(2011) Aziscohos Lake Common Loon Population

Transcription

AZISCOHOS LAKE
COMMON LOON
POPULATION AND PRODUCTIVITY SURVEY
AND MANAGEMENT REPORT:
2011 SEASON FINAL REPORT
Biodiversity Research Institute (BRI) is a nonprofit organization located in Gorham, Maine. Founded in
1998, BRI is dedicated to progressive environmental research and education that furthers local, regional
and global sustainability and conservation policies. BRI’s research efforts emphasize conservation biology issues in New England and across North and Central America.
To obtain copies of this report contact:
Biodiversity Research Institute
19 Flaggy Meadow Road
Gorham, ME 04038
(207) 839-7600
mike.chickering@briloon.org
www.briloon.org
Suggested citation: Chickering, M. D., J. Fair, K. Taylor, I. Johnson and D. Evers. 2011. Aziscohos
Lake Common Loon Population and Productivity Survey and Management Report: 2011 Season Final
Report submitted to NextEra Energy Maine Hydro. Report BRI 2011-24. Biodiversity Research Institute,
Gorham, Maine.
Note: This report was abridged from the full report BRI 2011-25
2011 AZISCOHOS LAKE COMMON LOON REPORT
AZISCOHOS LAKE COMMON LOON POPULATION AND PRODUCTIVITY
SURVEY AND MANAGEMENT REPORT
2011 SEASON FINAL REPORT
(ABRIDGED REPORT)
(Report BRI 2011-24)
Submitted By:
Michael Chickering, Jeff Fair, Kate Taylor, Ian Johnson and David Evers
BioDiversity Research Institute
19 Flaggy Meadow Road
Gorham, Maine, USA 04038
(207-839-7600)
April 2012
1.0 EXECUTIVE SUMMARY ...................................................................................................................................ii
2.0 INTRODUCTION ................................................................................................................................................. 3
2.1 STUDY AREA .................................................................................................................................................................................................. 3
2.2 HISTORY AND PURPOSE OF STUDY ................................................................................................................................................................. 4
3.0 OBJECTIVES ........................................................................................................................................................ 5
4.0 METHODS ............................................................................................................................................................. 5
4.1 LOON POPULATION, NESTING, AND PRODUCTIVITY SURVEYS ....................................................................................................................... 5
4.2 LOON MANAGEMENT EFFORTS ...................................................................................................................................................................... 7
4.2.1 Artificial Nesting Islands (Rafts)........................................................................................................................................................... 7
4.2.2 Informational Signs .............................................................................................................................................................................. 7
4.3 COLOR-BANDING AND MONITORING MARKED INDIVIDUALS ......................................................................................................................... 7
4.4 ABANDONED EGG COLLECTION ..................................................................................................................................................................... 8
5.0 RESULTS AND DISCUSSION ............................................................................................................................ 8
5.1 LOON POPULATION, NESTING, AND PRODUCTIVITY ON AZISCOHOS LAKE, 2011 ........................................................................................... 8
5.1.1 Nest Failures ...................................................................................................................................................................................... 11
5.1.2 Assessment of the Effects of Lake-level Changes on Common Loon Nesting Success on Aziscohos Lake in 2011. ............................. 12
5.2 ARTIFICIAL NESTING ISLANDS (RAFTS) USE AND EFFECTIVENESS .............................................................................................................. 13
5.2.1 Informational Signs ............................................................................................................................................................................ 16
5.3 COLOR BANDING AND MONITORING MARKED INDIVIDUALS ....................................................................................................................... 17
5.4 ABANDONED EGG COLLECTION ................................................................................................................................................................... 17
6.0 RECOMMENDATIONS .................................................................................................................................... 17
6.1 POPULATION MONITORING .......................................................................................................................................................................... 17
6.2 RAFT MANAGEMENT AND PLACEMENT........................................................................................................................................................ 17
6.3 COLOR-MARKING INDIVIDUALS .................................................................................................................................................................. 17
