Download loons - People

LOONS
Becky Marischen
Taxonomy


GAVIIFORMES
GAVIIDAE

Gavia stellata
Red-throated Loon

Gavia arctica
Arctic Loon

Gavia pacifica
Pacific Loon

Gavia immer
Common Loon

Gavia adamsii
Yellow-billed Loon
Life History
Loons are among the
oldest groups of birds still
living today.
 Closest living relatives
are penguins and the
tube-nosed swimmers
(Albatrosses and
Shearwaters).
 All five species are
restricted to the northern
hemisphere and all are
migratory.

General Characteristics

Appearance



All species have a red
pigment in the retina
that filters light when
loons dive beneath the
water's surface and
allows for sight
Sexes alike, males tend
to be larger
Grayish non-breeding
plumage and a striking
alternate plumage
General Characteristics cont.




dagger-like bills
feed primarily on small fish also
known to eat aquatic vegetation,
insects, mollusks, and frogs
lobed feet set far back on the
body - are very clumsy on land.
Diving
 loons have solid bones
 the extra weight helps
them dive
 Can also expel air out of their
feathers
 Use feet for propulsion, wings
for turning
 have been trapped in fishing
nets 240 feet below the
surface
 can stay underwater for
several minutes
General Characteristics cont.

Flight


Because of their large size and weight, loons require
about 1/4 mile of lake surface to become airborne
Once airborne, loons are powerful fliers

Pilots have checked them flying at speeds up to 80 mph
Vocalization







Loon calls have been identified into four classifications:
Wail, tremolo, yodel and hoot.
The wail is perhaps the call most frequently heard.
The tremolo signals alarm or annoyance, frequently given
after a disturbance.
The yodel is given only by males, it serves as an aggressive
territorial proclamation.
The hoot is used as a contact call.
The vocalizations differs among species.
 The red-throat erupts into a rapid quacking, and the
pacific loon has a wailing siren of a voice, an ascending
whistle that it shortens to a piercing scream when
startled.
Loons can be heard day and night during breeding, but they
are nearly silent in the winter
Behaviors

The "penguin dance“
is a sign of extreme
agitation. This is
usually a territorial
behavior.

generally combined
with frantic calls and is
one of the last
available defensive
actions
Breeding Habitat

A suitable lake is
clear and large to
provide territories
typically between
100 and 200 acres



Must have an
adequate supply of
fish
It must also have
islands or inlets
suitable for nesting
Relatively free from
human disturbance
Breeding Behavior





Loons are territorial and generally one pair is found per lake,
except for large bodies of water.
Courtship consists mainly of head dipping and shallow dives.
 In spring, loons are frequently observed chasing each
other across the surface of a lake. This is primarily
territorial behavior, not courtship ritual.
Loon pairs mate for life, however, banding studies have
shown that loons will sometimes switch mates after a failed
nesting attempt and even between nesting attempts in the
same season.
They return every year to the same area to breed.
 often reuse the same nest each year
Both the male and female participate in nest building and
take turns incubating.
Breeding Behavior cont.


The nest is a loosely formed mound consisting of
reeds, sticks, grasses and muddy vegetation with
a slight hollow in the middle.
Because of their difficulty moving about the land,
loons build nests within a few inches of water.



When a nesting loon is disturbed, it slips off the nest and
submerges to keep the location of its nest unknown.
Incubation period is 23-31 days
Clutch size 1-3
 Usually only one chick survives to migration.
Breeding Behavior cont.

