Abstract:

Examines conservation status of northern goshawks in southeast Alaska by developing an "understanding of goshawk ecology in relation to past, present, and potential future habitat conditions in the region under the current Tongass Land Management Plan (TLMP)."

"Nearly 900,000 acres of the most productive old-growth temperate rain forest in southeast Alaska have been harvested during the past 90 years"

"Goshawks select productive old-growth forest with >60% of all adult goshawks telemetry relocations occurring in this cover type; nonforest, clearcut, and alpine cover types were least used and were avoided relative to their availability; the median breeding season minimum convex polygon use areas [home ranges] was about 10,000 acres."

"Goshawk nesting habitat is a nonrandom subset of the landscape with a significantly higher proportion of productive old-growth forest within a 60-acre analysis area surrounding known nests. The probability of persistence of goshawks has declined over the past 50 years owing to habitat loss and likely will continue to decline under current management plan regimes; however, the goshawk population is likely not in immediate peril."

"This analysis suggests that long rotation forestry (e.g., 300 years) and uneven-aged silvicultural management may maintain habitat characteristics important to sustaining goshawk populations well distributed across the region. Although habitat reserves are not considered an essential component of a forest-wide goshawk conservation strategy, reserves, in combination with extended rotations, may be important where the intensity of past management actions has precluded the opportunity to attain a desired combination of forest age classes achievable under long rotations. Reserves are most likely critical if extensive clearcut logging continues."

Preface
"Concern for the goshawk population viability on southeast Alaska evolved during the past decade and culminated with the petition to list the Queen Charlotte goshawk (A.G. laingi) as an endangered species under the Endangered Species Act. The FWS concluded in 1995 that listing the goshawk was not warranted at the time owing to insufficient information, but stated that "without significant changes in the existing Tongass National Forest Land and Resource Management plan, the long-term viability of the Queen Charlotte goshawk may be seriously imperiled."

This paper is a synthesis of available information to provide planners and the public with a scientific basis for evaluating the consequences of habitat management choices.

The Forest Ecosystem and its Management
"wind is the primary disturbance agent" (p. 1)
"The forest environment is dynamic and characterized by frequent small scale disturbances (p. 1)
"The minimum stand age necessary to attain the large tree component of the old-growth stand ranges from 150 to 260 years for the major forest types in southeast Alaska." (p. 6)
"Since industrial timber harvest bean in 1955, the total annual harvest have beenaveraging 394 MMbf/year in southeast Alaska." (p. 7)
"About 5.6 million acres of productive forest occur within the current boundaries of the Tongass NF. About 405,000 acres of productive old-growth forest were harvested between 1954 and 1995 An estimated total of 450,000 acres of productive old-growth forest has been harvested in the Tongass NF since 1909, generally on sites with the highest timber production capability and largest trees." (p. 7)

"Nearly 750,000 acres of lands previously contained within the Tongass NF have been conveyed to the State of Alaska or to Native Corporations; about 60 % of these lands were harvested by 1995." (p. 8)

"Clear-cut, even-aged management with opening sizes from 20 to 60 acres or more has been the predominant silvicultural technique used to harvest timber in southeast Alaska.Forest where tree harvesting has occurred are being managed with a rotation age of generally 100 years or less." (p. 8)
" The intensity of forest management for timber production emphasis differs significantly from the natural disturbance regimes" (est. 5 to 10 times the natural rate). (p. 8)

History of Northern Goshawk Management in the Tongass NF
Interest began in 1986 when it was recommended as a management indicator species for the TLMP. "old-growth forest were rated as the most important forest successional stage for both nesting and foraging. The goshawk was not selected owing to a lack of specific information and great monitoring difficulty. The reviews also suggested that the goshawk be considered a FS "sensitive species" in the Alaska Region.