6.4 INFORMATIONAL SIGNS ............................................................................................................................................................................... 17
7.0 LITERATURE CITED ....................................................................................................................................... 18
LIST OF TABLES
Table 1: Survey Record, Aziscohos Lake, 2011 ........................................................................................................................................................ 6
Table 2: Causes and Characterization of Common Loon Nest Failures ..................................................................................................................... 6
Table 3: 2011 Aziscohos Lake Loon Nesting and Productivity by Territory ........................................................................................................... 11
Table 4: Common Loon Population and Productivity on Aziscohos Lake 2006- 2011 ........................................................................................... 11
Table 5: Comparative Loon Nesting Summary: Raft vs. Natural Nests, Aziscohos Lake, 2011 .............................................................................. 14
LIST OF FIGURES
Figure 1: Rangeley Lakes Study Area ....................................................................................................................................................................... 3
Figure 2: Distribution of Common Loon Territories on Aziscohos Lake 2011 .......................................................................................................... 9
Figure 3: General Nest Location and Substrates on Aziscohos Lake 2011 .............................................................................................................. 10
Figure 4: Daily Reservoir Water Level for Aziscohos Lake May 1- August 31, 2011 ............................................................................................ 12
Figure 5: Numbers of Rafts Floated and Used on Aziscohos Lake, 1987- 2011 ...................................................................................................... 14
Figure 6: Map of Raft Sites and Status for 2011 ...................................................................................................................................................... 15
Figure 7: Percent Common Loon Nesting Success on Rafts vs. Natural Sites on Aziscohos Lake 1987- 2011 ....................................................... 16
APPENDICES (available in full report from BRI)
Appendix 1: Definition of Terms ............................................................................................................................. Error! Bookmark not defined.
Appendix 2: Loon Nest Site Location on Aziscohos Lake 2011 .............................................................................. Error! Bookmark not defined.
Appendix 3: Qualitative Population and Productivity Summary by Loon Territory, Aziscohos Lake 2011 ............. Error! Bookmark not defined.
Appendix 4: Band Information for Common Loons Banded in 2011 ....................................................................... Error! Bookmark not defined.
i
1.0 EXECUTIVE SUMMARY
Twenty-one territorial pairs of common loons were observed on Aziscohos Lake in 2011.
Nineteen (90%) of 21 pairs nested, initiating 20 nesting attempts. Eight (42%) of 19 nesting
pairs successfully hatched a total of 15 chicks, of which eight (53%) survived to fledge.
Productivity in 2011 was 0.38 chicks fledged/territorial pair, below the rate necessary over the
long term to maintain a loon population. Twelve (60%) of 20 attempted nests failed on
Aziscohos Lake in 2011, three (25%) due to mammalian predation, three (25%) to water level
decrease, one (8%) to over incubation and five (42%) nests were abandoned due to unknown
causes.
In 2011, two early-season spikes of > 0.5 vertical feet in the Aziscohos lake levels (May 19-20
and May 26-28; Figure 4) were followed by an unusually immediate, rapid, and continuous
draw-down of > 1.0 vertical feet / 30 days through late August. During the entire usual nest
initiation season May 15 - July 15, all nests initiated on nonfloating sites would have suffered >
0.5 vertical foot lake-level increases or a water-level decrease of > 1.0 vertical feet, magnitudes
of fluctuation known to significantly threaten common loon nesting success. Three (25%) of 12
common loon nest failures here in 2011 were directly attributed to lake-level recession, which
may also have affected additional nest failures, success of raft-borne nests, and lakewide
productivity by reducing survival rates of second chicks hatched.
Six (43%) of 14 nesting attempts on rafts were successful, compared to two (33%) of six nesting
attempts on natural nonfloating sites. Raft-hatched nests contributed 73% of loons fledged on
Aziscohos Lake in 2011. Under the current water-level management regime, artificial nesting
islands make a significant contribution to loon nesting success and overall productivity.
ii
2.0 INTRODUCTION
2.1 STUDY AREA
Aziscohos Lake is an artificial impoundment of 11.53 square miles (7,379 acres) extending
approximately 12 miles across Parkertown, Lynchtown and Lincoln townships in northwestern
Maine (Figure 1). It was created behind Aziscohos Dam on the Magalloway River in 1911 to
increase water storage in the Upper Androscoggin Storage System and to facilitate transport of
timber downriver. The reservoir, rimmed with substrates ranging from boulders at the south end
to granular sand in areas of the north end, provides habitat for many lacusterine wildlife species,
including the common loon (Gavia immer) and several species of its prey.
