Birds and Mammals in Aquatic
Ecosystems
ENV 311/ EEB 320
Winter 2007
Why Birds?
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Important predators of
invertebrates, fish, mammals,
reptiles and amphibians in
aquatic ecosystems
Major vectors for transport of
plants and wingless
invertebrates
Interesting and ubiquitous
members of aquatic
communities
Along with fish, enjoy fairly
broad support from the public
– Good way to generate
interest in habitat
preservation/restoration
Family Gaviidae
Gavia
• Loons
• Habitat: mainly northern
lakes
• Notes:
– Divers: feed mainly on fish
– Very distinctive
vocalizations
• Alarm call
• Short hoot
– 1 breeding sp. in MI:
common loon (Gavia immer)
University of Michigan Animal Diversity Web
Family Ardeidae
• Bitterns, Herons, and Egrets
• Habitat: Open wetlands,
lakeshores, rivers
• Notes:
University of Michigan Animal Diversity Web
– Often seen stalking prey:
feed mainly on fish, also
amphibians and
invertebrates
– Egrets/herons often build
nests in shrubs/trees and
may be colonial breeders
– Bitterns prefer dense
emergent vegetation and
tend to be solitary
Family Ardeidae
Bitterns
• 2 spp. in Michigan
• American bittern:
– Call distinctive—like a
piledriver in a puddle?
– Secretive, often strikes
vertical pose to blend in
with vegetation
Family Ardeidae
Herons and Egrets
• 6 spp regularly found in
MI
• Less secretive and
more easily spotted
than bitterns
• Egrets are white,
herons may be various
colors
University of Michigan Animal Diversity Web
Family Accipitridae
• Hawks and eagles
• 2 spp. that are most often
found in MI aquatic
ecosystems are:
– Bald eagle (above)
– Northern harrier (below)
• Bald eagle found along
rivers/wetlands, often preys
on fish
– Making strong recovery
from very low numbers for
last half of 20th century
• Northern harrier often hovers
over open wetlands, preys
on small mammals,
amphibians and other birds
University of Michigan Animal Diversity Web
Family Pandionidae
Pandion haliaetus
University of Michigan Animal Diversity Web
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Osprey (1 sp.)
Habitat: Mainly rivers and wooded edges of lakes
Notes:
– Build enormous nests of sticks high off the ground, 3-5 ft in diameter
– Feed mainly on fish but cannot swim—have been known to drown if they
hook into too large a fish
– As with many raptors, numbers have risen since elimination of DDT from
the food web
Family Laridae
• Gulls and terns
• Ring-billed gull
Common tern
• Gulls tend to be thicker-billed
and stouter; frequently walk
– Facultative
predator/scavenger
• Terns are sleeker, designed
for capturing fast prey
– More predatory on small fish
and invertebrates
• May build nests on rocky
shores, islands or floating
mats of vegetation
University of Michigan Animal Diversity Web
Family Anatidae
• Ducks, geese and swans
• Very diverse aquatic family
• Habitats vary, from wooded
wetlands and rivers (wood
duck) to open water (greater
scaup)
• Notes:
University of Michigan Animal Diversity Web
– Many feed by dabbling, i.e.,
sifting through mud for
nutritious invertebrates,
seeds, shoots, etc.
– Others are active predators
of fish (e.g. mergansers)
– Many valued by hunters—
benefit (?) from
conservation efforts
– Webbed feet for swimming
Family Anatidae
Ducks
• Short-necked, often with
colored primary feathers
– Most species migratory
– Most have sexually
dimorphic coloration
• Mallard (Anas platyrhyncos)
very common and spreading
in NA
• Am. black duck (Anas
rubipres) very closely related
to mallard and disappearing
due to interbreeding
Family Anatidae
Geese and Swans
• Longer-necked and
usually larger than
ducks
• Mainly migratory--most
prefer more northerly
breeding ranges than
ducks
• Canada goose (Branta
canadensis) is very
common near
water/grass in MI
Family Gruidae
Grus canadensis
• Sandhill crane
• Habitat: migratory; wetlands critical for breeding success; past
population declines mirrored wetland loss
• Notes:
– Omnivorous, but notorious for eating waterfowl eggs during
breeding season
– Elaborate mating dance
– Social, gregarious bird
Family Alcedinidae
Ceryle alcyon
• Belted kingfisher
• Habitat: waterways and
lakes with available
perches and abundant
food
• Notes:
– Nest in 1-2 meter long
tunnels, often in
riverbanks
– Voracious predator of
small fish
– Call is rattling
Family Charadriidae
• Sandpipers and phalaropes
• Habitat: shores of lakes,
wetlands, large rivers
• Notes:
– Speciose group (18 spp.
commonly migrate through
or reside in MI)
– Size ranges from sparrowsized to length of a small
hawk
– Many have very long
legs/bills for wading and
deep probing of the
substrate for invertebrates
Mammals
• Although most mammals will periodically visit
aquatic ecosystems, only a few species are
strongly associated with water in MI
– Some are voracious predators of fish and
mollusks
– Others may construct large structures and
significantly alter hydraulics of flowing waters
– All have physiological adaptations, such as
webbed feet and waterproof fur that allow them to
thrive in aquatic ecosystems
Castor canadensis
• American beaver
• Notes:
– Noted for its ability to
construct wood/earth dams,
altering flow to suit its needs
– Uses large, gnawing teeth
to fell trees
• Consumes nutritious
bark/buds
• Uses wood for dambuilding
– Characterized by large size
(may reach 35 kg)
waterproof coat and large,
paddle-like tail
– Trapped to near dangerous
levels in 19th century; now
common in most of NA
Lutra canadensis
• River otter
• Notes:
– Intelligent and very
adaptable predator—one
of the few natural
predators of snapping
turtles
– Prefers deep, relatively
isolated rivers with
healthy fish populations
– Highly adapted for speed
in water: sleek, with fully
webbed feet
Mustela vison
• Mink
• Notes:
– Well-adapted for hunting
on land and in water—
can swim well and run
fast
– Feeds on small
mammals, fish,
amphibians, birds
– As with other aquatic
animals, may take up
residence in old muskrat
or beaver lodges
Ondatra zibethicus
• Muskrat
• Notes:
– Looks most like a small
beaver, but can be
distinguished by its thick
rat-like tail
– Builds easily
recognizable lodges in
shallow wetlands
– Mainly herbivorous but
will take crustaceans and
mollusks as well
The End