Habitat use by Marbled Murrelets on southwest Vancouver Island and
implications for forest management
Final Report to Forest Science Program and Price-Waterhouse-Coopers for the year 2004-2005.
FSP Project Number: Y051061
Alan E. Burger, PhD Rick Page, PhD
Rob Ronconi, BSc Cathy Conroy, BSc
Department of Biology University of Victoria
Victoria, BC V8W 3N5
e-mail: [email protected]
30 April 2005
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ABSTRACT We report research undertaken on southwest Vancouver Island in 2004-05 on Marbled Murrelets (Brachyramphus marmoratus) a Threatened seabird which nests in the canopies of coastal old-growth forests. Our results are summarised here relative to the five primary objectives of our Forest Science Program 2004-05 project. Objective 1 - Radar surveys: In May-July 2004 we did 43 dawn radar surveys at 27 stations and a similar number of dusk surveys. With pooled data from 2002 and 2003 we covered 45 stations, 72 flight paths (some sites allowed tracking of >1 flight path), and 98 surveys including over 20,000 murrelet detections. We considered that 38 flight paths at 35 stations provided reliable baseline data for long-term monitoring of murrelets. Of these, 29 watersheds were suitable for habitat analysis; mean counts here totaled 4,323 murrelet, recorded in 86 surveys. Our past radar data were used in two journal papers (1 published, 1 in prep.). Objective 2 – GIS habitat database: Dr Rick Page was hired Jan 05 as GIS specialist and a work-station established in the Spatial Analysis Lab, Geography Dept., UVic. GIS databases were established including: Forest Cover data from Vegetation Resource Inventory (VRI); digital elevation raster from Gridded DEM; Landsat MSS images analysed by the Sierra Club/Wilderness Society; Biogeoclimatic (BEC) data; watershed boundaries, lakes and streams from the BC Watershed Atlas; Marbled Murrelet habitat algorithm applied to forest cover data; and spatially linked murrelet count data. Considerable time was spent in negotiating the use of data, integrating these data, correcting errors, and making adjustments to match NAD 83 spatial reference. Objective 3 – Landscape-level habitat analysis: Preliminary habitat maps were plotted with GIS and analysed with murrelet count data. We found a significant positive correlation between murrelet counts and habitat area per watershed but the relationship had modest predictability (R2 ~0.2) and showed a wide scatter of points. A draft journal paper was completed on habitat associations, but will be revised following our 2005 work. Modeling using hydrology tools in ARCGIS was initiated to model likely murrelet flight paths and improve estimates of catchment areas relevant to the radar stations. Objective 4 – Marine/Inland integration: Grad student Rob Ronconi completed a full field season in 2004 and then continued his analysis of data. Preliminary models show strong aggregations of murrelets at “hot-spots” off SW Vancouver Island. Analysis of field data, including fine-scale mapping data (theodolite surveys), hydroacoustic prey surveys, and activity-time budgets of foraging murrelets was completed and preliminary results presented at conferences and in reports. This work continues in 2005. Objective 5 – Apply results in management: An extension note on our radar methods was published via FORREX. A web site was established to provide research information and reports. In 2004-05 our team presented 12 papers at conferences and other meetings, participated in 13 meetings of the Marbled Murrelet Recovery Team and Habitat Recovery Implementation Group, drafted most of the Marbled Murrelet Recovery Plan and Recovery Action Plan, contributed to UBC murrelet monitoring workshop, helped draft a radar monitoring protocol, and helped review the US NW Forest Plan. We worked directly with forest and wildlife managers in industry and MOF, MWLAP, MSRM, BC Timber Sales, CWS, Parks Canada, BC Conservation Data Centre and consultants.
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TABLE OF CONTENTS
1 Introduction................................................................................................................. 4
1.1 Background......................................................................................................... 4 1.2 Forest Science Program project objectives 2004-05........................................... 4
2 Methods....................................................................................................................... 5 2.1 Radar and Audiovisual Surveys.......................................................................... 5 2.2 GIS Habitat Analysis .......................................................................................... 5 2.3 Landscape-level Habitat Associations ................................................................ 6 2.4 Marine and Inland Habitat and Behaviour Study ............................................... 6
3 Results......................................................................................................................... 7 3.1 Radar Counts of Marbled Murrelets ................................................................... 7 3.2 GIS Habitat Analysis .......................................................................................... 7 3.3 Landscape-level Habitat Associations ................................................................ 8 3.4 Marine and Inland Habitat and Behaviour Study ............................................... 8 3.5 Application of research in management and conservation ................................. 8
4 Discussion................................................................................................................... 9 4.1 Radar surveys on southwest Vancouver Island .................................................. 9 4.2 GIS Habitat Analysis .......................................................................................... 9 4.3 Landscape-level Habitat Associations .............................................................. 10 4.4 Marine and Inland Habitat and Behaviour Study ............................................. 10
5 Conclusions and Management Implications ............................................................. 10 6 Acknowledgments..................................................................................................... 12 7 Literature Cited ......................................................................................................... 12 8 Appendices and project deliverables ........................................................................ 14
8.1 Appendices to this report .................................................................................. 14 8.2 Other project deliverables ................................................................................. 14 8.3 Extension, presentations and management contributions ................................. 15
Tables ……………………………………………………………………………………17 Figures……………………………………………………………………………………22
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1 INTRODUCTION
1.1 Background Marbled Murrelets (Brachyramphus marmoratus) are small, diving seabirds which forage in nearshore seas and usually nest high in old conifers (Nelson 1997). Murrelets are listed as Threatened in Canada by COSEWIC, Red-listed by the BC Provincial Govt., and identified as a species at risk under the BC Forest and Range Practices Act (FRPA). Loss of nesting habitat due to ongoing logging of old-growth nesting habitat is the primary threat, but threats from oil spills and fisheries by-catch are additional threats. This has created conflict between the species’ needs for nesting habitat and industrial timber supply in many parts of coastal BC. Despite considerable research on this species, there are still large uncertainties and data gaps affecting management and conservation decisions (Burger 2002, CMMRT 2003). In particular, the inter-relationships between habitat quantity, habitat quality, nesting densities, and population size within watersheds remains unclear. Moreover research on the murrelet’s marine foraging component has not kept pace with inland research, and we may be missing important limiting factors. Our research aims to determine critical habitat features for murrelets. Most of our research has focused on inland nesting habitat, but we have also done considerable work on the murrelet at sea. Integrating the inland and marine research is seen as important by the Marbled Murrelet Recovery Team and has become a priority for our research. This report covers research undertaken by our UVic team on southwest Vancouver Island in 2004-05, combined with radar data collected in the same project in 2002 and 2003 (not funded by FSP in those years). This area supports one of the highest densities of murrelets in BC (Burger 1995, 2002) but conservation of murrelet habitat in this area is in competition with the extraction of some of the most valuable timber resources in Canada. There are therefore important conservation, economic and social implications to our research. Our team has worked in this region since 1990.
