Changes in Summer Abundance and Distribution of Mute Swans Along the Lower Great Lakes of Ontario, 1986 – 2011
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Changes in Summer Abundance and Distribution of Mute Swans along the Lower Great Lakes of Ontario, 1986 – 2011 Mute Swan Photo: Homer Caliwag Shawn W. Meyer, Shannon S. Badzinski, Michael L. Schummer and Christopher M. Sharp Introduction The MuTe Swan ( Cygnus olor ) is one of populaTions along The mid-ATlanTic coasT Three swan species ThaT occur in NorTh of The U.S., porTions of The Pacific coasT America, buT is The only swan ThaT is and The GreaT Lakes region (Ciaranca et noT naTive To The conTinenT. Near The al . 1997). Breeding populaTions became beginning of The 20Th cenTury, MuTe esTablished wiThin coasTal and inland Swans were TransporTed inTo NorTh marshes in porTions of The GreaT Lakes America from Europe and Asia where region of The U.S. and Canada during They were released inTenTionally or es - The laTe 1950s Through The 1970s (PeTrie caped from capTive or semi-capTive col - and Francis 2003). In OnTario, The firsT lecTions leading To esTablishmenT of feral MuTe Swan nesT was documenTed in The 48 Ontario Birds April 2012 souThwesTern parT of The province in laTion of MuTe Swans is a conservaTion 1958 and swans were firsT observed on concern in The LGL region and else - The lower GreaT Lakes (LGL) (Lakes On - where in NorTh America. Tario, Erie, ST. Clair and Their connecTing DespiTe being an invasive, non-na - rivers) during The 1960s (Peck 1966, Tive species, MuTe Swans are proTecTed KnapTon 1993). Since ThaT Time, Their currenTly under The Migratory Birds Con - abundance and disTribuTion has in - vention Act, 1994 in Canada. MuTe creased subsTanTially in OnTario, parTic - Swans and oTher non-naTive species, ularly along The shorelines, marshes and however, are noT federally proTecTed in rivers associaTed wiTh lakes ST. Clair, Erie The U.S. since enacTmenT of The Migra - and OnTario (PeTrie and Francis 2003, tory Bird Treaty Reform Act in 2004 Badzinski 2007). (UniTed STaTes Fish and Wildlife Service The LGL are an imporTanT spring 2005). PeTrie and Francis (2003) and and auTumn sTaging area, providing feed - Bailey et al . (2008) suggesTed removing ing and resTing habiTaT for millions of MuTe Swans from The lisT of federally waTerfowl and oTher waTerbirds (Dennis proTecTed species in Canada To faciliTaTe et al. 1984, Schummer and PeTrie 2011). conTrol before populaTions aTTained lev - SubsTanTial and increasing numbers of els ThaT could affecT healTh and funcTion MuTe Swans have The poTenTial To affecT of The LGL coasTal marsh ecosysTem, waTerfowl (and oTher weTland-depen - componenTs which are criTical To sus - denT and aquaTic organisms) and Their Taining populaTions of naTive fish and habiTaT in The LGL region in a varieTy wildlife. Canada is currenTly reviewing of ways (PeTrie and Francis 2003). As The federal proTecTion sTaTus of MuTe one of The larger-bodied waTerfowl nesT - Swans. In The meanTime, accuraTely ing in NorTh America, MuTe Swans ag - moniToring abundance and disTribuTion gressively defend nesT siTes, broods and of These swans over Time is criTical in foraging areas. Thus, They compeTe wiTh The developmenT of managemenT sTraTe - oTher wildlife for criTical habiTaT re - gies for MuTe Swans and The habiTaTs sources and can cause physical harm To They negaTively affecT in OnTario and humans (Ciaranca et al. 1997, Therres ThroughouT Canada. and Brinker 2004). MuTe Swans also The populaTion and range expansion consume and uprooT subsTanTial quan - of MuTe Swans in The LGL region and TiTies of aquaTic vegeTaTion during for - ThroughouT OnTario has been well doc - aging which can reduce availabiliTy of umenTed using daTa from several differ - food To naTive herbivores and alTer abun - enT long-Term, mulTi-species surveys. dance and composiTion of aquaTic planTs PeTrie and Francis (2003) used daTa in aquaTic ecosysTems (Cobb and Harlan collecTed beTween 1980 and 2000 from 1980, Allin and Husband 2003, TaTu The Breeding Bird Survey (BBS), ChrisT - et al. 2007). Thus, an increasing popu - mas Bird CounT (CBC), The MidwinTer Volume 30 Number 1 49 Figure 1. The lower Great Lakes shoreline, marsh complexes, rivers, and inland lakes surveyed during the Mid-Summer Mute Swan Survey in Ontario. The red line indicates the aircraft flight path recorded by an onboard Global Positioning System (GPS) during the 2011 survey. Produced by CWS –ON under licence with OMNR. Queen’s Printer (c) 2011 WaTerfowl Survey (MWS) and 197 1– OnTario from The 1980s Through 2000s 2000 aerial surveys of migranT waTer - (Badzinski 2007). None of The above- fowl aT Long PoinT – Lake Erie, OnTario, menTioned surveys, however, were de - To documenT a rapid increase in MuTe signed specifically To moniTor The MuTe Swan abundance in The LGL region. IT Swan populaTion in The province. was esTimaTed ThaT The populaTion of The