Direct Exploitation Flashcards
How has hunting changed in humans over history?
Early humans were nomadic hunter-gatherers with localised, low-intensity impacts.
As populations grew and expanded, large species were rapidly extirpated in new regions.
Wild harvesting remains significant in both developing and developed nations
what is the protein limitation hypothesis?
suggests that bushmeat serves as a dietary staple, rather than a luxury good - Brashares, J.S. 1 (2004)
what is the example of American Bison?
- 1800s: Declined from widespread across N. America to near extinction by 1889
what are the % survival of life after human colonisation in Australia, N America, Madagascar/ New Zealand and Africa?
Australia: <10% of megafauna species survived human colonisation (~50,000 years ago).
North America: Steep decline (~10,000 years ago), ~25% survival.
Madagascar/New Zealand: Complete megafauna extinction after colonisation (~1,000 years ago).
Africa: ~75% survival; co-evolved with humans, allowing adaptation.
Describe how bushmeat lead to over-exploitation?
Bushmeat commonly sold in Africa, S. America.
Wild meat is crucial for protein, income, and cultural traditions in rural communities (Milner-Gulland & Bennett, 2003).
Urban demand is growing rapidly, intensifying pressure on wildlife (Ingram et al., 2021).
Bushmeat trade is vast: 5 million tonnes of wild meat consumed across Neotropics and Afrotropics.
what are the ecological consequences of bushmeat hunting?
Overhunting leads to local extinctions, reduced biodiversity, and trophic cascades (Ripple et al., 2016; Milner-Gulland & Bennett, 2003).
Defaunation is widespread: average mammal population declines of 13%, >40% for large mammals in the tropics (Benítez-López et al., 2019).
Loss of seed dispersers (e.g., primates, bats) threatens forest regeneration (Ripple et al., 2016).
The “empty forest syndrome” is common—habitats remain, but key species are gone (Fa et al., 2009).
Even protected and “intact” forests show severe mammal losses (Benítez-López et al., 2019).
what are the drivers for bushmeat hunting?
Protein scarcity, poverty, and weak regulation fuel overhunting (Fa & Brown, 2009).
Access and infrastructure (roads, settlements) increase hunting pressure (Benítez-López et al., 2019).
Weak law enforcement in many protected areas makes regulation difficult (Ingram et al., 2021).
In West Africa, bushmeat consumption increases when fish stocks decline, showing bushmeat as a substitute protein source (Brashares et al., 2004).
Economic and nutritional needs blur lines between subsistence and commercial hunting (Ingram et al., 2021).
what are the species most at risk to bushmeat hunting?
Large-bodied species (e.g., primates, ungulates) are most vulnerable due to high value, slow reproduction, and easy detectability (Ripple et al., 2016; Fa et al., 2005).
In Africa, 52% of “intact” forests and 62% of wilderness areas are missing large mammals (Benítez-López et al., 2019).
In African forests, mammals make up 99% of bushmeat; especially duikers, rodents, and monkeys (Fa & Brown, 2009).
- Ungulates: 40–73%
- Rodents and primates: 12–30% (Fa & Brown, 2009; Fa et al., 2005
what are some bushmeat hunting techniques and the impacts?
Snaring is widespread—efficient but indiscriminate, targeting medium to large terrestrial mammals (Fa et al., 2005).
firearms are also a common form as are more selective (Fa & Brown, 2009).
Bushmeat trade has shifted from local use to high-volume, commercial exploitation.
what are the current harvest rates in bushmeat hunting?
Extraction rates exceed sustainability: e.g., 200 carcasses/hunter/year in Central Africa (Fa et al., 2005).
Harvest rates are far higher than in the Amazon, due to larger average mammal size and easier access (Fa & Brown, 2009).
what are the health and socioeconomic concerns with bushmeat hunting
Although Hunting supports millions of people where livestock or fish are unavailable (Milner-Gulland & Bennett, 2003).
Wild meat trade carries zoonotic disease risks (Ingram et al., 2021).
Declining wildlife may worsen food insecurity and poverty, especially in biodiversity hotspots like Madagascar, Indonesia, and Brazil (Ripple et al., 2016).
what are some recommended conservation strategies to reduce over-exploitation of bushmeat hunting?
trengthen law enforcement, protected area management, and anti-poaching efforts (Ingram et al., 2021).
Promote alternative protein sources (e.g., livestock, aquaculture) to reduce pressure (Milner-Gulland & Bennett, 2003).
Restrict use of snares and firearms, particularly in high-risk regions (Fa et al., 2005).
what is another form of overexploitation in aquatic environments?
Fishing always has bycatch (e.g., turtles); a persistent, global issue.
what are two marine examples of overexploitation
Atlantic Cod: Overfishing led to collapse → ban implemented.
Great whale harvest - Whales: Sequentially targeted (e.g., Fin → Sperm → Sei whale) until unprofitable.
what are the evolutionary and genetic impacts of hunting on animals?
Elephants now show shorter or absent tusks due to selective poaching—tusk size in males dropped by 21% and 27% in females (Chiyo et al., 2015).
Bighorn Sheep - trophy hunting focuses on large-horned males. Resulting in a decline in horn length of males, half in 40 years. Will then affect intrasexual selection.
Similar size-selective pressures are seen in fish and other hunted species for example Rock Lobsters in WA with Reduced carapace length from 1970 to 2005. Partly a result of removal of larger individuals and partly evolution towards smaller body size
(Ripple et al., 2016).
Evolutionary changes can alter mating systems, reduce fitness, and accelerate population collapse.
since 1500, how many vertebrate genera are extinct? and what is the % at risk of extinction currently?
73 vertebrate genera extinct; current rates are 35–511× higher than normal.
34% of vertebrate genera are now at risk of extinction.
what are the obstacles of implementing conservation strategies?
Limited enforcement capacity and poor infrastructure hinder success (Ingram et al., 2021).
Cultural traditions and economic needs make blanket hunting bans unfeasible (Milner-Gulland & Bennett, 2003).
There’s a need for cross-sectoral collaboration (conservation + development + food policy) (Ingram et al., 2021).