Water-level
management regimes on Aziscohos Lake required for minimum flows and flood control
downriver can cause water-level fluctuations on the reservoir during the loons’ nesting season that can negatively affect loon nesting success. A hydroelectric facility downstream of the dam
became commercially operational in 1989.
Figure 1: Rangeley Lakes Study Area
3
2.2 HISTORY AND PURPOSE OF STUDY
The common loon is a piscivorous water bird possessing adaptations for underwater locomotion
including heavy bones and posterior attachment of large webbed feet, which reduce terrestrial
mobility. Loons come to shore only for copulation, nest construction and incubation of eggs.
Shoreline nest placement and limited mobility on land make loon nests vulnerable to failure
caused by water level fluctuations.
Hydroelectric generation development at Aziscohos Dam required Federal Energy Regulatory
Commission (FERC) licensing of the Aziscohos Project. The common loon’s susceptibility to water-level changes during the nesting period prompted the U.S. Fish & Wildlife Service
(USFWS) and the Maine Department of Inland Fisheries & Wildlife to identify the common loon
as a species to be evaluated as part of the licensing process.
In 1986, the Androscoggin
Reservoir Company (ARCO) and Aziscohos Hydro Company, Inc. conducted the first common
loon population and productivity survey on Aziscohos Lake, documenting the negative impacts
of water level fluctuations on the nesting success of loons, and submitted a loon management
plan to FERC that was approved and incorporated into Article 33 of FERC License No. 4026002ME (Fair 1986). This plan evaluated the necessity and feasibility of the use of artificial
nesting islands on Aziscohos Lake and created directives for the manufacture, placement, and
maintenance of artificial nesting islands determined necessary.
From 1986-1999, common loon populations and productivity on Aziscohos Lake were surveyed
and water level fluctuations mitigated using artificial nesting islands by Jeff Fair (Fairwinds
Wildlife Services) and Bill Hanson (Senior Biologist, then Central Maine Power Co.) in
accordance with the FERC order. In 1999, NextEra Energy (NEE), then known as FPL Energy
Maine Hydro, became a partial owner of the Aziscohos Dam and assumed responsibility for the
project. At that time, Biodiversity Research Institute (BRI) assumed the responsibility of loon
surveys, management, and the preparation of annual reports. BRI biologists worked with Jeff
Fair (Fairwinds) and Bill Hanson (now with NEE) to ensure thorough standardization of survey
techniques and definitions to minimize observer bias and to maximize mitigation effectiveness
during the transition period. This long-term cooperative initiative between ARCO, FPLE, NEE,
4
USFWS, Fairwinds, and BRI has resulted in one of the most thoroughly monitored loon
populations in North America.
3.0 OBJECTIVES
1. To continue ongoing loon monitoring on Aziscohos Lake by quantifying breeding activities
and factors negatively affecting productivity.
a. To survey the common loon population throughout Aziscohos Lake to determine number
of territorial pairs, number of nesting pairs, frequency of nesting and nest success, hatch
rates, survival of fledglings, and productivity;
b. To identify, attribute, and quantify causes of nest failure including water-level
fluctuation; and
c. To assess the effects of lake-level changes on loon nesting success.
2. To enhance loon nesting success through deployment of artificial nesting islands (rafts) with
avian guards in loon territories most impacted by nest failures using strategies and techniques
described by DeSorbo et al. (2007, 2008).
a. To anchor, vegetate, and maintain rafts in appropriate sites;
b. To post informational signs as deemed necessary;
c. To assess the effectiveness of raft deployment and its contribution to loon productivity;
and
d. To make recommendations for the improvement, removal, and/or placement of rafts and
signs according to guidelines formulated in the management plan.
3. To continue loon demographic monitoring by color-banding and tracking known individuals.
4. To collect abandoned loon eggs for subsequent analysis.
4.0 METHODS
4.1 LOON POPULATION, NESTING, AND PRODUCTIVITY SURVEYS
Survey methods were consistent with those reported by Fair (1995) and ongoing studies
throughout the Northeast (see Evers 2007).
All known or potential loon territories and
surrounding areas were surveyed by boat or from shore using 10X binoculars or a 15-45X
spotting scope. Surveys were made every five to seven days, when possible, during peak loon
5
nesting and hatching periods from May through July, and through September to determine chick
survival (Table 1). All known nesting sites were checked regularly for nesting evidence, both
above and below the waterline in response to fluctuating water levels.