"In 1990, the ADFG recommended that at least one old-growth dependent forest raptor with a large home range be added to the Alaska Region sensitive species list and be considered in the TLMP revision process." (p. 8)

"In 1991, the goshawk was design agenda category 2 candidate species to be reviewed for possible addition to the Federal list of endanger and threatened species throughout its range." The subspecies, Queen Charlotte goshawk was also designated a category 2 candidate species. There were "spp. And subspecies for which the USFWS had information indicating that listing may be appropriate, but conclusive data on biological vulnerability and threat were not then available to support such actions. The FWS no longer maintains a list of these species." (p. 9)

Interim goshawk habitat management guidelines issued in 1992 for the Tongassrelied on concepts developed for goshawk habitat in the southeastern US. These established a 600-acre potential post-fledgling area (PFA) around nests, and a 6,000 acre foraging area surrounding the nest; however, 5 % of the PFA was allowed to be harvested. (p. 9)

"FS interim management guidelines were repeatedly identified as inadequate to sustain goshawk habitat by the FWS in project-specific environmental reviews such as those for timber sales. The FWS suggested that the landscape management approach should be adopted instead of nest by nest management. (p. 9)

"The AK region of the FS formally designated the Queen Charlotte goshawk a sensitive species in Jan 1994which triggered the requirement that all projects conduct biological evaluations to assess potential impacts of proposed management activities; it was also designated a spp. of special concern the by the ADFG in 1994." (p. 9)

"On May 9, 1994, the FWS received a petition from the Southwest Center for Biodiversity and nine additional organizations and individuals to list the Queen Charlotte goshawk as endangeredThe primary reason was concern over the loss of habitat owing to timber harvest in southeast Alaska. The FWS concludedthat the petitioners had presented substantial information indicating that listing may be warranted. On May 29, 1995, the FWS concluded that listing was not warranted at that time because of insufficient information. However, the FWS also stated that 'without significant changes in the existing Tongass National Forest Land and Resource Management Plan, the long-term viability of the Queen Charlotte goshawk may be seriously imperiled.'" (p. 11)

Later in 1995, "Congress passed legislation in the Fiscal Year 1995 Rescissions Bill (Section 502, Public Law 104-19) that prevented the FS from implementing habitat conservation areas on the Tongass NF and limited goshawk nest protection to 300 acres in fiscal year 1995.By mid-1995, progress on the TLMP revision and this assessment indicated that an interim amendment was unnecessary and that goshawk conservation could be fully addressed in the TLMP revision. (p. 11)

Species Response to Timber Harvest

"Several factors may contribute to decreased productivity and density in goshawk populations following particular changes in forest structure and composition; 1) increased predation on adults and young goshawks as hiding cover is reduced and potential predator populations increase (e.g., great horned owls); 2) loss of cool thermal conditions at nest sites; 3) reduced prey abundance or availability, or both; 4) increased competition as predators that adapt to more open forest become abundant; and 5) increased disturbance and human-caused mortality due to increased access from the timber harvest road network." (p. 21)

Conservation Status of Northern Goshawks in southeast Alaska:
Major Questions

1. Do habitats differ in their capacity to support the principal prey species used by goshawks?
"Our review of the limited literature available does indicate that habitats in southeast Alaska differ in their capacity to support prey populations. Productive old-growth forest support a wider range of important prey than do other habitat cover types." (p. 61)

"Timber harvest may reduce populations of primary goshawk prey species owing to the association of these prey species with productive old-growth forest where timber management occurs." (p. 61)

"Landscapes with partial cuts that retain patches of old trees will provide a greater diversity of forest structure that likely will support larger prey populations than will landscapes with uniform even-aged forest structure." (p. 61)

 

2. Do habitats differ in their capacity to support goshawk populations or to support particular functional activities? What are the characteristics of those habitats? Are these habitats limiting goshawk populations? How does forest management influence habitat quality for goshawks?

"Studies in southeast Alaska show that goshawks chose nest sites with an average of 9 to 11 percent more productive old-growth forest around the nest than in the surrounding 10,000 acre plot, respectively;" although nest areas did show broad variation. (p. 62)

" Given the strong association of nest sites with productive old-growth forest in southeast Alaska and the lower probability of reoccupancy of small nest stands observed elsewhere, nesting by goshawks is likely to be lower in area with fewer acres of productive old-growth forest" (p. 62)

"Goshawks were relocated in productive old-growth forest 67% of the time and half of that occurred in the very high or high volume class strataThese observations indicate that goshawks are using a nonrandom subset of the environment." (p. 63)

"Clearcuts reduce the amount of productive old-growth forest and thus the area frequently used by goshawks." (p. 63)

