The impact of the conservation reserve program on eastern meadowlark production and validation of the eastern meadowlark habitat suitability index model



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Eastern meadowlark (Sturnella magna) productivity on Conservation Reserve Program (CRP) lands was compared to productivity on rangelands in Lyon County, Kansas in 1990 and 1991. Nests in CRP fields had lower cowbird parasitism rates, larger clutch sizes, and higher hatch rates than nests in pastures in 1991. Most young were fledged from unparasitized nests in CRP fields in both years of the study. Nest survival rates were similar between CRP fields and pastures. Parasitized nests had lower survival rates than unparasitized nests at the time of hatching. Cowbird parasitism appears to be a major cause of lowered productivity of eastern meadowlark nests. Eastern meadowlark selection for nest site vegetation characteristics was determined by comparing microhabitats at nests with random sites in CRP fields and pastures. Eastern meadowlarks selected for less dense litter and more homogeneous vegetation structure in both land use types. Nests in CRP fields had a higher proportion of grass than was available at random sites. Percent litter cover and litter depth were selected for in pastures. Plots 5 m from the nest had finer litter materials than random plots and litter density was intermediate between nests and random plots. Residual cover was greater at plots near the nest in CRP fields. Litter depth was greater near the nest than at random plots in pastures; percent litter cover near the nest was intermediate between nest sites and random plots in pastures. No differences in microhabitat were found between successful and unsuccessful nests or between parasitized and unparasitized nests. The eastern meadowlark Habitat Suitability Index (HSI) model was tested for eastern meadowlarks by comparing densities with HSI values in 34 fields in eastern Kansas. Applicability of the model for western meadowlarks (S.neglecta) was examined in 20 fields in western Kansas. The relationship between HSI values and eastern meadowlark densities was poor. This was primarily due to high densities of meadowlarks in fields with high forb coverage. These fields may have had high densities because they were attractive fields for feeding meadowlarks. The relationship improved when HSI values and densities were averaged over the 3 years of the study. The model was best for predicting breeding habitat potential rather than actual use. There was no discernible relationship between western meadowlark densities and the eastern meadowlark HSI model.



Meadowlarks -- Geographical distribution, Passeriformes -- Kansas -- Lyon County -- Geographical distribution, Meadowlarks -- Habitat, Agricultural Conservation Program -- Environmental aspects -- Kansas -- Lyon County