General Technical Report RMRS-GTR-22
The Northern Goshawk in Utah: Habitat Assessment and Management
Recommendations
General Technical Report RMRS-GTR-22
The Northern Goshawk in Utah: Habitat Assessment and Management Recommendations
Recommendations
In North America, goshawks nest in nearly every forest type. Populations in Utah are similar in that they nest in a broad range of vegetation types ranging from subalpine fir to ponderosa pine. The forests and woodlands of Utah that provide goshawk habitat are diverse in species composition and structure. The history of land-use is also highly variable with domestic livestock grazing occurring for 100 to 150 years and timber harvest beginning in the late 1800's. Tourism and snow skiing have also become important land uses along with timber and water production. With such land uses came the desire to protect the forests and woodlands from fire; effective fire exclusion began in the mid-1900's. As a result, the forests and woodlands of Utah are now dominated by dense stands of late seral species that are prone to epidemics of diseases and insects. More important, many of the forests and woodlands of Utah are prone to large-scale, stand-replacing fire events. The condition of present day forests is far different than those that occurred before European settlement.
Conservation of the northern goshawk will require the restoration and protection of degraded habitats and protection of native processes. The following recommendations describe actions and long-term management strategies aimed at sustaining the habitat of the goshawk and selected prey species for the forests and woodlands of Utah. Synthesis of these attributes can be used to define a desired habitat condition on a particular site or landscape. The decision to apply these recommendations is up to the specific private land owner or administrator. Because these recommendations are directed at both habitat and native processes, they will benefit a myriad of other plant and animal species, not just goshawks. The recommendations are presented in two spatial scales. The first spatial scale is the entire State of Utah and contains general recommendations for achieving long-term goals related to maintenance of goshawk habitat. The second spatial scale contains goals and recommendations for specific potential vegetation types.
State of Utah Recommendations
The forests and woodlands of Utah are dominated by unstable stands of late seral species. Early and mid-seral species should be increased using both mechanical means and fire.
Goshawk habitat throughout the State is well connected. These connections should be maintained and strengthened. Activities near the edges of the high value habitat should be designed to maintain or enhance goshawk habitat values, irrespective of ownership.
Numbers and distribution of large trees in the landscape should be increased. Policies should be adopted to manage for the production of large early seral species through cleanings, thinnings, and weedings, using mechanical means or fire. For a properly functioning system, approximately 40 percent of the landscape should be in large trees (relative to average for the cover type and potential vegetation type) of a variety of species (Quigley and others 1996; Reynolds and others 1992; USDA Forest Service 1997).
It should be recognized that stands with a large numbers of dead trees still have high habitat value for goshawks in the short-term. Management activities should be designed to maintain these structural attributes while facilitating the development of future stands. Group selection or other similar treatments might be preferred over clearcutting in order to maintain habitat values while decreasing the risk of loss from windthrow or other similar disturbances.
Nest Sites -- Both short- and long-term management activities should be planned to ensure that nest sites contain large trees (relative to average for the cover type and potential vegetation type) with open understories and dense canopies (relative to average for the cover type and potential vegetation type). Sites near water are preferred and should be over 30 acres (Reynolds and others 1992). Occupancy rate of nest stands is positively correlated with stand size (Woodbridge and Detrich 1994).
Foraging Areas and General Home Range -- Landscapes should include all of the attributes important for the goshawk and its prey such as: hunting perches, large trees, grasses, forbs, shrubs, and interspersion of forest age/size classes (Reynolds and others 1992) in a variety of seral stages. A properly functioning systems incorporates all these attributes (USDA Forest Service 1997).
Potential Vegetation Type Recommendations
In general, when the potential vegetation types of Utah are in a proper functioning condition (USDA Forest Service 1997) they will provide excellent habitat for the goshawk and its prey. The following recommendations highlight the necessity of managing forest landscapes within their biophysical limits, and understanding how disturbances influence the resulting stand compositions and structures.
Subalpine Fir -- The subalpine fir potential vegetation type is capable of providing high quality goshawk and prey habitat. It is currently dominated by late seral species throughout the State. Habitat should be improved by promoting early seral species such as quaking aspen, Douglas-fir, and lodgepole pine in a forest mosaic with Engelmann spruce and subalpine fir. These mixed forest cover types (especially mixes with quaking aspen) would be highly used by the goshawk and would have lower risk of epidemics of insects and diseases, and stand-replacing fire. Fire or mechanical treatments or both should be used to create conditions favorable to lodgepole pine and quaking aspen. Treatments will be most effective if initiated where lodgepole pine and quaking aspen are still present. Patch size can be variable in this type, tending to be large (10 to 100 acres) at lower elevations but small (tree length in diameter) at the upper elevations.
