: Scientific [common] nebulosa (Great gray )

Forest: Salmon–Challis National Forest Forest Reviewer: Mary Friberg Date of Review: 02/28/2018 Forest concurrence (or recommendation No if new) for inclusion of species on list of potential SCC: (Enter Yes or No)

FOREST REVIEW RESULTS:

1. The Forest concurs or recommends the species for inclusion on the list of potential SCC: Yes___ No_X__

2. Rationale for not concurring is based on (check all that apply): Species is not native to the plan area ______Species is not known to occur in the plan area ______Species persistence in the plan area is not of substantial concern ____X___

FOREST REVIEW INFORMATION:

1. Is the Species Native to the Plan Area? Yes_X__ No___

If no, provide explanation and stop assessment.

2. Is the Species Known to Occur within the Planning Area? Yes_X__ No___

If no, stop assessment. Table 1. All Known Occurrences, Years, and Frequency within the Planning Area

Year Number Location of Observations (USFS Source of Information Observed of District, Town, River, Road Individual Intersection, HUC etc.) s 1989-2005 16 Leadore Ranger District USFS NRIS Wildlife (April 2017)

1982-2010 26 Middle Fork Ranger District Idaho Fish and Wildlife Information System (January 2017); USFS NRIS Wildlife (April 2017) 1976-2002 5 North Fork Ranger District Idaho Fish and Wildlife Information System (January 2017); USFS NRIS Wildlife (April 2017) 1975-2013 29 Salmon-Cobalt Ranger District Idaho Fish and Wildlife Information System (January 2017); USFS NRIS Wildlife (April 2017)

a. Are all Species Occurrences Only Accidental or Transient?

Yes___ No_X__

If yes, document source for determination and stop assessment.

b. For species with known occurrences on the Forest since 1990, based on the number of observations and/or year of last observation, can the species be presumed to be established or becoming established in the plan area?

Yes_X__ No___

If no, provide explanation and stop assessment

c. For species with known occurrences on the Forest predating 1990, does the weight of evidence suggest the species still occurs in the plan area?

Yes___ No___

Provide explanation for determination

N/A. Occurrences have been documented since 1990.

If determination is no, stop assessment d. Map 1, Great Gray Owl Range in Idaho (IDFG 2017a)

IDFG (Idaho Department of Fish and Game). 2017a. Great Gray Owl Strix nebulosa. Internet website https://idfg.idaho.gov/species/taxa/15848. Accessed on August 14, 2017.

e. Map 2, Great Gray Owl Range in Montana (MNHP and MFWP 2017).

Montana Natural Heritage Program and Montana Fish, Wildlife and Parks (MNHP and MFWP). 2017. Montana Field Guides. Great Gray Owl Strix nebulosa. Internet website: http://fieldguide.mt.gov/speciesDetail.aspx?elcode=ABNSB12040. Accessed on August 14, 2017.

f. Map 3, Great Gray Owl Observations on Salmon-Challis NF (Idaho Fish and Wildlife Information System [January 2017], USFS Natural Resources Information System Wildlife [April 2017]).

August 14, 2017 3. Is There Substantial Concern for the Species’ Capability to persist Over the Long-term in the Plan Area Based on Best Available Scientific Information?

Table 2. Status summary based on existing conservation assessments

Entity Status/Rank (include definition if Other)

NatureServe G5—Secure/Common (widespread and abundant) Global Rank Nature Serve S3— Vulnerable (At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), State Rank recent and widespread declines, or other factors)

Idaho State IDAPA – protected non-game List Status SGCN Tier 3 (species that do not meet the above tier criteria, yet still have conservation needs. In general, these species are relatively more common, but commonness is not the sole criterion and often these species have either declining trends rangewide or are lacking in information)

USDA Forest Region 4 sensitive Service

USDI FWS Not listed as endangered or threatened species Other IUCN Red List Category: LC - Least concern Not on PIF watchlist

Table 3. Status summary based on best available scientific information.

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations 1 B2 Based on general distribution maps (Map 1; IDFG 2017), great gray Idaho Department of Fish and Game Distribution on are year-round residents throughout SCNF. Occurrences have (IDFG). 2017a. Strix Nebulosa. Internet Salmon-Challis been documented on the Leadore, North Fork, Salmon-Cobalt, Challis- website: National Forest Yankee Fork, and Middle Fork Ranger Districts of the Forest, but the https://idfg.idaho.gov/species/taxa/15 majority are in the north–central region of the Forest (Map 3). Based 848. Accessed on August 14, 2017. on the above information and the distribution of habitat on the Forest (see Criterion 6), populations are likely broadly distributed with some gaps. Confidence is moderated by the fact that most sightings were documented prior to 1996, thus they may not indicate the distribution today. In addition, observations on the Lost River Ranger District (southwest portion of Forest) are lacking.