1.2 Forest Science Program project objectives 2004-05 As outlined in our Feb. 2004 FSP proposal, our research in 2004-2005 covered five main topics which overlap and integrate with each other: 1. Radar surveys to count Marbled Murrelets – our goal was to complete 4 dawn
surveys at 30 watersheds which could be used for long-term population monitoring (an important objective in the draft Marbled Murrelet Recovery Plan) and to link murrelet counts with landscape-level habitat features (see point 3).
2. Habitat classification - our goal was to assemble a GIS database of forest cover, topographic and other features on southwest Vancouver Island which would give us a powerful tool for landscape-level habitat analysis and provide input for management of murrelets in this area.
3. Landscape-level habitat associations – our goal was to combine the radar counts (objective 1) and GIS habitat data (objective 2) in order to assess which habitat
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features might best predict the numbers of murrelets nesting in watersheds and estimate the densities (murrelets per ha of habitat) on southwest Vancouver Island.
4. Modeling marine and inland habitats – this is Rob Ronconi’s PhD study which aims to explain the spatial and temporal distribution of breeding murrelets on southwest Vancouver Island with reference to both marine (foraging) and inland (nesting) habitats. This study is also investigating behavioural and habitat parameters which determine fine-scale spatial distribution of foraging murrelets.
5. Apply our results to the management of murrelets and timber lands – our goal is to interact with government agencies, the forest industry and the Marbled Murrelet Recovery Team to apply the results of our research directly in the conservation and management of Marbled Murrelets in British Columbia. This we achieve through publishing our results in peer-reviewed scientific journals, interim reports, and extension notes, giving presentations to stakeholders and the public, participating in workshops and conferences, providing information via our web-site and through direct interaction with forest and wildlife managers.
2 METHODS
2.1 Radar and Audiovisual Surveys We followed established methods for counting Marbled Murrelets with radar (Burger 1997, 2001, Manley et al. 2005). We used a Furuno FR-810D 10 kW marine surveillance radar using 9410 MHz (X-band) transmitted through a tilted 2 m scanner. The scanner was mounted on the roof of a truck or, at sites with no road access, on a small sailboat. Observers had many years of murrelet radar experience (Burger and Conroy) or were trained by us (Fern Wager). Morning surveys began 90 minutes before sunrise and continued for 60 minutes after sunrise or 15 minutes after the last murrelet detection. Dusk surveys were undertaken to familiarize the observer with the local flight paths; the dusk survey data were archived but were not reported here. To reduce the possibility of counting the same birds twice, we restricted our analysis to counts of incoming (flying inland from the sea) murrelets recorded before the official sunrise (Burger 2001). We deleted any surveys in which rain or technical problems prevented surveys for more than 10 minutes of survey time during peak periods of murrelet activity. Based on previous studies Marbled Murrelets were identified on the radar screen on the basis of their image size, speed, flight-path and flight bearing (Burger 1997, 2001). A second observer, usually positioned about 50-100 m from the radar unit undertook a standard audio-visual (AV) survey, following the RIC (2001) protocol, and was also in radio-contact with the radar observer to report any birds (e.g., mergansers, pigeons) which might be confused with murrelets on the radar screen.
2.2 GIS Habitat Analysis Compilation of GIS data for Vancouver Island and the initial results of analysis are summarized in the separate report submitted as Appendix 2 (see below).
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• Data were collected from cooperating government agencies and companies and translated into ARC/GIS coverages in a consistent NAD83 BC Albers projection on a TRIM base from the BC Watershed Atlas.
• Where necessary, a manual adjustment was made for data originally in NAD27 to compensate for the residual errors from the automated translation.
• We also acquired assorted additional data on land use designations and planning for future modeling of management implications of murrelet habitat protection and loss.
• Forest cover stands formed the smallest analytical unit within which other data (like elevation, distance from ocean and area of ancient forest) were compiled using GIS overlays and summaries.
• Habitat was defined by data provided by MSRM that represented the application of an algorithm from the MMRT that identified old and tall trees as potentially possessing nesting platforms for Marbled Murrelets.
• Habitat was also similarly defined by application of the MSRM algorithm to the mapped forest cover data and a Sierra Club interpreted image of ancient forests.
• We used ARC/GIS 9 on a 2.4 GHz computer with dual processors and unlimited storage at the Spatial Sciences Lab in the Department of Geography at the University of Victoria.
2.3 Landscape-level Habitat Associations Topographic parameters for watersheds and forest stands were calculated using the Digital Elevation Mapping and GIS routines (e.g. mean elevation, distance from ocean). Nesting habitat for murrelets was mapped using the Marbled Murrelet Recovery Team (MMRT 2003) algorithm (essentially height class 4+ (>28.5 m) and age class 8+ (>140 years)) or where these forest cover data were not available using the “Ancient Forest” algorithm applied to satellite imagery (Sierra Club mapping). We manually identified all of the Watershed Atlas watersheds upstream of a radar station and measured the area of habitat within these. These were then compared with the radar counts of murrelets entering these watersheds. Data were available for 23 watersheds on southwest Vancouver Island. Further details of analysis are summarized in the separate report (Appendix 2) and in our draft journal paper submitted as deliverables (see below).
2.4 Marine and Inland Habitat and Behaviour Study Rob Ronconi’s study is summarized in Appendix 3, submitted as a separate file – see below. Methods are described in that report, and involved the following:
• GIS analysis of existing distributions of murrelets along the West Coast Trail (WCT) to determine foraging aggregation “hot spots” and areas seldom used by murrelets;
• Behavioural observations of foraging murrelets to determine activity-time budgets in preferred and not-preferred marine areas;
• Use of a surveyor’s theodolite to accurately map the fine-scale distribution of foraging murrelets and other seabird species with which they interact;
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• Spatial analysis of these mapped data to determine seasonal changes in spatial distribution and investigate possible underlying causes;
• Analysis of the interactions between Marbled Murrelets and a potential larger competitor the Common Murre (Uria aalge).