Mid-Summer MuTe Swan MuTe Swans on The LGL increased by Survey (MSMSS) is a broad scale, coor - 10% To 18% per year beTween 1980 dinaTed, inTernaTional moniToring ini - and 2000 and iT was predicTed ThaT iT TiaTive conducTed ThroughouT sTaTes and could double by 2010 (PeTrie and Fran - provinces in The ATlanTic Flyway aT cis 2003). The firsT and second Breed - Three-year inTervals since 1986 To deTer - ing Bird ATlases of OnTario showed ThaT mine abundance, producTiviTy and dis - MuTe Swans became more common TribuTion of MuTe Swans in various and widely disTribuTed along The LGL jurisdicTions and regions. DaTa collecTed coasTline, parTicularly around Lake On - during The survey are used To Track and Tario and aT inland locaTions in souThern mon iTor populaTio n size and, in some 50 Ontario Birds April 2012 sTaTes, To seT and evaluaTe populaTion ST. Lawrence River, Lake OnTario (in - managemenT goals for MuTe Swans. In cluding EasT Lake, WesT Lake and Lake OnTario, The survey TradiTionally has cov - Consecon), Niagara River, Lake Erie, De - ered The norThern shoreline of The ST. TroiT River, and Lake ST. Clair, as well as Lawrence River and The LGL, including over associaTed or nearby marsh com - The associaTed coasTal marsh complexes. plexes (Figure 1). During 2011, The sur - This survey provides The mosT currenT vey area was expanded inland To include and deTailed informaTion on abundance Rice Lake, Odessa Lake, and The Rideau and disTribuTion of MuTe Swans in The Canal sysTem beTween KingsTon and OTT - province. The purpose of This paper is awa. The survey is conducTed from a To describe changes in MuTe Swan abun - fixed-winged aircrafT flying aT an alTiTude dance beTween 1986 and 2011 and dis - of ~100 m, aT a speed of ~150 kph and TribuTion beTween 2002 and 2011 in The 250 m off of The shoreline. Survey rouTes LGL region of OnTario. over large weTland complexes and inland lakes are flown To maximize coverage of Methods suiTable habiTaT where swans may occur. The MSMSS is an inTernaTionally coor - The shoreline and inland survey area is dinaTed aerial survey ThaT is conducTed divided inTo secTors, which are smaller aT Three year inTervals beTween 1 and 30 geographic uniTs based on landscape fea - AugusT in norTheasTern NorTh America. Tures and readily idenTifiable landmarks In OnTario, This survey has been flown, ThaT enable deTerminaTion of abundance TradiTionally, along The shorelines of The and disTribuTion of swans aT finer scales. Figure 2. Number of Mute Swans observed along the lower Great Lakes of Ontario during the Mid-Summer Mute Swan Survey 1986 – 2011. Trend line indicates 2-yr moving average. 3,500 3,000 3,000 • • 2,500 2,500 • 2,000 2,000 1,500 1,500 e c n • 1a ,000 d • n 1,000 • u b 5A 00 • 500 • 0 0 1980 1985 1990 1995 2000 2005 2010 2015 Year Volume 30 Number 1 51 Two observers, one on each side of The and 2011 showed an increase from 85 aircrafT, use a Tape or digiTal voice To 126 broods, represenTing abouT an recorder To record abundance of adulTs 8.0% per year increase (Table 1). (including sub-adulTs), cygneTs and The local abundance of MuTe Swans broods/family groups, as well as associ - changed aT several areas wiThin The Tradi - aTed informaTion on daTe, Time, general Tional LGL survey area beTween 2002 locaTion ( e.g. , name of lake, river, bay), and 2011 (Figure 3). On Lake OnTario, survey segmenT, general habiTaT Type ( e.g. , The greaTesT raTes of increase occurred aT lake, impoundmenT, river, marsh), devel - The easT end in The viciniTy of Prince Ed - opmenT zo ne (as of 2008: urban, sub ur - ward CounTy (including EasT Lake, WesT ban, rural), and laTiTude / longiTude (as Lake, Bay of QuinTe, and KingsTon area), of 2011). DaTa are Transcribed following whereas decreases occurred in cenTral surveys, enTered inTo a sTandard elec - Lake OnTario jusT wesT of Prince Edward Tronic daTabase and archived on a cen - CounTy and aT HamilTon Harbour (Fig - Tralized server wiTh EnvironmenT Canada. ure 3a). The greaTesT raTe of increase was ArcGIS was used To creaTe maps showing approximaTely 170% per year aT WesT Temporal and spaTial paTTerns in abun - Lake – Prince Edward CounTy, whereas dance and disTribuTion of MuTe Swans The greaTesT decrease was approximaTely in The LGL region of OnTario. 18% per year along The shoreline be - Tween Presqu’ile Bay and Bowmanville. Results BeTween 1986 and 2011, eighT MuTe Table 2. Abundance and average percent change per year the Midwinter Survey - Lower Great Lakes (MWS-LGL) and Swan surveys were conducTed on The LGL. Over This Timeframe, The ToTal 1986 1989 1993 1996 abundance of MuTe Swans increased from 615 To 3,062 in The TradiTional LGL Survey survey area in OnTario; This represenTs MSMSS 1 an average increase of 15.9% per year Ontario ( (Table 1). Since 2005, The MuTe Swan 615 811 1,100 1,200 - 2 - - 3 populaTion in The LGL has increased aT a slower raTe (approximaTely 1.0% per year) (Figure 2 and Table 2).