Confidence in Rank: High, Medium, or Low

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations 2 C Great gray owls are native to and distributed across North American NatureServe. 2017. NatureServe Distribution in and Eurasian boreal forests. Within North America, they are unevenly Explorer: An online encyclopedia of surrounding distributed and variable, and population statuses are unknown in many life [web application]. Version 7.1. geographic area areas. Known breeding areas range from boreal forests in Alaska, east NatureServe, Arlington, Virginia. to Ontario, and south to northern Minnesota, Wisconsin, Idaho Internet website: (outside the Snake River Plain), western Montana, northwestern http://explorer.natureserve.org. Wyoming, northeastern Utah, west-central Nevada, and the Sierra Accessed on August 14, 2017. Nevada (Ulev 2007; NatureServe 2017). Within the southern regions of Ulev, E. D. 2007. Strix nebulosa. In: the great gray owl’s range, they are typically found at elevations within Fire Effects Information System, mountains (Ulev 2007). Within the Columbia River Basin, the great gray [Online]. U.S. Department of owl is widely distributed across most forested areas, although Agriculture, Forest Service, Rocky population levels typically are low (Wisdom 2000). Mountain Research Station, Fire Sciences Laboratory (Producer). Because great gray owls are widely distributed outside the Forest, a Internet website: ranking of C was assigned for this criterion. http://www.fs.fed.us/database/feis/a nimals//stne/all.html. Accessed on Confidence in Rank: High, Medium, or Low August 14, 2017. Wisdom, M. J. et al. 2000. Source habitats for terrestrial vertebrates of focus in the Interior Columbia Basin: Broad-scale trends and management implications. FS General Technical Report.

3 B Great gray owls are generally resident , fairly sedentary, and have Duncan, J. R. 1997. Great gray owls Dispersal small home ranges for their size; averaging 4.5 km in one Oregon study (Strix nebulosa nebulosa) and forest Capability (Bull et al. 1988 in Ulev 2007). Johnsgard (1988) documented juveniles management in North America: a and adult movements from their nest site over a year and found review and recommendations. Journal juveniles moved 9-31 km and adults 3-34 km (Johnsgard 1988 in of Raptor Research. 31(2): 160-166. NatureServe 2017). Juvenile natal dispersal distances also appear Franklin, A.B. 1988. Breeding biology

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations moderate. For example, Bull et al. (1988 in Ulev 2007) found juveniles of the Great Gray Owl in southeastern dispersed a maximum distances of 7.5-32.0 km. Idaho and northwestern Wyoming. Condor 90:689-696. Although not migratory, great gray owls do make large elevational and NatureServe. 2017. NatureServe latitudinal movements in winter to escape deep snow condition and Explorer: An online encyclopedia of find easier access to prey. Winter movements of several 100 km may life [web application]. Version 7.1. occur (NatureServe 2017). In addition, extensive breeding home range NatureServe, Arlington, Virginia. dispersal, in terms of number of birds and distance covered (41-864 Internet website: km), has been documented in response to prey population crashes http://explorer.natureserve.org. (Duncan 1992 in Duncan 1997). Forest cover may be important for Accessed on August 14, 2017. minimizing predation of dispersing adults and juveniles (Duncan 1997). Ulev, E. D. 2007. Strix nebulosa. In: Thus, great gray owls, although fairly sedentary, display the capability Fire Effects Information System, to disperse long distances in response to stress and forested cover may [Online]. U.S. Department of be important in providing protection to dispersers (Rank B). Agriculture, Forest Service, Rocky Mountain Research Station, Fire Confidence in Rank: High, Medium, or Low Sciences Laboratory (Producer). Internet website: http://www.fs.fed.us/database/feis/a nimals/bird/stne/all.html. Accessed on August 14, 2017.