Lodgepole Pine -- Although the lodgepole potential vegetation type has a limited distribution in the State, it is of high value to the goshawk (fig. 6). The persistent lodgepole cover on this type is probably an interaction of insects, diseases, and fire. Fires historically occurred at low frequencies, but over large areas (hundreds to thousands of acres) (Bradley and others 1992). Treatments should be planned to ensure that a lodgepole seed source is present to ensure rapid regeneration. Most likely, no other tree species with the exception of quaking aspen will be available to regenerate the sites. Where quaking aspen is a seral species, it should be maintained. Openings can be large (up to hundreds of acres) where serotinous cones are present, but need to be small (25 acres) when nonserotinous cones are present.
Figure 6 -- An active goshawk nest located in a lodgepole pine stand experiencing high mortality.
Engelmann Spruce -- The Engelmann spruce potential vegetation type is similar to the subalpine fir potential vegetation type, and mixed stands of early and mid-seral species are excellent habitat. At the higher elevations, openings for regeneration should be small (tree length in opening diameter) being cognizant of the potential for wind damage. At the lower elevations, patch size should be appropriate for effective regeneration of quaking aspen and lodgepole pine, given site conditions and the availability of seed source or clone.
Ponderosa Pine -- Stands of ponderosa pine located on the ponderosa pine potential vegetation type are often overly dense, containing numerous small trees. Treatments should be planned to convert these stands, occupied by small crowded stems, into open stands dominated by large fire resistant trees (fig. 7). Cleanings, weedings, and thinnings through mechanical means or fire could be used to create these conditions (fig. 8). Nonuniform, irregular tree spacing should be encouraged. Quaking aspen regeneration should be encouraged in this potential vegetation type to add diversity and promote stability. The goshawk recommendations developed for ponderosa pine by Reynolds and others (1992) are applicable to this potential vegetation type.
Figure 8 -- Cleaning a ponderosa pine using prescribed fire.
Quaking Aspen -- Quaking aspen is the only cover type that occurs on this potential vegetation type. Unlike seral quaking aspen on other potential vegetation types, long persistent versions of this tree can successfully regenerate under an existing canopy of mature trees; therefore it often occurs in uneven-aged stands. Treatments designed to stimulate quaking aspen regrowth should take this into account, perhaps by creating successive small openings rather than large-scale overstory removals through fire or mechanical means. However, if stands are basically healthy, there should be no need to treat quaking aspen stands on this potential vegetation type.
Douglas-fir -- The Douglas-fir potential vegetation type supports a variety of forest cover types, including lodgepole pine, quaking aspen, and ponderosa pine. All are important to goshawks and they should be regenerated in this type. Both fire and mechanical means are appropriate for managing the array of early and mid-seral species that are possible. This potential vegetation type is currently dominated by dense, multistoried stands of Douglas-fir that are unstable or prone to epidemics of insects and diseases, and prone to stand replacing fires. Treatments need to be planned to rejuvenate stands without destroying the forest structure important to the goshawk. For example, group selection, group shelterwoods and variable spaced shelterwoods along with stand maintaining fires are all feasible options.
White Fir -- The white fir potential vegetation type is capable of supporting a wide variety of tree species, including many that are important to goshawks (for example, quaking aspen, ponderosa pine, Douglas-fir). It has high potential as goshawk habitat. However, most of the type is presently occupied by multi-storied stands dominated by white fir. These stands, cluttered with many small limbs, reduce flight lanes without providing perches or nest platforms for the goshawk. Fire and mechanical means are also appropriate in this type for managing the array of early and mid-seral species that are possible. Similar to the Douglas-fir type, treatments should be planned to introduce and maintain the seral species, yet not eliminate the mature forest structure important to the goshawk.
Pinyon/Juniper -- Although no nests have been located in Utah, this potential vegetation type may be important as winter foraging habitat. Currently, the pinyon/juniper potential vegetation type is predominantly covered by late seral pinyon pine and juniper trees. This potential vegetation type is prone to stand-replacing fires and the introduction of exotic species. The successional pathways of this potential vegetation type are indeterminate, and usually conditions after disturbance are less stable than the current late seral condition. It is believed to be useful for prey to increase the other seral stages (for example, the open shrubby stage). Early and mid-seral stages are productive and support many of the birds taken by goshawks, along with black-tailed jackrabbits (Lepus californicus) and ground squirrels.
Title: Recommendations: RMRS-GTR-22 - The Northern Goshawk in Utah: Habitat
Assessment and Management Recommendations
Electronic Publish Date: May 26, 1999
Expires: Indefinite
Last Update: January
15, 2002