Location of Sampling Stations: Three watershed units (C3A, C3B, C3C) constitute 'patches' that are alternately burned in a 3-year rotation within a single, fenced pasture (i.e., patch-burn grazing). Two additional watersheds are serving as controls: a grazed, annually/uniformly-burned watershed (C1A) and an ungrazed, annually/uniformly-burned watershed (1D).
Frequency of Sampling: Bird surveys require three visits each summer from late May through June. Sampling of vegetative structure is done on several visits through July.
Variable Measured: Per each transect for bird surveys variables measured are: Watershed ID, Transect ID, Date, Start time, End time, Observer ID, Categorical sky conditions/precipitation, Wind speed (kph) and direction, Temperature (oC), Cardinal direction of end of transect where survey started.
Per each bird detected on each transect survey: Species, Sex, Visual (saw bird), Song (heard bird's song), Call (heard alarm call from bird), Fly only (bird flew overhead and never landed in survey area), Flush (bird flushed from habitat due to observer), Distance (perpendicular distance from transect line, m), Group size (numbers of individuals if occurred in a flock), Comments (sex ratio of group, found nest, etc.).
For each nest observers record: Nest identification number, Species constructing nest, Watershed ID, Way in which nest was found (R=Rope Drag, S=Saw Nest, FW=Flushed While Walking, FF=Followed Female), GPS coordinates of nest (easting and northing in UTM), Bearing and distance from nest marking flag to nest, Qualitative descriptions of vegetative characteristics surrounding nest (to aid in re-finding nests), Nest fate (fledged found, depredated, deserted, trampled, other).
During each nest visit to the nest observers record: Date, Time (24-hr), Observer initials, Whether a parent bird flushed from the nest, Number of host (bird species that built nest) eggs, Number of host young, Number of brown-headed cowbird eggs, Number of brown-headed cowbird young, Age score of young (0 = bare, eyes sealed; 1 = downy, eyes sealed; 2 = downy, eyes open; 3 = feathers starting to unsheathe; 4 = feathered), Parental behavior (0 = none detected, M1 = male seen near but not heard, F1 = female seen near but not heard, M2 = male near and chipping, F2 = female near and chipping, F3 = female near with food, M3 = male near with food), If the nest appeared disturbed, If fecal sacs were present around the nest, If fledglings were spotted within the nest vicinity, Whether or not monitoring will be discontinued, Comments (misc.).
For vegetation sampling variables measured are: Date, Observer ID (of person making visual estimates), Watershed ID, Transect ID, Point ID (sample location along transect, 1-5), UTM-X (easting coordinate, UTM NAD 1983), UTM-Y (northing coordinate, UTM NAD 1983).
Frame Point ID (sample location at each point, 1-12), Percent grass (estimated percent horizontal coverage of grasses), Percent forb (estimated percent horizontal coverage of forbs), Percent shrub (estimated percent horizontal coverage of woody plants), Percent bare (estimated percent horizontal coverage of bare ground), Percent litter (estimated percent horizontal coverage of litter).
Litter depth (depth of litter in cm at lower left corner of frame), VOR Point (ID number of cardinal direction from which VOR reading taken), VOR (Visual Obstruction Reading; dm), Elevation (elevation of sampling point in m), Aspect (directional aspect of hill in degrees).
Methods: Three watershed units (C3A, C3B, C3C) constitute 'patches' that are alternately burned in a 3-year rotation within a single, fenced pasture (i.e., patch-burn grazing). Two additional watersheds are serving as controls: a grazed, annually/uniformly-burned watershed (C1A) and an ungrazed, annually/uniformly-burned watershed (1D).
