Value of the conservation reserve program to birds in the Texas southern high plains
Date
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The Conservation Reserve Program (CRP) in the Texas Southern High Plains (SHP) was investigated to document its influence on avian populations. U.S. Soil Conservation Service personnel in the Texas SHP were surveyed by questionnaire for information about the land enrolled in the CRP through February 1988. Information included type of cover established, acreage enrolled, establishment success and cost of establishment in conservation practices 1, 2, 4, 10, and 12. A total of 903,215 ha was enrolled in 71 counties. The most common cover types averaged $145.90/ha to establish and were successfully established in 87% of the cases.
Avian use of CRP lands was studied in a 4-county area of the Texas SHP. Studies were conducted In 1988 and 1989 on lands containing the 3 most commonly established grass mixtures (blue grama/side-oats grama; blue grama/Kleingrass; and blue grama/plains bluestem). Passerine bird density on CRP lands during winter was investigated using line transect surveys. Density and biomass estimates were determined for the most common passerines. Savannah sparrows and western meadowlarks showed an average winter density of 1.65 and 0.74 birds/ha, respectively. Avian biomass estimates on CRP lands averaged 10.99 kg/100 ha for the most common passerines. Blue grama/Kleingrass cover types produced the highest values for passerine density and avian biomass estimates.
A total of 425 avian nests were located on CRP lands in 1988 and 1989. For the most common passerines, nest success and clutch sizes differed from 1988 to 1989. Differences in nest density among CRP cover types were also detected for several passerine bird species. Nest productivity was determined for the most common passerines nesting on CRP lands.
Waterfowl nesting results on CRP lands from 1988 and 1989 showed an average nest success of 21%, nest density of 0.12 nests/ha. Waterfowl production in the 4-county area for only the 3 vegetation types studied was estimated using 1988 and 1989 nesting information, CRP enrollment figures for the area, and waterfowl survival estimates. Waterfowl production was estimated at 8,531 ducklings per year from 1,185 successful nests. Recruitment estimates were 2,986 ducklings in the fall population and 1,164 females in the spring population.
Results of nest searches on CRP lands from 1988 and 1989 showed an average ring-necked pheasant nest success of 22%, nest density of 1.56 nests/ha, and an average clutch size of 11.2 eggs. Based on nesting results, blue grama/Kleingrass mixtures produced fields of the highest quality nesting cover. This cover type produced the greatest pheasant nest densities (2.10 nests/ha), nest success (28%), and vegetative structure. Pheasant production in the 4-county area for only the 3 vegetation types studied was estimated using 1988 and 1989 nesting information, CRP enrollment figures for the area, and pheasant survival estimates. The 4-county area enrolled 47,021 ha of CRP land containing the studied grass species combinations. Based on the above data, the 3 CRP cover types produced 164,474 chicks annually from 16,138 successful nests. Recruitment estimates were 41,119 males (0.87 males/ha) in the fall, and 23,839 females (0.51 females/ha) in the spring population. Under these conditions, spring hen density on CRP lands was 51 hens/km2 from the previous years nesting effort. Initial evaluations of CRP in the SHP have shown that pheasants, waterfowl, and passerines respond positively to increases in secure, high-quality habitat.