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 Version 1  March 31, 2000

Prepared for Lester B. Pearson College and the Department of Fisheries and Oceans,
with support from the Department of the Environment, Canadian Wildlife Service
by Joanna Smith, jlsmith@intergate.bc.ca

INTRODUCTION

    Long-term monitoring is a widely recognized method to examine population trends. Monitoring is a particularly useful tool for examining trends in marine bird populations because it encompasses long-term environmental and biological variation. Essentially, monitoring is repeated observations over time to determine the state of a system. It is important that protocols are designed in such a way that variables are easily measured and address the specific project objectives.

    In this document, the term marine birds refers generally to those birds that forage in or near the ocean and breed in close proximity to it (e.g. gulls, cormorants, oystercatchers and guillemots). Marine birds are generally long-lived, have low reproductive output and are characterised with delayed maturity such that many species do not begin to breed until they are between 5 and 6 years of age.

    A long-term monitoring program for nesting marine birds on Race Rocks Ecological Reserve has been established for Lester B. Pearson College of the Pacific and the Department of Fisheries and Oceans by the Canadian Wildlife Service. The objectives of this program are to collect reliable scientific data that can be used to 1) assess trends in marine bird abundance and recruitment at Race Rocks Ecological Reserve; 2) provide information for province-wide analyses of birds trends, particularly species of concern and 3) provide educational opportunities to students of Pearson College.

    Further information regarding the inventory and monitoring of seabird colonies can be found in An Inventory Manual for seabirds at sea and at colonies in British Columbia (Resource Inventory Committee, 1995, by Alan Burger and Andrea Lawrence). This manual is a draft but can be downloaded from http://www.elp.gov.bc.ca/rib/wis/spi/ric_manuals.htm.

  1. Visits to Seabird Colonies

Seabird colonies are usually difficult to access and in British Columbia, are often protected as Ecological Reserves, Provincial and National Parks or Reserves. Surface nesting birds are very sensitive to disturbance and will leave their nest when humans approach, leaving eggs and chicks vulnerable to predation from gulls, crows, eagles and other predators.

It is important to minimise visits and disturbances to colonies because the breeding success of a species can be greatly affected by the presence of people. The following suggestions will reduce the impact the investigator and visitors will have on the breeding success birds at Race Rocks:

  • Colony surveys should be undertaken by experienced observers or those working within an established program.
  • Individuals doing the surveys should be well-organised and remain in the colony for the least amount of time possible.
  • Chicks and eggs should not be handled.
  • Investigators should keep at least 30 m away from nesting cormorants. Cormorants are extremely sensitive to disturbance.
  • Sea-kayaks and other boats not associated with a monitoring or inventory program should remain at distances greater than 100m from nesting birds.
  1. long-term MONITORING AT RACE ROCKS
  • Develop observation data sheets or use those displayed in the Appendix (RRR 1-6). Data sheets for field should be printed on waterproof paper.
  • Record all observations with as much information, and as accurately as possible. Include the date, location, time, observer(s), weather and any other relevant information.
  • Make notes of other species seen at the colony (e.g. eagles, crows, river otter, marine mammals) or signs of their presence (scat, tracks, location of dens, predated birds or eggs).
  • As far as possible, count every bird during a survey. In the case where there are hundreds of birds, count off a ‘block’ of 10-25 birds, then visually repeat this block across the flock.
  • Record both the presence and absence of observations. For example, "0 eggs" means that later someone will know that eggs for looked for but none were found.
  • Record nest contents as follows:

:Start - nest incomplete but evidence of fresh construction

:Empty - nest complete and freshly built but empty

:1E, 2E, 3E ...etc. - contains 1,2,3, etc. ...eggs

:1Y, 2Y, 3Y ...etc. - contains 1,2,3, etc. ...chicks

:1Y2E...........etc. - contains 1 chick and 2 eggs...etc.

