Western ( Aechmophorus occidental is)
and Eared (Podiceps nigricollis)
Grebes of Central Alberta:
2004 Field Summary
Alberta Species at Risk Report No. 94
Digitized by the Internet Archive
https://archive.org/details/westernaechrnopho00berg_0
Western (Aechmophorus occidentalis )
and Eared ( Podiceps nigricollis)
Grebes of Central Alberta:
2004 Field Summary
Gavin Berg
Lisa Wilkinson
Hugh Wollis
And
Dave Prescott
Alberta Species at Risk Report No. 94
/Iberia
SUSTAINABLE RESOURCE
DEVELOPMENT
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Management Plan
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gentian de la nauvagine
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Illustration: Stephen Hanus
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This publication may be cited as:
Berg, G., L. Wilkinson, H. Wollis, and D. Prescott. 2004. Western (. Aechmophorus occidentalis ) and Eared
(. Podiceps nigricollis) Grebes of Central Alberta: 2004 Field Summary. Alberta Sustainable Resource
Development, Fish and Wildlife Division, Alberta Species at Risk Report No. 94. Edmonton, AB.
li
TABLE OF CONTENTS
ACKNOWLEDGEMENTS v
EXECUTIVE SUMMARY vi
1.0 INTRODUCTION 7
2.0 STUDY AREA 7
3.0 METHODS 8
3. 1 Stony Plain A rea 8
3.2 Parkland Area . 8
4.0 RESULTS 9
4.1 Stony Plain Area 9
4.1.1 Western Grebes.... 9
4.1.2 Eared Grebes 10
4.2 Parkland Area 12
5.0 DISCUSSION 12
5.1 Western Grebes in the Stony Plain Area 12
5.2 Eared Grebes in the Stony Plain Area .13
5.3 Western Grebe Populations in the Parkland Area 14
5.4 Management Concerns and Human Impacts on Grebe Colonies 14
6.0 MANAGEMENT IMPLICATIONS AND FUTURE DIRECTION 16
7.0 LITERATURE CITED 17
8.0 APPENDICES 18
Appendix 1. Map of Study Areas in Alberta 19
Appendix 2. Western and eared grebe observations on lakes surveyed in 2004 20
Appendix 2 Western and eared grebe observations on lakes surveyed in 2004 (continued) 21
Appendix 3. Western grebe nest quality during post breeding season total nest counts 22
iii
LIST OF FIGURES
Figure 1. Total number of western grebe nests counted on colonies within the Stony Plain area,
2001-2004 10
Figure 2. Estimated total number of eared grebes counted on lakes within the Stony Plain area,
2001-2004 11
LIST OF TABLES
Table 1: Summary of Stony Plain western grebe data, 2004 10
Table 2. Summary of eared grebe data, 2004 11
Table 3. Summary of western grebe observations in the Parkland Region, 2004 12
IV
ACKNOWLEDGEMENTS
We thank Matt Besko of Alberta Sustainable Resource Development, Rick and Chantal Pattenden of
Mainstream Aquatics Ltd, and Andrew Forrest, for their assistance during nest count surveys. Also,
thank you to Jim Allen, Michelle Wells, Ken Froggatt, Leslie Beattie, Laura Froggatt, Ian Prescott, Eric
Prescott, Jim Potter, and Kevin Wingert for their work with preliminary surveys of lakes in the Parkland
area for grebe populations. Alberta Sustainable Resource Development provided funding and in-kind
support. Additional funding was provided by the North America Waterfowl Management Plan, which
was administered by the Alberta Conservation Association.
EXECUTIVE SUMMARY
This project is in its fourth year and is designed to monitor population trends and reproductive success
of western grebes and eared grebes within the Stony Plain, Alberta area. Surveys are projected to span a
five-year period, and the results are being used for conservation and management efforts. Western
grebes are the priority species because they are provincially listed as “sensitive”. This project also
provides information to support lake habitat conservation and public education. In 2004, surveying
effort was focused on the primary western and eared grebe populations identified in the previous years
of this project. Ground nest surveys were conducted after the nesting period, the results of which were
used to derive a total breeding adult population estimate. In addition, surveys were initiated in the
Parkland region in 2004, to identify waterbodies that supported potential western grebe breeding
colonies.
