51

The Status ofColonial WaterbirdsNesting at Hamilton

Harbour, Lake Ontario,1959-1987

byRob Z. Dobos,john Struger,

Hans Blokpoel and D.V. Chip Weseloh

Hamilton Harbour, RegionalMunicipality of Hamilton­Wentworth, located at the west.ernend of Lake On tario, is home towhat may be the most diversecolony ofwaterbirds on theCanadian Great Lakes. Sevenspecies of colonial waterbirds, theDouble-crested Cormoran t(Phalacrocorax au'Titus) , Snowy Egret(Egretta thula) , Black-crownedNight-Heron (Nyctiwrax nycticarax) ,

Ring-billed Gull (LaTUS delawaren­

sis), Herring Gull (L. argenlalus) ,

Caspian Tern (Sterna caspia) andCommon Tern (S. hirundo) , nestedthere in 1986. The purpose of thispaper is to document the numbersof these species which have nestedat Hamilton Harbour in recent

years.Hamilt.on Harbour is separated

from Lake Onl.ario by a large sand­bar, the Burlington Reachstrip(Figure 1). Landfi lIing has beencarried out on the Harbour side ofthe Reachstrip south of theBurlington Beach Canal by theHamilton Harbour Commissioners(HHC) over the past 30 years to cre­ate the present Confined DisposalFacility (CDF) , for containment ofharbour dredged sediments, andthe Pier 25, 26 and 27 pon facilities(Figure I). The berms and filledcells of the CDF have provided a rel­atively isolated site for the nestingof colonial waterbirds since the mid­1970s.

Rob Z. Dobos, Canadian Wildlife Service. Present address: 1319 Book Rd. W.,R.R. #1 ,jerseyville, Ontario LOR IRO.

john Struger, Canadian Wildlife Service. Present address: 269 Wexford Ave.S., Hamilton, Ontario LBK 2P1.

Hans Blokpoel, Canadian Wildlife Service, 1725 Woodward Dr., Ottawa,Ontario KIA OE7.

D. V. Chip Weseloh, Canadian Wildlife Service, P.O. Box .=5050,867 Lakeshore Rd., Burlington, Ontario L7R 11\6.

VOLUME 6 NUMBER 2

CJ EXTENT OF WATERBIRD COLONIES IN 1987

52

BURLINGTON

FARRE

ISLANDSNEARE ISLAND \.

HAMILTON HARBOUR

ST£:LCO

HAMILTON

500 0 500 mI •••• , ,

N

t

LAKE ONTARIO

(j.",ON'PARKDALE ~~

,nEl WO.K'V

Figure 1: Location of waterbird colony site on Hamilton Harbour,Lake Ontario

ONTARIO BIRDS AUGUST' 1988

The flat earth and rubble sub­strate which is largely unvegetatedhas proven suitable for the nestingof Herring and Ring-billed Gullsand Common and Caspian Terns. Asmall grove of Eastern Cottonwood(POPUlus deltoides) trees on thenorthwest end of the site has sup­ported a colony of Black<rownedNight-Herons, Double<restedCormorants and the first knownnesting of the Snowy Egret inCanada (Curry and Bryant 1987).

Two small islands in the north­east corner of the harbour, whichare 3 km distant from the CDF andare known locally as the HydroIslands (also referred to as Neareand Farre Islands by Morris et aL[1976]), each support a colony ofCommon Terns and a few Herringand Ring-billed Gulls (Figure 1).These artificially created rock pileswere the supports for hydro towerswhich have since been removed.Both the Pier 27 and Hydro Islandssites have been designated asEnvironmentally Sensitive Areaswithin the Hamilton-WentworthRegion's Official Plan (Ecologistics1976).

Thispapersumma~esall

records for colonial waterbirds nest­ing at the Pier 27 and Hydro Islandssites during the period 195~1987.

Species CompositionAn annual summary of the numberof nests ofeach colonial waterbirdspecies on Hamilton Harbour, from1959 to 1987, is provided in Table1. A species by species discussion ispresented below.

