Project Prairie Birds

A Citizen Science Project for Wintering Grassland Birds

Vegetation Sampling

• Measure vegetation after all avian surveys have been completed each season to minimize disturbance of birds occupying the transects (measure only once per year; or measure a few days before a prescribed burn is scheduled).
• Collect cover data with a 1 m square homemade “hula-hoop” made of 3/4” PVC connected with PVC elbows. From the staked and monumented starting point where avian surveys were conducted, toss the square to the left about one or two meters (see Figure 4). As the square lays flat (or as flat as possible), determine the percent composition (in multiples of 10) of the following cover: grass (standing alive or dead; includes sedges, rushes and reeds), forbs (these are broad-leaved herbaceous plants), woody shrubs, leaf litter (flattened, dead vegetation) and bare ground (includes soil or rock). Count the number of fire ant mounds and gopher mounds within the square. Determine the percent of the area in the square covered by water (not standing rainwater) and measure the average water depth. Alternate your tosses at each 25 m spot.

Yellow-rumped warbler
Photo Copyright Michael L. Gray

• To determine vertical thickness, use the Density Board Technique (see Figure 5).
• In wooded situations, record basal area of trees using a 1-factor metric prism (includes instructions) at each of the five toss sites. Place in one of the three different size classes depending on the diameter of the trees at breast height (4 1/2’ above ground). This will help to structurally describe the wooded conditions.
• Count the total number of woody shrubs, the total number of trees and the total number of snags (standing, dead trees) in the 20 x 100 m transect area.

Figure 4
Measure vegetation along the same transect line where avian surveys were conducted. Toss the square (“hula-hoop”) a total of five times, once every 25 meters, as seen here.

Image showing where to measure vegetation along the transect line where the avian surveys were conducted as described above.

Figure 5
One person should stand the board up and hold it steady in the center of the square on every toss. A second person, the observer, will walk 15 meters due north from the board, then turn and face the board.

From a kneeling position, the observer will estimate the percentage (in multiples of 10) of the board that is obstructed by vegetation. The board should have a total of four equal sections, two painted black and two painted white, in an alternating fashion. This contrast aids in determining the amount of vegetation covering the board. In the example above, the first (bottom half-meter) section is 100% obstructed by vegetation. The second section is obstructed by 80% vegetation; this is how it should be scored on the vegetation data sheet.

Image showing the Density Board Technique as described above.