(For “Adobe .pdf” file
copies or “hardcopies of articles” contact Daryl Boness - see LAA Board of
Director’s listing for email address)
1. Piper, W. H., D. C.
Evers, et al. (1997). “Genetic monogamy in the common loon (Gavia immer).”
Behavioral Ecology and Sociobiology 41(1): 25-31.
We conducted behavioral
observations and genetic analysis on breeding pairs of common loons in the
upper Great Lakes region from 1993 through 1995 to look for behavioral evidence
of extrapair copulations (EPCs) and to determine parentage of young. Pairs
remained close to each other (usually within 20 m) during the pre-laying period,
leaving little opportunity for EPCs to occur. Males and females both maintained
physical proximity by approaching each other when they became separated.
Copulations were obvious but infrequent, occurring about once every other day
during the prelaying period. Multilocus DNA fingerprinting was consistent with
behavioral findings: 58 young from 47 different families were all genetic
offspring of parents that raised them. Perfect genetic monogamy (genetic
parentage of young by parents that rear them) in loons might arise as a
consequence of the need for vigorous territorial defense to prevent territorial
takeover. .pdf file available
2. Paruk, J. D., D.
Seanfield, et al. (1999). “Bald eagle predation on common loon chick.” Wilson
Bulletin 111(1): 115-116.
We report predation of a
Common Loon (Gavia immer) chick by an adult Bald Eagle Haliueetus
leucocephalus) in northern Wisconsin.
.pdf file available
3. Piper, W. H., K. B.
Tischler, et al. (2001). “Mother-son pair formation in common loons.” Wilson
Bulletin 113(4): 438-440.
Reproduction among close
relatives is rare in birds. Here we report two cases of pair formation between
mothers and sons in a marked population of Common Loons (Gavia immer) in
northern Wisconsin, one of which resulted in the fledging of a chick. Short
distance natal dispersal by males coupled with short distance breeding
dispersal by adults after territorial displacement sets the stage for
occasional mother-son pairings in this species, although data from multilocus
DNA fingerprints indicate that such pairings are infrequent. .pdf file available
4. Piper, W. H., M. W.
Meyer, et al. (2002). “Floating platforms increase reproductive success of
common loons.” Biological Conservation 104(2): 199-203.
Many southern populations of
the common loon (Gavia immer) face threats from lead and methylmercury
contamination, lake acidification, shoreline development and human recreation.
It is now clear that the task of conserving loon populations will depend upon
mitigating these varied threats. In a controlled experiment, we examined the
efficacy of using floating nest platforms to increase reproductive success of
loons and thus help sustain local populations. Platforms were attractive
nesting sites both on lakes that had consistently hatched chicks from natural
sites and on lakes where chick production had been sporadic. When compared to
natural nest sites, platforms increased hatching success by 69% and fledging
success by 32%, apparently through reduction in mammalian egg predation. A well-managed
effort to introduce nesting platforms might be a viable strategy to help
sustain threatened populations. Abstract
only available
5. Timmerman, S. T. A.,
G. O. Craigie, et al. (2004). “Common loon pair rear four chick broods.” Wilson
Bulletin 116(1): 97-201.
Common Loons (Gavia
immer) normally lay a single clutch of two eggs each breeding season. They
occasionally lay one- or three-egg clutches, and rarely, four-egg clutches.
Participants of the Canadian Lakes Loon Survey provided seven independent
observations of loon pairs rearing four-chick broods. Photographic evidence
confirmed two separate instances of adult loon pairs at Anglin Lake,
Saskatchewan, and Kasshabog Lake, Ontario, exhibiting parental behavior toward
a four-chick brood. Occurrence of four-chick broods may be the result of
supernumerary clutches, nest parasitism, post-hatch brood amalgamation, or a
combination of these factors. .pdf
file available
6. Nocera, J. J. and P.
D. Taylor (2000). “Behavior of post-nest failure and non-breeding common loons
during the breeding season.” Wilson Bulletin 112(4): 532-534.
Common Loon (Gavia
immer) breeding, pre-migratory, and wintering behavior has been well
described, but no previous author has characterized failed and non-breeding
loon behavior during the summer breeding season. We quantified the summer
behavior of non-breeding and failed breeding loons from 15 lakes in Kejimkujik
National Park (Nova Scotia, Canada) and the Lepreau watershed (New Brunswick,
Canada). Time-activity budgets and event quantifications were used to describe
behavioral state and event patterns. The behavior of failed and non-breeders in
summer is similar to that described for pre-nesting, pre-migratory, wintering,
and breeding loons (except those with young chicks) with foraging the
predominant behavior and peering the predominant event. We propose that the
behavioral regimen of adult loons is relatively constant throughout the year,
with the exception of a two-week period following chick hatching when adults
brood their young. .pdf file
available
7. Kenow, K. P., M. W.
Meyer, et al. (2002). “Use of satellite telemetry to identify common loon
migration routes, staging areas, and wintering range.” Waterbirds 25(4):
449-458.