The young are precocious and leave the nest within a day
or two.
 Chicks ride on their parents' backs more than half the
time in their first week of life.
 this help keeps them dry, warm, and safe from
predators
 loon chicks must be fed by their parents
 their diet consisting mostly of small food items;
snails, small fish, crayfish, minnows, and some
aquatic vegetation
 about 8 weeks the chicks begin to dive for some of their
own food
 by 11 or 12 weeks of age, the chicks are providing
almost all of their own food
 sometime in the third month the chicks learn to fly
 Immature loons resemble adults in winter plumage.
Migration and Population



Loons migrate in loose aggregations and roost
together in flocks of as many as several hundred
birds.
Adults migrate first and chicks follow later
 The chicks will not return to their natal lakes
until they are three or four years old and are
ready to breed.
The abundance and even in some cases the
geographical ranges of these species are still
poorly known.
 Loons are widely distributed, making it difficult
and expensive to survey populations.
Red-throated Loon: Gavia stellata
As its name implies, the red-throat has a
triangular throat patch of vivid, rusty red.
Red-throated Loon: Gavia stellata




Red-throated loons, Pacific loons,
and arctic loons are smaller varieties
and readily distinguished from their
larger cousins by gray rather than
black heads
The Red-throat is the smallest,
slightest of the divers
 stands at 53-69 cm and its
wingspan ranges from 106-116
cm
This loon species is unique in being
able to take off from land.
The Red-throated Loon is an uncommon migrant in
Kentucky. Recorded mostly in larger bodies of water such
as the Green River Reservoir.
Red-throated Loon: Gavia stellata


Range
 Breeds far into the high Arctic, and winters
mainly on the northern coasts of the Atlantic
and Pacific. Also in the Great Lakes.
 spends the winter along the Pacific coast from
the Aleutian Islands to Baja
Nest failures due to predation are more common
than those due to human disturbance, because
their North American range in does not overlap
much with where humans live.
Red-throated Loon: Gavia stellata
Arctic Loon Gavia arctica
Arctic loons have a greenish-black throat, but
otherwise look similar to Pacific loons.
Arctic Loon Gavia arctica



The Arctic Loon breeds
on the tundra, and is
usually found only on the
west coast in winter. It
rarely wanders eastward
in the winter, and into
the Great Lakes region.
They are found in
extreme western Alaska
(Cape Prince of Wales).
The Arctic Loon is a rare
visitor to the Great
Lakes, and is only seen
there in winter.
Pacific Loon: Gavia pacifica
The throat of the Pacific loon is purplish black while its
black back has bars and spots of white, similar to the
common and yellow-billed.
Pacific Loon: Gavia pacifica

Pacific loons until recently were considered a
subspecies of Arctic loon.

Their average length is 66 cm.
The Pacific Loon is a very rare vagrant in
Kentucky. It is known in the state from fewer
than 10 records.
The Arctic Loon breeds on the tundra, and is
usually found only on the west coast in winter. It
rarely wanders eastward in the winter, and into
the Great Lakes region.


Pacific Loon: Gavia pacifica
Yellow-billed Loon: Gavia adamsii
Yellow-billed Loon: Gavia adamsii

Range


Breeds from
northern Alaska
and northern
Canada east nearly
to Hudson Bay.
Winters along
coast from Alaska
south to British
Columbia, and
occasionally to
California.
Distribution of Yellow-billed Loon in Canada
Yellow-billed Loon: Gavia adamsii




The yellow-billed is the largest of the loons (3036 inches long) and one of the largest diving
birds in North America.
The yellow-billed loon is similar to the common
loon, but it has white spots on its back and a
straw-yellow bill even in winter.
It is the least abundant of the five loons that nest
regularly in North America.
Compared to other loon species, the yellow-billed
loon is far more restricted to the Arctic. It has an
almost circumpolar distribution, but is not
common anywhere in the world.
Common Loon: Gavia immer
Common Loon: Gavia immer
Breeds in North America
from Alaska and
southern Baffin Island,
south to northern United
States; also in
Greenland and Iceland.
Winters along the coast
from southern parts of
its breeding range south
to the Gulf of Mexico,
and in parts of Europe.
Common Loon: Gavia immer




