Habitat fragmentation #I

1. 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

2. 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)

6. Slide 6 Habitat loss and fragmentation Increasingly leading to ex situ breeding and conservation efforts

7. Components of habitat fragmentation: apportionment of remaining habitat into smaller and more isolated fragments

8. II. What constitutes a barrier? • Species Specific • Cumulative effects -dams in rivers -roads in parks -canals -power lines -fences -fire lands -other ???

9. Dams as barriers

11. Roads as barriers

13. 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:

14. Roads as avenues for invasion by humans and exotic species 20 yrs later Initial road

15. 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

16. 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

17. 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

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

22. Initial exclusion, isolation and consequent loss of biota

23. Island Area Effects: Competition and overgrazing Reindeer in southern Norway

24. Edge Effects • temperature, light, humidity, wind, fire • predation • exotic species • disease • pollution

26. Edge Effects: increased vulnerability to predation

30. Nest predators in fragmented Landscapes

32. Cowbirds parasitize the nests of >200 bird species • Originally restricted to the northern part of the Great Plains

35. Endangered Kirtland’s warbler - highly parasitized by cowbirds

39. 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

40. Solutions?

41. Humanely disposing of cowbirds

42. Edge effects: Greater vulnerability to invasion by exotics

43. Edge Effects: Enhanced incidence of infectious disease

44. 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?

48. Decline of migratory songbirds: • Reproductive failure in temperate breeding areas due to habitat fragmentation • Destruction of tropical habitat

49. 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

50. 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