Document Details

Nest-site re-use and management of nest habitat attributes of Marbled Murrelets in coastal forests
Burger, Alan E.
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 ...
Report Number
Executive summary

EIRS Search Options

Useful Contacts