  • If recording anecdotal information, note the date and the name of person that supplied the information.
  • Organize completed data sheets by species and by year.
  • Enter all data onto a computer spreadsheet or database after it is collected (e.g. Excel). Back-up data to disc and make hard copies.
  • In this manual, dates for surveys have been approximated from reported laying and hatching dates in areas outside the Juan de Fuca Strait. Dates may need to be adjusted if laying is earlier or later on Race Rocks than these other areas.
  • At the end of the field season, send summaries of breeding information and any band records to the: Canadian Wildlife Service, 5421 Robertson Road, RR #1, Delta, B.C., V4K 3N2.
  1. daily bird CHECKLIST

Objective

To record the presence of birds on or near Race Rocks Ecological Reserve.

Timing: January - December

Frequency :Daily

MATERIALS

Data sheet (RRR-6), notebook and pencil

Binoculars

20x spotting scope (optional but useful)

Bird book

METHODS

Throughout the day, note all birds seen and/or heard on or around Race Rocks and the surrounding islets. If a boat trip is made, note species seen and/or heard.

  1. Each day, tick off birds (Ö ) that were seen and/or heard on or immediately around Race Rocks and surrounding islets. This indicates birds actually using Race Rocks either as a breeding site, seasonal residence, or stopover.
  2. Birds that fly overhead or are outside the boundaries of the reserve can be noted in the comments.
  3. Add up the number of species seen each day.
  4. At the end of the month, calculate the average number of species seen each day. Add all of the daily totals together then divide by the number of days that counts were made.
  5. Make a note of the day that the highest numbers of species were seen each month.
  6. Record all data on RACE ROCKS DAILY CHECKLIST
  1. Survey methods for marine birds

    GLAUCOUS-WINGED GULL

Larus glaucescens

[GWGU]

LIFE HISTORY

Sexes similar. Variable four-year gull. Long-lived. Territorial. Chicks are semi-precocial. Constructs nests of grassy material. Will re-use nest from previous year. Laying: begins late May - late June. Clutch size: 2-3 eggs. Incubation: 25-28 days from last egg. Will re-lay if lose first clutch. Hatch: late June to early July. Chicks fledge: July - August. Opportunistic scavenger, predator on land, as well as surface feeder. Sensitive to human disturbance.

STATUS

Abundant, widespread breeders in all coastal habitats (Campbell et al. 1990a). Over the last 50 years, the population of Glaucous-winged Gulls in British Columbia has increased in numbers by about 3.5 times, and is expanding into new habitats, often near urban environments. However, recent surveys have found that some colonies are experiencing local declines. Within the Strait of Georgia, the number of nesting GWGU has declined by almost 16% (Sullivan and Hazlitt, pers. comm).

OBJECTIVES

  1. To census the population of Glaucous-winged Gulls on Race Rocks Ecological Reserve.
  2. To determine the approximate timing of breeding.
  3. To estimate number of eggs and hatching success.
  4. To estimate chick survival.

TIMING

May - July

Frequency

Initial visit in May, 1-2 day colony survey in June and July.

MATERIALS

Waterproof data sheets (RRR-1), notebook and pencil

Aerial photo and/or waterproof map of Race Rocks to mark nesting locations

METHODS

During the third week of May, note if laying is underway. Visit all GWGU nests beginning 15-21 June (earlier or later depending upon the year).

  1. Map the colony. Use aerial photos(preferred), topographic or field sketch maps.
  2. Count the number of adult and juvenile gulls on the colony before counting nests.
  3. Record the presence of Bald Eagles, crows, otters, etc. in the Comments section.
  4. Walk steadily through the colony, systematically counting all nests. Use 1-3 people.
  5. Look carefully in all rock cracks and hollows for nests, as well as in grass and other vegetation.
  6. Cover entire colony and avoiding double counting.
  7. Record nest contents (see Section 3: Long-term monitoring).
  8. Note the number of eggs predated.
  9. Be careful not to step on nests or chicks while surveying in dense vegetation.
  10. To measure hatching success, visit the colony 25 days after the last egg survey and count the total number of chicks. Do not worry if chicks cannot be attributed to a particular nest.