3 RESULTS
3.1 Radar Counts of Marbled Murrelets A complete database of dawn and dusk radar counts has been submitted as a product of this FSP grant (Excel file: Burger Appendix 1 Radar Database.xls). Our present analysis focused only on dawn surveys. Between 18 May and 23 July 2004 we did 43 radar and AV surveys at dawn (excluding those omitted because of rain or technical problems) at 27 stations (Table 1), covering 45 flight paths (Table 2), and recorded over 10,000 murrelet detections on the radar. We pooled the data with that from 2002 and 2003 to provide data from 45 stations, 72 flight paths (some sites allowed tracking of >1 flight path), and 98 surveys which included over 20,000 murrelet detections (Tables 1 and 2). The locations of the stations and symbols showing the mean number of murrelets counted at each station are shown in Figure 1. Some of these surveys were exploratory pilot surveys testing new sites which proved to be unsuitable and were not re-surveyed (e.g., Bamfield, Carmanah/Bonilla, China Creek Camp). We considered that 38 flight paths at 35 stations provided reasonably reliable counts that could be used as baseline data for long-term monitoring (see flightpaths labelled with asterisks in Table 2). To compare numbers of murrelets with habitat variables we needed to focus on flight paths where birds appeared to be heading into specific watersheds. As discussed below defining the precise catchment area for each of these flight paths was sometimes difficult, but we began by identifying 29 watersheds into which we could see murrelets flying and where we could count these birds with reasonable accuracy (Table 3). At some of these watersheds (Henderson Lake valley, Macktush Creek, Nitinat River, San Juan River, and Toquart River) we used data from two nearby stations which both reliably sampled murrelets entering the watersheds. In these cases we had used more than one location, in some cases because we were forced to move or because we wanted to test alternative sites and found them similar. The sum of the mean counts at these stations was 4,323 murrelets, recorded in 86 surveys over the three years.
3.2 GIS Habitat Analysis Initial results of this analysis are summarized in the separate report submitted as Appendix 2 (see below). We identified variations in mapping in different areas that affected the indicated age and height of forest stands. These variations appeared to be due to the standards used during the original forest inventory and did not reflect actual forest conditions. Age classes 8 and 9 were treated as equal as were height classes 4 through 8. Old and tall forest (as identified on the forest cover maps) was consistently mapped as ancient forest by the Sierra Club interpreted image. These 2 sources of information were in agreement. The greater spatial resolution of the interpreted image could be used to
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improve the estimates of canopy closure in the forest cover data. A preliminary map of likely nesting habitat on southwest Vancouver Island is shown in Figure 2.
3.3 Landscape-level Habitat Associations Initial results of this analysis are summarized in the separate report submitted as Appendix 2 and in our draft journal paper (see below). The number of murrelets counted by radar stations was positively correlated with the amount of habitat upstream (Figure 3). Both the MMRT map and the Sierra Club Ancient Forest map were significantly correlated (P < 0.05) with radar counts but a relatively small percent (ca. 20%) of the total variation in the counts was explained by these relationships.
3.4 Marine and Inland Habitat and Behaviour Study Results from the first season of Rob Ronconi’s study are summarised in the separate report submitted as Appendix 3 (see below). Key results from this preliminary analysis include:
• GIS analysis identified nearshore marine habitats along the WCT which consistently supported high densities of foraging Marbled Murrelets (“hot spots”) whereas other areas along this coast were consistently used by very few murrelets. Understanding this distribution relative to the availability of forest nesting habitat and marine habitat quality will be a key element of Ronconi’s ongoing study.
• Activity-time budgets of murrelets on the water were determined (25% diving; 74% resting; 1% other activities). Analysis focused on diving activities. Diurnal trends in diving were described and there were some significant differences among coastal sites in proportions of time spent diving.
• Fine-scale mapping using the theodolite showed significant seasonal changes in the spatial distributions and nearest-neighbour distances of foraging Marbled Murrelets. Some of these changes might have been due to interactions with larger Common Murres.
3.5 Application of research in management and conservation Section 8.3 (below) provides details of the project deliverables, extension output, presentations, workshops, contributions to the Marbled Murrelet Recovery Team, and direct contributions to forest and wildlife managers on Vancouver Island in 2004-05. An extension note on our radar methods was published via FORREX. A web site was established to provide information on our research and make our publications freely available as PDF files (http://web.uvic.ca/~mamu/ ). In 2004-05 our team presented 12 papers at conferences and other meetings, participated in 13 meetings of the Marbled Murrelet Recovery Team and Habitat Recovery Implementation Group, drafted most of the Marbled Murrelet Recovery Plan and Recovery Action Plan, contributed to the UBC murrelet monitoring workshop and the resultant publication (Arcese et al. 2005), and contributed to the US NW Forest Plan review. We worked directly with forest and wildlife managers in industry and MOF, MWLAP, MSRM, BC Timber Sales, CWS, Parks Canada, BC Conservation Data Centre and consultants.
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4 DISCUSSION
4.1 Radar surveys on southwest Vancouver Island Our goal was to complete 4 dawn surveys at 30 watersheds to allow long-term population monitoring and landscape-level habitat analysis. At the end of the 2004 season we had surveyed 45 stations but some proved unsuitable and we considered data from 38 flight paths at 35 stations reliable for long-term monitoring (Table 2). For habitat associations we considered radar data from 29 watersheds to be reliable for habitat analysis (Table 3). Our objectives were therefore achieved in providing an adequate sample for monitoring and habitat analysis. Due to minimal funding in 2002 and 2003 (before our FSP grant) we do require an additional season of surveys (summer 2005) to achieve an adequate multi-year coverage, as recommended in other analyses (Burger 2001, Cooper et al. 2001) at some stations. In addition, in 2004 we identified for the first time some important flight paths with large numbers of murrelets (Gordon and San Juan Rivers) which are using forests which are currently being logged. It is therefore important to re-survey these sites in 2005 to confirm their importance to murrelets. Overall, our radar surveys confirm previous results from at-sea boat surveys (Sealy and Carter 1984, Burger 1995) which show that southwest Vancouver Island is one of the most important areas for breeding Marbled Murrelets in British Columbia. On average in 2002-2004 we counted 4323 murrelets entering 29 watersheds, and since we did not sample all the watersheds in the area the overall total of murrelets within southwest Vancouver Island is likely to be about double this number. Watersheds with exceptionally high counts which should be the focus for management priorities include: China Creek (mean count 270 murrelets, although we suspect most of these are heading well inland); Gordon River (287), Henderson Lake valley (384), Klanawa (214), Lucky Creek (258), Walbran (394 in the upper valley alone), Nitinat (367), San Juan (446), Sarita (180), and Toquart (388). We have already provided these data on the Henderson, Lucky Creek, and Toquart valleys to forest management authorities (Ministry of Water, Land & Air Protection, Nanaimo; BC Timber Sales) as part of the Arrowsmith Timber Supply Review covering these drainages.