53

DQ'Ub~CTested QmnorantDouble-crested Cormorants (DCC)first nested in Hamilton Harbour in1984, when one nest was found onthe ground. The number has sincerisen to 51 nests in 1987, all in trees(Table 1). The cormorants nestedin the upper branches of the cot­tonwoods (Figure 2). These birdshave yet to exploit the ground nest­ing habitat available to them.

At present, Hamilton harbour isthe only cormorant colony on west­ern Lake Ontario. In size, it ranksas the sixth largest among the 9active colonies on Lakes Ontarioand Erie (Weseloh, in prep.). Sincethe mid-1970s, when numbers wereat a low due to toxic chemicalinduced reproductive failure (Priceand Weseloh 1986), the nestingpopulations of DCCs has increasedmarkedly on all the Great Lakes.

SnouIJ EgretSnowy Egrets nested for the firsttime in Canada at Hamilton har­bour in 1986, as described in detailby Curry and Bryant (1987); thespecies did not nest there in 1987.However, one bird, believed to be asecond summer Snowy Egret, wasobserved at the colony throughoutthe summer of 1987.

Bladt-£TO'W'r&ed Night-HeronBlack<rowned Night-Herons(BCNH) were first recorded nestingat the Pier 27 colony in 1975, withfive nests reported (Table 1). Thenumber has grown steadily to 212nests in 1987 (Table 1). TheBCNHs nest mostly in the lower

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54

Table 1: Colonial waterbird populations nesting on Hamilton Harbour,1959-1987

Year Double- Snowy Black- ~- Herring Caspian Common

crested Egret crowned billed Gull Tern TemCormorant Night-Heron Bull

1959 0 0 15c 0 0 0 -1961 0 0 - 2f 0 0 '!Jf

1966 0 0 - 0 0 0 66f

1967 0 0 - 0 0 0 8'!Jf

1968 0 0 - 0 0 0 79f

1970 0 0 - 0 0 0 +.\

1971 0 0 - 0 0 0 95".

1972 0 0 - 0 0 0 150ft

1973 0 0 - 0 0 0 42ft

1975 0 0 6d 0 0 0 0

1976 0 0 - 0 7j 0 0

1977 0 0 - 0 14, 0 0

1978 0 0 - 17A - 0 0

1980 0 0 1, '!J29i 102, 0 0

1981 0 0 19, 2400i 1M, 0 0

1982 0 0 l'!Jf 5000f 50f 0 +g

1984 1a 0 51a 11224i 202, 0 +g

1985 2a 0 98g 1'!J778, 150g 0 225g

1986 14a Ib 18'!Ja 16000, 106, 48, +41

1987 51a 0 212a 21207, 225, 1M, 55'!J,

- No data available g Lamond (1985)+ Nesting, but not censused " North (1978)a L Simser, pers. comm. i Blokpoel and Tessier (1986)b Curry and Bryant (1987) j Blokpoel (1977)c North (1959) Ie Gilbert!On (1975)d North (1975) ". Morris et al. (1976), CWScensus ft Morris and Hunter (1976)f Ontario Nest Record Scheme

branches of the cottonwood trees Frontenac County, Lake Ontario).(Figure 2). Sufficient nesting sites Such a situation could also occur atappear to be available for future the Hamilton Harbour colony.

,

increases in nesting birds. However, The earliest record of BCNHsBCNHs are know to desert their nesting in the Hamilton Harbourcolony site iflarge numbers of area was of three nests in 1936 atDCCs nest above them in the same Van Wagner's Beach,just east of thetrees (e.g., at Pigeon Island, harbour (Sheppard 1944).

ONTARIO BIRDS AUGUST 1988

Anothern BCNH colony was locat­ed in a grove of trees on an oldinlet on the southeast shore of theharbour behind the Firestonefactory. Fifteen nests were reportedthere in 1959 (Table 1). This colonywas substantially larger before thistime and was believed to have num­bered over 100 nests during the1950s (R Curry, pers. comm.).