"Past timber harvest in southeast Alaska has emphasized even-aged clearcut silviculture that differs from natural disturbance processes and has long-term consequences on forest structure and goshawk habitat. Clearcutting removes high quality goshawk habitat and creates low-quality habitat. Clearcut stands likely remain poor quality goshawk habitat for over 100 years." (p. 64)

"Twenty-three and 28 percent was the minimum proportion of productive old-growth present in any breeding season use area for adult males and females, respectively. We do not know the relationship between the amount of productive old-growth forest and either goshawk fitness or relative abundance." (p. 64)

3. Do the life history and ecology of the goshawk suggest that populations are vulnerable to habitat change?

"Several aspects of goshawk life history suggest that the species may be vulnerable to habitat changes: goshawks are long-lived birds, have a low reproductive rate, occur in low densities, and at least in southeast Alaska, do not migrate. This parallels that of other large avian predators, such as the bald eagle and spotted owl Population growth rates for these species are most sensitive to changes in adult survival rates." (p. 65)

"The very large areas used by goshawks are a conservation issue for two reasons: 1) populations of individuals requiring large ranges may be energetically stressed, have lower reproductive success, and are less resilient to further stress; and 2) land management must provide habitat within large areas to meet individual as well as populations needs. Reductions in productive old-growth forest that reduce prey populations likely would further stress individual goshawks" (p. 65)

4. Given that goshawks select particular habitats, are these habitats declining or at risk under current management?

"Nearly 900,000 acres of productive old-growth forests have been converted to early seral forests within the temperate rain forest ecosystem in southeast Alaska. The amount of habitats used and selected by goshawks.have declined in the past and continue to decline under current management." (p. 66)

"We can concludethat the projected harvest of an additional estimated 1.5 million acres of productive old-growth forest planned under the current TLMP (USDA 1979) can only further adversely affect the conservation status of the goshawk." (p. 66)

5. Is evidence available that goshawk distribution or abundance is declining in all or part of southeast Alaska?

"Data on goshawk density, survival, reproduction, and dispersal in southeast Alaska are too limited to directly determine the trend in any demographic characteristic for the population. Due to the lack of historical information, direct estimates of status and trend will be difficult for the near future. Preliminary data and literature review suggest that adult goshawk survival in southeast Alaska might be within the range judged necessary for population stability. The annual estimated survival of adult goshawks averaged 72 percentnot too different from the minimum 80-86 percent adult survival calculated by the McGuire and Call [PVA study]" (p. 66)

Although demographic data was not available to determine population trends, the authors speculated on inferences made from trends in habitat change patterns: "Considerable amount of the most productive old-growth forest habitats selected by goshawks have been removed in southeast Alaska, and the decline will continue under the current Tongass Land management plan. goshawk abundance has likely declined during the past period of intensive timber harvest." (p. 66)

6. What is the current conservation status of the goshawk in southeast Alaska?

"cannot precisely be determined" but
"1. The probability of persistence for goshawks throughout southeast Alaska has declined since the middle of the 20th century.
2. Goshawks in most ecological provinces with limited or no habitat modification are likely not in immediate peril.
3. A sound habitat management strategy is important to maintain long term, well distributed populations" (p. 67)

"Harvest of productive old-growth forest reduces habitat quality for 8 of the 10 goshawk principal prey species and may negatively affect forest structure for foraging goshawks." (p. 68)

Management Considerations
Response to forest change at the stand scale-
"the dual effects of clearcutting-eliminating a selected habitat type and creating an avoided (one) at the stand scale-serve to focus management considerations on the productive old-growth forest component of the landscape." (p. 69)

Uneven-ages silviculture-
Light, single-tree selection is expected to retain high value nesting habitat as long as large, old trees remain on the site through time. Group or single tree selection also maintains relatively high value foraging habitat throughout the management cycle. Thus, uneven-aged silviculture that emulates natural disturbance patterns will have a high likelihood of sustaining suitable goshawk habitat." (p. 70)

Even-aged Silviculture-
These treatments are "considered among the least valuable treatments for nesting or foraging owing to inadequate forest structure remaining in the stand." (p. 71)

Intermediate Treatments-
"could theoretically enhance stand suitability for goshawk habitat use" .but "the consequences for goshawks are less certain (than for other treatments discussed)." (p. 71)

