Samenvatting Wildlife Ecology & Conservation

Week 1-3
Part I: Importance & Threats
LMon: Importance of Biodiversity
Biodiversity

 Types
1. Genetic
2. Species
3. Ecosystem
 Diversity causes stability



Current extinction rates

 25% of mammals, 13% of birds, >21 000 plants & other organisms
 Similar rate as other 5 global mass-extinctions



Main threats

 Habitat loss:
 Agriculture
 Logging
 Development (e.g. housing)
 Direct mortality:
 Hunting (overexploitation)
 Invasive species
 Dilemma of world population growth
 Natural resources increasingly needed -> degradation -> undermines future use
 Key factor in species threat: population density of people
 Not always a relationship -> less mammals in very dense Europe already, not that many
threatened now



Slowing/halting human pop growth

 By
 Empowering & educating women
 Access to contraception
 Problem: economies based on growth
 Change in mindset needed
 More protected areas



Genetic diversity (GD)

 Low GD can reduce:
 Pop viability

,  Resistance to diseases



Climate change

 No evidence as direct cause of extinction
 Expected to have negative (indirect) effects in future



Anthropogenic (human caused) threats

 Largely determined by:
 Income
 Pop density
 Development activities



Solutions; what can we do?

 More substantial conservation efforts
 Proactive policies (e.g. shifts in agricultural practices)
 Improved land-use planning
 Shifting diets



Conservative successes

 >31 bird species saved from extinction by conservation programs
 Protected areas cover 14% of land surface
 Eradication of invasive species
 Captive breeding & re-introductions



Future threats

 Current + increased but uncertain threat of climate change effects



LTues: Overexploitation
Overexploitation

 Oceans
 Fishing
 Wildlife
 Hunting & poaching
 Relationship with overfishing (coastal areas without enough fish -> turn to bushmeat,
more hunting)
 Forests
 Timber extraction & logging
 Fuelwood collection & charcoal production

,Tragedy of commons

o Incompletely defined & enforced property rights
o Users do not consider social benefits & costs
o Benefits for individual, negative effects for all
o Harmful effects on 3rd parties: depletion of wildlife



Extent of problem

 Overexploitation 1 of 5 main threats
 1.5 km2 net forest loss between 2000-2012
 Tropics: agriculture & urban expansion
 Boreal: fires
 Large mammal species: pop decreased after humans entered continent
 301 mammal species threatened due to hunting
 Less in developed countries (EU), all in developing countries (Africa) -> hunting not
needed & lot of mammals already extinct
 Mostly in Asia, Africa & South-America
 Larger body mass (kg) -> higher chance of being hunted
 Also affects birds (parrots as pets)



Causes of overexploitation

 Forests
 Timber/logging
 Fuelwood/charcoal
 Uncontrolled fires
 Livestock grazing
 Hunting (bushmeat)
 Food
 Medical products
 Ornaments
 Pet trade (parrots)



Human induced megafauna extinctions

o Hunting or climate change?
 Ongoing debate



Causes increased hunting pressure in tropical forests

o Loss of forest
o Increase in human pop size (people get very old)
o Urbanization

, o Increased access (roads & fragmentation)
o Mobility of hunters
o Modern hunting technologies (weapons)
o Commercialization
o Extractive industries (logging)

Bushmeat hunting on African Savannahs

o Elevated demand (for meat)
o Human encroachment
o Poverty & food insecurity
o No regulation (no legal alternative)
o Political instability



Extinction rates since 1500

o Continental: 6 birds, 3 mammals
 Hunting
o Island: 123 birds, 58 mammals
 Hunting & predation by invasive species



Parrots => most threatened wildlife species

o Threats:
 Pet trade
 Habitat loss, fragmentation & degradation
o At risk:
 Large bodied, slow breeding
 Most species ecologically specialized



Cascading effects of hunting

o Large mammals
 Less top-down control
 Ecological release small mammals
 Loss of predators due to prey depletion
 Less seed dispersal -> increased rodent pop
o Small mammals
 Less seed dispersal
 Less vegetation & invertebrate consumption
 Less soil disturbance
 Prey depletion



Potential solutions