Daily Rules, Proposed Rules, and Notices of the Federal Government
Section 4(b)(3)(A) of the Act (16 U.S.C. 1531
Our standard for substantial scientific or commercial information within the Code of Federal Regulations (CFR) with regard to a 90-day petition finding is “that amount of information that would lead a reasonable person to believe that the measure proposed in the petition may be warranted” (50 CFR 424.14(b)). If we find that substantial scientific or commercial information was presented or is available in our files, we are required to promptly conduct a species status review, which we subsequently summarize in our 12-month finding.
On October 6, 2011, we received a petition, dated September 30, 2011, from Mark N. Salvo, WildEarth Guardians, requesting that the Prince of Wales flying squirrel be listed as an endangered or threatened species and that critical habitat be designated under the Act. The petition clearly identified itself as such and included the requisite identification information for the petitioner(s), as required by 50 CFR 424.14(a). In a December 20, 2011, letter to petitioner(s), we responded that we reviewed the information presented in the petition and determined that issuing an emergency regulation temporarily listing the species under section 4(b)(7) of the Act was not warranted. We also stated that when budget and workload enabled us to direct resources to the petition, we would make an initial finding on whether the petition presented substantial information indicating that the petitioned action may be warranted. We received funding in January 2012. This finding addresses the petition.
There are no previous Federal actions concerning the status of the Prince of Wales Flying squirrel under the Act.
The Prince of Wales (POW) flying squirrel (
The distinctness of the POW flying squirrel as a subspecies is well documented. Howell (1934, p. 64) proposed the original subspecific designation based on the darker pelage coloration and whiter underparts of only two specimens from POW Island compared to those of the mainland subspecies (
There is little information about the historical range of the POW flying squirrel, but genetic studies indicate that flying squirrels probably colonized the archipelago after the last glacial maximum during the Holocene (Bidlack
There is no information regarding population size or trend of the POW flying squirrel within any parts of its range. During the most recent status review of this insular subspecies, the International Union for the Conservation of Nature (Hafner
Densities of the POW flying squirrel are among the highest flying squirrel densities recorded in North America (Smith 2007, p. 863). This subspecies occupies a variety of forested habitats with densities often increasing with forest complexity. Spring densities (number/ac) average 0.7 squirrels/ac (1.8 squirrels/ha) in upland old-growth forests of Sitka spruce (
Specific habitat correlates of density and use of the POW flying squirrel vary by season, forest type, and scale (Smith
To sum, densities of large trees (greater than 29 inches [in] (74 centimeters [cm]) diameter at breast height [dbh]) and understory cover of blueberry and huckleberry shrubs (
Despite the high number of endemic species in Southeast Alaska, the small mammal community is relatively low in numbers or variety of species compared to the coniferous forests of Washington and Oregon where at least 57 native terrestrial mammal species have been observed (Carey 1995, p. 653; Smith and Nichols 2003, p. 1054; MacDonald and Cook 2007, pp. 15-17). Only 15 native mammal species have been documented on POW Island (MacDonald and Cook 2007, p. 142), and the POW flying squirrel is the only arboreal or forest-floor squirrel (MacDonald and Cook 2007 p. 177). Across most of the range of the northern flying squirrel, the American red squirrel (
In most parts of its range, the northern flying squirrel feeds on truffles and plays an important role in dispersing their spores in coniferous forest ecosystems (Weigl 2007, p. 900). In contrast, the POW flying squirrel relies less on truffles and feeds on a greater diversity of food items than other subspecies of northern flying squirrel (Maser
The northern flying squirrel uses dens for shelter and to carry out important ecological and life history functions such as avoiding predators, caching food, thermoregulating, and reproducing. Flying squirrels use multiple dens within their home range, or core den area, and, therefore, the availability of suitable den sites on the landscape is strongly linked to the persistence of local squirrel populations. Pyare
In their study, the authors found that squirrels used 3.5-7.1 dens/month and moved 195-711 yards (yd [178-650 meters (m)]) between dens (Pyare
Although the POW flying squirrel occupies a variety of forested habitats to meet its life-history needs, the persistence of squirrels, especially in a managed landscape, relies heavily on their ability to disperse to suitable habitats. Flying squirrels can glide from one tree to another or can walk or run on the ground, but Flaherty
While there is presumably a fragmentation threshold in which flying squirrel dispersal would cease (or be drastically reduced), there is no information available that quantifies this threshold, and there is no evidence that this threshold has been reached on the highly managed forested landscapes within the POW Complex. Bidlack and Cook (2002, p. 256) found that there is contemporary gene flow among squirrel populations in the POW Complex, although that flow is primarily affected by distance between populations, and Pyare
The northern flying squirrel has several life-history traits characteristic of a K-selected species (Smith 2007, p. 862), which produce few offspring and live in stable environments. It is relatively long-lived (greater than 7 years), produces small litters (usually 2-3 young) after a long gestation period (37-42 days), and exhibits density-dependent population growth (Fryxell
Section 4 of the Act (16 U.S.C. 1533) and its implementing regulations at 50 CFR 424 set forth the procedures for adding a species to, or removing a species from, the Federal Lists of Endangered and Threatened Wildlife and Plants. A species may be determined to be an endangered or threatened species due to one or more of the five factors described in section 4(a)(1) of the Act:
(A) The present or threatened destruction, modification, or curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued existence.
