Transcript Us and them - Chapter 24

Birds & People
Good Things Birds Do For Us
• Food
• Eggs
• 2 billion chickens
per year (18
kg/person)
• 100 million turkeys
• 11 million ducks
Good Things Birds Do For Us
• Feathers ornamentation
Good Things Birds Do For Us
• Guano - fertilizer
• Peruvian islands
Good Things Birds Do For Us
• Insect control
• Northern Flicker
removed >60% of
over-wintering cornborer larvae from
Mississippi cornfield
• Bird houses - Purple
Martin - mosquitoes
Good Things Birds Do For Us
• Rodent control
• Hawks, owls small rodents
Good Things Birds Do For Us
• Scavengers
• Vultures, gulls,
crows
Good Things Birds Do For Us
• Recreation
• Hunting economics
• Falconry
Bad Things Birds Do To Us
• Crop damage
• U.S. - 6 million
bushels of
corn/year
• Waterfowl, doves,
crows/jays, robins,
starlings,
blackbirds, turkeys
Bad Things Birds Do To Us
• Competition
• Wild game, fish
Bad Things Birds Do To Us
• Fouling of roosts
• Droppings - pigeon
2.5 kg/year
• Odor, corrode
masonry
• Histoplasmosis,
chlamydiosis
Bad Things Birds Do To Us
• Airport problems
• Plane strikes
• ~15,000
collisions/year in U.S.
• $300 million/year
• 300 people deaths
• Gulls - 31%,
blackbirds - 13%
Bird Trauma Through Time
• 3 million years ago 25% of birds went
extinct at beginning of
Pleistocene
• Major climatic
changes
– Habitat changes
– Distribution
changes
– Viability impacts
Human Impacts
• Humans have
become a major
factor affecting
birds
• ~1000 species
now threatened
Human Impacts
• Destruction of
habitat
• Excessive human
predation
• Introduced
species
• Toxins
Human Impacts
• Many bird groups especially
problematic
• Neotropical migrants
• Grassland species
• Migrant shorebirds
• Seabirds of Southern Hemisphere
• Rain forest species with restricted
ranges
Human Impacts
• 10 countries now harbor 400 threatened
species with restricted ranges
Human Impacts
• Past 300 years
• ~90 bird extinctions
• 91% due partly to species introductions
(especially on islands)
• 32% due partly to habitat changes
• 25% involved excessive human predation
In the U.S.
• Endangered species - one that is in danger
of extinction throughout all or a significant
portion of its range
• Threatened species - one that is likely to
become endangered in the foreseeable
future throughout all or a significant portion
of its range
Small Island Effect
• Island-bound flightless &
nesting seabirds
• Susceptible to rats, hogs,
goats, cats brought to
islands by ships/sailors
• Dodo in western Indian
Ocean
• Great Auk of northern
Atlantic Ocean
– Food to resupply ships
that had crossed
Atlantic
Hawaiian Island Problems
• Bird pox & malaria
brought by introduced
mosquitoes
• Worse problem caused
by first Polynesian
colonists 1500 years
ago
• Lowland forest
destruction extinction of 39 spp.
of land birds
Modern Threats
• Human activities directly responsible
for deaths of ~270 million birds/year
• Does not include losses due to
destruction of breeding habitat,
interference with reproduction
Modern Threats
• Hunters - 120
million
• Vehicle collisions 57 million
• Windows - 80
million
– 2/3 of hunter kill
– IL house - 61/year
– NY house - 47/year
Modern Threats
• CATS! 1 billion!
Environmental Poisons
• Pesticides - DDT
• Bald eagle, other
raptors
• Reproductive failure 15-20% thinning of
eggshells
• Reproductive output
cut by nearly 2/3 until
DDT ban
• Recent recoveries to
near normal
Environmental Poisons
• Xenobiotics
• Chemicals that
interfere with
endocrine system
• Disrupt normal course
of development
• Fungicides,
herbicides,
insecticides, assorted
chemicals, food
products, metals
Environmental Poisons - PCBs
• May lead to:
• Thyroid dysfunction
• Compromised immune
systems
• Decreased fertility
• Decreased hatching
success
• Gross birth deformities,
behavioral abnormalities,
sex reversal
Cormorants
Environmental Poisons - PCBs
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Extra eggs
Female-female pairings
Feminization
High male mortality
Embryonic/chick
mortality
• Reduced growth
• Deformities
• Altered nest defense,
incubation behavior
Herring Gulls
Lake Michigan, Ontario