The Hamilton Harbour BCNHcolony was the second largest onwestern Lake Ontario in 1987. Acolony at Tommy Thompson Park(Leslie Street Spit), MetropolitanToronto, numbered 591 nests in1987 (Blokpoel, unpubl. data). Acolony on a small island in theNiagara River directly above theHorseshoe Falls, RegionalMunicipality of Niagara, had 155nests in 1987, while a colony atMugg's Island in Toronto Harbour,Metropolitan Toronto, had morethan 50 nests in 1986, but wasdeserted in 1987 (E. Machell, pers.comm.). Data from the OntarioBreeding Bird Atlas (Cadman et al.

1987) indicate that only fivecolonies in Ontario had more than100 nests during the period 1981­85, those being at Middle Islandand East Sister Island, EssexCounty, in western Lake Erie,Nottawasaga Island, Simcoe County,in southern Georgian Bay andMugg's Island and TommyThompson Park, MetropolitanToronto (Goodwin 1987). TheBCNH population has fluctuatedconsiderably in Ontario over thelast 50 years. It has recovered fromlow numbers during the 1960s and

55

early 1970s and at present thespecies appears to be expanding itsrange within the province(Goodwin 1987).

Ring-billed GuU

The Ring-billed Gull (RBG) wasfirst reported nesting on HamiltonHarbour in 1961, with nests beingfound along the south shore ofWindermere Basin, behind theParkdale Steel Works (ONRS1961a). It was not recorded againuntil 1978, when 17 nests wererecorded at the CDF (Table 1).Numbers increased rapidly toapproximately 2,400 in 1981,11,224 in 1984 and 21,207 in 1987at the CDF site (Table 1). RBG'shave experienced rapid populationgrowth throughout the entire GreatLakes. The Great Lakes RBG popu­lation has more than doubled from1976 to 1984, with an average annu­al growth rate of 11 % (Blokpoeland Tessier 1986). On LakeOntario, the saturation ofnestingsites at several colonies, succession­al increases in vegetation (reducingthe amount of available nestinghabitat) and control programs todeter nesting at the TommyThompson Park and Mugg's Islandcolonies in Toronto most likely con­tributed to the rapid increase at theHamilton colony. Available nestingsites are still abundant on the filledcells of the CDF, depending onplans by the HHC to develop thesite (Figure 3).

The Hamilton Harbour RBGcolony was the fifth largest on all ofLake Ontario in 1984. Colonies at

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56

Little Galloo Island, TommyThompson Park, Gull Island andHigh Bluff Island, NorthumberlandCounty, as well as at the PortColborne mainland, RegionalMunicipality of Niagara, (thelargest on Lake Erie and withinclose proximity to HamiltonHarbour) were larger than theHamilton Harbour colony in 1984(Blokpoel and Tessier 1986).

Herring GullHerring Gulls were first recordednesting at Hamilton Harbour in1976, when 7 nests were counted(Table 1). By 1980 the number hadrisen to 102 (Table 1). Since 1984the number of nests has remainedfairly stable, with 225 nests countedin 1987 (Table 1). The HerringGulls nest mostly at the northernend of the waterbird colony, alongthe connecting dykes and along the

periphery of the RBGs.The Herring Gull has been

shown to be the most widespreadbreeding species in Ontario(Cadman et al. 1987). In recentyears, its population has been slowlyincreasing on Lakes Ontario andHuron (Weseloh et aL 1987). TheHamilton Harbour colony is one ofthe largest on western LakeOn tario, with other large coloniesbeing located at Tommy ThompsonPark in Toron to, Scotch BonnetIsland and Gull Island nearBrighton, above the Horseshoe Fallson the Niagara River, and on thePort Colborne breakwall.

Common TernThe first reported nestings ofCommon Terns in the Hamiltonarea were in 1946 (15 nests) and1949 (two nests) (North 1972). Thefirst record ofCommon Terns nest-

Figure 2 Double<rested Cormorant and Black<rowned Night-Heron nests, TollgatePonds, Hamilton Harbour. Photo courtesy CWS.