Table 1: Survey Record, Aziscohos Lake, 2011
Month
May
June
July
August
September
Survey Dates
26
3, 9, 15, 24, 30
6, 14, 18, 28
10, 19, 25
6, 22
Loon pairs were considered territorial for the season when occupying a territory > four weeks.
Nesting pairs were defined as those laying at least one egg; a nesting attempt was evidenced by a
constructed nest dish or scrape with at least one egg present or current year eggshell fragments or
other evidence of current year egg presence. Successful nesting pairs hatched at least one chick.
Causes of nest failure (Table 2) were attributed according to evidence observed and/or waterlevel records.
Table 2: Causes and Characterization of Common Loon Nest Failures
1:
Avian predation (AP): characterized by a small hole in the egg.
2:
Mammalian predation (MP): characterized by smashed eggs/egg shells, tracks around nest, and or scat.
3:
Water level increase (WLI): increase in lake level causing nest floods. Eggs washed off nests, or eggs still
in nest, chilled in standing water.
4:
Water level decrease (WLD): decrease in water level causing eggs to be stranded in unreachable nests.
5:
Human disturbance (HD): human intrusion, human related activities.
6
Loon disturbance (LD): loon intrusion into nesting territory.
7.
Over incubation (OI): loons remaining on nest past normal incubation times (27-30 days).
8.
Unknown (UNK): cause unknown.
Lake-level data were analyzed and compared with timing of surveyed nest discoveries using the
analytical technique from Fair (2006) to help assess the role of water level fluctuations in cases
6
of unknown causes of nest failure. Loon chicks surviving past six weeks of age were assumed to
have survived or fledged (Evers 2007).
4.2 LOON MANAGEMENT EFFORTS
4.2.1 Artificial Nesting Islands (Rafts)
During May, BRI and NEE biologists floated, vegetated, and anchored rafts with avian guards
(Fair 1993) on Aziscohos Lake in where established pairs have experienced successive nest
failure due to artificial water level fluctuations or shoreline predation and have a suitable
flotation site (DeSorbo et al 2008). Rafts were observed during each lakewide survey and
monitored periodically for proper placement, buoyancy, and adequate nesting materials
throughout the season. After nesting, rafts were stored on site above high water to dry for the
winter.
4.2.2 Informational Signs
Informational signs were placed in areas of high visibility or high traffic in order to minimize
impacts of human activities on nesting loons. Signs can attract attention and this potential effect
was taken into consideration before deployment.
4.3 COLOR-BANDING AND MONITORING MARKED INDIVIDUALS
Loons were captured using well-established night-lighting and vocalization playback techniques
as described by Evers (1993, 2001). Adult and juvenile birds of sufficient tarsus size were
banded with USFWS aluminum bands and a unique combination of plastic colored leg bands,
enabling identification of individual birds to be made from a distance in future observations.
Captured birds were weighed, two second secondary feathers collected by clipping at the base of
the quill, and blood samples taken from the metatarsal vein for contaminant analysis.
During surveys, bands were observed opportunistically using binoculars or spotting scopes.
Band combinations observed in the field were recorded and later referenced against a color band
identification list to confirm the individual(s).
7
4.4 ABANDONED EGG COLLECTION
Whole, verifiably abandoned loon eggs were opportunistically collected to determine 1) egg
viability as indicated by developmental stage and 2) egg mercury concentration. Collected eggs
were placed in a labeled zip-lock plastic bag and frozen for future analysis.
5.0 RESULTS AND DISCUSSION
5.1 LOON POPULATION, NESTING, AND PRODUCTIVITY ON AZISCOHOS LAKE, 2011
Twenty-one territorial pairs of common loons were observed on Aziscohos Lake in 2011 (Figure
2). Nineteen (90%) of 21 pairs nested, initiating 20 nesting attempts including one renest (Figure
3). Eight (42%) of 19 nesting pairs successfully hatched a total of 15 chicks, of which eight
(53%) survived to fledge. Table 3 summarizes nesting activity by loon territory.