Surveys of adult birds. Eight, 300-m line transects were established in each watershed. Observers visit each watershed three times between the last week in May through the end of June, where two 'core' transects per watershed are sampled upon each visit. Six additional transects per watershed are sampled, but only once in a given year (two peripheral transects are sampled per visit to each watershed). The transects were established using a stratified-random design, where each watershed was partitioned into two topographical blocks: and upland block (constituting the approximate upper half of the main watershed drainage) and a lowland block (constituting the approximate lower half of the main watershed drainage). Using ArcMap 10 (ArcGIS, ESRI, Inc.), twenty points (20-m minimum spacing) were randomly distributed within each watershed as single end-points for potential transects. The potential transects where fixed-width belt transects (sampling area 200 m x 300 m) and were only aligned in north-south or east-west orientations and directed toward approximate watershed interiors from end points. The twenty points were labeled with as many numbers (1-20) from which four points per watershed block were randomly selected and used as survey transects contingent upon the following conditions:
- The sampling area (200 m x 300 m) of all core transects must fall within the entirety of a watershed block and not overlap other core transects per watershed.
- 200 x 300-m peripheral transects can overlap with each other, core transects, and can cross into other blocks but must be contained within the entirety of a watershed.
- No ponds, roads, or woodlots must fall within any 200 x 300-m belt transect.
- If a complete set of eight transects could not be accommodated by the first 20m random points then additional rounds of 10 transect end-points were distributed and the selection routine repeated.
Bird surveys were conducted between 06:00 and 09:30. For each transect surveyed observers recorded: watershed ID, transect ID, date, start time (24-hr), end time (24-hr), observer ID, categorical sky conditions/precipitation, wind speed (kph) and direction, temperature (°C), and the cardinal direction from which the survey was started. On each transect observers recorded for each individual bird seen or heard perpendicular to the transect line and within the watershed boundary: species ID, perpendicular distance (m) from the transect (limited only be the watershed boundary, i.e.,), gender, whether or not the bird was seen, vocalizations (song and/or call), whether the bird only flew over the surveyed watershed and never landed, the numbers of individuals if in a group, and other comments (e.g., sex ratio within groups). The survey data will allow estimates of relative abundance, absolute density (determined from distance sampling), and species composition/diversity among the patch-burned and control watersheds.
Nest surveys. Nests are search for systematically among the watersheds or included in the data set if found haphazardly by observers. At a minimum observers record for each nest the ID of the species constructing the nest, nest contents (including clutch size of host and number of eggs or young of the brown-headed cowbird, Molothrus ater), and nest location (at least to watershed ID, GPS coordinates in UTM NAD 83 also desired). Nests may be monitored every three to four days to estimate survival of eggs and young. During monitoring visits observers record nest contents, date and time of monitoring visit, observer initials, estimated age of young, parental behavior, disturbance to nest material, presence of fecal sacs or fledglings in the nest vicinity, and the estimated fate of offspring. Locations of nests that are monitored are marked with a small piece of blue, vinyl flagging tied onto vegetation 5 m from the nest. The compass bearing from this flag is recorded. Additionally, descriptions of nest site characteristics (plant species and structure, etc.) are recorded to aid in re-finding nests. Notation on how the nest was found (following parents, flushed while walking, etc.) is also recorded. Data from nest monitoring can be used in estimating daily survival rates and levels of brood parasitism by cowbirds.
Vegetation sampling. Vegetation structure was measured along each survey transect at five, equidistant points (spaced 75 m apart) between mid-July and mid-August. At each sampling occasion observers recorded: date (mm/dd/yyyy), observer initials (of person doing visual estimates), watershed ID code, transect ID code, ID code for sampling point along transect (1-5), and easting and northing coordinates (UTM NAD 1983). At each sampling point, samples were taken at 0 m (frame abutting the point center), 2 m, and 4 m from the point center in each cardinal direction (location ID points 1-12). At each location, a 20 x 50-cm Daubenmire frame was used to estimate horizontal coverage of vegetative / structural functional groups (grass, forb, bare, litter). Each cover type was scored using one of six cover classes (0-5%, 5-25%, 25-50%, 50-75%, 75-95%, 95-100%). Litter depth (cm) was measured in the lower left corner of the frame (relative to the view of the observer). Vertical visual obstruction of vegetation was measured at the center of the sampling point (the five points along the transect) from a distance of 4 m in each of the four cardinal directions. Elevation was estimated using a Garmin GPS. Hill aspect was estimated at each point to the cardinal directions or their 45o midpoints (e.g., N or NE).
Summary of All Changes:
Dec 2020: PBG051 - added six new columns to the dataset, cleaned up the data, and updated the species code.