4.2 GIS Habitat Analysis We met the primary objective of this program to compile a GIS legacy database of maps that can be used for subsequent Marbled Murrelet analysis and research. Analysis using these data has just begun since the project began late in the fiscal year. Tripp (2001) reviewed a number of models that have been developed for Marbled Murrelet nesting habitat in BC and found that stand age and tree height were the only 2 characteristics consistently identified as necessary to define murrelet nesting habitat. These are currently the two primary habitat features used by the Marbled Murrelet Recovery Team to map habitat across British Columbia. There are substantial problems with the current forest cover mapping to accurately assess these variables on Vancouver Island. The VRI standards will eventually resolve these issues but completion of the mapping is many years in the future.
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Previous work (Burger 2001) indicated that the amount of area logged may be important in the relationship between murrelets and habitat area. In 2005-06 we will develop estimates of the area logged including harvests since 1999. Estimates of canopy closure have been identified as a possible factor in improving habitat models (MMRT 2003). The canopy completeness variable in the current forest cover maps of Vancouver Island is unreliable. We will use the satellite image of Ancient Forests to estimate the variability within a forest stand as an approximation of canopy closure.
4.3 Landscape-level Habitat Associations Though we found a significant relationship between the amount of habitat and the number of murrelets counted, the regression explained very little of the total variation in the count and the data points show a wide scatter around the regression. We need to resolve several problems in identifying the areas of habitat and the catchment areas into which murrelets were likely to be going inland of each radar station. Problems with the GIS databases are discussed in the previous section. We suspect that the area that is accessible to birds flying up a watershed is not well defined where the topography is less mountainous, as is the case on SW Vancouver Island. This may have resulted in the watershed boundaries being a poor representation of the total amount of habitat available to these birds. We plan to use GIS hydrology tools as one component in determining a more useful model of habitat availability in the coming year. John Deal (CANFOR pers. comm.) also considers this an important topic of investigation on Northern Vancouver Island.
4.4 Marine and Inland Habitat and Behaviour Study Rob Ronconi has completed the first of three field seasons in his study and his data and analysis are therefore incomplete. Preliminary analysis shows strong spatial affinities for specific foraging areas along the WCT coast, an area supporting one of the densest populations of Marbled Murrelets in British Columbia (Burger 2002). Ronconi’s continued research into marine habitats and prey availability will help explain the spatial distributions of foraging murrelets. These field data will then be integrated into a larger GIS modeling study incorporating additional spatial and habitat data from both marine and terrestrial sources. Ultimately we hope to demonstrate whether marine factors or nesting habitat parameters are limiting murrelet populations and spatial distribution. This has been identified by the Marbled Murrelet Recovery Team as important information needed for the overall conservation and management of murrelets.
5 CONCLUSIONS AND MANAGEMENT IMPLICATIONS
Although our radar/habitat project has been running for three years (2002-2005), full funding (mainly from our FSP grant) was not available until the field season of 2004.
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Consequently the project needs to continue in 2005-06 to provide adequate multi-year radar counts and improved GIS analysis of likely nesting habitat. Although we have exceeded our goals of sampling 30 watersheds or flight paths, much of our early effort was directed at testing radar stations, some of which proved to be unsuitable because of access problems, unexpected flight paths used by the murrelets, or unsuitable location for the radar unit. By the end of the 2005 field season we will have sufficient data from most of the suitable stations to provide a rigorous habitat analysis (e.g., Burger 2001) and solid baseline for future population monitoring (Arcese et al. 2005). As outlined above and in Appendix 2, our GIS habitat analysis was hampered in 2004-05 by the late delivery of the FSP funds. Nevertheless we were able to assemble much of the GIS data required for habitat analysis and perform preliminary mapping of habitat and comparisons of habitat with murrelet counts. Work in 2005 will focus on improving the quality and coverage of GIS data, refining habitat algorithms to predict likely nesting habitat, using hydrology tools and other GIS software to improve our estimate of the likely catchment areas for murrelets associated with each radar station and hence allow a more rigorous analysis of the associations between murrelet numbers and habitat area. Our data already allow some priorities to be set for the maintenance of nesting habitats for Marbled Murrelet on southwest Vancouver Island. Our radar counts have identified watersheds which support large sub-populations of murrelets. Some of these watersheds are currently undergoing management reviews and our data are therefore important in the current management of these forests. We have already provided these data on the Henderson, Lucky Creek, and Toquart valleys to forest management authorities (BC Ministry of Water, Land & Air Protection, Nanaimo; BC Timber Sales) as part of the Arrowsmith Timber Supply Review covering these drainages. As documented in section 8.3 we have also frequently provided both formal (papers, reports, presentations, workshops) and informal (meetings, phone calls, e-mails) input into the management of Marbled Murrelets and their habitat for much of their BC range. In the longer term we have laid the groundwork for ongoing population monitoring following the procedures recommended for British Columbia by Arcese et al. (2005) and the Canadian Marbled Murrelet Recovery Team (MMRT 2003). Once we have resolved the definitions of likely catchment areas and improved our habitat algorithm, we will re-calculate our estimates of density. Density measures are helpful in management of murrelets, either for determining the amounts of forest needed to maintain target populations of murrelets, or for estimating the likely populations using protected areas (e.g., Carmanah-Walbran Provincial Park, Pacific Rim National Park Reserve) and other areas of maintained habitat. These are goals identified as important in the draft Marbled Murrelet Recovery Plan (2005 draft under review) and Marbled Murrelet Nesting Habitat Action Plan (draft completed April 2005).
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6 ACKNOWLEDGMENTS
We gratefully acknowledge the major funding from the Forest Science Program for this research. Additional funding came from the Endangered Species Recovery Fund (World Wildlife Fund Canada and Canadian Wildlife Service), NSERC Discovery Grant to AEB, Canadian Wildlife Service, NSERC scholarship to RAR, and Society of Canadian Ornithologists award to RAR. Dr. Doug Bertram kindly facilitated funding from the Canadian Wildlife Service. The University of Victoria provided essential accounting, logistic, computer, library and office facilities. The Department of Geography kindly provided GIS lab facilities to Rick Page and we are particularly grateful to Drs. Peter Keller and Rosaline Canessa for this support. We thank 2004 field assistants Heather Milligan and Fern Wager for their excellent work and Derek Shaw (Oceania Research) for boat support in Barkley Sound. We thank the following for support of Rob Ronconi’s work on the West Coast Trail: Gerry and Janet Etzkorn of Carmanah Light Station, Canadian Coast Guard, Pacific Rim National Park Reserve and their wardens, especially Bob Hansen.
