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U.r.b.a.n. a.n.!.m.a.l.s. (biotic homogenisation (promoted by urbanisation…
U.r.b.a.n. a.n.!.m.a.l.s.
6th extinction
(C)HIPPO(D)
invasive species
competitive exclusion
population growth
extreme growth and density in cities
habitat transformation
irreversible
transforming croplands
Urbanisation (esp. sprawl) brings people closer to protected areas (PAs)
25% of PAs < 17 km from city of > 50 000 people
a lot more urbanisation in the future
pollution
cities as major source
climate change
UHI as microcosms
overharvesting
packaged and processed food consumption increases drastically in cities
livestock most damaging agri
demand for wildlife
illegal poaching
disease
urbnnisation promoting emergence and spread
threats of built elements
roads
attract animals
food
garbage, prey, carrion, salts, fruits, water
mating
Unnatural polarised light sources trigger maladaptive behaviours
in polarotactic taxa, leading to reproductive failure.
roadkill
Mortality may increase or decrease with traffic volume
Mortality higher closer to key habitats
depends on size, taxa, mobility, speed, timing
barriers
small, disconnected populations
population isolation of rats on Changi Hill (1957)
Some animals will not approach / cross roads
effects
roads physically replace whatever was previously on the site
alters surrounding env
noise pollution , light pollution, traffic, and pesticides
vehicles
buildings
bird kills
Long‐distance migrants most vulnerable
higher mortality with
individual high‐rises than low‐rises
urban residences than rural residences
residences with feeders than without
mesopredator release
e.g. badgers, snakes, coyotes, cats
Birds extirpated from tiny fragments.
lots of cats
top human source of bird mortality (2.4B/year)
mostly unowned in urban, prey on native
nest predators
urban: cats; non-urban: Cooper's hawk
noise on biota
vulnerability
survivalbility
navigation, foraging, avoid prey, begging, individual recognition
bat: avoided sound treatment, reduced capture success
bat: reduced capture success/efficiency with increasing proximity to highway noise
hummingbird & deer mouse prefer noisy, scrub jay prefer quieter
mating
territorial defense, sexual selection
frogs alter calls to higher freq > lower freq impt in selection
different timing of calls
louder vocalisations
more energy used, higher predation risk
mixed effects on plants
insects
Most abundant animals, key
ecosystem services
Can adapt, exhibit behavioural
plasticity due to natural noise
hearing range within anthrophony
gaps: Behavioural bias in literature, difficulties in drawing ecologically sound conclusions, no understanding of fitness impacts.
biases in urban ecology research (2)
temperate regions vs tropics, arid etc.
Birds & reptiles vs reptiles, nematodes, amphibians, mammals
subsidisation
Access to resources provided by humans
problem
spread of diseases
change behaviour
invasive species
sugar water grow fungi (bird-feeders)
light on biota
lights
bright lights, skyglow
birds, insects, reptiles
navigation, migration, breeding, singing
streetlights
moths more attracted to rural light.
bats go to rural light more
Street lighting disturbs commuting bats
risk of predation
slow-flying
effects of LEDs mixed
compromise anti-predator behaviours of moths
urbanisation gradient
finding animals
6 categories
(2) golf course
(4) residential
(1) open space
intermediate disturbance, high productivity, watering for recreational space
no. 1 for Shannon Diversity of butt & birds
(5) office park
(3) reserve
(6) business district
species remaining
1st: preserve, open space, golf, residential, office park, business
more exotic plants (40%) in parks than animals
patch & matrix effect
Relative species richness of urban parks higher
winners and losers
URBAN ADAPTERS, URBANOBLIVIOUS
May benefit from
urbanization
most native, pref for patchy/edge/altered habitats, intermediate urbanisation
synanthropic, URBAN EXPLOITERS, URBANOPHILES
Positively affected by
urbanization
Generalists; rely on
human resources
many urban pests
rocky habitat specialist
non‐synanthropic, urban avoiders, urbanophobes
native, habitat specialists, large body, large home range
Sensitive to persecution and
habitat disturbance
population density/urbanisation
(1) reveal degree of synanthropy, (2) affect divergence of traits between urban & rural populations
crows increase with housing density, European robin (Normal), willow warbler decreases
ecological trap
source-sink theory
Source
: superior, preferred
Sink
: inferior, used only if source full
inferior habitat preferred over superior habitat
Mismatch between perceived (looks good) and actual habitat quality (impaired reproduction or survival)
Leads to extirpation or extinction
e.g. Cooper's Hawk in Tucson, Arizona
feeding chicks parasite doves and pigeons
urban hotspots of biodiversity
extinction risk
increases with urbanisation
number 1 problem
incre with urban pop in SEA
25 biod hotspots
more pop dense in these places than global average
pop growth rates also higher than global average
growing diversity in urban areas
most studies in temperate regions
spp richness falls but abun incre (arthro & aves)
human control of plants, less on animals
biodiversity patterns in your city
biotic homogenisation
the new pangaea
Removal of barriers between previously distinct
biogeographic regions :star:
promoted by urbanisation and other anthro pressures
Increased introduction of exotics
Homeostatic nature of cities
cities built by humans for humans
Ameliorated habitat for exotics
irrigation
Subsidisation + more predictable resource availability
more stable climate (UHI)
reduced predation (lack of top predators)
breakdown of trend: analogous species (e.g., fruigivorous birds) between analogous habitats (e.g., rainforests) decreases as distance increases
Jaccard's Simlarity Index
suburban
urban
bird assemblages in 2 urban areas compared
doesn't vary much even as distance increases
natural