanceof WaterPipits (Anthusspinoletta) breeding in the mountainsof California.This commonnesting species of alpinetundra was not knownto breedin Californiauntil the 1970s;a reviewof historical evidencesuggests recent colonization. Mensural and plumagecomparisons show California populationsto be A. s. alticola, the breedingrace of the Rocky Mountains. This is of biogeographicalinterest, because the abundantwintering and migratorypipit of California is A. s. pacificus,while alticola normally occurshundreds of miles to the east.Water Pipits currentlynest in mesicalpine vegetation throughout much of the southernand centralSierra Nevada.Breeding densities are highestand mostuniform in the southernmostpart of this range.The only known breedingpopulation in California outsideof the Sierra Nevada occurson San Gorgonio Mountain in southernCalifornia. We hypothesizethat the previous absenceor rarity of breeding Water Pipits in the Sierra Nevada may be attributable to the most recentpaleoclimatic xerothermic period, the Hypsithermal(ca. 5,000 to 2,900 years BP), whichimuoverished many alnine biotasof arctic-oldcordilleran affinitv. Climate and habitat differencesmay prevenipa$cus from breedingin California, and geographicbarriers may have hindered colonization by alticola. The occurrenceand timing of the present colonizationmay be fortuitous.Alternatively, it is possiblethat prior colonizationof Great Basinranges by alticola facilitatedeventual dispersal to the SierraNevada. Key words: Water Pipit; Anthus spinoletta;Sierra Nevada;historical status; colonization; biogeography;alpine. INTRODUCTION and Montana (Verbeek 1970; Miller and Green, The Water Pipit (Anthus spinoletta) is a principal pers.
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