Notes

  1. It is preferable to do the first nest count before chicks hatch. However, if the count is done too early, gulls will still have 1-2 eggs to lay. A second nest survey can be done 2-3 weeks later to account for late nesters and for other birds that have lost their first clutch.
  2. It may be desirable to wear a hat when in a gull colony for protection. When gulls defend their nest, they may fly at you from behind. Putting a stick in your hat can help prevent gulls from getting too close.
    1. BLACK OYSTERCATCHER

Haematopus bachmani

[BLOY]

 See this file on the Black oystercatchers food requirements

LIFE HISTORY

Sexes similar. Females have slightly heavier, longer bills and males have slightly thicker, redder bills. Long-lived. Solitary nesters. Territorial. Begin to breed at 2+ years. Chicks are precocial. Eggs are laid in an open scrape, lined with small rocks and shells. Nest sites usually re-used each year. Clutch size: 1 - 3 eggs. Incubation: 26-32 days after clutch complete. Will lay second clutch if lose first. Nestling period: up to 4 months. Chicks are fed near the nest by both parents initially, then within the pair’s territory. Parents and chicks feed on intertidal invertebrates, especially mussels, chitons and limpets. Sensitive to human disturbance.

STATUS

High regional priority species. Internationally significant populations in B.C. with estimated 30-35% of global population occurring here. Global population (estimated at less than 11,000 birds) is likely stable but regional declines especially in areas of high human disturbance. Identification and protection of breeding sites a priority in British Columbia (Hazlitt, S. pers. comm.)

OBJECTIVES

  1. To census the population of Black Oystercatchers on Race Rocks Ecological Reserve.
  2. To determine the approximate timing of breeding.
  3. To estimate productivity.
  4. To estimate chick survival.

TIMING

May - August

Frequency

3-4 surveys per season, each lasting 1-2 days

MATERIALS

Waterproof data sheets (RRR-2), notebook and pencil

Aerial photo and/or waterproof map of Race Rocks to mark nest locations

GPS unit to assist in accurate positioning of nests on map

Spotting scope to look for bands

METHODS

Each year, survey all Black Oystercatcher nests on Race Rocks and surrounding islets. Conduct surveys during high tide and calm weather. Look for all known and any new nest sites. Your presence near a nest may increase the chance of predation so only visit nest areas to survey contents, thereby minimising disturbance.

  1. Conduct first survey from 20-30 May to look for nest-holding pairs. Look for new pairs.
  2. Record number of adults seen at each nest.
  3. Map the location of all known and new nests. Estimate the distance to the nearest Glaucous-winged Gulls nest.
  4. Conduct second survey from 8-15 June. Visit all nest sites and examine nests for eggs.
  5. Record the contents of each nest and note number of adults present.
  6. Conduct third survey from late June to early July. Visit all nests for eggs and chicks (see notes below).
  7. Record the contents of each nest, including empty nests.
  8. On all surveys, check for leg bands on adults and record the colour, sequence and banded leg.
  9. Kayaks and other vessels visiting Race Rocks should keep well clear (> 100 m) of the nesting Black Oystercatchers.

Notes

  1. Look for chicks during high tide because less territory is available to them. Estimate the number of chicks near each nest.
  2. To search for chicks, initially watch parents from a distance of about 20-30 m for 5 to 10 minutes to narrow down the potential search area.
  3. Finding chicks can be tricky. They are well camouflaged. Once the parent gives an alarm call, chicks instinctively hide in cracks, crevices and even seaweed. Once in a hiding spot, the chicks will remain motionless until the parent gives an "all clear" signal.
  4. Once the chicks are motionless, begin your search.
  5. If you haven’t located the chicks after about 10 minutes, move away and hide again. Usually the adults will rejoin chicks after about 10 minutes and you can start the search over.
    1. PIGEON GUILLEMOT

Cepphus columba

[PIGU]

LIFE HISTORY

Sexes alike. Semi-colonial. Nests in natural rock piles, cliff cracks and under piles of debris. Chicks are semi-precocial. Clutch size: 1-2 eggs. Laying: begins late May to early July. Incubation: first egg 32 days, second egg 29 days. Nestling period: 38 days. Diet: fish, crab, shrimp, other marine invertebrates. Sensitive to human disturbance.

