This map shows the range of the Red-throated Loon (Gavia stellata) in the Northwestern
United States.

This part of the NW project started in September 2005 and was coordinated by the Wyoming Natural Diversity Database at the University of Wyoming.

Each of the 5 Natural Heritage Programs assisted with collecting species occurrence data, providing biological expertise, and building review teams within their respective states. The five Natural Heritage Programs are:

• Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY
• Idaho Natural Heritage Program, Idaho Department of Fish & Game, Boise, ID
• Montana Natural Heritage Program, University of Montana, Missoula, MT
• Washington Natural Heritage Program, Washington Department of Natural Resources, Olympia , WA
• Oregon Natural Heritage Information Program, Institute for Natural Resources, Oregon State University, Portland, OR

We mapped each species’ range (total areal extent occupied by a species), distribution (spatial arrangement of environments suitable for occupation by a species), and habitat (environments with the combination of resources and conditions that promote occupancy, survival, and reproduction by a species). We used this approach to potentially make regional maps more useful to local land managers.

We used two modeling approaches for the NWGAP. First a deductive modeling approach, which represents biologically-suitable environments based on land cover types.  And second, an inductive modeling approach, which represents physically-suitable environments within a species distribution modeled with the MAXENT algorithm based on environmental parameters (e.g., elevation, climate gradients) at known points of species occurrence (Phillips et al. 2004, Phillips et al. 2006).  The final NWGAP species distribution model is the spatial intersection of both these models.

Species Explorer

With our interactive Northwest Species Explorer, you can preview, download data, or obtain web mapping services for each NWGAP species’ range and distribution model.  

You can download data for northwestern species on our Data Download page.

Species ranges

The range data are attributed to 10-digit hydrologic units (HUCs) by the following codes:
Occupancy ("OCC"):
1: Known recent resident
2: Suspected recent resident
3: Accidental occupant
4: Historical resident
99: Never a resident

Season of Occurrence ("SEAS"):
1: Summer only
2: Winter only
3: Spring/Fall only
4: Year-round
99: Never a resident

Origin ("ORIG"):
1: Native – indigenous
2: Native – reintroduced
3: Exotic
99: Never a resident

Species distribution models

The model displayed is the final species distribution model, which is a binary representation of presence/absence for each species within its range.  It is the spatial intersection of the deductive model (biologically-suitable environments) and inductive model (physically-suitability environments).