BALD EAGLE NESTING RECORDS FOR THE CITY OF NANAIMO: 2003 2012
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BALD EAGLE NESTING RECORDS FOR THE CITY OF NANAIMO: 2003 – 2012
Introduction
The Bald Eagle is among the most charismatic and widely known species of wildlife in North America. Bald Eagles occur in
large numbers along the west coast of Canada and are symbolic of the natural world. In an effort to understand the habitat
needs of Bald Eagles, between 1987 and 1995 biologists with the Ministry of Environment, the Canadian Wildlife Service,
and several forest companies worked together to catalogue over 3,000 Bald Eagle nest sites around Vancouver Island, the
southern Gulf Islands, and in the lower Fraser Valley. In the late 1990’s the Wildlife Tree Stewardship Program (WiTS) was
created as a multi agency partnership supported by BC Hydro and administered by BC Nature (the Federation of BC
Naturalists) to maintain an on-line atlas and data-base of Bald Eagle nest observations on the Community Mapping Network
(http://www.cmnbc.ca/).
The information presented here is a summary of Bald Eagles nest records for the City of Nanaimo. It is hoped that this
report will encourage the inclusion of additional nest locations and nest observations. This report follows a series of similar
Bald Eagle nest reports produced by the WiTS program from 2009 to 2013 that cover other areas of Vancouver Island and
the Gulf Islands.
City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 1 of 12Bald Eagle Nesting Habitat Bald Eagles build large nests, often two metres across and weighing a few hundred kilograms. Along the east coast of Vancouver Island eagles prefer to nest in Douglas-fir, especially large veteran trees with a broken top or an open branch structure that will support a large nest. As coastal forests are cleared for residential construction, lone veteran nest trees are at increased risk for wind-throw, are considered as hazards and are often cut down. As eagles lose their Bald Eagle Tree Preference preferred nest trees they nest in smaller less suitable trees where nest failure due to Douglas-fir 64% collapsing tree limbs is common. Black cottonwood 13% Bald Eagles establish nesting territories which they defend for the nesting season and Grand-fir 8% periodically at other times of the year. Eagle territories are typically centred on Sitka spruce 8% prominent points of land or estuaries, sites where currents are disrupted and fish and Big-leaf maple 4% waterfowl are concentrated. The ideal nesting site for Bald Eagles is a tall tree where Garry oak 1% they can both look after their chicks and view the ocean for their next meal. Western hemlock
Methods
The health and wellbeing of local Bald Eagle populations is measured as the number of eagle chicks produced per year per territory
(Potupalski 1974; and Sprunt et al.1973). Biologists group eagle nests into territories based on observations of nesting activity
records over several years. Eagle nesting territories can shift in location, be divided and merged over time. The WiTS program
follows a scientific method laid out by Sergej Postupalsky in 1974.
Nests are visited at least twice each year, primarily by WiTS volunteer monitors. The first nest visit is to determine whether a
nesting territory is occupied, the second visit to determine presence of chicks.
The first observation, between the 15th of March and 30th of April, is timed for early in the nesting season when the presence of
eagles near a nest should represent the commitment to a nesting attempt. At this time, the presence of eagles on or near a nest
would receive an “Active” score. If the eagles are in the immediate area, though clearly not on or near a nest, a score of “Occupied
Territory” would be given with the assumption that the pair is defending the territory and likely nesting in an alternate nest.
The second observation, between the 15th of June and 31st of July, is timed for late in the nesting season to count the number of
eagle chicks before they leave the nest.
Depending on foliage and the visibility of a nest it will often take more than two nest site visits to get a good observation.
The importance of the timing in the two visit method centres on eliminating bias when scoring nesting success or
failure. For example, if a nest is empty late in the nesting season, unless there was a previous observation earlier in
the season there would be no way to determine if the nest was not used that year or if a nesting attempt had failed
early and the adult birds had left. If a site visit is made mid season and chicks are present it is not possible to predict if
the chicks will survive to the point when they would naturally leave the nest.
Nest observations outside of the prescribed periods are useful for a basic determination of nest use. These are shown in pink
highlight on the summary tables in this report. Most WiTS nest tree monitors keep a casual eye on the nests throughout the year
and are encouraged to record all their observations.