7 LITERATURE CITED
Arcese P., Bertram, B., Burger, A. E., Cullen, S., Deal, J., Gibbs, J., Fall, A., Harfenist, A., Harper, W., Jones, G., Lank, D., Lindsay, D., Manley, I., Selak, E., Runyan, S., Schroeder, B., Staudhamer, C., Steventon, D., and Sutherland, G. In prep. Monitoring designs to detect population declines and identify their causes in the Marbled Murrelet. Draft Journal Paper and Report to BC Ministry of Water, Land & Air Protection, Victoria, BC.
Burger, A. E. 1995. Marine distribution, abundance, and habitats of Marbled Murrelets in British Columbia. Pages 295-312 in Ecology and conservation of the Marbled Murrelet (C. J. Ralph, G. L. Hunt, Jr., M. G. Raphael and J. F. Piatt, eds.). Gen. Tech. Rep. PSW-GTR-152, Pacific Southwest Research Station, Forest Service, U.S. Dept. Agriculture, Albany, CA.
Burger, A. E. 1997. Behavior and numbers of Marbled Murrelets measured with radar. J. Field Ornithology 68:208-223.
Burger, A. E. 2001. Using radar to estimate populations and assess habitat associations of Marbled Murrelets. Journal of Wildlife Management 65:696-715.
Burger, A. E. 2002. Conservation assessment of Marbled Murrelets in British Columbia: review of the biology, populations, habitat associations, and conservation (Marbled Murrelet Conservation Assessment, Part A). Technical Report Series No. 387, Canadian Wildlife Service, Delta, BC. Available at: http://www.sfu.ca/biology/wildberg/bertram/mamurt/links.htm
Cooper, B. A., M. G. Raphael, and D. Evans Mack. 2001. Radar-based monitoring of marbled murrelets. Condor 103:219-229.
Manley, I. A., A. E. Burger, and B. K. Schroeder. 2005. Guidelines and data forms for collecting data during Marbled Murrelet radar surveys: recommendations for long-term monitoring. Draft report to Ministry of Water, Land and Air Protection.
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MMRT (Marbled Murrelet Recovery Team). 2003. Marbled Murrelet Conservation Assessment 2003, Part B – Marbled Murrelet Recovery Team advisory document on conservation and management. Canadian Wildlife Service, Delta, British Columbia. http://www.sfu.ca/biology/wildberg/bertram/mamurt/links.htm
Nelson, K. 1997. Marbled Murrelet (Brachyramphus marmoratus). In: Birds of North America, No. 276 (A. Poole and G. Gill, eds.). Academy of Natural Sciences, Philadelphia, and American Ornithologists’ Union, Washington, DC.
RIC (Resources Inventory Committee). 2001. Inventory methods for Marbled Murrelets in marine and terrestrial habitats, Version 2.0. Standards for components of British Columbia’s biodiversity, No. 10. Ministry of Environment, Lands and Parks, Resources Inventory Committee, Victoria, BC. (http://srmwww.gov.bc.ca/risc/pubs/tebiodiv/murrelet2k1)
Sealy, S.G. and H. R. Carter. 1984. At-sea distribution and nesting habitat of the Marbled Murrelet in British Columbia: problems in the conservation of a solitary seabird. Pp. 737-756 in Status and conservation of the world’s seabirds (J.P. Croxall, P.G.H. Evans and R.W. Schreiber, eds.). International Council of Bird Preservation Technical Publication No. 2., Cambridge, UK.
Tripp, T. 2001. A synopsis of Marbled Murrelet habitat suitability models in BC. Unpublished report to Ministry of Water, Land and Air Protection, Habitat Branch, Victoria, BC.
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8 APPENDICES AND PROJECT DELIVERABLES
8.1 Appendices to this report The following appendices have been submitted to the MOF Library as separate files. Appendix 1. Excel spreadsheet – radar database with dawn and dusk surveys. [file: Burger Appendix 1 Radar Database.xls] Appendix 2. Report on GIS Habitat Analysis (Page and Burger) [file: Burger Appendix 2 Page GIS Report.pdf Appendix 3. Report on Rob Ronconi’s graduate research 2004-05. [file: Burger Appendix 3 Ronconi Report.pdf]
8.2 Other project deliverables In addition to the appendices, the following products of our Marbled Murrelet research have been submitted to the MOF library as pdf files. Journal papers published, in press or completed draft Arcese P., Bertram, B., Burger, A. E., Cullen, S., Deal, J., Gibbs, J., Fall, A., Harfenist,
A., Harper, W., Jones, G., Lank, D., Lindsay, D., Manley, I., Selak, E., Runyan, S., Schroeder, B., Staudhamer, C., Steventon, D., and Sutherland, G. In prep. Monitoring designs to detect population declines and identify their causes in the Marbled Murrelet. Draft Journal Paper and Report to BC Ministry of Water, Land & Air Protection, Victoria, BC. [file: Arcese et al. Monitoring Draft Paper.pdf]
Burger, A. E., T. A. Chatwin, S. A. Cullen, N. P. Holmes, I. A. Manley, M. H. Mather, B. K. Schroeder, J. D. Steventon, J. E. Duncan, P. Arcese, and E. Selak. 2004. Application of radar surveys in the management of nesting habitat of Marbled Murrelets Brachyramphus marmoratus. Marine Ornithology 32:1-11. [file: Burger et al. 2004 MO MaMu BC Radar.pdf]
Burger, A.E., M.M. Masselink, A.R. Tillmanns, A.R. Szabo, M. Farnholtz, and M.J. Krkosek. In press. Effects of habitat fragmentation and forest edges on predators of marbled murrelets and other forest birds on southwest Vancouver Island. In T.D. Hooper, editor. Proceedings of the Species at Risk 2004 Pathways to Recovery Conference. March 2-6, 2004, Victoria, BC. [file: Burger et al._final_SAR MaMu.pdf]
Burger, A. E., R. E. Page, C. J. Conroy, and B.K. Schroeder. In prep. Application of radar counts and forest cover GIS data to assess habitat associations of Marbled Murrelets breeding on southwest Vancouver Island. Journal paper in prep. [file: Burger et al. SWVI MaMu paper.pdf]
Additional report Manley, I. A., A. E. Burger, and B. K. Schroeder. 2005. Guidelines and data forms for
collecting data during Marbled Murrelet radar surveys: recommendations for
Marbled Murrelet FSP Project Y051061 15
long-term monitoring. Draft report to Ministry of Water, Land and Air Protection. [file: RadarSurvey Protocol 25 Mar05.pdf]
8.3 Extension, presentations and management contributions Extension Note linked with this FSP project Burger, A. E. 2004. Radar a useful tool for managing Marbled Murrelets. Link (FORREX
newsletter. Forest Research Extension Partnership, Kamloops, BC.) 6(2) p. 7. . [file submitted to MOF Library: Burger FORREX radar 2004 vol6.pdf]
Web-site As proposed we have set up a web site with descriptions of our Marbled Murrelet research, background material, pdf copies of our completed reports and publications, and links to other relevant sites for Marbled Murrelet management and conservation. http://web.uvic.ca/~mamu/ Presentations at conferences, workshops and public meetings Burger, A. E. Interactions of seabirds, plankton and schooling fish off southwest
Vancouver Island. Western Juan de Fuca Ecosystem Symposium. Institute of Ocean Sciences, Sidney, BC. May 2004.