ONTARIO BIRDS AUGUsr 1988

ing specifically on the Harbour wasin 1961, when three nests werefound on the south shore ofWindermere Basin behind theParkdale Steel Works (ONRS1961a). Nesting was first reportedat the Hydro Islands in 1966, with66 nests recorded (ONRS 1966).Nesting occurred at the HydroIslands up to 1972 inclusive (ONRS1967; ONRS 1968; Gilbertson 1975;Morris et aL 1976). In 1971 oneCommon Tern nest was also foundat the Pier 27 CDF site (ONRS1971) . In 1973 the terns nested (42nests) on the mainland shorelineadjacent to the islands due to inun­dation of the islands resulting fromrecord high water levels (Morrisand Hunter 1976). A year later thiscolony was deserted, probably dueto the combined effects of the lossof nesting habitat and several yearsof reduced reproductive success

57

induced by toxic chemical bioaccu­mulation (Morris and Hunter1976). Common Terns did not sub­sequently nest on the Harbour un til1982 (Lamond 1985). Numbershave since increased to a total of553 nests in 1987 (Table 1). Ofthese, 151 were located at the Pier27 site adjacent to the RBG colony.

The only other Common Terncolony on western Lake Ontario isat Toronto's Tommy ThompsonPark, which historically supportedover 1000 nests, but in 1987 hadonly 332 nests. Data from the Atlasof the Breeding Birds ofOntario indi­cate that less than 5% of the 1231Ox1 0 km squares in whichCommon Tern breeding wasconfirmed had more than 100 nests(BlokpoeI1987b). HamiltonHarbour is, therefore, a major nest­ing area for Common Terns in theprovince. Other Common Tern

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colonies in the vicinity of Hamiltonand the number of nests at each in1987 were as follows: 1~~1 at PortColborne breakwall (R.D. Morris,pers. comm.); 157 on the NiagaraRiver [Tower Island, Far Crib, NearCrib and Buckhorn Weir] (G.Batcheller, pers. comm.); and 496at Buffalo, New York [Donnelly'sPier, Reef Lighthouse and ShortBreakwater] (G. Batcheller, pers.comm.).

Caspian TernCaspian Terns have nested atHamilton Harbour since 1986,when 48 nests were counted. In1987, the number increased sub­stantially to 1M nests (Table 1).These birds nest in an area within

Figure 3: Ring-billed Gull nesting habi­tat, Pier 27, Hamilton Harbour.Photo by Hans Blo1cpoeL

ONTARIO BIRDS AUGUsr 1988

the RBG colony. All Caspian Terncolonies in Ontario are associatedwith nesting RBGs (Blokpoel1987a). The only other CaspianTern colony on western LakeOntario is at the Tommy ThompsonPark, which has decreased from 197nests in 1985 to 45 nests in 1987.The rapid growth of the Hamiltoncolony may be attributed to immi­gration of displaced birds from theToronto colony. The Caspian Ternis considered rare in Ontario andCanada (BlokpoeI1987a), thus theHamilton colony is significantprovincially and nationally.

Future of the Pier 27coloniesOver the last decade, the colonialwaterbird nesting area at Pier 27has become one of the most impor­tant nesting sites on the GreatLakes, with populations of birdsthat are regionally, provincially ornationally significanL There is onlyone other colony site on theCanadian Great Lakes that has hadas many as seven spiecies nesting asdid Hamilton Harbour in 1986.Seven colonial waterbird speciesnested at the Tommy ThompsonPark in 1982: BCNH, RBG, HerringGull, Common Tern, Caspian Tern,Great Black-backed Gull (LaTUSmarinus) and California Gull(L. ca~

ifarnicus) (Fraser 198~). Both ofthese colonies have become estab­lished on man-made sites. Very littlesuitable nesting habitat for colonialwaterbirds existed on the Harbourprior to the 1970s. However, thefuture of the Pier 27 site is not

secure, due to eventual develop­ment plans for port and industrialfacilities by the lllIC.