In considering what factors might constitute threats, we must look beyond the mere exposure of the species to the factor to determine whether the species responds to the factor in a way that causes actual impacts to the species. If there is exposure to a factor, but no response, or only a positive response, that factor is not a threat. If there is exposure and the species responds negatively, the factor may be a threat and we then attempt to determine how significant a threat it is. If the threat is significant enough that it may drive or contribute to the risk of extinction of the species such that the species may warrant listing as a threatened or endangered species as those terms are defined by the Act, this does not necessarily require empirical proof of a threat. The combination of exposure and some corroborating evidence of how the species is likely impacted could suffice. The mere identification of factors that could impact a species negatively may not be sufficient to compel a finding that listing may be warranted. The information must include evidence sufficient to suggest that these factors may be operative threats that act on the species to the point that the species may meet the definition of a threatened or endangered species under the Act.
In making this 90-day finding, we evaluated whether or not information regarding the threats to the POW flying squirrel, as presented in the petition and other information available in our files, is substantial, thereby indicating that the petitioned action may be warranted. Our evaluation of this information is presented below.
According to the petitioner, the POW flying squirrel is an island endemic species that occupies forest habitats and, therefore, is vulnerable to negative impacts of logging and associated habitat fragmentation. There is a long history of logging in Southeast Alaska, especially on POW Island where roughly 39 percent of the old-growth forest has been harvested. This has resulted in a complex matrix of forest stands of varying age, muskeg (bog, marsh, or peatland; an area of mosses, sedges, and open growth of scrubby trees), less productive forests, and the presence of roads (WildEarth Guardians 2011, p. 2). The petitioner raises concern that the composition and spatial configuration of remaining forests within the range of the POW flying squirrel is not sufficient for the squirrel to meet its life-history needs and, therefore, to persist into the future.
There are two pinchpoints, or narrow land corridors connecting larger areas of old-growth forest, on POW Island that are currently not protected and, therefore, are susceptible to future development. The Neck Lake and Sulzer Portage areas are nearly surrounded by private lands that have previously been subject to intense logging. These areas are connected to fragments of old-growth habitat intermixed with water, rugged terrain, and logged stands. All of these features are implicated by the petitioner in preventing movement of squirrels across the pinchpoints. The petitioner suggests that if these two pinchpoints are developed and the forest is removed, flying squirrel populations on either side of the pinchpoints may become isolated from one another. Although there is an existing series of old-growth reserves in Tongass National Forest lands on POW Island, flying squirrels may have a difficult time moving among these reserves especially if additional logging occurs as is planned within the next 100 years.
The petitioner raises three primary concerns related to the destruction, modification, or curtailment of habitat or range of the POW flying squirrel, none of which were supported by the information in our files or the petition itself. First, the petitioner suggests that current and future forest composition within the POW Complex is not adequate for the persistence of the POW flying squirrel, assuming that this subspecies is an old-growth obligate. Second, the petitioner identified lack of connectivity among forest habitat patches and habitat fragmentation as factors reducing the population viability and long-term persistence of POW flying squirrels. Third, the petitioner raises concern about possible future development and additional logging within the range of the POW flying squirrel. We do not find substantial information supporting any of these assertions related to this threat.
