Lecture 8: Overexploitation 2 Flashcards
(22 cards)
Lecture outline
1.Define wildlife trade vs. overexploitation
2.Discuss global patterns of wildlife trade
3.Evaluate the drivers and impacts of wildlife trade
Defining wildlife trade vs overexploitation
In previous lecture, we defined overexploitation as the unsustainable harvesting of a resource :
Overgrazing in pasture
Overharvesting in cropland
Overfishing
Overharvesting of timber
Overharvesting of game
The first two (& sometimes 3) are not ‘wild’ resources
Wildlife trade is about the trade of wildlife, so typically excludes personal and subsistence use
Literature sometime ignores trade of fish & timber
^ Indeed, the most major piece of international legislation that governs wildlife trade might lead you to think that only fauna and flora matter – CITES (ratified by 184 parties)
^BUT – under another convention, the CBD (ratified by 196 nations) there is no obvious reason why we wouldn’t regulate the trade of all forms of biological diversity
(CBD’s governing body is the Conference of the Parties (COP))
Wildlife can be seen as a natural resource
Therefore, wildlife trade can drive overexploitation via unsustainable harvesting of wildlife
global patterns of wildlife trade:
illegal trade issues
Illegal wildlife trade is one of the world’s largest illegitimate businesses, generating US$8 billion to $21 billion annually
https://www.traffic.org/about-us/illegal-wildlife-trade/
global patterns of wildlife trade:
legal trade issues
Legal trade can be devastating too: for example, the plumage trade of the mid-1800 and early 1900’s
The plumage trade caused declines in many bird species like the great egret
But, this was not tolerated by all, and many pioneering women were instrumental in both regulating plumage trade and founding major conservation NGOs – the RSPB in the UK and Audubon in the USA
e.g. -Mother of the Birds”/ “The Dragon” —
Etta Lemon, who founded the RSPB
RSPB
e.g. “Bird Ladies” Harriet Hemenway and
Minna Hall, whose work led to the formation of the National Audubon Society
Wildlife trade spans the tree of life and geographies too
Spans the tree of life:
*All taxa assesses were impacted by wildlife trade
*23% birds, 27% mammals, 9.4% amphibians, 12.4% reptiles
*Trade is associated with species at greatest risk of extinction
See Scheffers et al. (2019) Science
It spans geographies too
*Birds – most traded species in Andes, West and East Africa
*Mammals – hotspots across Africa and SE Asia
*Amphibians – hotspots in Amazon basin and South/SE Asia
*Reptiles – hotspots in SE Asia, Madagascar and Australia
Wildlife trade is linked to phylogeny
certain families contain a higher % of traded species (red)
For example, Psittacidae (parrots), Cervidae (deer), Dendrobatidae (poison dart frogs) and (chameleons)
Drivers of wildlife trade
Wildlife trade includes trade of species as:
*Pets (alive) – household pets, expositions, circuses, or zoological gardens
*Products (dead) – bush meat, trophy hunting, clothing, medicine, or religious purpose
Species can also be traded locally, nationally or internationally:
What a species is traded for, and how, influence observed patterns of trade
* E.g. bushmeat doesn’t need to be attractive whereas feathers for fashion do
* E.g. an animal that looks and/or sounds unpleasant won’t make a desirable household pet
* E.g. not every culture wants to consume the same food or medicine
Case study: Are colourful passerines more likely to be traded?
Senior et al 2022 identified that
bright and unusual colouration found to be a driver in passerine bird trade
^ this colouration driven trade could result in loss of colouration diversity in the wild
Passerines aka songbirds are also chosen for their beautiful songs
Southeast Asia is a global hotspot for wild bird trade
See Harris et al 2017
bird species that trade at a high price are in decline in the wild
Particularly in Indonesia, birds are highly prized for their songs
*Deep cultural roots of bird keeping, with several favoured species used for singing competitions
*Market price is a strong predictor of trends in species declines over time
*Link to last week – trappers typically don’t travel further into forest than 5km, so forests with relatively less edge (more interior) are likely harder for trappers to target
Ability to mimic speech also increases chance of parrots being traded at a high price: Romero-Vidal et al. (2020) Diversity
^ This paper, for example, identified attractive species of bird as those that were:
colourful, large and able to imitate human speech
*This aggregate metric (‘attractiveness’) was a strong predictor of market price
*Abundance in the wild was not associated with price
The Nemo/Dory/Hedwig effect?
Was thought to be a rise in wildlife trade specifically associated with particularly movies featuring animals - Now largely debunked and also shown to increase awareness improving conservation efforts in some areas, see the following papers:
Megias et al 2017
Investigating the impact of media on demand for wildlife: A case study of
Harry Potter and the UK trade in owls
doi: 10.1371/journal.pone.0182368
Did the movie Finding Dory increase demand for blue tang fish? (2020)
Volume 49, pages 903-911, Ambio
Pteridomania – the Victorian craze for ferns
The Victorian ‘fern fever’ demonstrates how culture and fashion can drive trade of particular species and taxa – It even inspired the design of the custard cream!