Territorial population in 2011 was the same as the past five year’s average, however the number
of nesting pairs and therefore overall nesting frequency were the highest recorded in the last five
years. The 2011 productivity appeared to be back to the expected long-term average after a
decline in 2008 and 2009 (0.21 and 0.27 respectively) (Table 4), though still below 0.48 chicks
surviving / territorial pair necessary over the long term to maintain a loon population (Evers
2007). Average productivity for Aziscohos Lake 1987-2010 was 0.34 chicks / territorial pair;
2011 productivity was 0.38 chicks / territorial pair.
Fifteen common loon chicks were hatched from nests on eight territories [Beaver Brook (2),
Camo Camp (2), Hammel Brook (2), Hurricane (2), Little Magalloway (2), South Hammond (2),
Tiger Gray (1), Yukon (2)]. Eight chicks from six of these territories [Camo Camp (2), Hammel
Brook (2), Hurricane (1), Little Magalloway (1), Tiger Gray (1), Yukon (1)] survived past six
weeks of age to fledge, reflecting slightly above the average number of chicks fledged here
2006-2010 (7 +/- 2 chicks).
8
Figure 2: Distribution of Common Loon Territories on Aziscohos Lake 2011
9
Figure 3: General Nest Location and Substrates on Aziscohos Lake 2011
10
Table 3: 2011 Aziscohos Lake Loon Nesting and Productivity by Territory
Territory Name
Aldrich Brook
Beaver Brook
Beaver Island
Big Brook
Big Magalloway
Bosebuck
Bosebuck North River
Buck Mountain
Camo Camp
Cold Brook
Dam
Emery's Misery
Grove
Hammel Brook
Hurricane
Lincoln Brook
Little Magalloway
Meadow Brook
North Hammond
Raven
Schist Cove
South Cove
South Hammond
Sunday Pond
Tiger Gray
Twin Brook
Yukon
2011 Total
Territorial Pairs
1
1
1
0
1
1
0
1
1
1
1
1
1
1
1
0
1
1
0
1
0
0
1
1
1
1
1
21
Nesting Pairs
1
1
1
0
1
0
0
1
1
1
1
0
1
1
1
0
1
1
0
1
0
0
1
1
1
1
1
19
Chicks Hatched
0
2
0
0
0
0
0
0
2
0
0
0
0
2
2
0
2
0
0
0
0
0
2
0
1
0
2
15
Chicks Surviving
0
0
0
0
0
0
0
0
2
0
0
0
0
2
1
0
1
0
0
0
0
0
0
0
1
0
1
8
Nest Fail
1
0
1
0
1
0
0
1
0
1
2
0
1
0
0
0
0
1
0
1
0
0
0
1
0
1
0
12
# Rafts Floated
1
1
0
1
0
0
0
1
1
1
1
1
0
1
1
0
0
0
1
1
0
0
1
1
1
1
1
17
Raft Used
1
1
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
0
0
1
0
0
1
1
1
1
0
13
Table 4: Common Loon Population and Productivity on Aziscohos Lake 2006- 2011
Parameter
Territorial Pairs (TP)
Nesting Pairs (NP)
Chicks Hatched (CH)
Chicks Surviving (CS)
Productivity (CS/TP)
Nesting Frequency (NP/TP)
Hatch Rate (CH/NP)
Survivorship (CS/CH)
2006
19
16
12
7
0.37
0.84
0.75
0.58
2007
23
18
10
9
0.39
0.78
0.56
0.90
2008
19
16
13
4
0.21
0.84
0.81
0.31
2009
22
17
15
6
0.27
0.77
0.88
0.40
2010 Average SD
21
21
2
16
17
1
13
13
2
8
7
2
0.38
0.32 0.08
0.76
0.80 0.04
0.81
0.76 0.12
0.62
0.56 0.23
2011
21
19
15
8
0.38
0.90
0.79
0.53
5.1.1 Nest Failures
Twelve (60%) of 20 attempted nests failed on Aziscohos Lake in 2011. Eight (67%) of 12 nest
failures occurred on rafts.
Causes of nest failure included three (25%) from mammalian
predation, three (25%) as a result of a water level decrease, one (8%) nest failed from over
incubation and five (42%) nests were abandoned due to unknown causes.
11
5.1.2 Assessment of the Effects of Lake-level Changes on Common Loon Nesting Success on
Aziscohos Lake in 2011.