Response to forest change at the landscape level-
"We do not suggest that goshawks require extensive tracts of productive old-growth forest on the Tongass NF, but rather that landscapes with large proportions of early seral forest reduce the cumulative habitat quality for goshawks across the landscape." (p. 72)

"We conclude that timber harvest management regimes with longer effective rotations [e.g., 300 years] will provide a higher probability of goshawk population persistence than shorter rotations. One possible goshawk conservation strategy is to manage 66 percent of the productive forest in equal proportions of mature sawtimber and productive old-growth forest habitat cover types with the remaining one-third managed under an even-aged, short rotation design." (p. 75)

Goshawk Conservation Strategies

1. Static habitat reserves-"Given observed landscape patterns, if spatially static reserves are a component of landscape conservation strategythen goshawk persistence likely will benefit from more and larger reserves in landscapes that have a greater proportion of the forested land base in early seral stand conditions." (p. 80)

2. Disturbance ecology-based matrix management-"We hypothesize that management strategies that do not employ reserves, but rather provide suitable habitat throughout a larger area such as all lands available for timber harvest, will lead to higher persistence probabilities than a reserve-based approach." (p. 82)

"Judicious use of both reserves and dynamic landscape strategies depends on local landscape conditions and habitat cover type composition.a management approach across the Tongass emphasizing reserves in areas with high levels of past or currently projected extensive timber harvest, and long rotation or uneven aged management schemes elsewhere, likely will provide the highest persistence probability." (p. 82)

"Reserves and long timber harvest rotations have complementary roles in minimizing risk. Reserves provide the means to increase the probability of persistence by providing high quality habitats, especially in landscapes where options for long rotation silviculture have been lost. The degree to which a reserve network reduces risk depends on placement, size, and compositionLong rotations minimize the local intensity of timber harvest and provide a forest age class distribution of stands more favorable to the goshawk. Long rotations maintain the majority of a landscape in a marginal or suitable habitat cover type of goshawk habitat use well distributed across a landscape and precludes the need to explicitly quantify, with insufficient information, the size, spacing, and composition of reserves. However, both strategies can provide opportunities to apply adaptive management concepts and to learn more about goshawk habit relations.

Summary

Life History
Aspects of the goshawk's life history that may put it at risk of endangerment: it is long-lived, has low reproductive rates, occurs at low densities, and doesn't migrate.

Status
Probability of persistence over the past 50 years has probably declined due to habitat loss, and is likely to continue to decline.
The present population is likely not in immediate peril.
Petitions to list the Queen Charlotte goshawk were issued n 1995.
The FWS responded to petitions by stating that listing was not warranted at that time, but without serious changes in the Tongass Land Management Plan, goshawks would be seriously imperiled.
Preliminary data from southeast Alaska indicates that present populations are probably not in peril, but there is major concern over habitat issues.

Habitat
Several factors that may contribute to decreased productivity and density include: 1) increased predation on adults and young goshawks as hiding cover is reduced and potential predator populations increase (e.g., great horned owls); 2) loss of cool thermal conditions at nest sites; 3) reduced prey abundance or availability, or both; 4) increased competition as predators that adapt to more open forest become abundant; and 5) increased disturbance and human-caused mortality due to increased access from the timber harvest road network
Telemetry (year-round) locations: >60% were in old-growth forest.
Nesting occurred primarily in old-growth forest.
Old-growth forest is the main habitat for the main prey items of the goshawk.
The minimum proportion of old-growth forest used by adult males was 23%, and for females, it was 28%.
Old growth has been declining on the Tongass, and continues to decline
900,000 acres of old-growth forest have been harvested on the Tongass during the past c. 100 years.
Timber management over the last 100 years has historically been in the form of even-aged management and clear-cuts, which creates poor goshawk habitat.
Harvest may also be reducing the numbers of goshawk prey species.

Recommendations

Apply long rotations (300 years)
Use un-even aged silviculture (group or individual tree selection), which emulates natural disturbance and creates/maintains high value goshawk habitat.
Do not use even-aged silviculture, which has the least value for goshawks.
Judiciously use both reserves and dynamic landscape strategies, employing adaptive management, for goshawk conservation strategies.