Burger, A. E. Application of radar surveys in the management of nesting habitat for Marbled Murrelets in British Columbia. American Ornithologist’s Union, Quebec City. Aug 2004.
Burger, A. E. Radar and other methods for studying habitat of the Marbled Murrelet on Vancouver Island. Vancouver Island Region Wildlife Management Society. Lake Cowichan, BC. Jan 2005
Burger, A. E. Biology and Conservation of Marbled Murrelets. Pacific Rim Marine Wildlife Community Forum, Ucluelet, BC. March 2005.
Burger, A.E., D. F. Bertram & P. Arcese. Trends in habitat areas and populations of Marbled Murrelets in British Columbia. Pacific Seabird Group and Waterbird Society conference, Portland, Oregon. Jan 2005.
Page, R. Using GIS hydrology tools to model habitat of a threatened species: the Marbled Murrelet on Vancouver Island. University of Victoria, Department of Geography colloquium. March 2005.
Ronconi, R.A. & A.E. Burger. Towards identifying important marine habitat for marbled murrelets along the West Coast Trail. West Coast Vancouver Island Species at Risk Workshop, Bamfield Marine Sciences Centre, Bamfield BC. June 2004
Ronconi, R.A. & A.E. Burger. Activity budgets of marbled murrelets at-sea in southwestern Vancouver Island. Pacific Ecology and Evolution Retreat, Brackendale, BC. Oct. 2004.
Ronconi, R.A. Studying a Pacific enigma: the mysterious life of fogbirds at sea. 24th Annual Vertebrate Symposium, University of Victoria. Nov. 2004.
Ronconi, R. & A. E. Burger. Spatial distribution and activities of Marbled Murrelets off SW Vancouver Island. Canadian Wildlife Service Waterbird Meeting, Victoria, BC. Nov. 2004.
Marbled Murrelet FSP Project Y051061 16
Ronconi, R.A. Marbled Murrelets at sea: a Pacific enigma. Vancouver Island Region Wildlife Management Society. Lake Cowichan, BC. Jan 2005
Ronconi, R. & A.E. Burger. New techniques for mapping fine-scale distributions of birds at sea: a case study investigating competition between murres and murrelets. Pacific Seabird Group and Waterbird Society conference, Portland, Oregon. Jan 2005.
Workshops and Recovery Team contributions A.E. Burger contributed the following: • Marbled Murrelet Recovery Team – meetings and conference calls: 15 April 2004; 6
May 2004; 9 Sep 2004; 28 Oct 2004; 2 Dec 2004; 28 Jan 2005; 4 Mar 2005. • Contributed to Marbled Murrelet Recovery Strategy – submitted for review April
2005. • Marbled Murrelet Nesting Habitat Recovery Implementation Group – meetings and
conference calls: 29 Sep 2004; 27 Oct 2004; 1 Dec 2004; 27 Jan 2005; 3 Mar 2005; 17 Mar 2005.
• Drafted the Marbled Murrelet Nesting Habitat Action Plan for the Marbled Murrelet Recovery Team – draft and revisions completed 20 Apr 2005.
• Workshop on Monitoring Marbled Murrelets using radar in British Columbia. University of British Columbia. 13-14 May 2004.
• Reviewed the Marbled Murrelet 5-year Progress Review within the U.S. Northwest Forest Plan, USF&WS.
• Reviewed and re-wrote Marbled Murrelet status report for the BC Conservation Data Centre, Ministry of Sustainable Resource Management, Victoria, BC.
Consultations on Marbled Murrelet Management In 2004-2005 our team contributed directly to the management of Marbled Murrelets through these channels: • BC Ministry of Forests (Louise Waterhouse, Nanaimo; Doug Steventon, Smithers); • Ministry of Water, Land and Air Protection (Stewart Guy, Victoria; Trudy Chatwin,
Nanaimo; David Donald, Campbell River; Anne Hetherington, Smithers; Alvin Cober, Queen Charlotte Islands);
• Forest Practices Board (on murrelet issues in two parts of BC); • Canadian Wildlife Service (Dr. Doug Bertram); • Parks Canada (Bob Hansen and Danielle Bellefleur, Ucluelet; Cliff Robinson,
Vancouver); • BC Timber Sales – Arrowsmith Timber Supply Area (Laurie McCulligh) • BC Conservation Data Centre MSRM (Leah Ramsay) • Manning Cooper environmental consultants (John Cooper, Errington); • EBA Engineering (Nanaimo) and Toquaht First Nation (Barkley Sound); • Vancouver Island Region Wildlife Society (First Nations, hunters and trappers).