One of the larger loons about 70-90 cm in length and weighs
on average 9 lbs, but ranges from 6-14 lbs
The Common Loon is the state bird of Minnesota and the
national bird in Canada
 The loon is the Canadian equivalent of the Bald Eagle.
The Common Loon has the most reliable information on
population numbers of the loon species, this is because of its
southern distribution and its overlap with human populations.
 Common Loon populations in Canada have been estimated
at between 250,000 and 500,000 individuals.
 Estimated 15,000 loons in the Upper Great Lakes States of
Minnesota, Wisconsin, and Michigan
 comprise nearly three-quarters of the loon population
outside of Alaska.
In Kentucky the Common Loon is common in large bodies of
water in migration and uncommon to common in winter.
 Usually seen in winter plumage
Management Concerns
Cause of Death
Number of
Birds
% of
Total
Trauma
27
38.0
Lead intoxication
19
26.8
Aspergillosis
6
8.5
Gastric foreign
body/entanglement
5
7.0
Intestinal parasitism
2
2.8
Other
6
8.5
Unknown
6
8.5
Total
71
100.0
Management Concerns




Of the 27 killed by trauma
 Seven individuals were shot
 9 died of injuries due to collisions with boats, cars, or
power lines
 6 drowned in fishing nets
 in 5 cases the source of the trauma was not determined
In 15 of 19 birds killed by lead poisoning a fishing weight
was present in the gizzard.
All but one of the six loons dying of aspergillosis had some
other serious disease condition as well.
At least 51 of 71 birds (72%) died as the result of trauma,
entanglement or lead poisoning, all of which are
consequences of human actions.

1993, the Ontario Ministry of Natural Resources (OMNR) and the
Canadian Cooperative Wildlife Health Centre (CCWHC)
Management Concerns: Disturbance



Human activities are largely responsible for the
disappearance of loons from many lakes.
Development of shorelines and islands destroying nesting
habitat.
Disturbance of loons, especially during sensitive nesting and
chick-rearing periods, can reduce or wipe out loon
populations.


More disturbances = more time away from incubating eggs
Pollution of lakes used by nesting loons can lead to
accumulations of toxins in eggs and young and the loss of
food for chicks and adults.
Loons are also susceptible
to oil spills, especially on the
winter range

Management Concerns: Acidity

Recent studies have indicated that loon nesting
success and survival of young may decrease with
increased lake acidity, the result of acid rain.
 Acidity can result in decreases in fish and other
foods,
 This causes chicks on very acid lakes to starve.
 Acidification of lakes may also increase the rate
of methylmercury production by microbes in
lake sediments and water, resulting in higher
concentrations of mercury in the food chain.
Management Concerns: Mercury



A significant proportion of loons found dead in
the United States and Canada have high
concentrations of mercury in their tissues.
Canadian research has demonstrated that loons
nesting near industrial sources of mercury
pollution occupy few potential territories and lay
few eggs, resulting in poor reproductive success.
Increased methylmercury concentrations in fish,
the loon’s main food source, is the result of
environmental mercury pollution, acidification,
and flooding of forested land for hydroelectric
development. These activities pose a threat to
the health and reproductive success of loons in
many locations throughout their range.
Management Concerns: Mercury
Management Concerns: Lead
Loons die of lead poisoning after eating
fish with lead sinkers, and possibly after
picking up discarded sinkers from lake
bottoms. The lead is partially dissolved in
the loon’s gizzard then absorbed into the
blood and body tissues.
 The absorbed lead causes nerve, kidney,
and other tissue damage.
 Abandoned or unattended fishing line and
hooks also cause loon injury and death.

Lead Poisoning
Management Concerns




To protect the loons on lakes used for recreation,
boats should be kept well away from swimming
birds, particularly when they are with chicks that
are too young to dive or fly.
Some shoreline areas should be left undisturbed
to accommodate loon nests, and boaters passing
these areas should travel at speeds that do not
cause wash.
Seaplanes should come and go as far from
nesting areas as possible, taxiing to other parts
of the lake.
Anglers have the responsibility of using non-lead
sinkers and of ensuring that no hooks or lines are
left unattended or abandoned.
The End