We estimated the population of western grebes in the Stony Plain study area to be approximately 1270
adults, much lower than in 2003 (2554 adults), and lower than all previous years of study. Generally,
nesting colony locations were similar to previous surveys. Western grebes inhabiting Wabamun Lake
and Lac Ste. Anne continue to be the dominant populations in the study area, representing 54. 1 % and
26.3% of the regional population, respectively. Since 2003, the Wabamun Lake colony decreased in size
by nearly 53% (likely due to high rates of corvid nest depredation), and the Lac Ste. Anne colony
decreased by 72%. These colonies were formerly considered nationally significant due to their size, but
are now considered only regionally significant. The Isle Lake population is the only colony that grew in
size, doubling from 2003. Western grebes appear to return each year to historical breeding sites on large
lakes, and are vulnerable to human disturbance, making site protection essential. In particular, critical
reed habitat for nesting colonies is being cleared as a result of human development.
In 2004, eared grebe colony searches were conducted on fifteen lakes. Eared grebes were observed on
nine lakes, for a conservative overall population estimate of 8865 adults. Only seven of these lakes had
breeding colonies, and three of these lakes supported the aforementioned western grebe colonies. The
number of eared grebes observed in 2004 was higher than all previous years of study, including a
dramatic increase from 2003 (up from 1880+). This increase can be attributed to a colony found on
Majeau Lake (3594+ adults), in a part of the lake that was not surveyed previously. For the fourth
consecutive year, George Lake supported the largest eared grebe population in the study area; numbers
increased significantly from 2003 but are slightly lower than 2002 surveys. Eared grebe population
sizes and colony locations appear to be highly variable, suggesting that they rely on a network of
waterbodies to sustain their regional population. Eared grebes appear to prefer shallow and undeveloped
lakes and generally avoid waterbodies with extensive boating.
This is the first year for surveys in the Parkland Region of Alberta. Initial results found that of the
eleven lakes surveyed, nine supported populations of western grebes, with the largest populations being
located on Buffalo and Gull lakes. Although no evidence of breeding activity was recorded, surveys in
future years will focus on trying to identify colonies and confirm breeding. Expanding western grebe
colony surveys throughout the province will provide valuable information for status evaluation and
conservation.
vi
1.0 INTRODUCTION
Western grebes (Aechmophorus occidentalis) and eared grebes ( Podiceps nigricollis ) are part of the
family Podicipedidae, an ancient species of diving specialists that rarely fly except to migrate. These
grebe species are colonial nesting waterbirds that build precarious floating nests of aquatic vegetation
either secured to emergent vegetation or free-floating. Both species have wide distributions across
western and central North America, with some colonies having thousands of nests.
As with many top predators in ecosystems highly impacted by humans, western and eared grebes are
sensitive to these impacts and could become threatened over the long-term. Currently in Alberta,
western grebes are listed as ‘sensitive’, while eared grebes are listed as ‘secure’ (Alberta Sustainable
Resource Development 2000). This project was developed because of the relatively sparse data available
to quantify these rankings. Surveying protocols have been developed and refined, population trend,
distribution and measures of reproductive success within the study area are being monitored, and
specific threats to western and eared grebe populations have been identified.
The information presented in this report represents the findings from the fourth year of surveying
western and eared grebes within the Stony Plain study area in Alberta (Appendix 1), with comparisons
to data from previous years of the study. Baseline data for this area for 2001 to 2003 are presented in
Hanus et al. (2002a, 2002b, 2003). A synthesis of provincial data for western and eared grebes is
provided in Hanus (2002). This report also includes data collected from the first year of surveying for
western grebes in the Parkland region.
In 2004 our objectives were to:
1) Monitor the primary colonies of western and eared grebes in the Stony Plain study area
(Appendix 1), with emphasis on western grebes due to their ‘sensitive’ status in Alberta;
2) Opportunistically inventory other lakes in the study area to locate new colonies;
3) Initiate western grebe surveys in the Parkland region; and
4) Assist with colonial waterbird surveys in Lac La Biche and Cold Lake areas.
2.0 STUDY AREA
A detailed description of the Stony Plain study area is provided in Hanus et al. (2002b). Briefly, this area
is located in central Alberta (Appendix 1), and includes the counties of Barrhead, Lac Ste. Anne,
Parkland, and Westlock. The legal land description for the study area includes townships 48 to 66 and
ranges 23 to 28 west of the fourth meridian, and townships 48 to 66 and ranges one to nine west of the
fifth meridian (i.e. between 53° and 55° north latitude, and 113° and 1 15° west longitude). The
north/south and east/west maximum distances are approximately 143 km and 135 km, respectively, and
the total area is 1 1 592.6 km2. Specific details of lakes with active and/or historic grebe breeding
colonies are in Hanus et al. (2002b).