STATUS

Locally abundant to very abundant summer visitor and fairly common to common post-breeder in fall. Widespread coastal breeder (Campbell et al. 1990b). Previous colony counts on Race Rocks: 1977 - 14 birds, 1974 - 400 birds, 1987 - 78 birds (Campbell et al. 1990b).

OBJECTIVE

To estimate the number of breeding Pigeon Guillemots on Race Rocks Ecological Reserve.

TIMING

May - August

Frequency

Initial count in May, 3-4 days of colony survey in July and August

MATERIALS

Waterproof data sheets (RRR-3), notebook and pencil

Aerial photo and/or waterproof map of Race Rocks to mark nest locations

GPS unit to assist in accurate positioning of nests on map

METHODS

Pigeon Guillemots nests are widely dispersed and difficult to locate. It is generally not possible to determine the number of nests and breeding pairs by direct counts. No nest checks will be made in this monitoring program.

  1. Beginning in mid-May, survey for Pigeon Guillemots attending Race Rocks and surrounding islets.
  2. Conduct surveys in the morning (dawn to 1000 hr.), preferably at high tide.
  3. Count the number of birds on the shore and within 200 - 300 m of the colony.
  4. Map areas where Pigeon Guillemots congregate.
  5. Repeat colony survey 3-4 times during the breeding season, 2-3 weeks apart.
    1. PELAGIC CORMORANT

Phalacrocorax pelagicus

[PECO]

LIFE HISTORY

Sexes alike. Colonial. Nests on cliffs facing water. Chicks are altricial. Clutch size: 3-5 eggs. Egg laying: begins in May. Incubation: 26 - 31 days. Young hatch asynchronously. Chicks remain in nest for 2 months. Diet: non-schooling fish near rocky bottoms and reefs. Very sensitive to human disturbance.

STATUS

Pelagic Cormorants on the Queen Charlotte Islands ( P.p. pelagicus) are Red-Listed however other populations are not listed. In 1987, 120 Pelagic Cormorants were found nesting on Race Rocks (Campbell et al. 1990 ).

OBJECTIVE

To census Pelagic Cormorants nests on Race Rocks Ecological Reserve.

TIMING

First survey late June. Second survey mid to late July

Frequency

Survey colony twice during breeding season.

MATERIALS

Waterproof data sheets (RRR-4), notebook and pencil

Aerial photo and/or waterproof map of Race Rocks to mark nest locations

Binoculars

METHODS

Conduct all surveys from a boat and stay at least 30m away from cormorant nests. Do not survey the colony from land.

  1. Conduct first colony survey in late June, after egg-laying has begun.
  2. Map the colony. Use aerial photos (preferred) or topographic maps or field sketch-maps.
  3. Count the number of adults and nests and if possible, record the contents of each nest.
  4. Do a second survey 30 days later, counting adult cormorants and nestlings.
  5. For each survey, estimate the number of inaccessible nests and if necessary, estimate the number of birds present. Make detailed notes on how the estimate was derived.

Notes

  1. Kayaks and other vessels visiting Race Rocks should keep well clear (> 100 m) of the nesting cormorants May - July.
    1. BRANDT’S CORMORANT

Phalacrocorax penicillatus

[BRCO]

LIFE HISTORY

Sexes alike. Colonial. Nests on open ground on rocky areas near water. Clutch size: 4 eggs (range 3-6). Chicks are altricial. In southern California, egg laying begins March. Hatching in May. Very sensitive to human disturbance.

