Thursday, February 4, 2010

HCPC’s Wildlife Connectivity Analysis for the Blue Mountains Ecoregion: A Focal Species Based Approach to Identifying Wildlife Movement Corridors

HCPC is now part of an expanding new frontier in wildlife conservation. This new frontier is being driven by the growing recognition that long-term species viability necessitates protecting and restoring opportunities for wildlife movement across landscapes. And for the conservation community to ever move beyond battling habitat fragmentation project by project, we must engage in big-picture solutions. That is what HCPC’s plan to map corridors that allow regional wildlife to move within and between core habitats throughout the Blue Mountains ecoregion is all about.

Reviewing existing wildlife connectivity models has taught us that connectivity planning is generally based on the following steps: 1) Selecting focal species; 2) Performing GIS-based landscape permeability and core habitat analyses; 3) Conducting fieldwork to ground-truth conditions within mapped connectivity areas to identify conservation management needs and restoration opportunities; and 4) Producing a final, comprehensive report that identifies wildlife corridors/linkages on a scale useful to federal land managers and other key decision-makers.

We began Step 1 by selecting species from diverse taxonomic groups that would collectively represent a wide range of habitat requirements and movement needs. This process was started by cross-referencing several different leading sources on wildlife that are native to the Blue Mountains ecoregion, such as Oregon’s Natural Heritage Information Center, Oregon’s State Wildlife Action Plan (the “Oregon Conservation Strategy”), and federal agency lists of rare, threatened, and endangered species by region. We then collaborated with state and federal agency wildlife experts and other interested parties for review and feedback.

What species have we chosen and why?

Rocky Mountain Gray Wolf: Gray wolves are a highly mobile species that readily disperse or migrate hundreds of kilometers. Wolves are threatened by direct human-caused mortality and as an endangered, yet ecologically important keystone predator are considered a conservation priority.

American Marten: Marten are small forest carnivores that are closely associated with mature, mixed-conifer forest habitat. Marten provide important ecological services, including cycling nutrients and dispersing seeds and have low survival rates in fragmented forests.

Wolverine: Wolverine are wide-ranging, mid-sized forest carnivores that depend on large, remote areas for their core habitat. Due to their specific habitat and movement needs, wolverine are good indicators for the suitability of wilderness and remote roadless blocks of habitat.

Rocky Mountain Elk: Elk are also a high-mobility species, covering large areas during seasonal migrations between summer and winter ranges. Elk generally avoid areas with human activities.

Rocky Mountain Bighorn Sheep: Loss and degradation of habitat, especially key winter forage sites, is a key threat for Bighorn Sheep. This lack of adequate winter range seems to be limiting population growth of reintroduced Wallowa herds. Bighorns are also threatened by the spread of disease through interactions with domestic sheep.

Columbia spotted frog: This spotted frog serves as an indicator species for the health of wetland ecosystems and its inclusion on our focal species list helps address connectivity on a smaller-scale. The introduction of exotic trout and cattle grazing appear to be the major negative influences and the species is showing serious population declines throughout Oregon.

Rocky Mountain Tailed frog: This uniquely tailed frog is an indicator for healthy riparian areas and stream corridors, particularly headwater streams because of its vulnerability to management practices that alter streams (such as increases in stream temperature or sediment load, and reduction of woody debris or stream bank integrity).

Western Toad: Well-documented population trends continue to show steep reductions in Western Toad numbers throughout major portions of its range. This species may serve as a good indicator of climate change impacts, acidification, and ozone depletion/increased UV radiation.

Western Painted Turtle: This turtle is also considered indicative of good quality riparian habitats and is considered a “habitat specialist” because it requires marshy ponds, small lakes, slow moving streams and quiet off-channel portions of rivers, muddy bottoms with aquatic vegetation, open ground for nesting, and logs or vegetation for basking.

Greater Sage Grouse: Sage grouse are considered an indicator species for sagebrush habitat. Once widespread and abundant, sage grouse were historically found in 16 western states. Unfortunately, sagebrush conversion to agriculture, heavy livestock grazing, eradication of sagebrush with herbicides and burning, and continued development and fragmentation of sagebrush rangelands have dramatically reduced populations and eliminated the grouse from many parts of its former range.

Flammulated Owl: This neotropical migratory bird (typically arrives in NE Oregon in May and migrates south for winter) is considered a “habitat specialist” because of its close association with mature conifer forests, particularly large ponderosa pine trees and snag and its heavy reliance upon large primary cavity nesters (e.g. pileated woodpeckers) to excavate nest cavities. Loss of cavity nesters like the pileated woodpecker from a forest community would be disastrous for the owl.

Pileated Woodpecker: This woodpecker is an indicator species for mixed-conifer old-growth forests due to its dependence on large diameter trees and snags for nesting, roosting and foraging. Pileateds are threatened by habitat fragmentation; reductions in snag availability from past fire suppression and forest management. They are also considered a “keystone habitat modifier,” because only pileateds are creating large cavities in hard snags and decadent live trees that a wide array of other species (like Flammulated owls) use.

Photos from top to bottom:

Marten, Elk, Gray Wolf, Wolverine: Gerald and Buff Corsi © California Academy of Sciences

Bighorn Sheep: Lorraine Elrod © California Academy of Sciences

Western Toad: Gerald and Buff Corsi © California Academy of Sciences

Sage grouse: Dr. Lloyd Glenn Ingles © California Academy of Sciences

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