Biology 461/561 Ornithology

Dr. David Swanson, Office: CL 180


Purpose = Use two different methods to provide population estimates within a riparian corridor woodland. These types of studies are important in the fields of population biology, community ecology, and conservation biology.

    1. Description of Method
      1. Stations established at 200 m intervals along a linear transect
      2. 10 min sampling interval at each station
      3. Identify (sight or sound) and count birds and their distance from the station center
      4. Only count birds potentially using the habitat (e.g., an American Kestrel flying over the habitat would count because it could hunt within open regions of the woodland, but a Great Blue Heron flying over the woodland would not count because it does not use this type of habitat).
    2. Data Analysis
      1. 1) Plot the density (total birds and individual species) for concentric 10 m bands (1-10, 10-20, etc.) extending outward from the station center. Each 10 m band will have different ;areas (areas are larger the further from the station center), so you must use the appropriate areas for density calculations within each band.
      2. 2) Determine the Inflection Point = distance at which the number of birds detected begins to fall off. SEE EXAMPLES ON HANDOUTS 1, 2.
      3. 3) Habitat Density is then determined by summing the densities inside the inflection point. If more than one station is used in the census (as is usually the case), then the total density calculated must be divided by the number of stations censused.
    1. Description of Method
      1. Linear 1 km transect
      2. Walk transect line slowly (about 1 km per hour)
      3. Identify and count birds and their distance from the transect line
    2. B) Data Analysis
      1. Plot number of individuals in successive 5 m bands (10 m total band width because bands on both sides of the transect lines are included). No need to worry about calculating and plotting densities in this method because all bands have the same area (10 m x 1 km).
      2. Determine inflection point. SEE EXAMPLES ON HANDOUTS 1, 2.
      3. Sum numbers of birds and area inside inflection point (remember to include both sides of the transect line in your area calculations) to calculate population estimate.