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Table 1. Location of radar stations used in 2002-2004 and number of completed dawn surveys at each site. Station UTM location No. of surveys per year code Station location NAD Easting Northing 2002 2003 2004 Total BAM01 Bamfield 83 343199 5411296 1 1 CAR01 Carmanah Point 83 371250 5385800 4 4 CAR02 Carmanah/Bonilla 83 372917 5388479 1 1 CAY01 Caycuse 83 376755 5405635 2 1 3 CHI01 China Creek Camp 83 368909 5446034 1 1 CHI02 China Creek Boat 83 369514 5444930 2 2 COL01 Coleman River (at Alberni Inlet) 83 363150 5428650 1 1 DAR01 Darling River 83 351962 5399571 1 2 1 4 EFI01 Effingham Inlet Boat #1 83 342125 5433550 1 1 EFI02 Effingham Inlet Boat #2 83 341760 5438740 1 1 EFI03 Effingham Estuary 83 341760 5438740 2 2 EFI04 Effingham Inlet Bypass 83 342125 5433550 1 1 FCA01 Franklin Camp 27 372800 5425750 2 2 FLK01 Francis Lake 27 375400 5423640 2 2 FRB01 Franklin River Boat (at Alberni Inlet) 83 366193 5439171 2 2 GOR01 Gordon River 27 396050 5381075 2 2 HAT01 Nitinat Hatchery 27 378950 5412850 2 2 KLA01 Klanawa River 83 359300 5402247 1 2 1 4 KLA02 Gorge Creek 83 356550 5404648 1 2 2 5 KLA03 Bottard Creek 83 352750 5403834 1 2 2 5 LUC01 Lucky Creek Boat 83 329650 5433000 1 2 3 MAC01 Macktush (site 1) 83 366165 5440525 1 1 MAC02 Macktush (site 2) 83 366500 5441500 1 1 MAG01 Maggie Lake 83 322076 5432324 1 2 3 NAH01 Nahmint Bay Road 83 363319 5436581 1 1 NAH02 Nahmint Lake (Upper Nahmint) 83 350481 5449741 1 2 3 NAH03 Nahmint Bay Boat 83 363306 5435657 1 1 NIT01 Nitinat Village (Nitinat River) 83 377002 5407534 2 1 3 NIT02 Nitinat Camp (Nitinat River) 27 377010 5407060 2 2 NUM01 Numukamis Bay (Carnation Creek) 83 352828 5419612 2 2 PAC01 Pachena Bay 83 344876 5406668 2 2 2 6 PIP01 Pipestem Boat 83 336650 5433100 1 1 2 RIT01 Ritherdon (at Alberni Inlet) 83 354758 5424010 1 1 SAR01 Sarita Log Sort (Sarita River) 83 350900 5416409 2 2 4 SAR02 Sarita Lake (Upper Sarita) 83 362555 5419169 1 1 SJN01 Port Renfrew Dock 27 395250 5378750 2 2 SNO01 Snow Creek (at North Sproat Lake) 83 341355 5460203 1 1 SOM01 Somass River 83 366296 5455522 1 1 SOM02 Alberni Quay (mouth Somass River) 83 367800 5455180 1 1 2 SPE01 Spencer Creek Boat (at Alberni Inlet) 83 361238 5426842 1 1 TOQ01 Toquart Log Sort 83 327454 5432622 1 1 TOQ02 Toquart Boat 83 329300 5434000 1 1 UCI01 Uchucklesit Boat (Henderson) 83 350250 5430950 1 2 3 USE01 Useless Inlet Boat 83 350104 5428027 1 1 WAL03 Walbran (Mid Walbran) 83 381750 5388250 1 2 2 5 Total no. of dawn surveys 25 30 43 98 No. of stations sampled 21 18 27 45
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Table 2. Mean and standard deviation (SD) of pre-sunrise radar counts of Marbled Murrelets at stations on southwest Vancouver Island, 2002-2004. At several stations murrelets were recorded flying in more than one flight path, shown as separate rows on the table. Many of these stations were sampled only once as exploratory surveys; see Table 3 for count data at reliable flight-paths. Sample size (N) is the number of dawn surveys. Flight paths marked with an asterisk are considered suitable for long-term monitoring. Station Station name (Watershed/Flight path) 2002 2003 2004 All years code Mean SD N Mean SD N Mean SD N Mean SD N BAM01 Bamfield (Trevor Channel) 36 1 36 1 CAR01 *Carmanah Point 114.5 61.0 4 114.5 61.0 4 CAR02 Carmanah/Bonilla 38 1 38 1 CAY01 *Caycuse (Caycuse River) 147.5 33.2 2 292 1 195.7 86.7 3 Caycuse (Nitinat Lake) 152 11.3 2 753 1 352.3 347.1 3 CHI01 China Creek Camp (Alberni Inlet) 10 1 10 1 China Creek Camp (China Creek) 2 1 2 1 CHI02 *China Creek Boat (overland to Creek) 269.5 293.4 2 269.5 293.4 2 China Creek Boat (up Alberni Inlet) 584 1 584 1 COL01 Coleman (Alberni Inlet) 191 1 191 1 *Coleman (Coleman) 6 1 6 1 DAR01 *Darling River 15 1 145.5 6.4 2 60 1 91.5 65.1 4 EFI01 *Effingham Inlet Boat #1 (Effingham) 180 1 180 1 Effingham Inlet Boat #1 (Skull Lake) 3 1 3 1 EFI02 Effingham Inlet Boat #2 (Effingham) 26 1 26 1 Effingham Inlet Boat #2 (No name Valley) 19 1 19 1 EFI03 Effingham Estuary (Brand Creek) 27 0.0 2 27 0.0 2 *Effingham Estuary (Effingham River) 20.5 9.2 2 20.5 9.2 2 Effingham Estuary (other) 27 1 27 1 EFI04 Effingham Inlet Bypass (East- Inlet) 129 1 129 1 Effingham Inlet Bypass (West- Skull L) 2 1 2 1 FCA01 *Franklin Camp ('Francis' Creek) 14 12.7 2 14 12.7 2 Franklin Camp (Main Valley - W and NW) 10.5 10.6 2 10.5 10.6 2 *Franklin Camp (North Coleman Creek) 18.5 23.3 2 18.5 23.3 2 FLK01 *Francis Lake ('Francis' Creek) 13.5 9.2 2 13.5 9.2 2 Francis Lake (main valley) 17 15.6 2 17 15.6 2 FRB01 Franklin River Boat (Alberni Inlet) 24 9.9 2 24 9.9 2
