The northern goshawk (Accipiter gentilis, hereafter goshawk) is widely recognized as a species sensitive to forest development. Forest development activities that affect the nest area represent the most direct potential impact to goshawks because: 1) of the critical importance of the nest area for reproduction of the species, 2) the relatively small size of the nest area (~24 ha) makes it susceptible to being completely removed by a cutblock, 3) goshawks exhibit very strong site fidelity to nest areas, often using them for periods of years or decades, and it is unknown how successfully they can establish a new nest area once an original one becomes unavailable, and 4) there is high overlap with suitable nest area habitat and the Timber Harvesting Land Base . This project directly assesses the response of northern goshawks to forest development within or immediately adjacent to known goshawk nest areas within an adaptive management framework. The goal of this adaptive management strategy is to provide forestry planners and regulatory agencies with local empirical data to confidently design and approve stand level forestry development plans that will maintain use of goshawk nest areas while minimizing impacts to timber development. This is the most comprehensive study to date that directly assesses the response of goshawk nest area use to stand level forest development, and will make a significant contribution to goshawk conservation and forest management at the regional, provincial, and international levels. The results presented here are a combination of data from two concurrent studies in west-central British Columbia, one in the Sub-Boreal Spruce biogeoclimatic zones and one in the Interior-Cedar-Hemlock biogeoclimatic zone. The results for the two projects are combined in this one report to maximize the sample size and power of our analysis. We are assessing the effects of forest development activities on goshawk breeding success with respect to two reproductive parameters. The primary factor is the rate of reoccupation of nest areas at the incubation stage. This is a critical stage in the breeding period because the birds are committing themselves to the nest area by laying eggs, and it implies that they have made a choice that the area is suitable for breeding. The second factor we examine is the number of chicks that successfully fledge from each nest area (nest productivity). This is a secondary factor because nest productivity is more a factor of foraging area quality than nest area quality.
Prepared by Todd Mahon, Wildfor Consultants Ltd., and Frank Doyle, Wildlife Dynamics.
Mahon, Todd. 2007. Effects of forest development near nest sites on the reproductive success of Northern Goshawks (Accipiter gentilis): an adaptive management approach: 2006/2007 annual report. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2007MR103
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), Northern, goshawk, British, Columbia
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