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Published byMae McGee Modified over 9 years ago
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Birds & People
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Good Things Birds Do For Us Food Eggs 2 billion chickens per year (18 kg/person) 100 million turkeys 11 million ducks
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Good Things Birds Do For Us Feathers - ornamentation
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Good Things Birds Do For Us Guano - fertilizer Peruvian islands
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Good Things Birds Do For Us Insect control Northern Flicker removed >60% of over-wintering corn- borer larvae from Mississippi cornfield Bird houses - Purple Martin - mosquitoes
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Good Things Birds Do For Us Rodent control Hawks, owls - small rodents
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Good Things Birds Do For Us Scavengers Vultures, gulls, crows
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Good Things Birds Do For Us Recreation Hunting - economics Falconry
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Bad Things Birds Do To Us Crop damage U.S. - 6 million bushels of corn/year Waterfowl, doves, crows/jays, robins, starlings, blackbirds, turkeys
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Bad Things Birds Do To Us Competition Wild game, fish
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Bad Things Birds Do To Us Fouling of roosts Droppings - pigeon 2.5 kg/year Odor, corrode masonry Histoplasmosis, chlamydiosis
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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%
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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
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Human Impacts Humans have become a major factor affecting birds ~1000 species now threatened
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Human Impacts Destruction of habitat Excessive human predation Introduced species Toxins
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Human Impacts Many bird groups especially problematic Neotropical migrants Grassland species Migrant shorebirds Seabirds of Southern Hemisphere Rain forest species with restricted ranges
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Human Impacts 10 countries now harbor 400 threatened species with restricted ranges
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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
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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
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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
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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
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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
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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
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Modern Threats CATS! 1 billion!
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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
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Environmental Poisons Xenobiotics Chemicals that interfere with endocrine system Disrupt normal course of development Fungicides, herbicides, insecticides, assorted chemicals, food products, metals
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Environmental Poisons - PCBs May lead to: Thyroid dysfunction Compromised immune systems Decreased fertility Decreased hatching success Gross birth deformities, behavioral abnormalities, sex reversal Cormorants
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Environmental Poisons - PCBs 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
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