The Parkland study area is located just south and east of the Stony Plain study area. Briefly, this area
includes the counties of Wetaskiwin, Ponoka, Red Deer, Camrose, Vegreville, Provost and
Lloydminster. The legal land description for this area includes townships 34 to 58 and ranges 1 to 26
west of the fourth meridian, and townships 34 to 51 and ranges 1 to 5 west of the fifth meridian. A few
additional lakes were surveyed outside of the Parkland region and were included in this data set for
simplicity.
7
The study areas are located within the parkland and boreal forest natural regions (Alberta Environmental
Protection 1994), in a landscape where much of the original vegetation has been cleared for agricultural,
urban, and industrial development. The proximity of the study area to several urban centres, such as the
cities of Edmonton and Red Deer, make many of these lakes attractive for recreation and cottage
development. Lakes are generally meso- to hyper- eutrophic.
3.0 METHODS
3. 1 Stony Plain Area
Field surveys occurred between June 16, 2004 and July 16, 2004. The focus in 2004 was to monitor the
primary colonies identified by Hanus et al. (2002a, b), rather than conducting a broad inventory
throughout the study area. Nevertheless, lakes with smaller populations and new sites were also
surveyed whenever the opportunity arose.
In order to survey populations of western and eared grebes and to locate their nesting colonies, we used
the meandering shoreline boat technique as described in Hanus et al. (2002b). Lakes surveyed in this
manner included Brock Lake, Erickson Lake, George Lake, Lac Ste. Anne, Lessard Lake, Majeau Lake
and Sandy Lake (Appendix 1). Several lakes or portions of lakes that were not suited to boating were
surveyed using the shoreline telescope survey (Hanus et al. 2002b), and included Arthur Lake, Goose
Lake, Schuman Lake, Oldman Lake and Prefontaine Lake (Appendix 1). Casual observations were also
noted from Wakamao and Big Lakes.
For western grebes, total nest counts were conducted once the majority of nests were abandoned to
ascertain the complete size of the colonies (Lac Ste. Anne - July 14, Wabamun Lake - July 15, and Lake
Isle - July 15, August 4). All nests were counted and classified as intact, partially floating, or sunken, to
derive an index of time since nest abandonment. Eared grebe nest counts, based from a canoe, were
conducted on George Lake, Brock Lake and Majeau Lake. Total nest counts for eared grebes were
conducted on George Lake (June 23), Majeau Lake (June 28) and Brock Lake (June 29). Clutch size
was not determined, in order to reduce time spent near the colony and minimize disturbance.
Colony locations were recorded using Garmin™ model Etrex handheld global positioning (GPS) units
set to NAD 83. For larger colonies, several GPS locations were recorded along their perimeter to
provide an index of size.
3.2 Parkland Area
Surveys were conducted between June 2, 2004 and July 30, 2004. The focus in 2004 was to identify
lakes with western grebe populations, and if possible, locate breeding colonies.
When conducting the surveys, researchers used the meandering shoreline boat technique as described in
Hanus et al. (2002b). Lakes surveyed in this manner included Pigeon Lake, Gull Lake, Battle Lake, Pine
Lake, Driedmeat Lake, Coal Lake, Glennifer Lake, Buffalo Lake, Orloff Lake, Buck Lake and Sylvan
Lake. The number and location of western grebes were recorded for each lake.
8
4.0 RESULTS
4. 1 Stony Plain Area
We surveyed a total of 15 lakes between June 16 and July 16 (an additional survey was conducted
August 4; in 2004. A summary table of results, survey dates, and methods used for each lake surveyed
is in Appendix 2. A summary of 2004 colony data is in Table 1 for western grebes, and Table 2 for
eared grebes, and a comparison of colony sizes from 2001 to 2004 is in Figure 1 for western grebes, and
Figure 2 for eared grebes.
4.1.1 Western Grebes
We estimated a total of 1270 adult western grebes, based on a count of 585 nests in three colonies. The
largest adult western grebe populations and breeding colonies were observed on Wabamun Lake and
Lac Ste. Anne, which represented 54.1% and 26.3% of the regional population, respectively.
A total of 1 14 nests were counted on Isle Lake in 2004, for an estimated colony size of 228 adults (Table
1). The Isle Lake colonies were located on two adjacent islands. The timing of counts of the west island
colony on July 1 5th proved to be a good time for grebes as nesting had mostly been completed (Appendix
3). However, the disturbance to the other colonial species, including Franklin’s gulls and Forester’s
terns, was considered too great on the east island colony to do the survey at the same time. This survey
was completed on August 4th after most of the nesting by the terns and gulls was complete, but
unfortunately, it was too late for a reliable count of grebe nests. Only 15 nests were identified, but there
were likely others that were indistinguishable because they were in an advanced state of deterioration.