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations 4 B North American populations are estimated to range from 20,000– Duncan, J. R. 1997. Great gray owls Abundance on 70,000 breeding pairs. Population levels follow trends of microtine (Strix nebulosa nebulosa) and forest the Salmon- rodent abundance (of the subfamily Microtinae, family Muridae), management in North America: a Challis National which fluctuate every 3–5 years (Duncan 1997) and are usually low review and recommendations. Journal Forest (NatureServe 2017; IDFG 2017). of Raptor Research. 31(2): 160-166. Idaho Department of Fish and Game Abundance of great gray owls on the Forest is not known. Breeding (IDFG). 2017. Idaho State Wildlife Bird Survey routes are not located in the bird’s primary habitat and Action Plan, 2015. Boise ID. Christmas Bird Count surveys are generally not either. Documented occurrences across the Forest are thus incidental observations. Several NatureServe. 2017. NatureServe occurrences of the great gray owl have been documented on SCNF Explorer: An online encyclopedia of over the past two decades, but only 2 individuals have been sighted in life [web application]. Version 7.1. the past 10 years (see Table 1). Given this and that populations NatureServe, Arlington, Virginia. typically occur in low numbers it is suspected that great gray owls are Internet website: uncommon on the Forest. http://explorer.natureserve.org. Accessed on August 14, 2017. Confidence in Rank: High, Medium, or Low

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations 5 D Population trends for the great gray owl on the Forest are not known Idaho Department of Fish and Game Population Trend (Rank D). Trends are difficult to obtain for the great gray because of its (IDFG). 2017b. Idaho State Wildlife on the Salmon- variable distribution, low density, and low detectability. No North Action Plan, 2015. Boise ID. Challis National American Breeding Bird Survey data exist for this species (Sauer et al. IMBCR (Integrated Monitoring in Bird Forest 2017). Christmas Bird Count data suggest relatively stable populations Conservation Regions). Internet over the past 10 years in Idaho, but declines have been noted in some website: areas such as Long Valley, near McCall (IDFG 2017; NAS 2017). Long- http://rmbo.org/v3/avian/Explorethe term trends are unknown. No Integrated Monitoring in Bird Data.aspx. Accessed on November 14, Conservation Regions data exist for this species (IMBCR 2017). 2017.

Confidence in Rank: High, Medium, or Low National Audubon Society (NAS). 2017. The Christmas Bird Count Historical Results. Internet website: http://www.christmasbirdco unt.org. Accessed on November 14, 2017. NatureServe. 2017. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Internet website: http://explorer.natureserve.org. Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr, K. L. Pardieck, J. E. Fallon, and W. A. Link. 2017. The North American Breeding Bird Survey, Results and Analysis 1966 - 2015. Version 2.07.2017 USGS Patuxent Wildlife Research Center, Laurel, MD.

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations 6 A The great gray owl requires both open areas for foraging and mature Idaho Department of Fish and Game Habitat Trend on forests for nesting/roosting, and thus are usually associated with (IDFG). 2017. Idaho State Wildlife the Salmon- mountain meadows in multilayered pine or spruce forests. In Idaho, Action Plan, 2015. Boise ID. Challis National over 90 percent of sightings were made in the lodgepole pine/Douglas- Eidenshink, J. B. Schwind, K. Brewer, S. Forest fir/aspen zone (IDFG 2017). Lower subalpine Forest appears to be Shu, B. Quayle, and S. Howard. 2007. A preferred (Beth Waterbury pers. commun.). Special habitat features include snags, which they rely on for nests (Ulev 2007). Because the project for monitoring trends in burn owls mainly feed on rodents (voles in particular), they prefer areas severity. Fire Ecology Special Issue near bogs, forest edges, montane meadows, and other openings (IDFG 3(1):3-21. 2017). The average distance from nest to foraging habitat in Idaho was Ulev, E. D. 2007. Strix nebulosa. In: reported as 143 m (Franklin 1988), and suitable foraging land should Fire Effects Information System, be available 1–3 km from nests (Ulev 2007). [Online]. U.S. Department of

Agriculture, Forest Service, Rocky Lower subalpine forest covers roughly 15 percent of the SCNF (USFS Mountain Research Station, Fire 2017). Old-growth forest provides large snags for nesting. Recent Sciences Laboratory (Producer). estimates indicate there are roughly 170,000-240,000 acres of old- Internet website: growth forest on the SCNF, but confidence is low (67 percent; USFS http://www.fs.fed.us/database/feis/a 2017). This however is an underestimate of habitat because mature nimals/bird/stne/all.html. Accessed on forests are also used. In addition, large snags are abundant across the August 14, 2017. Forest, but the extent they occur in Forested habitat versus in large areas beetle-killed and stand replacing fires is not known. Based on GIS USFS (United States Department of maps of burn severity (Eidenshink et al. 2007), extensive areas of Agriculture Forest Service). 2017. mixed severity fire have burned across the Forest since 1984. Mixed Salmon Challis National Forest Data severity fire regimes create a forest mosaic of mixed ages and Assessment, Terrestrial Ecosystems openings that favors great gray owls. Still, the long history of fire Section (Draft). suppression on the Forest has degraded habitat in other areas. Fire suppression has caused the vegetation in 75 percent of lower subalpine forest to be 17-33 percent departed from historical conditions (USFS 2017). While the availability of snags and woody debris may benefit this species by providing more nesting sites, it has likely reduced forest opening used for hunting.

