Manitoba

Survey Citation:
COSEWIC. 2014. COSEWIC assessment and status report on the western grebe (Aechmophorus occidentalis) in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 55 pp. www.registrelep-sararegistry.gc.ca/default_e.cfm

• Type
  shore; boat; air
• Time period
  2002, 2012
• Source
  Report
• Both Western and Clarks?
  N

Count Type	Range	Max	Year
Max Adults	>1000	11403	2002-2012
Most Recent Adults	1 to 100	?	2012
Max Nests	N/A	N/A	N/A
Most Recent Nests	N/A	N/A	N/A
Max Chicks	N/A	N/A	N/A
Most Recent Chicks	N/A	N/A	N/A

Comments:

Estimate of breeding Western grebe population in Manitoba using data from 2002 to 2012. Adults were either directly counted or the number of active nests were doubled (Beyersbergen and Calvert 2008; Wollis and Stratmoen 2010) and counts of adults on lakes without breeding observed were included (Wilson and Smith 2013). In Manitoba, only one survey was conducted in most colonies in the past 10 years (Wilson and Smith 2013). In 1979, an aerial survey of breeding sites in this province gave an estimate of 10270 adults in 11 colonies (Koonz and Rakowski 1985). Current estimate is 8653 to 11403 adult grebes (Wilson and Smith 2013). The population in this province considered relatively stable with less yearly fluctuations than Alberta and Saskatchewan (Wilson and Smith 2013). About 25% of Canada's breeding population is in one colony in Manitoba (not sure which one).

Survey Citation:
Forsyth, D. J., P. A. Martin, K. D. De Smet and M. E. Riske. (1994b). Organochlorine contaminants and eggshell thinning in grebes from prairie Canada. Environmental Pollution 85:51-58.

• Time period
  May 1986, July 1986
• Source
  Peer-reviewed
• Both Western and Clarks?
  N/A

Count Type	Range	Max	Year
Max Adults	N/A	N/A	N/A
Most Recent Adults	N/A	N/A	N/A
Max Nests	N/A	N/A	N/A
Most Recent Nests	N/A	N/A	N/A
Max Chicks	N/A	N/A	N/A
Most Recent Chicks	N/A	N/A	N/A

Comments:

Western grebe eggs were collected at Duck Bay (14 eggs total) and Ninette (20 eggs total) in Manitoba in 1986 as part of this study of organochlorine residues in grebe eggs. All sampled eggs had significant levels of DDE and PCB residues. DDD was detected in all western grebe egg samples. They are considered the most piscivorous of the grebes in North America and thus more vulnerable to contaminants. Western grebe large body mass relative to other grebes also decreases toxicant metabolism. The DDD, DDE, and PCB levels in the Manitoba lakes were comparable to a larger study in Klamath Basin, California in 1981 (Boellstorff et al. 1985). Contaminants might be taken up in their wintering and spring grounds.