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*Franklin River Boat (Franklin) 35 1.4 2 35 1.4 2 GOR01 *Gordon River (Gordon) 167 169.7 2 167 169.7 2 Gordon River (South San Juan) 227.5 276.5 2 227.5 276.5 2 HAT01 *Nitinat Hatchery (Big Nitinat) 148 32.5 2 148 32.5 2 *Nitinat Hatchery (Little Nitinat) 120.5 20.5 2 120.5 20.5 2 Nitinat Hatchery (Worthless) 7 1 7 1 KLA01 *Klanawa River (Klanawa) 179 1 181 182.4 2 317 1 214.5 125.6 4 *Klanawa River (West Klanawa) 50.5 60.1 2 11 1 37.3 48.2 3 KLA02 *Gorge Creek 67 1 156.5 95.5 2 189.5 62.9 2 151.8 76.1 5 KLA03 *Bottard Creek 33 1 78 4.2 2 162.5 24.7 2 102.8 58.9 5 LUC01 *Lucky Creek Boat 234 1 270.5 112.4 2 258.3 82.2 3 MAC01 Macktush (Alberni Inlet) 14 1 14 1 Macktush (Macktush) 2 1 2 1 MAC02 Macktush (Alberni Inlet) 4 1 4 1 *Macktush (Macktush) 2 1 2 1 MAG01 *Maggie Lake 17 1 15.5 17.7 2 16 12.5 3 NAH01 Nahmint Bay Road 29 1 29 1 NAH02 *Nahmint Lake (Upper Nahmint) 55 1 31 7.1 2 39 14.7 3 NAH03 Nahmint Bay Boat (Nahmint) 119 1 119 1 NIT01 *Nitinat Village (Nitinat River) 254 72.1 2 559 1 355.7 183.3 3 NIT02 *Nitinat Camp (Nitinat River) 384.5 120.9 2 384.5 120.9 2 NUM01 *Numukamis Bay (Carnation Creek) 70 28.3 2 70 28.3 2 Numukamis Bay (Sarita North) 17 1 17 1 PAC01 *Pachena Bay 43 18.4 2 92 72.1 2 139.5 27.6 2 91.5 55.9 6 PIP01 *Pipestem Boat (Black Peaks) 35 1 7 1 21 19.8 2 Pipestem Boat (Skull Lake) 32 1 32 1 32 0.0 2 RIT01 Ritherdon (Alberni Inlet) 180 1 180 1 *Ritherdon (Ritherdon) 24 1 24 1 Ritherdon (San Mateo Bay - May Creek) 7 1 7 1 SAR01 *Sarita Log Sort (Sarita) 150.5 9.2 2 211 67.9 2 180.8 52.8 4 SAR02 Sarita Lake (Upper Sarita) 38 1 38 1 SJN01 *Port Renfrew Dock (San Juan River) 457 215.0 2 457 215.0 2 SNO01 Snow Creek (North Sproat Lake) 19 1 19 1 *Snow Creek (Snow Creek) 0 1 0 1 SOM01 *Somass River 4 1 4 1 SOM02 *Alberni Quay (Somass River) 0 1 7 1 3.5 4.9 2
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SPE01 Spencer Creek Boat (Alberni Inlet) 341 1 341 1 *Spencer Creek Boat (Spencer) 89 31.1 2 89 31.1 2 TOQ01 Toquart Log Sort (Lucky Creek) 20 1 20 1 *Toquart Log Sort (Toquart) 354 99.0 2 272 1 576 84.9 2 426.4 155.0 5 TOQ02 Toquart Boat (Lucky Creek) 3 1 3 1 Toquart Boat (Toquart) 193 1 193 1 UCI01 *Uchucklesit Boat (Henderson) 279 1 436 159.8 2 383.7 144.9 3 USE01 *Useless Inlet Boat (Henderson) 386 1 386 1 WAL03 *Walbran (Mid Walbran) 371 1 241 11.3 2 485 66.5 2 364.6 126.6 5 No. of flight paths or watersheds sampled 27 26 45 72 *Suitable for long-term monitoring
Table 3. Mean radar counts of Marbled Murrelets at reliable flight paths used to compare with GIS habitat data. Note that at some watersheds counts were made at two nearby stations but the murrelets were heading into the same watershed.
Station/Watershed code Watershed Mean SD No.
surveys PIP01_LC Black Peaks Valley 21.0 19.8 2 KLA03 Bottard Creek 120.3 50.9 4 EFI03_BC Brand Creek 27.0 0.0 2 CAR01 Carmanah Valley 87.3 33.9 3 NUM01_CC Carnation Creek 70.0 28.3 2 CAY01_CR Caycuse River 195.7 86.7 3 CHI01_CC China Creek 269.5 293.4 2 COL01_CC Coleman Creek 6.0 1 DAR01 Darling River 91.5 65.1 4 MAG01_E Maggie River/Draw Creek 16.0 12.5 3 EFI03_ER Effingham River 20.5 9.2 2 FRB01_FR Franklin River 35.0 1.4 2 GOR01_G Gordon River 287.0 1 KLA02 Gorge Creek 151.8 76.1 5 UCI01 & USE01 Henderson Lake 384.3 118.3 4 KLA01_KR Klanawa River 214.5 125.6 4 LUC01 Lucky Creek 258.3 82.2 3 MAC01_MC & MAC02_MC Macktush Creek 2.0 0.0 2 WAL03 Mid Walbran Valley 393.5 125.7 4 NIT01 & NIT02 Nitinat River 367.2 143.9 5 PAC01 Pachena River 101.6 56.0 5 RIT01_RC Ritherdon Creek 24.0 1 SJN01 & GOR01_S San Juan River 445.7 153.3 3 SAR01 Sarita River 180.8 52.8 4 SNO01_SC Snow Creek 0.0 1 SPE01_SC Spencer Creek 89.0 31.1 2 TOQ01_TR & TOQ02_TR Toquart River 387.5 168.2 6 NAH02 Upper Nahmint River 39.0 14.7 3 KLA01_WK West Klanawa 37.3 48.2 3 Sum of mean counts 4323.2 86 Total no. of sites 29
Figure 1. Map of the study area on southwest Vancouver Island showing the location of radar stations sampled in 2002-2004 and watershed boundaries. The size of the circle at each site indicates the mean number of Marbled Murrelets counted at the site, including all flight paths.
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Figure 2. Map showing the extent of forest considered to be likely nesting habitat for Marbled Murrelets on southwest Vancouver Island. The habitat was defined as either forest cover data falling within age class 8+ (>140 years) and height class 4+ (>28.5 m), or where these data were missing, as “Ancient Forest” within the satellite imagery analysis done by the Sierra Club in 1999.
A) Forest Cover MMRT algortihm
y = 0.0199x + 105.82R2 = 0.1914
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B) Sierra Club Ancient Forest
y = 0.027x + 84.18R2 = 0.2265
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Figure 3. Relationship between the number of Marbled Murrelets counted on radar at 23 watersheds on southwest Vancouver Island and the estimates of likely nesting habitat within the watersheds. Habitat was estimated from: A) the application of the MMRT (2003) algorithm applied to Forest Cover data; and B) areas of “Ancient Forest” derived from the Sierra Club satellite imagery analysis. Each point represents a watershed.