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations

Logging has also reduced old-growth forest on the SCNF (USFS 2017) with roughly 143,000 acres having been commercially harvested over the last 90 years. However, only a small percentage of this has occurred in the lower subalpine forest (Bill Baer pers commun.) and most logging has been through selective harvest. This would reduce larger trees within stands, but would create openings.

Thus, logging is thought to be play a lesser role in habitat decline compared to fire suppression on the SCNF. The long history of fire suppression on there has likely resulted in moderate degradation of habitat for the great gray owl by reducing forest openings (Rank A). However, extensive acres of mixed severity fires have likely improved habitat where they occur.

Confidence in Rank: High, Medium, or Low

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations 7 B The Idaho State Wildlife Action Plan reports a medium level of overall IAP (Intermountain Adaption Vulnerability of threat to the great gray owl in Idaho (IDFG 2017). The primary threats Partnership). 2016. Intermountain Habitats on the include logging (e.g., removal of large-diameter trees used for nesting) Adaption Partnership: Climate Salmon-Challis and alteration of fire regimes, which may change the availability of old- Vulnerability Assessment Summaries. National Forest growth forests nearby meadows for nesting. Idaho Department of Fish and Game (IDFG). 2017. Idaho State Wildlife Current projections indicate 6,000 or more acres of timber may be Action Plan, 2015. Boise ID. commercially harvested on the SCNF over the next 15 years (USFS 2017b); these levels would not cause a substantial reduction in habitat NatureServe. 2017. NatureServe Forest-wide for great gray owls, although easily accessible lodgepole is Explorer: An online encyclopedia of sought after for post and pole fences and fuelwood. Fire suppression, life [web application]. Version 7.1. however, will continue to reduce habitat in the long term by increasing NatureServe, Arlington, Virginia. fuel build up and subsequent large-scale and severe fires and by Internet website: causing alterations in vegetative communities and forest structure. http://explorer.natureserve.org. Accessed on August 14, 2017. Subalpine spruce-fir forests are moderately vulnerable to climate USFS (United States Department of warming (Behrens et al. 2018). To project the future climate and Agriculture Forest Service). 2017b. impacts to resources in the Intermountain Region including the Salmon Challis National Forest Data Salmon-Challis, the Intermountain Adaptation Partnership (IAP) used Assessment, Terrestrial Ecosystems Representative Concentration Pathway [RCP] 4.5 and 8.5, which Section (Draft). capture a moderate and high future warming, respectively (Halofsky et al. 2018). Although pathways predicting lower warming exist, the 4.5 and 8.5 pathways were chosen by the IAP because they are, in comparison, well studied providing a large set of projections that enhance our understanding of the possible range in future climate. Thus, this represents best available science for our Forest with regard to a warming climate.

Although uncertainty exists about the magnitude and rate of climate change (For a discussion of this see Behrens et al. 2018), warming temperatures are the most certain consequence of increased CO2 in

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations the atmosphere. By 2100, median minimum and maximum temperature in the Middle Rockies subregion, which includes the Salmon-Challis, is projected to rise about 5-6˚F under the moderate warming scenario and about 10˚F under the high warming scenario. Regardless of scenario, the greatest departure from historical seasonal minimum temperatures occurs in the summer. Annual precipitation projections are highly variable with no discernible trend under moderate warming and a slight increasing trend with high warming (Joyce and Talbert 2018).

Summer drought and higher temperatures may stress subalpine and montane conifer forests and promote insect infestations. However, lodgepole pine and aspen are expected to persist, although they may be stressed from insects and pathogens (IAP 2016). Increasing fire and drought may favor meadow vegetation and possibly provide more foraging areas, but this benefit may be outweighed by the decrease in nesting sites (IAP 2016).