From ferns to orchids and cacti
orchids constitute > 70% of CITES listed species see: Hinsley et al. (2018) Botanical Journal of the Linnean Society
whilst 31% of the 1478 identified cacti species are threatened - Goettsch et al 2015 Nature Plants
Similarly, more than a half of all cactus species (57%) are used by people,
and unsustainable use is likely a large contributing factor hence nearly 1/3 of all assessed cacti are threatened with extinction
Could psychoactive species be at threat
Milana 2024 mbiol thesis:
Peyote takes 30 years to mature – increasing harvest for psychoactive benefits could be an issue
&
Harvesting impacts on fungi are generally unknown. Only 818 species (out of 2-11M) have a Red List assessment. Fungi are not mentioned in legislation - either ignored or lumped in with plants
Fauna Flora Funga is an organisation working to protect fungi alongside fauna and flora
Led by Giuliana Furci, César Rodríguez-Garavito and Merlin Sheldrake
The ‘Fauna, Flora, Funga’ initiative aims to get fungi the recognition they deserve as a distinct Kingdom of macroscopic (and microscopic) life
*Led by 3 exceptional people , including Giuliana Furci – a Chilean mycologist who was a visiting fellow at Durham last term
*Two of the major policy instruments that FFF is targeting are the Convention on Biological Diversity and CITES
*Besides making cool songs & legal history, FFF have also recently succeeded in getting Cop16 to agree to giving ‘funga’ the same legal consideration as flora and fauna
Other recent work has highlighted the need for such an initiative in wildlife trade legislation specifically:
Fungi could be given same status as
flora and fauna under conservation plan
proposal to Cop16 could see ‘funga’ get global legal consideration distinct from flora and fauna
see:
A call to include fungi in wildlife trade research and policy
Oyanedel et al. (2024) Conservation Biology
Do people really trade fungi?
Do people really trade fungi? Yes
*Many cordyceps species are highly valuable commodities because of their health benefits
with clinical evidence e.g. https://www.nature.com/articles/s41598-024-58742-z
*There have widespread population declines across the species’ range
*Largely attributed to overexploitation, with additional factors like climate change frequently implicated as well
One example is Himalayan caterpillar fungus (Ophiocordyceps sinensis) – one of the world’s most valuable biological commodities. “By 2017, high-quality pieces sold for more than 140,000 USD per kilogram in Beijing, more than three times the price of gold”
See distribution map in notes from
Hopping et al. (2018) PNAS
^Red = declining levels of cordyceps due to overexploitation
also:
https://www.zsl.org/what-we-do/conservation/protecting-species/illegal-wildlife-trade-crisis/impacting-plants-fungi-insects
Summary of factors that predict trade pattern across space, time and the tree of life:
*Aesthetics
*Health benefits
*Cultural and spiritual use
*Fashion and media trends
economic drivers of wildlife trade
*As with overexploitation in general, several economic phenomena contribute to patterns of wildlife trade
*When there are diminishing returns, the additional effort may not be worth the effort (returns), leading trappers to switch to congenerics
*Some evidence of this for birds & mammals in that there is phylogenetic clustering of trade (red line close to dashed line)
*Switch to something that looks/sounds/acts similar when target species gets rare
See Scheffers et al. (2019) Science
See also Courchamp et al. (2006) PLoS Biology
^ Negative returns in terms of reduced yield are not truly negative if the price increases with rarity – still make the same amount of money for lower yield
^ Fewer individuals -> value increases
Economic drivers: tragedy of the commons
Tragedy of the Commons and negative externalities remain a problem,
particularly in illegal wildlife trade
*Legal wildlife trade is regulated so, in theory, people should not be harvesting unsustainably or they will be penalised (the externality is internalised)
*BUT illegal wildlife trade is obviously unregulated, and poachers do not care if they deplete the resource for other people or even for themselves if rarity increases price
Temporal discounting
*Poachers are often not the people making the biggest gains from trade – often hunting and trapping is done by people in poverty looking for an income to survive
*Such people would likely discount the future heavily
What are the impacts of wildlife trade?
Wildlife trade is associated with declines in species abundance
see figures from Morton et al. (2021) Nature Ecology & Evolution
^ Most effects in this meta-analysis are negative and the confidence intervals don’t cross zero, indicating significant declines in abundance where trade occurs
^Declines were associated with national and international trade (not local trade)
Pets can escape & become invasive
see impact of escaped pet pythons on native wildlife in Hughes et al. (2023) Biological Reviews
Wildlife trade can facilitate the spread of zoonotic disease, see Bezerra-Santos et al. (2021) Trends in Parasitology
Trade supports local livelihoods see
Shrestha & Bawa (2014) Biological Conservation
& can be hugely lucrative for poor communities
Summary
*Unsustainable wildlife trade is an example of overexploitation
*What we trade and how varies depending on place, time and desirable traits
*All Kingdoms of life could be traded – fungi certainly are
*As in previous lecture, markets, governance and human behaviour drive wildlife trade
*Wildlife trade can have net positive effect, but often many negative effects