There are many definitions for old-growth forest. Generally, we consider old-growth forests to be in a late successional stage of forest development with both vertical and horizontal structural diversity including live trees and snags of a minimum number and size, canopy conditions with multiple layers, and logs and large woody debris (often on the forest floor). These forests are complex and involve several habitat variables. Species that rely on old-growth forests typically require habitat features of similar complexity.
The POW flying squirrel occupies a diversity of forested habitats within its range. Although squirrel densities are slightly higher in productive, upland old-growth forests than in lower productive, peatland-mixed-conifer forests in Southeast Alaska (Smith and Nichols 2003, p. 1049), two habitat features alone—density of large trees and understory cover of
We acknowledge that population density is not necessarily a reliable indicator of habitat quality. Smith and Nichols (2003, p. 1052) captured more reproductive females in upland-old-growth forest (3.9/trapping grid) compared to peatland-mixed-conifer forest (2.1/trapping grid in peatland-mixed-conifer). Based on this finding, Smith and Person (2007, p. 632) speculated that flying squirrels occupying peatland-mixed-conifer forests in some years represent population sinks that are sustained by immigration. However, Smith and Nichols (2003, p. 1052) reported no difference between the percentage of reproductive females captured in either habitat (75.5 percent in upland-old-growth, 75.9 percent in peatland-mixed-conifer), and, therefore, it is difficult to interpret the results of the study as they relate to identifying population sources, sinks, and habitat selection of the POW flying squirrel.
There is insufficient and mixed evidence that fragmentation and lack of connectivity influences habitat use of POW flying squirrels. In a heavily managed landscape, POW flying squirrels chose to den in areas with larger habitat patches, but also greater absolute amounts of edge than what was available across the landscape (Pyare
The Tongass Land and Resource Management Plan (2008, p. 2-4; hereafter, Tongass Land Management Plan; TLMP), which outlines management of 80 percent of the lands in Southeast Alaska, includes a conservation strategy aimed to maintain
Although the efficacy of many aspects of the conservation strategy remains untested, the POW flying squirrel was a design species in developing the criteria for habitat conservation areas, specifically the small reserves (Julin 1997, p. 19). Smith and Person (2007, p. 627) assessed the size and composition of these small reserves by modeling population viability of the POW flying squirrel in two habitat types (upland-old-growth, peatland-mixed-conifer). The primary purpose of this modeling exercise was to evaluate the potential of only individual small habitat reserves for flying squirrel population viability. The authors did not include medium and large reserves or corridors in their analysis. Furthermore, they assumed no immigration or emigration among small reserves. However, based on POW flying squirrel movements (Pyare
Although the conservation strategy does not extend to non-Tongass lands, the majority of land in the POW Complex (∼97 percent) is part of the Tongass National Forest and, therefore, is subject to the standards and guidelines described in the plan. The petition raises concern that the non-Federal lands on POW Island are not protected currently and, therefore, are available for development; other than the assertion by the petitioners, there is no information that suggests that this lack of protection or the non-Federal land ownership suffice as substantial information suggesting a threat to the POW flying squirrel, especially given the other land protections and management prescriptions on Federal lands within the range of this subspecies and the overall amount of existing forested land within the range of this subspecies (722,010 ha; Table 2 in petition, p. 20).
The petitioner states that a flawed assumption of the Tongass Land Management Plan is that second-growth forests will provide lesser but sufficient quality habitat for the POW flying squirrel (petition, p. 19). This statement was uncited, and we were unable to find reference to it within the management plan itself. Regardless, we did not find any information evaluating the use of second-growth forested stands specifically by POW flying squirrels, but Flaherty
In summary, we found that the information provided in the petition, as well as other information in our files, does not suggest that the destruction, modification, or curtailment of habitat or range of the POW flying squirrel may be a threat to the subspecies because it is a habitat opportunist, using a variety of forested habitats, does not avoid forest edges, is apparently dispersing successfully across the current landscape, and is presumably benefiting from the forest reserve system, which provides considerable amounts of forested habitat throughout its range. We conclude that the information provided in the petition describing this potential threat was inconsistent with the published literature and available reports in our files.