STATUS

Locally and seasonally abundant to very abundant resident. Common to abundant in Juan de Fuca Strait. In 1987, 3 nests were found on Race Rocks (Campbell et al. 1990a )

OBJECTIVE

To census the number of Brandt’s Cormorant nests on Race Rocks Ecological Reserve.

TIMING

First survey late June. Second survey mid to late July.

Frequency

Survey colony twice during breeding season

MATERIALS

Waterproof data sheets (RRR-5), notebook and pencil

Waterproof map of Race Rocks to mark locations of nests

METHODS

Conduct all surveys from a boat and stay at least 30m away from nests. Do not survey the colony from land.

  1. Conduct first colony survey in late June.
  2. Map the colony. Use aerial photos (preferred) or topographic maps or field sketch-maps.
  3. Count the number of adults and nests and if possible, record the contents of each nest.
  4. Do a second survey 30 days later, counting adult cormorants and nestlings.
  5. Estimate the number of inaccessible nests and if necessary, estimate the number of birds present. Make detailed notes on how the estimate was derived.

Notes

  1. Kayaks and other vessels visiting Race Rocks should keep well clear (> 100 m) of the nesting cormorants May - July.
  1. TREATMENT OF DATA 

    Attempt to calculate hatching, fledging and reproductive success for Glaucous-winged Gulls and Black Oystercatchers. To do this, calculate the following variables and use the equations below:

    a) Total number of eggs laid (including those lost to predation)

    b) Total number of chicks that hatched

    c) Total number of chicks that fledged

    Hatching success = :Total number of eggs hatched

    :Total number of eggs laid

    Fledging success = :Total number of chicks fledged

    :Total number of chicks hatched

    Reproductive success = :Total number of chicks fledged

    (also called Productivity):Total number of eggs laid

  2. OTHER GULL species THAT MAY VISIT RACE ROCKS 

    Herring Gull (Larus argentatus). Large gull with wings proportionately broad and short, giving a heavy appearance in flight and less elevated rear end when perched (Grant 1986). The Herring Gull is widely distributed in British Columbia. Offshore, it is a common to very common spring and fall migrant. Widespread but local breeder in the interior (Campbell et al. 1990b).

    Western Gull (Larus occidentalis). Resident coastal species that is rarely found inland. First-year birds resemble Herring Gulls. Western Gull hybridises with Glaucous-winged Gull (see below). Western Gull is a very stocky gull, with a heavily domed forehead, very stout and blob-ended bill and proportionately shorter- and broader-wing than other gulls (Grant 1986). Uncommon to fairly common resident on the southwest coast of Vancouver Island. Very rare, to rare summer visitor, rare to uncommon winter visitor in Juan de Fuca Strait. Breeds along Pacific coast from southern Washington to central Baja California. Winters south coastal B.C. to Baja, California (Campbell et al. 1990).

    Glaucous-winged x Western Gull. In Washington State, the breeding range of Glaucous-winged and Western Gulls overlaps and these two species interbreed to form hybrids. Many of these hybrids are seen in coastal areas of southern BC during the winter. Hybridizing causes considerable variations in plumage and makes identifying these two species difficult.

    Thayer’s Gull (Larus thayeri) Identification of Thayer’s Gull is best done at close range. At all ages, the dark colour on the outer primaries is on the outer web of each feather, therefore the dark is only visible from above; in flight, wing tips typically appear white. Thayer’s Gull is smaller and more slender than both Glaucous-winged and Western Gulls. Iris is usually dark. Legs are usually a deep rose-pink or purple tinged. Bill is pale yellow or greenish-yellow, with red or orange spot near gonys, and often whitish tip (Grant 1986). Abundant to very abundant migrant and visitor from mid-fall to mid-spring in Juan de Fuca Strait. Breeds in the arctic and winters along Pacific Coast, B.C. to Mexico.

