Standard Operating Procedure #1: Sample Designs Please cite this document as: Knutson, M., B. Route, and T. Gostomski. 2010. Standard operating procedure #1: Sample designs. In Gostomski, T., M. Knutson, N. P. Danz, B. Route, and T. W. Sutherland. 2010. Landbird monitoring protocol, Great Lakes Inventory and Monitoring Network. Natural Resource Report NPS/GLKN/NRR—2010/225. National Park Service, Fort Collins, Colorado. Contents Page Figures............................................................................................................................................. v Tables .............................................................................................................................................. v Introduction ..................................................................................................................................... 1 Species of Management Concern ............................................................................................... 1 Target Population and Sampling Frame ..................................................................................... 1 Objectives ....................................................................................................................................... 3 1. Inventory .............................................................................................................................. 3 2. Change Over Time ............................................................................................................... 3 3. Community Composition ..................................................................................................... 4 4. Management Action ............................................................................................................. 4 5. Adaptive Management ......................................................................................................... 4 6. Habitat Associations ............................................................................................................ 5 Revisiting Sampling Points ............................................................................................................. 7 Spatial Considerations .................................................................................................................... 7 Sample Size ..................................................................................................................................... 9 Sampling Designs ......................................................................................................................... 11 Design #1: Random design, for small to large land units ......................................................... 11 Design #2: Stratified random design, stratified by access, for small to large land units .......... 12 Design #3: Stratified random design, stratified by habitat type, for small to large land units ........................................................................................................................................... 13 Design #4: Multi-stage probabilistic design, stratified by accessibility, for large land units ........................................................................................................................................... 15 Literature Cited ............................................................................................................................. 19 iii Figures Page Figure 1. Diagram of macro-grid with mini-grids marked in gray. Each mini-grid contains twenty-five 300 m cells. ................................................................................................................ 15 Tables Page Table 1. Minimum sample sizes and the number of required visits per year for sampling relatively common species. Sample sizes and number of visits correlate to different levels of alpha risk and power and to a minimum detectable trend and the number of years of sampling required to observe that trend. ......................................................................................... 9 Table 2. Example of a sampling rotation for landbird monitoring using a multi-stage design over a 20-year period (from McIntyre et al. 2004). ........................................................... 17 v Introduction This SOP provides options for sampling designs to be used for purposes of monitoring landbirds during the breeding season. Several resources that describe basic sampling designs were used in developing this SOP (Cochran 1977, Thompson 2002, Hill et al. 2005). The monitoring coordinator for each park should work with his/her supervisor to define management and sampling objectives and to select the appropriate sampling design to meet their needs. There may be technical resources available to assist in generating a set of points the meet the sampling design criteria. Species of Management Concern For parks whose management objectives focus on a condition or change in the status of specific species, it will be necessary to define a subset of landbird species a priori that will serve as focal species for management. Scientific reasoning, coupled with statistical analyses of inventory or pilot data are used to identify appropriate focal species for future monitoring. These species may have one or more of the following attributes: 1. closely associated with major habitat types under management (habitat specialist or indicator species); 2. classified as a species of management concern by Partners in Flight, North American Bird Conservation Initiative (NABCI), or U.S. Fish and Wildlife Service (USFWS) Division of Migratory Birds; and 3. detected with sufficient frequency that the sampling objectives are likely to be attainable with available resources. Target Population and Sampling Frame Important issues to consider in a monitoring plan are the target population and the sampling frame. The target population is what you are interested in learning about (i.e., which landbird birds occur in the park or in a particular management unit or habitat?). The sampling frame, or area of interest, is the population of sampling units (locations) that most closely approximates where the target population may be found and that has some possibility of being sampled (e.g., entire park, a management unit, particular habitat[s] in the park). All monitoring plans should clearly define the target population in the objectives and define the sampling frame in the sampling design so that it is clear to which area or population the summary information applies. A fundamental rule of sampling design is that you cannot extrapolate your results to locations that had no opportunity to be sampled. For example, if large portions of your target area are inaccessible because they occur on private property, you might be very interested in the birds that breed in those locations (target population), but if those areas are not in the sampling frame (no possibility of being sampled), then you cannot attribute your results to those areas. You should be able to describe your sampling frame and create a map, blocking out any areas that were not in the sampling frame. It is rare that your sampling frame will encompass your entire population of interest; your sampling design is the best representation of the population of interest that you can achieve, given logistical and resource limitations. 1 Objectives In any new monitoring effort, the first step is to clarify the management questions and objectives. Why do you want to monitor birds? How will you use the information to guide your land management decisions? A workshop may be needed for key park staff, partners, and advisors to answer these questions, set objectives, consider alternatives, and design an adaptive management framework that integrates bird monitoring with management objectives and decisions. These decisions drive your sampling design. The sampling designs in this SOP can be used to address several potential management objectives, all of which employ estimates of bird abundance and occupancy. The specific objectives of a park monitoring plan should be explicitly stated before undertaking the monitoring (Johnson 2000). The objectives below are a template for expressing management objectives and the associated sampling objectives; they should be modified to match the park’s management objectives (Elzinga et al. 2001). Various resources are available to guide you in defining clear management objectives (Elzinga et al. 2001, Adamcik et al. 2004, Butler and Koontz 2005, Arkema et al. 2006, Schroeder 2006, Mahan et al. 2007). 1. Inventory Conduct an inventory of landbird species and estimate their abundance, density, or occupancy. The objective is to create a list of all landbird species in the target habitat. This objective is generally applicable when there is no baseline data for the site. For this objective, sample the largest number of points in the target habitat that you can, regardless of the size of the land unit. For the smallest land units, we simply want an inventory and some estimate of variance from which to estimate sample sizes for future monitoring. Thus, if the unit will only accommodate 10 points, we still sample the 10 points. For larger land units, the more points sampled, the higher the probability of detecting a large proportion of the species present. Management objective: I want to create a species list for the park or management unit, and I want to estimate the abundance (birds/point),