The petitioner raises concern about impacts of hunting on POW flying squirrel populations, especially given some of the K-selected life-history traits of this subspecies and the presumed small population size.
The State of Alaska does not regulate or require reporting of take of POW flying squirrels. Additionally, we are not aware of targeted hunting effort of squirrels within the POW Complex, as suggested in the petition. Although POW flying squirrels may be taken occasionally by recreational or subsistence hunters, we do not have any information to suggest that hunting pressure on squirrels could be having a population-level impact within the POW Complex. Given their small size and nocturnal habits, it is unlikely that flying squirrels are sought by hunters for meat or fur, and we are not aware of any cultural significance of the flying squirrel to First Nations in Southeast Alaska.
In summary, we found that the information provided in the petition, as well as other information in our files, does not present substantial scientific or commercial information indicating that overutilization for commercial, recreational, scientific, or educational purposes is a threat to the POW flying squirrel. Further, we are not aware of any other potential threats to the POW flying squirrel as a result of recreational or subsistence hunters within the POW Complex.
The petitioner presents information to suggest that habitat destruction and fragmentation may result in increased predation on the POW flying squirrel. Reduction of canopy cover reduces protection of the POW flying squirrel when gliding for movement and may force individuals to resort to travel on the ground, increasing their exposure to predators. The petitioner identifies several potential nonnative predators including the raccoon (
POW flying squirrels do not avoid natural or anthropogenic forest edges; in fact, Pyare
Raccoons and marten have been introduced to some islands within the POW Complex, but neither appears to be having population-level impacts on the POW flying squirrel. In 1941, eight raccoons were introduced to a small island in El Capitan Passage on the west coast of POW Island. The transplant was apparently successful with occasional sightings of raccoons on POW Island as recently as 2001 (Paul 2009, p. 110). However, this population of raccoons is small and localized, and it is unlikely to be having a population-level impact on POW flying squirrels on the POW Complex. In 1934, ten marten were introduced to POW Island for fur trapping opportunities. This species is now well-established in the area; from 2001 to 2006, trappers reported 323-1,026 marten taken annually on POW Island (Paul 2009, pp. 104-105). However, Flynn
We did not find any information describing existing or potential disease impacts to POW flying squirrels. In areas where the southern flying squirrel (
In summary, we find that the information provided in the petition, as well as other information in our files, does not present substantial scientific or commercial information indicating that disease or predation may be a threat to the POW flying squirrel. The POW flying squirrel does not avoid forest edges where predation risk is assumed to be greatest and is not impacted at the population level by introduced predators within the POW Complex. We conclude that the information presented in the petition does not establish a connection between habitat fragmentation and predation risk to the POW flying squirrel. The potential predators identified in the petition are not widespread or established and do not feed on squirrels regularly. Furthermore, POW flying squirrels do not avoid edges and may in fact select for them, suggesting that individual squirrels do not perceive increased predation risk at or near forest edges, as stated in the petition. We did not find any information describing existing or potential disease impacts to POW flying squirrels.
The petitioner identifies perceived inadequacies of the most recent Tongass Land Management Plan (2008) to protect old-growth forest habitats and reserve connectivity required to support metapopulations of POW flying squirrels across their range. The primary concern described in the petition relates to the efficacy of small old-growth reserves and the ability of POW flying squirrels to glide across large clearcuts. Flaherty
In addition to POW flying squirrel movement and habitat connectivity, the petitioner raises concern about forest composition, patch size, and land ownership and population viability of squirrels. Old-growth forests are not equal in ecological value; there are structural differences between old-growth forests of mixed conifer, peatland, and Sitka spruce and western hemlock. The petitioner claims that the POW flying squirrel may utilize second-growth forests, but they depend on old-growth forests for their survival. Private lands are not subject to the same forest management practices as those outlined in the Tongass Land Management Plan, and, therefore, these private lands are not protected and are subject to development.
