The first field season of a project to assess the distribution and abundance of priority grassland birds, like this Henslow's Sparrow, was completed in 2008. Photo by R. Schaefer.

Summer 2008

Field crews in Illinois, Indiana, Kentucky and Tennessee completed the first field season of a project designed to assess the distribution and abundance of priority grassland birds. More than 7000 birds were recorded during 3500 point counts conducted in 25 counties across the 4 states.

The project is designed not only to assess the current population levels of and habitat use by priority grassland species, but also to develop a monitoring protocol that can be used by state agencies and others to provide valid estimates of population sizes, taking into account detection distances. The protocol was developed by David Buehler and colleagues at the Univeristy of Tennessee; the work was funded through a grant from the U. S. Fish and Wildlife Service.

Because Northern Bobwhite conservation efforts, supported by CHJV partners, are likely to affect grass and shrubland birds, survey sites were selected to coincide with Northern Bobwhite conservation areas. CHJV staff provided spatial assistance in selecting sampling routes.

The survey targeted eight species: Bachman's Sparrow, Henslow's Sparrow, Grasshopper Sparrow, Field Sparrow, Dickcissel, Blue-winged Warbler, Prairie Warbler and Northern Bobwhite. The occurrence of other species was also noted. Of the target species, Field Sparrows were most commonly seen (3087 records) and Bachman’s Sparrows were the least (0 records).

The Henslow’s Sparrow is one of the most rapidly declining grassland species in North America, with a population decrease of an estimated 91% since the Breeding Bird Survey began in 1966. This summer, the field crews documented breeding locations for Henslow’s Sparrows in 14 counties where they were previously unrecorded, including four new counties in Illinois, two in Indiana, five in Kentucky, and three in Tennessee.

Observations on the habitat type at each survey location were used to calculate how often each species was found in each habitat type, in relation to its availability. For example, Dickcissels and Northern Bobwhites used cool season grasses proportionally more than its availability, while Field and Henslow's Sparrows used the same habitat type less than expected, based on availability.

More on the Grass and Shrubland Bird Assessment
2008 Annual Report of the Grass and Shrubland Bird Assessment

Each bar shows the total number of priority grassland birds observed during point counts in each state. The eight species indicated are: Blue-winged Warbler (BWWA), Dickcissel (DICK), Field Sparrow (FISP), Grasshopper Sparrow (GRSP), Henslow’s Sparrow (HESP), Loggerhead Shrike (LOSH), Northern Bobwhite Quail (NOBO), and Prairie Warbler (PRAW). NONE indicates point count locations where no species were observed.