A total of 154 nests were counted on Lac Ste. Anne in 2004 at the traditional breeding site, for an
estimated colony size of 308 adults (Table 1). The colony was in two discrete sections and at two
different stages of breeding, as the southeast section appeared to have completed nesting earlier. Timing
for the total nest count on July 14th was slightly early since 24% of nests were still considered active.
This value was similar to the extrapolated proportion of active nests from 2002 and 2003. Over 67% of
nests were considered in good condition (i.e. intact or partly submerged; Appendix 3). An additional
area at the west end of the middle basin of Lac St. Anne was surveyed, where western grebes were
suspected to nest, but no nesting activity was observed.
A total of 317 nests were counted in 2004 at Wabamun Lake, for an estimated colony size of 634 adults
(Table 1). By the time of the total nest count on July 15th no nests were active and 86% of nests were in
poor condition (i.e. submerged) suggesting earlier abandonment (Appendix 3). Crows were observed in
and around the western grebe nesting area during the site visit, and evidence of egg depredation was
apparent.
The western grebes observed on Sandy Lake in 2002 but not in 2003, were back in 2004, but there
continued to be no evidence of breeding (Table 1).
9
□ 2001
200
□ 2002
□ 2003
112004
Figure 1. Total number of western grebe nests counted on colonies within the Stony Plain area, 2001-2004.
Table 1: Summary of Stony Plain western grebe data, 2004.
Lake Name
Survey
Date
# of Adults
# of nests
observed
Isle Lake
15-Jul-04
228
114
Lac St. Anne (middle basin)
25-Jun-04
50+
0
Lac St. Anne (west basin)
21-Jun-04
41
0
Lac St. Anne (east basin)
14-Jul-04
308
154
Sandy Lake
05-Jul-04
9
0
Wabamun Lake
15-Jul-04
634
317
Totals
1270
585
4. 1 .2 Eared Grebes
We conducted searches for eared grebes on 15 lakes, including the three lakes on which western grebes
were found. We observed eared grebes on nine lakes, with breeding observed on seven of the lakes
(Table 2). In addition, casual observations from Big and Wakamao Lakes indicated presence of eared
grebes, but due to logistical constraints, further data were not gathered and these lakes are not included
in this report. For the fourth consecutive year, the largest eared grebe colony was on George Lake with
an estimated population of 4588 adults. Majeau Lake had the second largest population with an
estimated 3594 adults. The colony was located in an area of Majeau Lake that had not been surveyed
previously, although we suspected a colony was present in previous years. These two lakes combine for
92% of the regional population of eared grebes. All colonies identified in 2004 were found in open
water areas, with only one exception at Isle Lake where nests were found in reed beds.
10
Ring-billed gull nest predation was observed at the George and Majeau Lake colonies during nest count
surveys. If we approached the nests too closely, grebes left their nests and gulls quickly approached the
nests to consume eggs (we observed only one instance where a grebe returned to its nest and chased the
gull away). Evidence of eggshell fragments in nests suggested ongoing predation. Steps have been
taken to minimize disturbance during surveys (refer to Management Implications and Future Direction).
10000
9000
*
% 8000
o 7000
<0
O 6000
f 5000
CO
m— 4000
0
<5 3000
.Q
1 2000
z
1000
0
Brock George Isle Lake* Lac St. Lac St. Majeau Oldman Sandy Total
Lake Lake Anne Anne Lake Lake Lake
(East)* (west)
Lake Name
indicates only partial lake surveys
**population sizes estimated by doubling number of nests counted
Figure 2. Estimated total number of eared grebes counted on lakes within the Stony Plain area, 2001-2004.
Table 2. Summary of eared grebe data, 2004.
Lake Name
Survey
Date
# of Adults
# of nests
observed
Arthur Lake
22-Jun-04
2
0
Brock Lake
29-Jun-04
488
244
Chip Lake
16-Jul-04
80+
40
George Lake
23-Jun-04
4588
2294
Isle Lake
25-Jun-04
22
11
Majeau Lake
28-Jun-04
3594
1797
Oldman Lake
23-Jun-04
28
4
Sandy Lake
5-Jul-04
50+
0
Lac St. Anne (east basin)
14-Jul-04
6
3
Totals
8858+
4393
11
4.2 Parkland Area
A total of 71 1 western grebes were observed on nine of the 1 1 lakes surveyed (Table 3), but no colonies
were found. The highest numbers were on Buffalo and Gull Lakes. Buffalo Lake had extensive
emergent vegetation and is likely the major breeding lake in the area. Gull Lake, however, had limited
emergent vegetation, and thus has fewer potential nesting locations.
