Habitat Modeling and Assessment
Habitat modeling is an integral part of the Biological Planning component of Strategic Habitat Conservation (SHC) because it defines the components of habitat that can be affected through management and helps identify the habitat factors that most limit populations. Habitat models can be used to assess current habitat conditions to evaluate carrying capacity of landscapes. Further, these models can be applied to potential future habitat conditions to evaluate changes in carrying capacity.
Open Woodland & Forest Birds
In 2004, the CHJV partnered with the Lower Mississippi Valley Joint Venture to obtain a Science Support Partnership (SSP) grant to develop Habitat Suitability Index (HSI) models for a suite of priority forest-associated species. These models estimate the relative suitability of landscapes, and were developed from data points found in the literature, supplemented with expert opinion when quantitative data were lacking. The models were applied to spatial datasets spanning the Central Hardwoods and West Gulf Coastal Plain/Ouachitas Bird Conservation Regions. The primary datasets used included the National Elevation Dataset (NED), the National Land Cover Dataset (NLCD), the Forest Inventory and Analysis (FIA) database, and the National Hydrography Dataset (NHD). The suitability of these models for conservation planning was evaluated using Breeding Bird Survey data. The CHJV is currently conducting a project using point count data collected within the Central Hardwoods Bird Conservation Region to evaluate the models for site-scale planning, as well as to improve the linkage between model outputs and population density.
In addition to developing HSI models, the SSP project developed a model of relative productivity. This model, called the General Productivity Function, ranked forest patches based on two fragmentation indices: the amount of forest in a ten-kilometer (six-mile) radius, and the distance to a non-forested edge. The CHJV is gathering nest success data to evaluate this model.
No habitat models for grassland birds exist at this time. However, results from our Grassland Bird Monitoring Project will enable such models to be built. We expect to set breeding grassland bird objectives in late 2013 or early 2014.
The CHJV Wetland Science Team has identified Daily Ration Models (DRM) as the best approach for assessing habitat conditions for wetland birds. DRMs are energy supply and demand models that evaluate habitats based on the food they provide to migrating and wintering birds. The Team is developing habitat associations for each priority species. An assessment of public lands currently underway will estimate the amount of each habitat type on public lands managed for wetland species. This data combined with energy estimates taken from previous research for each habitat type will provide input to the DRM.