Occurrence and productivity of songbirds in prairie farmland under conventional versus minimum tillage regimes

摘要

Abundance and productivity of common bird species in prairie cropland under either conventional or minimum tillage were examined in southern Alberta, Canada. Cover types included spring cereals, winter wheat and summerfallow. Productivity was assessed using observations of nesting and brood-rearing behavior. Five species were sufficiently abundant to allow for some statistical analyses: homed lark (Eremophila alpestris), savannah sparrow (Passerculus sandwichensis), Baird's sparrows (Ammodramus bairdii), chestnut-collared longspur (Calcarius ornatus) and McCown's longspur (Calcarius mccownii). Abundance varied between conventional and minimum tillage regimes for most species in at least one cover type. Savannah sparrows in spring cereal and winter wheat and chestnut-collared longspurs in summerfallow tended to prefer minimum tillage. McCown's longspurs and homed larks occurred more frequently on conventional than minimum till spring cereal plots in at least 1 of the 2 years. For savannah sparrows, minimum till spring cereal and winter wheat were more productive than conventional till habitat. Summerfallow of either tillage regime did not appear to be as productive as minimum till cereal fields for this species. Chestnut-collared longspurs occurred predominantly in minimum till summerfallow and spring cereal habitat and showed almost no productivity in conventionally managed plots. McCown's longspurs tended to have higher productivity in minimum till plots. Homed larks had high productivity in minimum till winter wheat in 1996. Male Baird's sparrows occupied territories in minimum till winter and spring cereal fields in 1995, but did not attract mates; they were not detected in 1996. Minimum tillage appeared to confer benefits in productivity to species that nested in farmland.