Table 3. Summary of western grebe observations in the Parkland Region, 2004.
Lake
Lake Location (Township,
Range, Meridian)
Date
# WEGR
Pigeon
T46, 47, R28, 01,02, W4, 5
25 June 2004
20
Gull
T40-42, R28, 01, W4, 5
4 June 2004
320
Battle
T46, R02, W5
3 June 2004
0
Pine
T36, R24, 25, W5
30 July 2004
3
Driedmeat
T44, 45, R1 8-20, W5
18 June 2004
5
Buck
T46, R06, W5
12 June 2004
16
Orloff
T74, R23, 24, W4
June / July
0
Coal
T47, 48, R23, W4
18 June 2004
6
Glennifer
T35, R02, 03, W5
10 June 2004
10
Buffalo
T40, 40, R20, 21,22, W4
2 June 2004
309
Sylvan
T38, 39 R01, 02, W5
30 June 2004
22
5.0 DISCUSSION
5.1 Western Grebes in the Stony Plain Area
Western grebe colonies identified in 2001 were still present in 2004; however, the total population
estimate was lower in 2004 than in any other year of the study (Figure 1). A certain amount of variation
is expected due to imprecision associated with survey techniques, but this drop is noteworthy, even
taking into account that two of the surveys may have under-represented the number of active nests. The
western grebe population appears to have decreased by approximately 54% from 2003 (Hanus et al.
2003) , 52% from 2002 (Hanus et al. 2002b) and 33% from 2001 (Hanus et al. 2002b). Poston et al.
(1990) developed a ranking system for migratory birds inhabiting the Canadian Prairie Provinces, and
classified western grebe colonies with over 500 nests or breeding pairs as nationally significant, and
colonies with 100 to 500 nests or breeding pairs as regionally significant. Both Lac Ste. Anne and
Wabamun Lake colonies have decreased from nationally significant to regionally significant. Surveys in
northeastern Alberta also detected a decrease in western grebe populations from 2003 to 2004 (Found
2004) .
With the exception of Isle Lake, the colonies have generally decreased throughout the four years of
study. The location of the Isle Lake colony is split into two areas, and the distribution of nests has varied
between years; hence, we expect a certain amount of variability in nest counts. It is possible that in the
first year of study, when methods were being tested, colony size estimates were less accurate than in
12
subsequent years. However, colonies at both Lac Ste Anne and Wabamun Lake have decreased
significantly relative to 2002 (62% and 58% respectively) and 2003 (72% and 53% respectively; Figure
1). We suspect that nest predation by corvids is contributing to the decline of the Wabamun colony, and
the high corvid population is likely a result of increasing human development along the lakeshore. One
explanation for the change in numbers at Lac Ste. Anne is that we did not survey the reed beds to the
north west of the colony in 2004 to confirm whether a satellite colony had been established. A satellite
colony was found in 2001, but not in 2002 or 2003. The area should be surveyed in 2005 for
verification, however, it is unlikely that a satellite colony could account for the growing difference in
population size between years. It is also possible that a stochastic environmental event at the wintering
grounds could decrease the population size (e.g. Jehl et al. 2002). However, continued declines are likely
related to site-specific conditions on breeding lakes, and Lac Ste Anne has a high level of human activity
and development. Similarly, increasing human activity and degradation of shoreline habitat have been
suggested as reasons for the apparent western grebe decline in northeastern Alberta, although changing
water levels and natural population fluctuations are also possibilities (Found 2004).
Western grebes need to colonize large lakes, which provide adequate prey and areas of open water (refer
to Hanus et al. 2002b); however, these lakes tend to have high levels of human activity. As an example,
a proposed housing development adjacent to the western grebe colony on Lac Ste Anne has the potential
to negatively impact nesting grebes by reducing and fragmenting nesting habitat, and increasing human
presence and associated disturbances, including powerboats, dogs, and even corvids. Based on complete
shoreline surveys for emergent vegetation habitat in 2002, the colony is located within the largest and
most intact section of bulrush habitat remaining on the lake (Hanus et al. 2002a). Stringent mitigation
measures are required to protect the colony, although the success of such measures is uncertain given the
projected increase in human activity.
