Ecology and Management of Avian Botulism on the Canadian Prairies

1231AVIAN BOTULISM IN ALBERTA: A HISTORYcompiled by M.J. Pybusfrom records provided by Fish <strong>and</strong> Wildlife Division,Canadian Wildlife Service <strong>and</strong> Ducks Unlimited CanadaSummary: Mortality <strong>of</strong> wild waterfowl has been reported on at least 33 different lakes in Albertasince 1924. Some <strong>of</strong> these lakes no longer exist or currently do not support conditions suitable forinitiation <strong>of</strong> die<strong>of</strong>fs. Between 1980 <strong>and</strong> 1993, losses occurred repeatedly on 5 lakes (Beaverhill,Grantham, San Francisco, Utikuma, <strong>and</strong> Whitford); however, reported botulism problemsoccurred on at least one lake in all but 5 years (1982, 1983, 1985, 1987, 1993). From 1994 to2002, the pattern changed markedly with significant numbers <strong>of</strong> dead waterfowl found only onPakowki Lake from 1994 to 1997, followed by widespread losses on various lakes (but notPakowki) from 1998 to 2000 <strong>and</strong> only one lake in 2001. The mid 1980s were relatively dry years inthe prairie regions <strong>and</strong> losses were relatively minor. In the early 1990s, the prairies entered a wetphase <strong>and</strong> record high numbers <strong>of</strong> May ponds were observed. In particular, Pakowki Lake filledwith spring run<strong>of</strong>f <strong>and</strong> was used by migrant <strong>and</strong> resident waterfowl. In the late 1990s, the prairiesagain were relatively dry. <strong>Botulism</strong> losses decreased in the prairies <strong>and</strong> increased in the parkl<strong>and</strong><strong>and</strong> boreal areas. An apparent increase in disease losses in northern areas in recent years mayreflect increased surveillance <strong>and</strong> control effort.Estimates <strong>of</strong> the actual losses per lake are extremely difficult to assess <strong>and</strong> are thought to becompletely unreliable. As such, this report contains only the raw numbers <strong>of</strong> dead birds collectedor observed at each lake. Generally, observed losses range from 700 to 2500 birds per lake,primarily dabbling ducks. There are a few notable exceptions where losses greatly exceeded thisrange. Pakowki, Hay Zama, <strong>and</strong> Utikuma are large staging lakes for a variety <strong>of</strong> waterfowl <strong>and</strong>they tend to have large problems whenever mortality occurs. Kimiwan is an anomaly in that it hada large mortality in 1998, but little or no mortality in other years. Losses generally begin in mid tolate July <strong>and</strong> continue until early or mid- September, particularly in periods <strong>of</strong> prolonged hot dryweather. Blue-green algae toxins in the south <strong>and</strong> Newcastle Disease Virus in the north areconfounding factors in some die<strong>of</strong>fs <strong>and</strong> likely cause losses additive to those caused by botulismpoisoning.In 1992, Alberta began implementing a provincial Waterfowl Disease Contingency Plan(Anonymous 1992) that provided an overall approach to disease cleanup. It identified acommunications network <strong>and</strong> general responsibilities <strong>of</strong> the three primary agencies concernedwith waterfowl management/ conservation in Alberta (Environment Canada, Alberta Fish <strong>and</strong>Wildlife, <strong>and</strong> Ducks Unlimited Canada). In 1999, the Alberta Conservation Association joined asa full partner to the provincial contingency plan. In the late 1990s, regional surveillance plans<strong>and</strong> specific contingency plans for problem lakes were developed cooperatively among thepartners. A plan for dealing with disease on Pakowki Lake (Pybus et al. 1995) was used as amodel for other lakes.