Strategic Multi-scale Grassland Bird Population Monitoring


This Grassland Bird monitoring protocol is an enhancement of the North American Breeding Bird Survey (BBS) protocol.  This protocol was developed in response to some concern that the BBS under-surveys grassland habitats in the forest dominated eastern US, and to allow for multi-scaled inference.  The protocol uses counties as management units based on the assumption that the county is an appropriate size for tracking local scale management actions and population responses. Like the BBS, the protocol employs survey routes: each route consists of thirty point count stations stratified in open habitats in pre-determined focal counties, with five roadside routes per county. Data are collected within distance bands to allow calculation of detection distances.  Points are stratified by open area (survey only points with >50% “open” habitat), and one visit for four routes/county, two visits for one route/county.  Habitat data are collected within a 100 m radius of each survey point, allowing for analysis with bird detection data collected.  This project monitors 11 species that observers can easily learn, provide reliable results, and cater to a larger observer base.


This protocol allows for periodically and annually collected Agricultural Census data to be analyzed with bird data. In this case, counties were used as management units for grassland birds to match the scale of Agricultural Statistics collected by the US Department of Agriculture.  Counties can serve as a functional unit for state agencies and are a reasonable size for monitoring.  This allows for greater spatial precision than BBS data, because BBS sample sizes are generally too small for county level analyses.  This method was designed to evaluate the effects of management and document habitat conditions (e.g., habitat availability, management effort, land use change) by monitoring specific grassland type areas based upon predictive models and partner selected focal areas.  Routes are stratified across focal habitat, such that grassland bird communities are better targeted than they are through the randomized placement of BBS routes to track population trends at meaningful scales.  It is statistically rigorous, extensive in nature, cost effective, and implementable by Joint Venture/BCR partners providing a balanced sample design (scalable from point – route – county – state – BCR).


This protocol has similar weaknesses to other point count methods like the Breeding Bird Survey (e.g., detection probabilities in time and space, detection of rare species, roadside bias), although, in the Central Hardwoods Joint Venture region, efforts were made to address detection probabilities (removal model) and potential roadside bias by assessing differences in detection and occupancy with distance from road.

Examples of use

Central Hardwoods JV grassland bird monitoring.

Southeast PIF 2011 meeting presentation

For more information

Dr. David Buehler at University of Tennessee (

Southeast PIF 2011 meeting presentation