Similar to Factor A, the petitioner assumes that the POW flying squirrel requires productive, old-growth forest to meet their life-history needs, including survival, reproduction, and movement, and we did not find substantial information in the petition or our files to support this assumption. The Tongass Land Management Plan is designed to provide adequate amounts of forest habitat and connectivity of suitable structure and composition to maintain viable populations of the POW flying squirrel. Smith and Person (2007, pp. 631-633) concluded that small old-growth reserves are too small to assure a high probability (greater than 90 percent) of sustaining flying squirrel populations, but their simulations relied on the unrealistic assumption of no immigration and do not consider the other matrix components, such as medium and large reserves and stream and beach corridors (see Factor A for details on the composition of reserves and land status). As noted above in
We lack population trend estimates of the POW flying squirrel and, therefore, are unable to evaluate reliably the efficacy of forest management practices or critical components of the conservation strategy for squirrel populations in the POW Complex. However, over the last 50-60 years, extensive timber harvesting has occurred within the POW Complex, reducing the total amount of old-growth forest from 989,778 ac (400,549 ha) to 722,010 ac (292,187 ha; 27 percent, as of 2006; in petition, p. 20) with most of the logging occurring prior to the implementation of the conservation strategy in 1997. The POW flying squirrel not only persisted during this period of heavy timber removal and no conservation strategy, but also appears to be utilizing and dispersing successfully across the managed landscape (Bidlack and Cook 2002, pp. 250-252; Smith
In light of this information, we find that the information provided in the petition, as well as other information in our files, does not suggest that the inadequacy of existing regulatory mechanisms may be a threat to the POW flying squirrel. The POW flying squirrel is not an old-growth obligate species, is moving and dispersing successfully across the managed landscape, and is persisting in apparently viable populations under the existing conservation strategy and management guidelines in the Tongass Land Management Plan. As in the analysis for Factor A, we conclude that the information provided in the petition describing this threat relies on unsupported assumptions and does not fully recognize all components of the conservation strategy under the Tongass Land Management Plan.
The petitioner identified climate change and the introduction of the American red squirrel (
Most climate models for Southeast Alaska predict warmer and wetter weather with increases in rainfall and decreases in snowfall, especially at lower elevations, over the next 50-100 years (Bonsal and Prowse 2006, pp. 33-40). Despite higher projected precipitation, forests may be drier during summer months, and, therefore, fire, which currently is very uncommon in Southeast Alaska, may occur more often (Haufler
In Southeast Alaska, loss of snow cover at low elevations is causing changes in the distribution and decreasing the survival of yellow cedar (
The petitioner stated that the American red squirrel, a potential competitor to the POW flying squirrel, was introduced to POW Island, but no citation was provided in support of this claim (petition, p. 21), nor have we found any information supporting this statement in the literature or our files (e.g., Paul 2009, p. 111). Furthermore, MacDonald and Cook (2007, p. 26) do not include POW Island or Complex in the current range of the red squirrel. The red squirrel was introduced to other large islands in Southeast Alaska, such as, Admiralty, Baranof, and Chichagof islands, but there is no mention of any islands within the range of the POW flying squirrel (Paul 2009, p. 111).
In summary, we find that neither the information provided in the petition nor any other information in our files presents substantial scientific or commercial information indicates that other natural or manmade factors may be a threat to the POW flying squirrel. Potential impacts from changes in climate are contradictory and difficult to evaluate reliably, and the information presented in the petition regarding changes in climate is speculative and unsubstantiated. We found no reliable information indicating that red squirrels have been introduced within the range of the POW flying squirrel, contrary to what is stated in the petition.
In summary, the petition does not present substantial information that listing may be warranted. The POW flying squirrel is a habitat opportunist that occupies a diversity of forested habitats (Smith
Under section 4(b)(3)(A) of the Act, we conclude that the petition does not present substantial scientific or commercial information to indicate that listing the Prince of Wales flying squirrel under the Act as a threatened or endangered species may be warranted at this time. Although we will not review
A complete list of references cited is available on the Internet at
The primary authors of this notice are the staff members of the Juneau Fish and Wildlife Field Office (see
The authority for this action is the Endangered Species Act of 1973, as amended (16 U.S.C. 1531