    California Gull (Larus californicus) This species is intermediate in size, structure and plumage between medium- and large-sized gulls (e.g. Mew and Western Gulls, respectively). In flight, the California Gull is long-winged with a distinctively skinny body. Adult California Gulls distinguished by dark, blue-grey upperparts and wings with prominent white crescents. Wing tips black and slightly more extensive than Mew Gulls. The eye is dark at all ages. Legs yellow or greenish yellow, often grey-green in winter (Grant 1986). On the coast, a very common to abundant spring migrant; common in summer and very abundant fall migrant. Uncommon to fairly common in winter. In B.C., nests on Grant Island, Okanagan Lake (Campbell et al. 1990b).

    Heermann’s Gull (Larus heermanni). At all ages, the uniform all-dark plumage makes this species unmistakable among other west coast gulls. Almost exclusively an offshore or coastal species. Slim, elegant build, with proportionately longer legs, attenuated rear end when perched and long winged in flight (Grant 1986). Abundant to very abundant summer and fall visitor on southern Vancouver Island, very rare in winter (Campbell et al. 1990b).

    Mew Gull (Larus canus). Resembles the larger Herring Gull. For this species, check the characters of size, bill shape, head pattern and tone of grey on the upper parts. On the ground, a characteristically elegant bird, with a small, slim-looking bill, a rounded head with ‘gentle’ expression, long wings and a dainty gait. Adult winter has black tipped primaries divided by white blotches, dusky head markings and a pale bill. Adult summer has white head and yellowish-green bill (Grant 1986). Abundant to very abundant spring and fall migrant on the coast. Uncommon to common visitor in the summer. Breeds Alaska, northwestern Canada, south to northern and coastal British Columbia and east to northern Saskatchewan (Campbell et al. 1990b). 


  3. GLOSSARY

     See the list of bird Name Acronyms

    Altricial: At hatching, chick is immobile, without down, eyes are closed and needs to be fed.

    Blue-List Species considered to be Vulnerable in British Columbia. Vulnerable species are of special concern because of characteristics that make them particularly sensitive to human activities or natural events. Blue-listed species are at a lower level of risk than Red-listed species.

    Clutch : The number of eggs that a bird typically lays.

    Colonial:Nesting in large groups.

    Fledge: Typically, when a chick departs the nest. However, in some species where chicks are fed off the nest, fledging occurs when the chick can fly and begins to feed itself (e.g. Common Murre, shorebirds).

    Gonys: The prominent ridge formed by the fusion of the two halves of the lower mandible towards the tip. Especially noticeable in gulls and marked in some species by a red spot.

    Hatching success: The percent ratio of eggs that successfully hatch to the number of eggs that were laid in a colony

    Hybrid:Species that interbreed and produce viable offspring.

    Incubation:Parental care of egg to keep it warm for development. Typically a shared duty between both parents.

    Juvenile:In general, plumage at point of fledging, until gains adult plumage.

    Nestling period:The period of time that a chick is fed and cared for by the parents.

    Precocial:At hatching, chick is mobile, downy, and is either fed, shown food or finds own food.

    Primaries:The large, outer most flight feathers on a bird’s wing.

    Productivity:The ratio of the numbers of chicks that successfully fledged to the number of eggs that were laid.

    Red-List :Species assigned to or considered for the formal designation of either Extirpated, Endangered or Threatened by the Province of British Columbia.

    Scrape:A simple depression, usually with a rim sufficient to prevent eggs from rolling away. Occasionally with lining added.

    Semi-precocial:At hatching, chick is mobile, downy, eyes open and remains at nest to be fed. 

    Commonality Scale (from Campbell et al. 1990, originally published in Bull 1974).