The lllIC has recognized theecological significance of the site tosome degree, by allowing most ofthe nesting area to remain undUrturbed until it is required for devel­opment in approximately 15 years.Thus, the short-term prospects forthe colonies look promising. Infact, it is likely that Ring-billed Gullswill continue to increase rapidly innumbers, and in the process arelikely to encroach upon, or com­pletely usurp the nesting areas ofCommon and Caspian Terns. TheRBGs arrive several weeks beforethe terns do, and their burgeoningnumbers are likely to overtake thenesting areas of the terns. Onetechnique to prevent this encroach­ment and to maintain nesting habi­tat for Coriunon Terns is to excludegulls by installing wires ormonofilament early in the season.The gulls tend to avoid the 'wired'area, while terns can sometimes beinduced to nest beneath the wires.To prevent~Gs from completelytaking over the tern colonies at thetwo Hydro Islands, CWS has alreadydiscouraged colonizing gulls bydestroying their eggs (under CWSpermit) in recent years.

Although the short-termprospects for the Pier 27 coloniesare reasonably good, the coloniesare most likely to disappear oncePier 27 is further developed into anoperational harbour facility. Thedisplaced birds would probablymove out of Hamilton Harbour

59

because, apart from the two smallHydro Islands, there are presentlyno other suitable nesting sites inthe Harbour. In order to preventthis loss ofvaluable and interestingwaterbird colonies, alternative nest­ing habitat in Hamilton Harbourcould be built and maintained foroptimal use by a diversity of colo­nial waterbird species. HHC mightbe interested in greatly enlargingthe Hydro Islands or in construct­ing new islands in HamiltonHarbour. Those islands could thenbe managed for colonial waterbirdsby a local naturalist group (e.g., theHamilton Naturalists' Club withassistance from CWS). In fact, theHamilton Harbour RemedialAction Plan (RAP) for the clean-upof Hamilton Harbour is at presentconsidering a proposal to encour­age the birds now nesting at theCDF to move to an expandedHydro Island site.

AcknowledgementsWe would like to thank thoseornithologists who have providedtheir data on nesting waterbirds onthe Great Lakes, and historicalinformation, including Len Simser(Royal Botanical Gardens), GastonTessier (Canadian Wildlife Service),Robert Curry (HamiltonNaturalists' Club) and Eric Machell(Toronto Bird Observatory). Also,we thank the Hamilton HarbourCommissioners for permitting CWSto census waterbirds nesting ontheir site.

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northern Uke Ontario and the upper St.Lawrence River. Can. Wild!. Serv. Prog.Note No. 75.

BloItjlO6~ H. 1987a. Caspian Tern. I'll Cadman,M.D., P.F.J. Eagles and F.M. Helleiner.1987. Atlas of the Breeding Birds ofOntario. University ofWaterloo Press,Waterloo, Onto

BloItjlO61, H. 1987b. Common Tern. I'llCadman, M.D., P.F.J. Eagles and F.M.Helleiner. 1987. Atlas of the BreedingBirds ofOntario. University ofWaterlooPress, Waterloo, Onto

BloItjlO6~ H. and G.D. T~sVt: 1986. The Ring­billed Gull in Ontario: a review ofa newproblem species. Can. Wild!. Serv. Occas.Pap. No. 57.

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Goodwin, C.E. 1987.Black<rowned Night­Heron. I'll Cadman, M.D., P.FJ. Eagles andEM. Helleiner. Atlas of the Breeding Birdsof Ontario. University of Waterloo Press,Waterloo, Ont.

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North, G. W. 1959. Noteworthy bird records.Wood Duck 13:16.

ONTARIO BIRDS AUGUST 1988

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Shlppard, R W. 1944. Black<rowned NightHeron nesting in Lincoln County,Ontario. Canadian Field-Naturalist 58:31­33.

We.uloh, D.V. In prep. Double<restedCormorants of the Great Ukes: increasedbreeding populations, 1972-1987.Unpublished report, Canadian WildlifeService, Burlington, Ontario.

We.uloh, D. v., R Mimau, S.M. T.pllt, H.BloII.poftand B. RtJtdiff. 1986. Colonialwaterbirds nesting in Canadian UkeHuron in 1980. Can. Wild!. Serv. Prog.Note No. 165.28 pp.