Forest Investment Account (FIA) - Forest Science Program
FIA Project Y081158

    Nest-site re-use and management of nest habitat attributes of Marbled Murrelets in coastal forests
Project lead: Burger, Alan (University of Victoria)
Author: Burger, Alan E.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
BACKGROUND: Marbled Murrelets are small seabirds which usually nest on large mossy limbs (platforms) in old coastal conifers. Due to reductions of nesting habitat, the species is federally Threatened and covered by the Species at Risk Act (SARA). In BC it is Red-listed and listed under the Forest and Range Practices Act (FRPA) and the Identified Wildlife Management Strategy (IWMS). Past research has improved knowledge of the forest habitats used for nesting, but significant data gaps remain which hinder conservation management compatible with sustainable timber extraction. This project will provide key information on: A) The re-use of nest trees in different years by murrelets and the environmental factors affecting re-use; B) Regional and local factors which affect tree architecture, limb size and epiphyte development and hence platform availability. Platforms are defined as limbs or deformities >15 cm in diameter. Most murrelet nests in BC have been on platforms provided by mossy pads typical of old seral trees on the coast, but in drier areas large limbs can provide platforms without epiphytes. Murrelets do not construct a nest but the single egg is laid in a depression in the moss or duff. Reviews during recovery planning by the Marbled Murrelet Recovery Team (Burger 2002, MMRT 2003) revealed considerable raw data available to address these questions and focus future research. The data were collected as part of other research by universities, government and industry, but were not analysed to specifically address these issues. This proposal is for funds to collate, analyse and publish the existing data on these topics (Year 1), followed by a focused field project on platform development to fill in gaps and test hypotheses (Year 2). Part of this work will be undertaken by Mike Silvergieter as a component of his MSc thesis at SFU. THE NEED FOR THIS INFORMATION Nest re-use – This information is needed to address policy issues and field management of murrelet habitat. Under the SARA, the Marbled Murrelet’s “Residence” is currently defined as a nest tree, but uncertainty over the extent of re-use of nest trees raises uncertainty on how this definition will be applied in law and in forest management. Our analysis will also clarify the application of the IWMS (2004) guidelines and management of known nest sites. In highly modified California redwood forests nest re-use seems fairly frequent (Herbert & Golightly in review) but our unpublished data (UVic) suggests that nest trees are seldom or never re-used on SW Vancouver Island where habitat is still plentiful. An intermediate situation seems to occur on the Sunshine Coast, BC (Manley 1999). We will pool all the data available in BC and address the nest re-use issue from a province-wide perspective. Platform/moss development – Current management objectives (e.g., MMRT 2003, IWMS 2004) are to maintain old forest stands providing potential nest platforms (canopy limbs or deformities of diameter 15 cm or larger). We don’t know, however, what size and types of trees reliably provide platforms. Platform availability cannot be predicted solely on the age/size of trees or from moss availability, but requires an understanding of the regional and local factors affecting both tree architecture and epiphyte growth. This information is urgently needed: a) to help ensure that forests maintained as habitat do include adequate platforms; b) to develop policies and field practices for partial-retention cutting that ensure retention of suitable trees with platforms so that murrelets might still nest; and c) to facilitate the recruitment of older second-growth forests to provide future habitat in areas where old forests are severely depleted, such as the southern mainland coast and SE Vancouver Island (see MMRT 2003). Platforms and moss are also key elements assessed during low-level helicopter surveys now routinely used by the forest industry to assess and confirm suitability for murrelet nesting of forest stands (Burger 2004). Our analysis will improve the reliability of the helicopter surveys, but also enhance the use of cheaper alternative methods. Air photos and other remote sensing methods can show the size and age of trees but not the availability of platforms. Similarly, habitat algorithms based on forest cover and other GIS data have mixed success in predicting platform and moss availability. Understanding the forest age, tree species and environmental conditions which provide suitable platforms, moss and canopy architecture for nesting murrelets will improve the reliability and application of these cheaper methods. DATA AND ANALYSIS (details in Section 6) Nest re-use – Data on nest trees are available from several regions in BC, from radio-telemetry studies (SFU and others), and numerous other studies which used tree-climbing to locate nests. Nest re-use will be assessed from: a) nest checks made over successive years; and b) assessing the status (active when found or in a previous year) and number of nest remains found per tree. Platform/moss development – Habitat plots were sampled following standardized RISC (1997 and 2001) protocols. Relevant data to be extracted from databases and field notes will include: tree species, diameter, height, estimated number of platforms, moss and mistletoe development, and biogeoclimatic variables. We propose a cross-sectional study (assessing platform and moss availability across a range of existing tree age/size classes in one time interval). Analysis methods – Factors affecting the re-use of nests and availability of platforms and epiphytes (the dependent variables) will be tested using current multivariate statistical techniques and information-theoretic methods (e.g., Akaike’s criteria). Additional tests will examine effects of population density (estimated from radar studies) and habitat availability (using GIS and other products from our current FSP studies). FIELD WORK AND FINAL ANALYSIS (Year 2, 2008-09) We will deploy a ground crew (2 students) to undertake habitat plots (RISC protocol) aimed at filling data gaps on platform/moss development and testing the specific hypotheses generated in Year 1. We anticipate 150 plots in 3 regions, likely SE Vancouver Island, North Coast and Central Coast. The actual sampling sites and protocols will be based on the results of Year 1 analyses. This field sampling will allow us to complete the BC-wide analysis of platform development by March 2009. REFERENCES: Burger 2004: MMRT (2003) & Burger (2002) see: IWMS (2004): Manley, I. 1999. MSc Thesis, Simon Fraser University RISC (2001) protocol, Series 10 at
Related projects:  FSP_Y092158
Contact: Burger, Alan, (250) 479-2446,


Executive Summary (45Kb)

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Updated August 16, 2010 

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