    Very abundant:Over 1,000 individuals per day per location

    Abundant :200 to 1,000 individuals per day per location

    Very common:50 to 200 individuals per day per location

    Common :20 to 50 individuals per day per location

    Fairly common:7 to 20 individuals per day per location

    Uncommon :1 to 6 individuals per day per location

    Rare:1 to 6 individuals per season per location 

  4. ACKNOWLEDGMENT 

    The following people helped with the monitoring protocol: Ken Morgan (Canadian Wildlife Service), Garry Fletcher (Pearson College), Carol and Mike Slater (Pearson College), Stephanie Hazlitt (Bird Studies Canada) and Cindy Wright (Institute of Ocean Sciences).

  5. Literature Cited 

    Bull, J. 1974. Birds of New York state. Doubleday/Natural History Press, Garden City, NY 655 pp.

    Campbell, R.W., N.K. Dawe, I. McTaggart-Cowan, J.M. Cooper, G.W. Kaiser and M.C.E. McNall. 1990a. The birds of British Columbia, Volume I. Non-passerines. Canadian Wildlife Service and Royal British Columbia Museum.

    Campbell, R.W., N.K. Dawe, I. McTaggart-Cowan, J.M. Cooper, G.W. Kaiser and M.C.E. McNall. 1990b. The birds of British Columbia, Volume II. Non-passerines. Canadian Wildlife Service and Royal British Columbia Museum.

    Grant, P. J. 1986. Gulls: A guide to identification. Second Edition. T&AD Poyser, Calton.

    Hazlitt, S.L. 1999. Territory quality and parental behaviour of the Black Oystercatcher in the Strait of Georgia, British Columbia. M.Sc. Thesis, Simon Fraser University. 109 pp.

  6. References

Ehrlich, P.R., D.S. Dobkin and D. Wheye. 1988. The Birder’s Handbook. Simon and Schuster Inc. New York.

Emms, S.K. and K.H. Morgan. 1989. The breeding biology and distribution of the Pigeon Guillemot (Cepphus columba) in the Strait of Georgia. In: Vermeer, K. and R.W. Butler (eds.) The ecology and status of marine and shoreline birds in the Strait of Georgia, British Columbia. Can. Wildl. Serv. Spec. Publ., Ottawa

Gaston, A.J. and I.L. Jones. 1998. The Auks. Oxford University Press.

Kaufman, K. 1990. A field guide to advanced birding. Peterson Field Guide Series. Houghton Mifflin Company, Boston. 299 pp.

Resource Inventory Committee. 1995. An inventory manual for seabirds at sea and at colonies in British Columbia. DRAFT. February 1995.

Sullivan, T.M. and S. Hazlitt. Population trends and reproductive success of nesting Glaucous-winged Gulls in the southern Strait of Georgia. (in prep)

Vermeer, K., K.H. Morgan and G.E.J. Smith. 1989. Population trends and nesting habitat of Double-crested and Pelagic cormorants in the Strait of Georgia. In: Vermeer, K. and R.W. Butler (eds.) The ecology and status of marine and shoreline birds in the Strait of Georgia, British Columbia. Can. Wildl. Serv. Spec. Publ., Ottawa.

Vermeer, K., K.H. Morgan and G.E.J. Smith. 1989. Population and nesting habitat of American Black Oystercatchers in the Strait of Georgia. In: Vermeer, K. and R.W. Butler (eds.) The ecology and status of marine and shoreline birds in the Strait of Georgia, British Columbia. Can. Wildl. Serv. Spec. Publ., Ottawa.

Vermeer, K., K.T. Briggs, K.H. Morgan, and D. Siegel-Causey. 1993. The status, ecology and conservation of marine birds of the North Pacific. Can Wildl. Serv. Spec. Publ., Ottawa.

Vermeer, K. and K. Devito. 1989. Population trend of nesting Glaucous-winged Gulls in the Straight of Georgia. In: Vermeer, K. and R.W. Butler (eds.) The ecology and status of marine and shoreline birds in the Strait of Georgia, British Columbia. Can. Wildl. Serv. Spec. Publ., Ottawa.

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