Wildlife - Threats to Wildlife

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Human Threats to Wildlife

  • climate change
  • plastic pollution
  • air pollution
  • water pollution (e.g., chemicals)
  • habitat destruction
  • the illegal pet trades
  • pesticides and insecticides
  • trophy hunting
  • invasive species
  • fragmentation of populations
  • roads (e.g., being hi by cars)
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Human Threats to Wildlife - Key Threats

  • Key Threats
    • pollution
    • human encroachment
    • climate change
    • introduced species
    • habitat fragmentation
    • road traffic accidents
    • hunting
    • illegal trade
    • habitat destruction
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Pollution

  • pollution can come in a variety of forms
  • each form of pollution can cause potentially irreversible damage to the environment as well as to species populations
  • this can be through direct harm to plants and animals themselves or destruction of their habitats
  • e.g., air pollution, water pollution, soil pollution, sound pollution, light pollution
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Pollution: What is air pollution?

  • 'air pollution occurs when harmful or excessive quantities of substances including gases and biological molecules are introduced into Earth's atmosphere'
  • this has a negative impact on not just our own health but also that of our wildlife
  • the major effects of air pollution on wildlife include direct mortality debilitating injury and disease, physiological stress, anaemia, and bioaccumulation.
  • Some air pollutants have caused a change in the distribution of certain wildlife species.
  • There was a study conducted in Finland next to a copper smelting complex on the Pied Flycatcher. This led to the discovery that birds within this range produced less eggs but the success of the eggs hatching was greatly reduced.
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Pollution: Water Pollution

  • 'water pollution occurs when contaminants are introduced to the natural environment'
  • water is able to dissolve more substances than any other liquid on Earth
  • can be from a variety of sources:
    • agricultural run off
    • oil spills
    • sewage and wastewater
    • radioactive substances
  • eutrophication
    • human activities have led to large increases in the levels of nitrogen and phosphorus in the environment
    • in water, the overabundance of nutrients can fuel the excessive growth of phytoplankton and algae (eutrophication)
    • some algal blooms produce deadly toxins and can kill fish, marine mammals and seabirds
    • once eutrophication has occured and all the available nutrients have been consumed bacteria then use all the available oxygen. This can lead to hypoxia and the creation of 'dead zones' where fish cannot survive.
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Pollution: Soil Pollution

  • 'contamination of the soil by xenobiotic (human made) chemicals or alteration to natural soil environment'
  • can cause land to become barren and unable to grow plants
  • detrimental effect on microorganisms impacting food chains thus presence of species
  • destruction of habitats
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Pollution: Sound Pollution Part 1

  • 'propagation of noise that is harmful to animals'
    • propagation = transmission through a medium
  • commonly associated with urban areas
  • think road traffic, aeroplanes, ships, sonar etc.
  • can lead to aniamls vacating areas in order to hunt prey/avoid predation
  • knock on effect on landscape as plants are not being germinated
  • sonar effect on whale species
    • for whales, 'listening' is as important as 'seeing' is for humans
    • noise pollution threatens whale populations, interrupting normal behaviour, driving them away from areas, and even injuring or causing death
    • sound can travel 4 times faster and further in water
    • whales subjected to military sonar will neither dive nor feed reducing survival potential
    • some species react to sound by surfacing causing 'the bends'
    • decompression sickness has been observed in cetaceans that have surfaced quickly, with ears and eyes bleeding. In some cases, the noise is so sharmful it can even blow out their ear canals. The animals become disorientated and wind up beached which typically results in death.
    • 600 pilot whales recently become stranded on a New Zealand beach, around 400 of which died before volunteers can refloat them back into the sea. Short-finned pilot whales are the most susceptible to mass trandings as they are very social animals that travel and fish in large pods.
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Pollution: Sound Pollution Part 2

  • reduce noise pollution
    • develop technology that reduces the noise of cars, ships and aeroplanes
    • create laws that introduce silent zones in the oceans
    • research to understand the effects on species
    • educate future generation to think differently
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Pollution: Light Pollution

  • 'light pollution is excessive and inappropriate artificial light'
  • for billions of years animals have evolved to depend on predictable rhythms of day and night. Humans have drastically changed this cycle.
  • Plants and animals depend on Earth's daily rhythm to govern life-sustaining behaviours such as reproduction, nourishment, sleep and protection from predators.
  • CASE STUDY: moths are phototactic (drawn to light). There are a number of theories why this is the case.
    • phototaxis 'an organism's automatic movement toward or away from light'
    • in a behaviour called transverse orientation, some insects navigate by flying at a constant angle relative to a distant light source, such as the moon. But around man-made light the angle to the light source changes as a moth flies by. The moth is confused and therefore stuck in a cycle.
    • but there is no definitive answer to why moths are drawn to light
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Pollution: Plastics

  • there are now 'plastic islands' around the globe
    • there is one patch that is larger than France, Germany and Spain combined
  • uses for old plastic
    • ecological floating parks can house a variety of vegetation which in turn attracts wildlife. The underside is left rough to encourage growth of aquatic plant life and for fish to lay their eggs. Can expand land mass for humans.
    • using old plastic bottles as planters
    • melting down plastics into home furnishing (e.g., radios)
    • put recycled plastics instead of leather seats in cars
    • using reshaped plastics into jewellery beads etc.
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Human Encroachment