City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 3 of 12Bald Eagle Nest Locations and Nesting Records The WiTS Bald Eagle data base has records for 58 Bald Eagle nest sites in the City of Nanaimo. Nest locations are found primarily along the coast of Vancouver Island (Map 1). There are some inland nest sites: three near Westwood Lake; two at Brannen Lake and one at Long Lake. Records of known Bald Eagle nest trees in the City of Nanaimo were compiled over the last ten years and presented in Tables 1, 2 and 3. With a quick glance at the tables one may conclude that there is a lot of missing information and little continuity over the years. Around 13% of boxes in the tables have information, and of those only one record followed the prescribed methodology (that there be at least two nest visits each year during the nesting season, one in the early spring one near the time the chick are ready to fledge). Compared to other areas on Vancouver Island information on nest trees in the City of Nanaimo is very low. In the Comox Valley, looking at a similar compilation of nest records, we have 43% of the potential records and of those almost half have followed the described methodology. On the Saanich Peninsula we have 45% of the potential records with 96% of these following the described methodology. Compiling and tabulating the eagle nest records has two purposes: 1) to provide information on eagle nest locations to the local and provincial governments for use in planning and land-use decisions; and 2) to present the nest records for the nest monitors to see what information has been collected and what information is missing. It is hoped that local naturalists and other citizens with Bald Eagle nest information may share what they know and help fill in some of the missing information. City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 4 of 12
Map 1: Bald Eagle nest locations in the City of Nanaimo City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 5 of 12
Table 1: Summary of Bald Eagle Nest Observations in South portion of the City of Nanaimo City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 6 of 12
Table 2: Summary of Bald Eagle Nest Observations in central portion of the City of Nanaimo City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 7 of 12
Table 3: Summary of Bald Eagle Nest Observations in north portion of the City of Nanaimo City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 8 of 12
Bald Eagle Nesting Productivity
Across North America, measuring the production of young at Bald Eagle nests is based on a common method that records the
number of chicks raised to fledging in each occupied territory (Postupalsky 1974). It is thought that, on average, the fledging of 0.7
eagle chicks per occupied territory per year is necessary to sustain a local population (Sprunt et al. 1973). We have insufficient
information available to evaluate Number of eagle chicks
the production of young eagles in Years Nest success fledged per occupied
the City of Nanaimo. In the Capital territory
Regional District, to the south, the
Capital Regional District 2001 – 2010 71.8 % 1.16
production of eagle chicks is higher
Comox Valley Regional District 2000 - 2009 64.2% 0.9
than is thought needed to sustain
Strathcona Regional District 2000 - 2007 51.4% 0.7
the population. In more northern
areas along the east coast of Vancouver Island there are less eagle chicks produced, but the numbers are still what are deemed
necessary to maintain the population.
Health and Vitality of the Bald Eagle Population and Local Natural Systems
The success and vitality of Bald Eagles, one of the top predators in the food chain, is a good measure of the health of the natural
systems in any local area. Without the top predators the natural checks and balances of nature give way to unnatural abundances
and ill health of many species lower in the food chain. At the same time, an overabundance of eagles due to feeding by local
residents and the availability of non natural food sources such as garbage can result in problems which include: injury and death of
eagles due to fighting, poisonings, eagle predation upon pets and livestock, and eagles unintentionally injuring people as they go for
food. In the past 20 years Bald Eagles have had a negative impact on nesting Great Blue Herons and cormorants in the Vancouver
Island area.
City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 9 of 12Legal Protection of Bald Eagle Nests
x All Bald Eagle nests in British Columbia are protected under Section 34 of the provincial Wildlife Act regardless
of land tenure.
x The Wildlife Act provides year-round protection for Bald Eagle nests whether or not the eagles are using the
nests.
x Protection extends to the tree that the eagle nest is situated in.
x When eagle nests are occupied during the nesting season, the Wildlife Act protects the birds, their nest and
eggs from being molested – therefore it can be extended to more than the tree, as disturbance in the vicinity
that directly causes abandonment of the nest could be determined to be molestation.
