Tilley B Reservoir

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
  1991, 2011
• Source
  Report
• Both Western and Clarks?
  N

Count Type	Range	Max	Year
Max Adults	1 to 100	100	1991-2011
Most Recent Adults	1 to 100	?	2011
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:

From Table A.2, maximum counts of breeding Western grebes from surveys mostly conducted during nesting season from June and July from 1991 to 2011 (sourced from Wilson, A. and Smith, P.A. 2013. Distribution and population status of Western Grebes in Canada. Unpublished report for the Canadian Wildlife Service). No break out of data per year or other details.

Survey Citation:
Alberta Sustainable Resource Development and Alberta Conservation Association. 2013. Status of the western grebe (Aechmophorus occidentalis) in Alberta: Update 2012. Alberta Sustainable Resource Development. Alberta Wildlife Status Report No. 60 (Update 2012). Edmonston, AB. 48 pp.

• Type
  boat
• Time period
  2010
• Source
  Report
• Both Western and Clarks?
  N

Count Type	Range	Max	Year
Max Adults	1 to 100	~100	2010
Most Recent Adults	1 to 100	~100	2010
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:

Data from Table 2 ("Most recent abundance estimates from known western grebe breeding lakes in Alberta based on structured surveys; at some lakes, more recent observations have been made but these were not complete counts"). Table 2 data is from H. Wollis unpubl. data. Estimates of western grebe numbers are a minimum estimate for that year derived from nest counts (x2 for breeding adult numbers) or boat surveys of adult grebes, using highest estimate.

Survey Citation:
Prescott, D. R. C., J. Unruh, S. Morris-Yasinski, and M. Wells. 2018. Distribution and abundance of the western grebe (Aechmophorus occidentalis) in Alberta: an update. Alberta Environment and Sustainable Resource Development, Fish and Wildlife Policy Branch, Alberta Species at Risk Report No. 160, Edmonton, AB. 23 pp.

• Type
  boat
• Time period
  2010, 2016
• Source
  Report
• Both Western and Clarks?
  N

Count Type	Range	Max	Year
Max Adults	1 to 100	<100	2010
Most Recent Adults	0	0	2016
Max Nests	1 to 100	presence	2010
Most Recent Nests	0	0	2016
Max Chicks	1 to 100	presence?	2010
Most Recent Chicks	0	0	2016

Comments:

Sources are AESRD and ACA (2013) and FWMIS (Accessed Nov 2015 including field surveys from 2015 and 2016). This report is an update of Western grebe distribution in Alberta based on previous provincial status reports, additional breeding records (between May 1 to August 31) through end of 2014 from new sources. Lakes were visited in 2015 and 2016 for occupancy and habitat conditions. In a given year, if there are multiple sources of data, the highest count was given. From the Appendix, I entered only lakes (67) with evidence of breeding (either chicks or nests, but doesn't specify which and no nest nor chick numbers provided). Otherwise, 318 lakes supported adult grebe populations. This report compiled a list of 35 priority lakes for grebe surveys and management actions through the provincial recovery plan based on high population and habitat scores. New lakes with breeding reveal a changing system of lake occupancy and possibly higher populations than previously thought in Alberta.

Survey Citation:
Environment and Climate Change Canada. 2021. Management Plan for the western grebe (Aechmophorus occidentalis) in Canada [Proposed]. Species at Risk Act Management Plan Series. Environment and Climate Change Canada, Ottawa. 5 iv + 52 pp.

• Time period
  1983, 2015
• Source
  Management plan
• Both Western and Clarks?
  N

Count Type	Range	Max	Year
Max Adults	1 to 100	<100	2010
Most Recent Adults	0	0	2016
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:

From Appendix B, data columns are historical high count, high count since 2000, and most recent count. Since minimum count was not stated, I entered the minimum from these columns though it might not be the actual minimum across the span of years reported. Also, there is no detail on years that were excluded from surveying so range of survey years may be inaccurate. Footnote for this lake indicates that for 2015 to 2016, breeding was confirmed and potential habitat was available, but there were no Western grebes. Sources are Prescott et al., 2018 and Alberta Environment and Parks, 2018.