  • Human encroachment is the invasion/overrunning of wildlife
  • Example: Sand Lizard & Wild Birds lose much of their traditional habitats and food sources through housing development and farming
  •  ‘Encroach: means to trespass on or the invasion of and overrunning something or someone’
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Climate Change

  • The Earth’s climate is constantly changing due to natural causes
  •  Human activities also contribute significantly to changes
  • Effects include rising sea levels, heavier rainfall, droughts, warmer summer and flooding
  • Bird population can also be affected
  • Breeding seasons for mammals affected due to food availability and temperature
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Introduced Species

  • An introduced, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its native distributional range, which has arrived there by human activity.
  • Can be described as either intentional or accidental
  • e.g. American Mink, Grey Squirrel, Ring-necked Parakeet
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Introduced Species: Competition

  • Invasive non-native species are thought to be one of the biggest threats to global biodiversity, second only to habitat loss
  • There are almost 2,000 established non-native species in Great Britain
  • Invasive species have been introduced to the UK from every continent in the world (apart from Antarctica)
  • American signal crayfish is a threat to the native white clawed crayfish by out-competing them for food, habitat and spreading a ‘crayfish plague’
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Human Fragmentation

  • The process in which natural habitat is rendered functionally unable to support the species present
  • Prior to major human activity, Britain had a diverse matrix of habitats
    • e.g. forests, wetlands, grasslands, heathlands
  •  The organisms that previously used the site are displaced or destroyed, reducing biodiversity
  • Made a big impact in Britain with nearly 500 known species of animals & plants have become extinct
  • In some urban areas, 100% of ponds have been lost which has affected the Common Frog
  • Over 200,000 miles of hedgerows have disappeared – affected birds, mammals and invertebrates
  • Areas have become ‘fragmented’
  • Native vegetation is cleared for human activities such as agriculture, rural development and urbanisation
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Human Fragmentation and Habitat Destruction Exampl

  • Examples:
    • Wild Cat: destruction of its woodland habitat, shooting, road traffic and breeding with pet or feral cats. This creates kittens which are no longer ‘pure’ wild cats and passes on diseases like feline leukaemia.
    • Medicinal leech: habitat loss due to draining of marshland
    • Common dormouse: ancient woodlands shrinking or being broken up
    • White-clawed crayfish: habitat destruction due to flood defence works, construction, dredging and farming
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Road Traffic Accidents

  • Hundreds of thousands of wild birds and animals are killed and injured on Britain’s roads every year
  • Recent research indicates that over 74,000 deer may be involved in vehicle collisions each year in Britain
    • Fallow (40%), Roe (32%) and Muntjac (25%)
  • This is a major animal welfare problem and incurs significant human costs as well
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Hunting

  • In the UK hunting generally refers to hunting with hounds
  • e.g. fox hunting, stag hunting or mink hunting
  • Shooting is the shooting of game birds
  • What and when you can hunt can vary depending on where in the UK you are
  • Jailed and fined up £5,000 for hunting illegally or up to £20,000 for causing unnecessary suffering to an animal
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Illegal Trade

  • The UK might not be a major international hub for illegal wildlife trade, but wildlife crime is still a big problem here, despite successful campaigning work

  • Can include trading in furs, reptile skins, ivory trade & illegal importation of tortoises
  • In 2003, WWF and TRAFFIC (our wildlife trade monitoring) successfully pushed to make it an arrest offence to illegally trade in wildlife and the maximum prison sentence was increased from 2 to 5 years
  • Smuggled endangered species are typically sold illegally as pets, fashion items, medicines or exotic houseplants. 
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Threats to Biodiversity

  • Main causes of extinction
    • 39% are due to introduced species
    • 36% are from habitat destruction
    • 23% from over-exploitation
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Threast to Biodiversity: Introduced Species

  • Introduction of species into different habitats free from natural predators and competitors can lead to a population explosion which can displace local species
  • Eradication of invasive species is expensive, time consuming and difficult and unsustainable on a large scale
  • The Brown Tree snake was introduced accidentally to US territory of Guam
    • No natural predators, so species proliferates
    • Major threat to native birds, rodents and domestic pets
    • Expensive, time consuming and dangerous to remove by hand
  • Introduced species to Britain include: grey squirrel, American mink, red eared slider, signal crayfish, coypu, muntjac deer
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Threats to Biodiversity: Habitat Loss and Fragment

  • Any form of human activity will result in modification of the natural environment
  • Human populations and resource consumption have increased dramatically resulting in a reduction of population size of other species
    • Leads to the reduction in genetic diversity increasing species vulnerability to disease and in extreme cases extinction
  • Human disturbance may lead to unsuitable habitat or fragmented habitat resulting in small sub-populations which may be too small to sustain themselves
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Threats to Biodiversity: Over-exploitation

  • Over exploitation of species is usually the result of food use - but can involve the pet, fur or trophy hunting trades
  • Forests, fish and wildlife have been over exploited to the point of extinction
  • Harvesting of species at a rate faster than the natural reproductive capacity results in extinction
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