5.2 Eared Grebes in the Stony Plain Area
The regional eared grebe population in 2004 was 8858, almost 5 times greater than in 2003 (Figure 2),
but similar to 2001 and 2002 (Hanus et al. 2002a, b, Hanus et al. 2003). If eared grebes from the newly
discovered Majeau Lake colony are exempt, the revised estimate is approximately 5264 adults, which is
still higher than 2003, but lower than 2001 and 2002 estimates (Figure 2). The most significant change
in population occurred at George Lake between 2002 and 2004.
There are several possible explanations for the change in population estimates, such as imprecision
associated with survey methods and reduced survey effort. Colonies built near the shoreline are often
difficult to see and could easily be missed if entire lakes are not surveyed; only a partial lake survey
occurred on George Lake in 2003 due to logistic constraints. Eared grebes may also have nested on
alternate lakes not included in the survey (e.g. Majeau Lake prior to 2004). Eared grebes are able to use
a variety of water bodies, with a preference for shallow wetlands <3 m deep (Boe 1992). Eared grebes
may be faithful to breeding ponds or regions, but natal philopatry has not been documented (Cullen et al.
1999). Thus, we expect that eared grebes will not necessarily return to the same lake to breed every year,
and may rely on a subset of lakes in the region.
Changes in water levels and other environmental factors, at both nesting and wintering sites, could also
affect colony size. For example, in 1998, an El Nino event resulted in an increase in surface water
temperatures at eared grebe wintering grounds, likely forcing prey to cooler water below the sustainable
foraging depths of the grebes. This resulted in the starvation of hundreds of thousands of eared grebes
and a huge drop in population numbers. In the following two years, the population rebounded to normal
levels (Jehl et al. 2002).
13
Several important breeding populations of eared grebes are present in the study area. Poston et al. (1990)
defined nationally significant colonies as those over 800 nests, regionally significant colonies as having
300 to 800 nests, and locally significant colonies as having fewer than 300 nests. In three out of four
years of this study, the George Lake colony was ranked as nationally significant (it was regionally
significant in 2003). This lake provides ideal nesting habitat for eared grebes because it is relatively
shallow, submergent vegetation is highly abundant and readily available for nest construction, there is
minimal human presence on and around the lake, a powerboat restriction is in place, and the shorelines
are relatively intact. The new colony found on Majeau Lake in 2004 is nationally significant. The
population at Oldman Lake has plummeted 90% since 2003, possibly due to the considerable drop in
water level (Hanus et al. 2003), although survey effort has also declined.
It appears that eared grebe colonies, while fluctuating in population size, are likely more stable than
western grebe colonies, and have more options for nesting locations. However, continued monitoring is
recommended to understand population trends and identify important breeding habitat, recognizing that
eared grebes rely on a network of waterbodies and are sensitive to human disturbance.
5.3 Western Grebe Populations in the Parkland Area
Initial observations showed that a number of lakes in the region support western grebes, although no
colonies have been located. Because surveys were reconnaissance in nature and many lakes were
surveyed after the primary breeding season, evidence of breeding could easily have been missed. Lakes
with poor nesting habitat may have supported transient or non-breeding populations. Several lakes
appeared to have suitable nesting habitat for western grebes, so future research should focus on locating
nesting colonies earlier in the breeding season.
5.4 Management Concerns and Human Impacts on Grebe Colonies
A variety of recreation activities and associated development have the potential to negatively impact
colonial water birds. This applies in particular to grebes because they build primitive floating nests made
of aquatic vegetation, which are susceptible to wave action. Recreation activities can lead to both direct
(destroying nesting habitat and nests) and indirect (disturbing nesting birds) impacts on colonies, and are
discussed below.
Western grebes begin the nesting process in spring using dead standing emergent bulrush habitat.
During the winter, snowmobiles that drive across bulrush patches flatten reeds, so that when spring
arrives, these plants lay on the surface of the water or are submerged, rendering them useless for hiding
cover and protection from waves. This was evident on Isle Lake following the winter of 2001/02,
causing the western grebes to build nests at an adjacent island where reeds were available, but the
location was poor due to wind exposure and competition from other colonial nesting birds (Hanus et al.
2002b). During spring and summer, waves from motorboats can destroy essential reed habitat used for
nesting and can potentially submerge nests.
Although destruction of nesting habitat is the primary impact of recreational activities, these activities
can also create disturbances that result in grebes temporarily abandoning nests. When birds leave their
nests, a number of deleterious things can occur, particularly when they leave hastily and dislodge eggs
into the water or do not cover eggs with vegetation. This increases vulnerability of eggs to avian
predators, and exposes eggs to extreme temperatures. In addition, new hatchlings still in the nest, and
unable to survive on their own, may become permanently separated from their parents.
