Title	Jornada bird censuses, 1972
Publication Type	Report
Year of Publication	1972
Authors	Raitt RJ, Pimm SL
Series Title	US/IBP Grassland Biome
Pagination	20
Date Published	1972
Institution	Colorado State University
City	Ft. Collins, Colorado
ISBN Number	Technical Report No. 271
Call Number	00567
Keywords	bird, census, book, books, chapter, chapters, grassland, bird census, list, birds, report, reports
Abstract	Jornada grassland birds have been censured since 1971 by two methods: (1) intensive counts on two replicate plots (1600' x 2400'), at monthly intervals in 1971, at weekly intervals in 1972, and (2) roadside counts repeated twice each month, usually on consecutive days. In both 1971 and 1972 low numbers of breeding insectivores, Mourning Doves, and raptors have been replaced in the fall by large numbers of migrant and wintering Mourning Doves, raptors, Lark Buntings, Horned Larks, and various sparrows. The result has been a reversal of the usual situation in temperate grasslands of much higher numbers in the breeding season than in fall and winter. More precipitation occurred in 1972 than in 1971, but bird densities increased less than was expected. Parallels between temporal changes in insect abundance and bird densities indicate a probable dependence of the latter on the former.