While some eagle nest trees are located in parks or conservation lands, most are found on private land and may be additionally
protected through local bylaws. Some local governments on Vancouver Island have included Bald Eagle nest protection in their
Official Community Plans (OCPs) and have created Development Permit Areas (DPAs) around nest trees. These DPAs require the
landowner or developer to consult with a Qualified Environmental Professional to guide construction practices to not disturb the
nesting eagles or damage the nest trees. Following Provincial Develop with Care Guidelines (Ministry of Environment 2006)
construction activities may be timed to avoid disturbing the eagles, surrounding vegetation may be protected, and consideration
given to changes in the water table to assure that nest trees will not suffer. In rural electoral areas of the Comox Valley Regional
District and the Strathcona Regional Districts, DPAs cover 200m around the base of each nest tree. In a more urban jurisdiction, the
City of Campbell River, DPAs cover 60m around the base of each nest tree. In March of 2012 the District of Saanich created 60m
Environmental Development Permit Areas around identified Bald Eagle nest trees.
In municipal jurisdictions with DPAs around identified Bald Eagle nest trees, a key component is
to know the location of the nests and if the nests are being used by the eagles
City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 10 of 12Disturbance of Nesting Bald Eagles
Bald Eagles are most susceptible to disturbance when human activity patterns near their nests are changed. In remote areas, the
presence of a hiker, a forestry worker, a biologist, or even a boat landing at the shore a few hundred metres from a nest tree may be
all that is needed to flush eagles from their nest. While Bald Eagles living in more populated areas such as the Strait of Georgia
appear to habituate to the proximity of human settlement and activity, each pair is unique. Some eagles choose to nest by busy
highways and seem totally oblivious to constant noise and traffic, though may be highly disturbed by someone walking near the base
of their nest tree. Eagles nesting in a residential neighbourhood may not appear to notice the local residents working in their
gardens but might be very disturbed if someone starts ripping off and replacing a roof. Bald Eagles most often will abandon their
nests if disturbed early in the nesting season before bonding with their chicks.
Guidelines to behaviour in the vicinity of eagle nests may be found in a provincial Develop with Care publication at:
http://www.env.gov.bc.ca/wld/documents/bmp/devwithcare2006/DWC%202006%20Sec%205-1%20VI%20Region.pdf
Funding for the WiTS Program
Funding for the WiTS program on Vancouver Island comes from nest site inventory and mapping contracts and from grants to fund a
coordinator to support volunteer nest tree monitors and to provide educational outreach. A great deal more could be done to
support monitors with secure funding. Volunteer monitors need training, encouragement, recognition for their work, and evidence
that the data they collect is being used in a meaningful way.
City of Nanaimo Bald Eagle Inventory 2003 – 2012 Page 11 of 12Acknowledgments
Funding to produce this report was provided by a Community Gaming Grant awarded by the BC Gaming Policy and Enforcement
Branch.
The WiTS program is a partnership between The Ministry of Forests, Lands and Natural Resource Operations, Environment Canada
(Canadian Wildlife Service) and BC Nature (The Federation of BC Naturalists). The nest records are available for public viewing on
The Community Mapping Network at (http://cmnmaps.ca/wits/). The WiTS program is a legacy to the Bald Eagle conservation work by
Ministry of Environment staff Rick Davies (deceased) and Karen Morrison (retired). Gretchen Harlow, Karen Morrison, Kerri-Lynne
Wilson and Ron Speller were instrumental in setting up the WITS program in this area. Terri Martin made all of the original site
visits.
Nest observations reported in the WiTS Atlas over the past 10 years in the City of Nanaimo were received from volunteer wildlife
tree stewards: Karen Barry, Bruce Cousens, Doug Gow, Sandra Gray, Maggie Henigman, Brian Kabaluk, Charlene Lee, Craig
McLennan, Ian Moul, and Trystan Willmott.
This report was prepared by Ian Moul, RPBio. Thank-you to Bev Ramey and Karen Morrison for reviewing earlier drafts.
Literature Cited
Postupalski, S. 1974. Raptor reproductive success: some problems with methods, criteria and terminology. Raptor Research Reports.
2:21-31.
Sprunt, A., W.B. Robertson, S. Postupalsky, R.J. Hensel, C.E. Knoder, and F.J. Ligas 1973. Comparative productivity of six Bald Eagle
populations. Transaction of the North American Wildlife and Natural Resources Conference 38:96-106.
Recommended Citation:
WiTS 2013. Bald Eagle Nesting Results: City of Nanaimo, Vancouver Island. Wildlife Tree Stewardship Program Local Area Report
2013:2
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