14
The increase in recreational properties on lakes impacts western grebe populations through removal of
shoreline vegetation for beach development. For example, at Wabamun Lake there is a distinct line
separating the area in front of cabins where vegetation has been cleared, from the area where there is no
development and the vegetation remains intact (the location of the western grebe colony). The
increasing demand for recreational property will continue to threaten western grebe colonies unless
appropriate legislation is put in place to protect vital nesting habitat. Caution must also be used to
protect shoreline habitat from activities that disturb nesting grebes (e.g., dogs, people wading into reed
beds).
The number of boats, size of motors, and types of water sport activities has increased dramatically
within a relatively short timeframe, with no indication of a reverse trend in the future. Western and eared
grebes require secluded areas for nesting, and if viable populations are to remain on lakes with a high
presence of boaters, some boating restrictions need to be established. This is especially critical for
western grebes, since they tend to colonize large lakes where boating activity is often significant. A
buffer of 250 m to 500 m (depending on the size of the lake) that excludes all boating activity during the
nesting period, including personal watercraft and canoes, would likely be effective. Existing motorized
boating restrictions on lakes, such as George Lake, should remain in place.
Nest predation is one of the most significant threats, which can be exacerbated by human activity and
settlement. The Wabamun Lake western grebe colony appears to be suffering from high rates of nest
predation by corvids, the presence of which may be increasing. Similarly, predation by ringed-billed
gulls at the eared grebe colonies on George Lake and Majeau Lake has been observed. In these
instances, predation increased as a result of researchers being in close proximity to colonies, causing
grebes to leave their nests. Throughout the course of this study, steps have been taken to minimize
disturbance by not entering colonies during breeding season and restricting the time spent close to
colonies (refer to Management Implications and Future Direction). Clearly, recreational boaters
(including canoes) in close proximity to colonies will disturb nesting grebes. As the frequency of
disturbance increases, the number of predators increases.
The sensitivity of western grebes to human disturbance has been well established, and it appears that
eared grebes are also sensitive to disturbance. Five of the nine water bodies with populations and/or
colonies of eared grebes are not highly developed recreation lakes and have either powerboat restrictions
or are unsuitable for powerboats. It appears that eared grebes may prefer secluded and shallow lakes
(e.g., Chip, George, Majeau and Oldman lakes) especially when nesting in open water areas, which is
consistent with Boe (1992), who found that eared grebes preferred wetlands without designated public
access, little or no fishing or motor boating, shorelines that were partially treed, and abundant
submergent vegetation. Boe ( 1 992) did not observe eared grebes on wetlands with buildings along the
shoreline, suggesting avoidance behaviour.
Finally, fishing also has repercussions on water birds. In addition to the boating activity associated with
fishing, abandoned fishing line poses a serious threat to water birds because diving birds can easily get
snared in the relatively invisible line. During our surveys we have found a number of water birds
(grebes, gulls and loons) tangled in fishing line and unable to fly, including two individuals in one eared
grebe colony and a loon that lost its foot due to entanglement. The number of entangled birds we have
found in this study is likely indicative of a widespread, serious problem. Obviously, it is important that
anglers are aware of the dangers of improper fishing line disposal and should not discard waste line in
the water.
15
6.0 MANAGEMENT IMPLICATIONS AND FUTURE DIRECTION
The Stony Plain study area supports sizable populations of both western and eared grebes, due in part to
the large number of medium to large fish-bearing waterbodies. It is likely that the Parkland region also
supports breeding colonies. Short-term results of this monitoring project indicate that western grebes
have a high fidelity to existing nesting sites. Western grebes rely on the largest lakes in the study area to
support their regional populations, where they need shoreline vegetation for nesting. Consequently,
nesting sites are very limited. These lakes are also some of the most developed and well-used lakes
within the study area. Public education should continue to focus on local groups, landowners, and land
managers at these lakes. Shoreline habitat protection and restoration should also become a priority for
this project in the future. Concern for western grebe status over the long-term continues to exist, due to
the decreased nesting success of the Wabamun Lake and Lac St. Anne colonies, and encroachment by
human disturbance and removal of remaining shoreline habitat.