In 2011, two early-season spikes of > 0.5 vertical feet in the Aziscohos lake levels (May 19-20
and May 26-28; Figure 4) were followed by an unusually immediate, rapid, and continuous
draw-down of > 1.0 vertical feet / 30 days through late August. Lake-level fluctuations during
the common loon nesting season are known to cause nest failure due to nest inundation when
water levels increase or nest stranding when water levels decrease. Changes > 0.5 feet vertical
increase and > 1.0 feet vertical decrease after nest initiation commonly threaten nesting success
(Fair 1979, 2006). Daily lake levels on Aziscohos Lake in 2011 exhibited fluctuations beyond
these thresholds throughout the season.
Figure 4: Daily Reservoir Water Level for Aziscohos Lake May 1- August 31, 2011
*Red line denotes full pond=1520.3 feet above sea level
12
During the entire prime nest initiation season May 25 - June 20 and during the entire usual nest
initiation season May 15 - July 15, all nests initiated on nonfloating sites would have suffered >
0.5 vertical foot lake-level increases or a water-level decrease of > 1.0 vertical feet according to
an assessment of daily lake levels using Fair’s (2006) method. Thus, every common loon nest
initiated on a nonfloating site on Aziscohos Lake in 2011 would have been threatened by the
effects of water-level fluctuations.
Of four nest failures on natural sites here in 2011, one (25%) was attributed to lake-level
drawdown, two (50%) were attributed to mammalian predation, and one (25%) remained
unattributed. Mammalian predation may be enhanced by lake-level recession by lengthening and
delaying incubating loons’ returns to the nest during nest change-overs between male and
female. Rapid lake-level recession also apparently caused two (25%) of eight nest failures on
rafts that had become stranded in shallow water or too close to shore, removing the advantages
of a floating nest site. Common loons are known to accommodate lake-level recession when it
occurs slowly; the rapidity of drawdown here may have influenced a portion of the five (25%) of
20 total common loon nest failures attributed to unknown causes on Aziscohos Lake in 2011.
Four (50%) of eight successful nesting attempts resulted in one chick (of two hatched in each
case) being found deceased at the nest on Aziscohos Lake in 2011. Common loon pairs may
leave the nest area with the first chicks hatched, abandoning the second to hatch hours to a day
later, when a disturbance persists at the nest site. Rapid lake-level recession and resultant
distance to the nest from the water or long shallow-water approaches may help explain this
unusual loss in productivity.
5.2 ARTIFICIAL NESTING ISLANDS (RAFTS) USE AND EFFECTIVENESS
Thirteen (76%) of 17 rafts floated were used by loon pairs on Aziscohos Lake in 2011 (Figure 5
and 6). Six (43%) of 14 nesting attempts on rafts were successful, compared to two (33%) of six
nesting attempts on natural nonfloating sites (Table 5). Raft-hatched nests contributed 73% of
loons fledged on Aziscohos Lake in 2011. Nesting success has generally been higher for nests
on rafts since mitigation management was first attempted (Figure 7).
13
Table 5: Comparative Loon Nesting Summary: Raft vs. Natural Nests, Aziscohos Lake, 2011
Raft Nests
Number of Nest Attempts
Number of Successful Nest Attempts
Success Rate
Chicks Hatched form Rafts
Total Hatches from all nests
Contribution to Productivity
2011
13
6
46%
11
15
73%
Natural Nests
Number of Nest Attempts
Number of Successful Nest Attempts
Success Rate
Chicks Hatched form Natural Sites
Total Hatches from all nests
Contribution to Productivity
Figure 5: Numbers of Rafts Floated and Used on Aziscohos Lake, 1987- 2011
14
2011
6
2
33%
4
15
27%
Figure 6: Map of Raft Sites and Status for 2011
15
Figure 7: Percent Common Loon Nesting Success on Rafts vs. Natural Sites on Aziscohos Lake 1987- 2011
Under the current Aziscohos lake water-level management regime, artificial nesting islands make
a significant contribution to loon nesting success and overall loon productivity.
Loon
productivity here remains below sustainable levels most years, but is much higher than years
prior to initiation of conservation efforts (Fair 1986) and is affected by factors beyond waterlevel management. Productivity levels for sustainable populations are better measured for larger
area populations.
