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14 September 2009 – Pringle lecture l. Components of fragmentation A. Reduction in total amount of habitat type B. Apportionment of remaining habitat into smaller and more isolated patches II. What constitutes a barrier? III. Biological responses to habitat fragmentation

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habitat fragmentation i

14 September 2009 – Pringle lecture

l. Components of fragmentation

A. Reduction in total amount of habitat type

B. Apportionment of remaining habitat into

smaller and more isolated patches

II. What constitutes a barrier?

III. Biological responses to habitat fragmentation

A. initial exclusion

B. isolation

C. island-area effects

D. edge effects

IV. The case of migratory songbirds

V. Protecting wildlife/biotic integrity in a fragmented landscape:

Challenges facing remnant natural areas

Habitat fragmentation #I

i components of habitat fragmentation
I. Components of Habitat Fragmentation

A. Natural heterogeneity vs fragmentation caused by humans

(rich internal patch structure vs simplified patches)

  • Biota in human-altered fragmented landscapes are affected

at different levels of biological organization

a. changes in gene frequencies of local populations

b. continent wide changes in species distribution and

ecosystems (Panda Example)

slide6

Slide 6

Habitat loss and

fragmentation

Increasingly leading

to ex situ breeding and

conservation efforts

slide7

Components of habitat fragmentation: apportionment of

remaining habitat into smaller and more isolated

fragments

ii what constitutes a barrier
II. What constitutes a barrier?
  • Species Specific
  • Cumulative effects

-dams in rivers

-roads in parks

-canals

-power lines

-fences

-fire lands

-other ???

slide13
Road Impacts:
  • Animal vehicle collisions cause 200 deaths per year in the US and cost US 1 billion annually in property damage
  • 35 million reptiles and frogs per year in Australia
  • 43,002 deer in Pennsylvania in 1990
  • 30,306 deer in Ohio in 2002
  • >10,000 deer per year in Kansas
  • 102 black bears in North Caroina in 2002
  • Ecological hot spots of mortality:
slide15

What constitutes a barrier for domestic livestock is a

corridor for ‘wildlife:

The case of hedgerows in Britain

and the importance of protecting historical landscape features

in highly fragmented landscapes

slide16

The ‘wildlife’ in hedgerows:

Many small mammals

house mice, door mice,

shrews, weasels, voles

Most of Britain’s woodland

birds use hedgerows at

least some of the time

High diversity of plants

relative to surrounding

countryside

Greater number of species

in older hedges

slide17

In Britain, roughly a quarter of the hedgerows (96,000 miles)

were removed between 1945-85. An additional 56,000 miles lost

between 1984-90

slide21

III. Biological responses to habitat fragmentation A. initial exclusion B. isolation C. island-area effects D. edge effects

edge effects
Edge Effects
  • temperature,

light, humidity,

wind, fire

  • predation
  • exotic species
  • disease
  • pollution
slide30

Nest predators

in fragmented

Landscapes

slide32

Cowbirds parasitize the nests of >200 bird species

  • Originally restricted to the northern part of the Great Plains
slide39

Brown headed cowbird chick in nest of yellow warbler

Smaller-bodied host birds have less chance of raising any of

their own young than do larger-bodied birds

slide44

Where have all the birds gone?

Are migratory song bird declines in North America primarily a result of habitat fragmentation in temperate regions or habitat destruction in the tropics?

decline of migratory songbirds
Decline of migratory songbirds:
  • Reproductive failure in temperate breeding areas due to habitat fragmentation
  • Destruction of tropical habitat
protecting migratory songbirds
Protecting migratory songbirds:
  • Recognizing the importance of intact source areas- i.e. large areas of intact forest which serve as refuges producing surplus birds that can later disperse and re- populate sink areas
  • Restoring forests in areas that are currently sinks
habitat fragmentation i50

I. Components of fragmentation

A. Reduction in total amount of habitat type

B. Apportionment of remaining habitat into

smaller and more isolated patches

II. What constitutes a barrier?

III. Biological responses to habitat fragmentation

A. initial exclusion

B. isolation

C. island-area effects

D. edge effects

IV. The case of migratory songbirds

V. Protecting wildlife/biotic integrity in a fragmented landscape:

Challenges facing remnant natural areas

Habitat fragmentation #I