Continued monitoring is recommended, with emphasis on post-breeding nest surveys for all western
grebe colonies to estimate adult breeding population size. Further investigation is needed to locate and
monitor colonies in the Parkland area to determine the population size and possibly reproductive
success. Additional lakes should be included in future studies to determine the number of lakes used by
western grebes to ultimately evaluate their provincial status. Determining reproductive parameters, such
as clutch size, can provide valuable measures of reproductive success, but should only be calculated on
an intermittent basis, such as a minimum interval of five years, to minimize disturbance. Western grebe
nests should only be counted after hatching has occurred (around the 15th of July in central Alberta), but
before nests deteriorate and become unrecognizable. Because eared grebe nests are more fragile and
ephemeral, an accurate count can only be made before nest abandonment. However, because they nest in
open water, their eggs are highly vulnerable to avian predators. Consequently, detailed nest counts
should be conducted quickly, towards the end of nesting season, and at a minimum interval of five years.
In the interim, approximate nest counts can be made annually using a telescope and binoculars from an
adequate distance to minimize disturbance. We recommend monitoring the largest eared grebe colonies
in the area using approximate counts to assess population trends, and when possible, survey smaller
breeding colonies.
16
7.0 LITERATURE CITED
Alberta Environmental Protection. 1994. Natural Regions of Alberta: Summary. Alberta Environmental
Protection. Edmonton, AB. 18 pp.
Alberta Sustainable Resource Development. 2000. The general status of Alberta wild species, 2000.
Alberta Environment/Alberta Sustainable Resource Development. Edmonton, AB. 46 pp.
Boe, J. S. 1992. Wetland selection by eared grebes, Podiceps nigricollis, in Minnesota. Canadian Field-
Naturalist 106:480-488.
Cullen, S. A., J. R. Jehl, Jr., and G. L. Nuechterlein. 1999. Eared Grebes {Podiceps nigricollis). The
Birds of North America 433: 1-27.
Hanus, S. 2003. Waterbird survey compilation for the Stony Plain Area, 2001 to 2003. Alberta
Sustainable Resource Development, Fish and Wildlife Division. Hinton, Alberta.
Hanus, S., L. Wilkinson, and H. Wollis. 2002a. Western (Aechmophorus occidentals) and Eared
( Podiceps nigricollis) Grebes of Central Alberta: 2002 Field Summary. Alberta Sustainable
Resource Development, Fish and Wildlife Division, Alberta Species at Risk Report No. 60.
Edmonton, AB. http://www3.gov.ab.ca/srd/fw/riskspecies/
Hanus, S., H. Wollis, and L. Wilkinson. 2002b. Western {Aechmophorus occidentals) and Eared
{Podiceps nigricollis) Grebes of Central Alberta: Inventory, Survey Techniques, and
Management Concerns. Alberta Sustainable Resource Development, Fish and Wildlife Division,
Species at Risk Report No. 41. Edmonton, AB. 45pp. http://www3.gov.ab.ca/srd/fw/riskspecies/
Hanus, S., L. Wilkinson, and H. Wollis. 2003. Western {Aechmophorus occidentals) and Eared
{Podiceps nigricollis) Grebes of Central Alberta: 2003 Field Summary. Alberta Sustainable
Resource Development, Fish and Wildlife Division. Edmonton, Alberta.
Jehl, J. R. Jr., W. S. Boyd, D. S. Paul, and D. W. Anderson. 2002. Massive collapse and rapid rebound:
population dynamics of eared grebes {Podiceps nigricollis) during an ENSO event. The Auk 119
(4): 1162-1166.
Poston, B., D. M. Ealey, P. S. Taylor, and G. B. McKeating. 1990. Priority migratory bird habitats of
Canada’s prairie provinces. Minister of Supply and Services Canada. Edmonton, AB. 107 pp.
Purdy, R.O., D.C. Parkyn, and J.D. Folinsbee. 1983. Wildlife surveys of selected Edmonton area lakes
June-July 1982. Unpub. Rep. Alberta Energy and Natural Resources, Fish and Wildlife Division.
139 pp.
17
8.0 APPENDICES
18
Appendix 1. Map of Study Areas in Alberta
19
Appendix 2. Western and eared grebe observations on lakes surveyed in 2004
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Appendix 3. Western grebe nest quality during post breeding season total nest counts
Lake
Date
Total # of
Nests
# of Intact
Nests
# of Partially
Submerged Nests
# of Submerged
Nests
Isle Lake
July 15,2004
99
25
59
15
Isle Lake
Aug. 4, 2004
15
0
7
8
Lac Ste Anne
July 14, 2004
154
28
76
50
Wabamun
July 15, 2004
317
0
45
272
22
Species at Risk Report Series
For a complete list of titles in the Species at Risk report series, visit the following website, an<
select ‘Project Reports’:
http ://www3 . gov, ab. ca/srd/fw/speciesatrisk/' index.html
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