Multicriteria decisions and portfolio analysis: land acquisition for biological and social objectives.

Resource allocation for land acquisition is a common multiobjective problem that involves complex trade-offs. The National Wildlife Refuge System (NWRS) of the U.S. Fish and Wildlife Service currently uses the Targeted Resource Acquisition Comparison Tool (TRACT) to allocate funds from the Migratory Bird Conservation Fund (MBCF; established through the Migratory Bird Hunting and Conservation Act of 1934) for land acquisition based on cost-benefit analysis, regional priority rankings of candidate land parcels available for acquisition, and the overall biological contribution to duck population objectives. However, current policy encourages decision makers to consider societal and economic benefits of lands acquired, in addition to their biological benefits to waterfowl. These decisions about portfolio elements (i.e., individual land parcels) require an analysis of the difficult trade-offs among multiple objectives. In the last decade the application of multicriteria decision analysis (MCDA) methods has been instrumental in aiding decision makers with complex multiobjective decisions. In this study, we present an alternative approach to developing land-acquisition portfolios using MCDA and modern portfolio theory (MPT). We describe the development of a portfolio decision analysis tool using constrained optimization for land-acquisition decisions by the NWRS. We outline the decision framework, describe development of the prototype tool in Microsoft Excel, and test the results of the tool using land parcels submitted as candidates for MBCF funding in 2019. Our results indicate that the constrained optimization outperformed the traditional TRACT method and ad hoc portfolios developed using current NWRS criteria.

A spatial model for the beneficial use of dredge spoil deposition: Creation and management of breeding habitat for reddish egrets in Texas.

Many species of coastal waterbirds have faced population declines in recent years as a result of loss and degradation of habitat. The creation of new habitat through strategic placement of dredge spoil can be an effective tool to mitigate habitat loss. The use of dredge spoil islands for nesting, wintering, and migratory stopover habitat by waterbirds has been documented extensively over the past several decades. Most of the reddish egret (Egretta rufescens) breeding population in the United States occurs in Texas, where it has declined by more than 30% since the 1970s. Reddish egrets breed on dredge spoil islands along the Texas coast, and the stability of breeding colonies has been variable since the 1970s. If nesting habitat is degraded or limiting in Texas, the creation of new nesting islands through strategic dredge spoil placement could benefit reddish egrets. We developed a spatially explicit prioritization model for targeted conservation of reddish egrets in the Laguna Madre, Texas, through colonial island establishment using dredge spoil. Prioritization is based on availability of foraging areas, potential competition at foraging areas, and distance of potential sites to the mainland. 'Priority areas' are potential nesting island locations that would maximize the foraging benefits for breeding reddish egrets. Model outputs show that highest priority areas in the Laguna Madre are located in the southernmost portion of the lagoon. Other priority areas are located in the lower Laguna Madre, and at the mouth of Baffin Bay. In addition, we provide a repeatable and transparent framework for the development of spatial support tools that help guide targeted placement of dredge spoil in an effort to conserve colonial waterbirds. We illustrate the model development for reddish egrets, a threatened species in Texas, however our framework can be applied to other similar species.

Decision support tool: Mottled duck habitat management and conservation in the Western Gulf Coast.

The Western Gulf Coast provides important habitat for migratory and resident waterfowl. The mottled duck (Anas fulvigula) relies on this region for all of its life-cycle events. Its relatively small population, limited worldwide range, and generally declining population trajectory has earned it a "Red" status on the Audubon WatchList and is a species of concern among state and federal agencies. The Western Gulf Coast (WGC) mottled duck population decline is believed to be primarily caused by the historical conversion and degradation of coastal wetlands and native prairie, and recent declines in cultivated rice. There is general agreement among experts that negative impacts to nesting and brood-rearing habitat are the most important threats to the WGC mottled duck population and increasing recruitment is essential to the growth and sustainability of the population. Our goal was to use available knowledge of mottled duck nesting and brood-rearing requirements to develop a model to aid managers in targeting areas for conservation and management. We developed four spatially explicit models that: 1) identify and prioritize existing mottled duck nesting habitat for conservation (e.g., protection or maintenance); 2) identify and prioritize existing mottled duck brood-rearing habitat for conservation; 3) identify and prioritize areas for grassland establishment; and 4) identify and prioritize wetland basins for freshwater enhancement. Spatial models revealed that only 6 km2 and 9 km2 of nesting and brood-rearing habitat, respectively, were identified as highest priority (top 10%) for conservation in the WGC. Brood habitat was identified as potentially limiting recruitment in the Texas Mid Coast and the Laguna Madre subregions of our study area, whereas grassland habitat was potentially limiting recruitment in Chenier Plain and Mississippi River Coastal Wetlands subregions. Spatial models also revealed that there is a high density of areas of high priority for grassland establishment inland in Texas and Louisiana. Likewise, there is a high density of wetland basins of high priority for freshwater enhancement throughout coastal Louisiana and the upper Texas coast. We used two separate measures to assess the performance of our Mottled Duck Decision Support Tool (hereafter MODU-DST) and found that it adequately identified patch suitability, as defined by our model, with ≥79% accuracy. Using data from the Cooperative Breeding Mottled Duck Survey, we also found that breeding mottled ducks were using landscapes with optimal spatial arrangement of nesting and brood-rearing habitat, which is reflected by higher mean priority rankings of nesting and brood-rearing habitat in the landscape.