The decline in suitable climate for subalpine conifer species is expected to occur slowly and allow for their upslope expansion (Behrens et al. 2018). The increased frequency, intensity, and size of forest fires on the SCNF due to climate warming could quickly reduce the occurrence of mature trees across the landscape (Behrens et al. 2018) and therefore reduce nesting habitat for the great gray owl. However, because lodgepole pine and Douglas-fir are more fire tolerant they are projected to persist and may become more prevalent in the subalpine (Behrens et al. 2018).In addition, growth rates of subalpine fir and Engelmann spruce may increase, but bark beetle infestations may be a stressor particularly on Engelmann spruce.

Based on the vulnerability of habitat to beetle infestations, increased

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations temperature, and increased fire caused by changes in climate, habitat on the Forest for the great gray owl will likely remain, but structure and distribution may depart from the natural range of variability (Rank A). Confidence is moderated by uncertainties in climate projections and responses of habitats important to the great gray owl.

Confidence in Rank: High, Medium, or Low

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations 8 B Great gray owls are large (average of length of 69 cm and weight of Franklin, A.B. 1988. Breeding biology Life History and 1298 g), non-migratory, and carnivorous (NatureServe 2017). Thus, of the great gray owl in southeastern Demographics they depend on the availability of nearby prey and suitable Idaho and northwestern montana. The foraging/nesting habitat, which directly impact reproductive rates and Condor 90(3):689-696. survival (Hayward et al. 1994; IDFG 2017). Hayward, G. D. 1994. Conservation status of great gray owls in the United In an Idaho and Montana study, the chance of survival from the egg to States. In: Hayward, G. D. and J. two years old was 31 percent (Franklin 1988). The main causes of Verner, tech. eds. Flammulated, owlet mortality are starvation, falling from nest, and predation. boreal, and great gray owls in the Predators include ravens, great horned owls, northern goshawks, United States: a technical conservation broad-winged hawks, and American martens (Ulev 2007). assessment. Gen. Tech. Rep. RM-253. USDA Forest Service, Rocky Mountain Once owls reach breeding age, survival rates are high (Ulev 2007). Age Forest and Range Experiment Station, at first breeding is probably at three years (Ulev 2007). Individuals can Fort Collins, CO: 202-206. be long lived. Birds older than 13 years have been reported (R.W. Nero, pers. comm. In Ulev 2007). Idaho Department of Fish and Game (IDFG). 2017. Idaho State Wildlife Food availability is the main factor influencing survival and breeding Action Plan, 2015. Boise ID. rates of adult owls, and starvation is responsible for at least 20% of NatureServe. 2017. NatureServe adult mortality (Ulev 2007). Owls typically will not breed if prey, Explorer: An online encyclopedia of particularly microtine rodents, are scarce. Main prey includes small life [web application]. Version 7.1. rodents such as pocket gophers and voles, as well as shrews, moles, NatureServe, Arlington, Virginia. mice, squirrels, and birds. Internet website: http://explorer.natureserve.org. Thus, the great gray owl is long lived species with low reproduction Accessed on August 14, 2017. (Rank B) suggesting an intermediate ability to recover from disturbances. Ulev, E. D. 2007. Strix nebulosa. In: Fire Effects Information System, Confidence in Rank: High, Medium, or Low [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer).

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations Available: http://www.fs.fed.us/database/feis/a nimals/bird/stne/all.html. Accessed on August 14, 2017.

Species (Scientific and Common Name): Strix nebulosa (Great gray owl)

Criteria Rank Rationale Literature Citations Summary and recommendations: The great gray owl is considered moderately vulnerable in Idaho based Date: 2/28/18 on statewide rankings (Table 1). This species is notoriously difficult to survey for and population trends for the Forest are not known and abundance is assumed to be uncommon. This species has strong dispersal capabilities and behaviors that allow it to move long distances in search of quality habitat, although forest cover may be important to protect dispersers from predation. In addition, the species’ life history strategy of longevity and forgoing reproduction in poor prey years is adapted to a variable environment, although uncommon abundance is a risk factor. Abundance and quality of habitat for nesting and foraging greatly influence reproduction and survival in this species. Fire suppression has likely moderately impacted the quality of habitat on the Forest by reducing forest openings for foraging, although wildland fires still occur and extensive areas have burned with mixed severity and thus have likely improved habitat in those areas. Changes in climate may impact great gray owl habitat through changes in subalpine forest distribution and structure, but habitat will likely remain as subalpine forest advance into the alpine. Thus, there is not adequate evidence at this time to indicate a substantial concern for the capability of the great gray owl to persist over the long-term on the SCNF, and it is not recommended as a potential species of conservation concern.

Evaluator(s): M. Friberg and L. Chipman