We developed a satellite
transmitter attachment technique for adult Common Loons (Gavia immer)
that would help in identifying important migration routes, staging areas, and
the location of wintering grounds of birds that breed in the north central
United States. During the autumn and winter of 1998, the migration of six adult
loons that were radio marked in northern Wisconsin and Minnesota was monitored.
The results of this work offer insight into autumn movement patterns of Common
Loons. Timing of autumn staging and migration to wintering grounds appeared to
be related to low pressure systems that delivered winter weather to the Upper
Midwest. Most of the radiomarked birds staged on the Great Lakes and then
followed one of two distinct migration routes to the Gulf of Mexico and
Atlantic coasts. Several of the birds used lakes and reservoirs in the
southeastern United States during migration. This study provides a basis for
more extensive studies of Common Loon migration. .pdf file available
8. Alvo, R. and M.
Berrill (1992). “Adult Common Loon feeding behavior is related to food fed to
chicks.” Wilson Bulletin 104(1): 184-185.
We observed adult Common
Loons (Gavia immer) feeding their young from hatching through fledging
to determine the food types fed to chicks and to relate changes in adult
feeding behavior to changes in the food types fed to the young. .pdf file available
9. Forrester, D. J., W.
R. Davidson, et al. (1997). “Winter mortality of common loons in Florida
coastal waters.” Journal of Wildlife Diseases 33(4): 833-847.
Diagnostic findings are
presented for 434 common loons (Gavia immer) found sick or dead on
Florida beaches from 1970 through 1994, primarily during the months of December
to April. The most commonly recognized problem was an emaciation syndrome
(66%), followed by oiling (18%), aspergillosis (7%), trauma (5%) and
miscellaneous disease entities (1%). The cause-of-death for 3% of the birds was
not determined. Many of the carcasses examined (n = 173) were obtained during an
epizootic, which occurred, from January to March of 1983 in which more than
13,000 loons were estimated to have died. An emaciation syndrome, characterized
by severe atrophy of pectoral muscles, loss of body fat and hemorrhagic
enteritis, was the primary finding in this epizootic. It was postulated to have
a complex etiologic basis involving synergistic effects and energy costs of
migration, molting and replacement of flight feathers, food resource changes,
salt-loading, intestinal parasitism, environmental contaminants, and inclement
weather. Abstract only available
10. Daoust, P. Y., G.
Conboy, et al. (1998). “Interactive mortality factors in common loons from
Maritime Canada.” Journal of Wildlife Diseases 34(3): 524-531.
Between August 1992 and
November 1995, 31 moribund or dead common loons (Gavia immer) found in
the three Maritime Provinces of Canada (New Brunswick, Nova Scotia, Prince
Edward Island) were necropsied. Eight of these birds were in good body
condition and died acutely from drowning or trauma. The remaining 23 birds were
in poor body condition and had either chronic lead poisoning, respiratory
mycosis, or oil contamination of their plumage. Loons in poor body condition
had significantly higher numbers of intestinal trematodes and significantly
higher levels of total renal mercury than loons in good body condition.
Therefore, poor body condition in many loons was associated with two or more
concurrent potential disease processes, although we could not establish a
cause-effect relationship among these processes in individual birds. These
results suggest that mortality in chronically ill wild animals can result from
synergism among several potentially debilitating agents present in their
environment. Abstract only
available
11. Sidor, I. F., M. A.
Pokras, et al. (2003). “Mortality of common loons in New England, 1987 to
2000.” Journal of Wildlife Diseases 39(2): 306-315.
Diagnostic findings are
presented on 522 common loons (Gavia immer) found dead or moribund in
New England (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island,
and Vermont, USA) between 1987 and 2000. Common loon numbers and range in New
England have decreased from historic levels over the last century due to a
number of proposed factors. Goals of this study were to identify and categorize
causes of mortality and quantify natural versus anthropogenic causes. The
majority of identifiable mortality in chicks was from intraspecific aggression
(25%) and other causes of trauma (32%). Death in immature loons was primarily
from fungal respiratory disease (20%) and trauma (18%). Causes of adult loon
mortality differed significantly in breeding and wintering habitats. Wintering
adults primarily died of trauma (17%) and infection (11%) and had significantly
poorer body condition than breeding loons. In breeding adults, confirmed and
suspected lead toxicosis from ingested fishing weights accounted for almost
half of all mortality. Direct anthropogenic factors accounted for 52% of loon
mortality in this study. Because of high carcass recovery rates, we believe
these data are a good representation of loon mortality in New England. Results
highlight the importance of human influences on conservation and management of
the common loon in New England. .pdf
file available
12. Belant, J. L., J.
F. Olson, et al. (1993). “Evaluation of the single survey technique for
assessing common loon populations.” Journal of Field Ornithology 64(1):
77-83.