5.2.1 Informational Signs
Informational signs were posted at the Bosebuck Camps in 2011. Signs were not posted in loon
territories since human disturbance has not been considered a significant factor in loon nesting
success on Aziscohos Lake.
16
5.3 COLOR BANDING AND MONITORING MARKED INDIVIDUALS
Five loons were captured and sampled (feathers and blood): three females, two males on a total
of four territories. All of the loons were recaptured individuals. The male and female from the
South Hammond territory were implanted with satellite transmitters. Data collected through the
satellite research is being used to track migratory movements and wintering locations.
5.4 ABANDONED EGG COLLECTION
Five abandoned loon eggs were collected from five territories in 2011: Big Magalloway (1),
Cold Brook (1), Dam (1), Sunday Pond (1), and Tiger Gray (1). In addition to the abandoned
eggs three chick carcasses were collected from nests, one from each Beaver Brook, Little
Magalloway and Yukon territories. One of the chicks on the Hurricane territory hatched from
the egg and died on the nest but was not collected do to extreme decay.
6.0 RECOMMENDATIONS
6.1 POPULATION MONITORING
Continue annual monitoring of all established pairs and color-marked individuals, transitional
pairs, nesting pairs, productivity, and effectiveness of raft management on Aziscohos Lake.
6.2 RAFT MANAGEMENT AND PLACEMENT
Continue raft management program on Aziscohos Lake in the loon territories currently being
offered rafts and expand or reduce where indicated according to DeSorbo et al. (2007, 2008).
6.3 COLOR-MARKING INDIVIDUALS
Continue capture, sampling, and color-marking of individual loons. Color-banding provides a
mechanism for understanding impacts by water level management and its influences on their
reproductive success (e.g., individual performance and within-season movements).
6.4 INFORMATIONAL SIGNS
Informational signs should be placed at the two public boat launches on Aziscohos Lake, Black
Brook Cove Campground and Twin Brook, as well as at Bosebuck Camps.
17
7.0 LITERATURE CITED
DeSorbo, C., D. K. Taylor, D. Kramar, J. Fair, J. Cooley, D.C. Evers, W. Hanson and H. Vogel. 2007.
Quantifying and characterizing the reproductive advantages gained by raft-nesting Common
Loons (Gavia immer) on artificial impoundments and natural lakes in ME & NH. Journal of
Wildlife Management: 71(4).
DeSorbo, C., J. Fair, K. Taylor, W. Hanson, D.C. Evers, H. Vogel and J. Cooley. 2008. Guidelines for
constructing and deploying Common Loon nesting rafts. Northeastern Naturalist 15 (1):75-86.
Evers, D.C. 2007. Status assessment and conservation plan for the Common Loon (Gavia immer) in
North America. U.S. Dept. of Interior, Fish and Wildlife Service, Biological Technical
Publication FWS/BTP, Washington, D.C. 123pp.
Evers, D. C. 2001. Common Loon population studies: Continental mercury patterns and breeding
territory philopatry. Ph.D. Dissertation, Univ. Minn., St. Paul.
Evers, D. C. 1993. A replicable capture method for adult and juvenile Common loons on their nesting
lakes. Pp. 214-220 in L. Morse, S. Stockwell, and M. Pokras (eds.). Proc. 1992 Conf. Loon and
its ecosystem. U.S. Fish. Wildl. Serv., Concord, NH.
Fair, J. 2006. Potential effects of water-level fluctuations on Common Loon nesting success on Brassua
Lake, Maine (1996-2006). Unpubl. Rept To FPL Maine Hydro, Lewiston, ME.
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Power Company, Lewiston, ME.
Fair, J. 1993. A cover for loon rafts to obstruct avian depredation. Pp. 325–326, In L. Morse, S.
Stockwell, and M. Pokras (Eds.). The Loon and its Ecosystem: Status, Management, and
Environmental Concerns. Proceedings of the 1992 Conference on the Loon and its Ecosystem.
US Fish and Wildlife Service, Concord, NH. 247 pp.
Fair, J. 1986. Aziscohos Lake 1986 common loon population survey results and management plan.
Unpubl. Rept. to Androscoggin Reservoir Co, Lewiston, ME. for submission to FERC. 17 pp.
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(2011) Aziscohos Lake Common Loon Population

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