We evaluated the accuracy
of a single survey in estimating the resident Common Loon (Gavia immer)
population on the Turtle-Flambeau Flowage, Wisconsin (USA), during 1986 and
1987, by comparing it to estimates obtained during an intensive productivity
and brood habitat study. On average, we located and verified 94% of the chicks
but only 56% of the territorial adults during the single surveys. Determination
of territorial adults was low because of our inability to classify adults
without broods and highly variable numbers of nonresident adult loons present.
We conclude that a single survey on large, multiple-pair lakes is ineffective
in estimating territorial adult Common Loon populations and will not provide
accurate trend data, although a single survey conducted when chicks are
approximately 6-weeks old will yield good estimates of fledging success. .pdf file available
13. Ford, T.-B. and
J.-A. Gieg (1995). “Winter behavior of the common loon.” Journal of Field
Ornithology 66(1): 22-29.
2-yr study was conducted
on the winter behavior of the Common Loon (Gavia immer) at Weekapaug,
Rhode Island. Behavior of loons was assessed by recording the type of activity
every 60 s for a 5-min period. Activity budgets showed an increase in the
amount of time spent feeding from 23% in 1987 to 38% in 1992, possibly due to a
decline in prey abundance. In addition, Common Loons spent more time in
shallower waters in 1991 and 1992 versus 1987, which may reflect increases in
time needed to find prey. Common Loon behavior was not correlated with water
depth or time of day. No territorial behavior was observed. .pdf file available
14. Piper, W.-H., K.-B.
Tischler, et al. (2000). “Territory acquisition in loons: The importance of
take-over.” Animal Behaviour 59(2).
We examined patterns of
territory acquisition and reconnaisance in common loons, Gavia immer,
from northern Wisconsin. Among all territory acquisitions, 41.5% occurred
through passive occupation of territories left vacant after the death or
desertion of a previous resident, 17% constituted founding of new territories
and the remaining 41.5% came about through take-over: either usurpation of
defended territories or appropriation of territories before the seasonal return
of previous owners. Take-overs occurred in both sexes, but individuals acted
alone, never in pairs. Displaced breeders usually took refuge on undefended
lakes near their former territories; about half of these loons later regained
former territories through passive occupation or took possession of new
territories elsewhere. As predicted by the reconnaissance hypothesis,
usurpations occurred most often in territories that had produced chicks during
the previous 12 months, suggesting that loons use the presence or absence of
chicks as a cue for territorial usurpation. Large individuals of both sexes
held onto territories longer than small individuals, an indication that body
size might be correlated with fighting ability. In terms of life history, loons
appear to locate good territories through reconnaissance, usurp them in a
subsequent year and recover from displacements by reclaiming their original
territories or new ones. Hardcopy
only available
15. Sperry, M. L.
(1987). “Common Loon Attacks on Waterfowl.” Journal of Field Ornithology
58(2): 201-205.
Observations of Common
Loons (Gavia immer) harassing and killing waterfowl in Northern
Minnesota [USA] suggest an impact on breeding waterfowl by affecting foraging
and courtship as well as brood disturbance and duckling mortality. Possible
benefits to loons from such interspecific attacks are discussed. .pdf file available
16. Fournier, F., W. H.
Karasov, et al. (2002). “Daily energy expenditure of free-ranging common loon (Gavia
immer) chicks.” Auk 119(4): 1121-1125.
We measured the daily energy
expenditure of free-living Common Loon (Gavia immer) chicks using doubly
labeled water (DLW). Average body mass of chicks during the DLW measures were
425, 1,052, and 1,963 g for 10 day-old (n = 5), 21 dayold (n = 6), and 35
day-old (n = 6) chicks, respectively, and their mean daily energy expenditures
(DEE) were 686 kJ day21, 768 kJ day21, and 1,935 kJ day21, respectively.
Variation in DEE was not due solely to variation in body mass, but age was also
a significant factor independent of body mass. Energy deposited in new tissue
was calculated from age-dependent tissue energy contents and measured gains in
body mass, which were 51, 54, and 33 g day21 from the youngest to oldest
chicks. Metabolizable energy (the sum of DEE and tissue energy) was used to
estimate feeding rates of loon chicks and their exposure to mercury in the fish
they consume. We calculated that loon chicks in Wisconsin consumed between 162
and 383 g wet mass of fish per day (depending on age), corresponding to intakes
of mercury of 16–192 mg day21. .pdf
file available
17. Sjolander, S. and
G. Agren (1972). “Reproductive Behavior of the Common Loon.” Wilson Bulletin
84(3): 296-308.
There is comparatively
little known about the behavior of the loon family, Gaviidae. The Common Loon (Gavia
immer) is the species most extensively treated in the literature,
especially in the comprehensive report by Olson and Marshall (1952)) but
nevertheless several important behavioral features still remain unknown,
especially those pertaining to courtship and mating. As a part of a more
extensive comparative study on the behavior of the Gaviidae the Common Loon was
studied during the summer 1970 on Iceland, where it was possible to obtain most
of this missing information. .pdf
file available