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Past and Present Threats to Birds

Past and Present Threats to Birds. DDT and Persistent Environmental Contaminants Vs. Land Cover Change. Changes in Land-use and Land- cover. Global changes:1700-1990 (Meyer and Turner 1992) Cropland +392 - 466% Irrigated Cropland +2400% Closed Forest -15.1%

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Past and Present Threats to Birds

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  1. Past and Present Threats to Birds DDT and Persistent Environmental Contaminants Vs. Land Cover Change

  2. Changes in Land-use and Land- cover • Global changes:1700-1990 (Meyer and Turner 1992) • Cropland +392 - 466% • Irrigated Cropland +2400% • Closed Forest -15.1% • Forest and woodland -14.9% • Grassland/pasture -1% • Lands drained 1.6 x 106 km2 • Urban settlement 2.5 x 106 km2 • Rural settlement 2.1 x 106 km2 (Lambin et al. 2001)

  3. Settlement Affects Native Habitat • Habitat Loss • Reduced connection among remaining patches • Perforation of large patches • Introduction of exotics • Degradation of remaining habitat

  4. Study Area • From 1999 to 2007, my students and I studied songbird communities and populations within forest patches from 3 landscape types: • Forest reserves (5) • Developed Subdivisions (9) • Changing landscapes (13)

  5. Reserve sites are primarily forested. Changing sites are undergoing residential development during the study Developed sites are older residential areas built prior to the onset of study.

  6. As Urbanization Increases and Forest is Reduced, Bird Diversity Increases, then Decreases (Marzluff 2005)

  7. Extinction (local extirpation) and colonization determine the pattern of diversity along a gradient of urbanization

  8. Expected Changes

  9. Spatial Changes

  10. Winners

  11. And Losers Pacific-slope Flycatcher

  12. Approaching a Tipping Point? Projected Forest Decline (Marzluff 2005 Urban Ecosystems 8:157-177)

  13. Conservation Lessons • Do not do the same thing everywhere • In urban areas, a variety of actions are needed and will have conservation benefits within and beyond urban areas • Reservation • Reduce Biotic Homogeneity • Connect People with Nature • Restoration, Education, Reconciliation • Conserving birds in urban areas may have substantial indirect benefits because people are involved

  14. Critical Reasoning Exercise • What are the similarities and differences in the environmental challenges posed to birds by (1) Persistent organic pollutants, like DDT and (2) Land cover change, like urbanization? • Why could we “easily” control DDT, but not land cover change? • What strategies to reduce the negative effects of land cover change on birds might we glean from Professor Wurster’s experience with DDT?

  15. Morphology of Voice Brackenbury 1982 and Gill 2005

  16. Syrinx Gill 2005

  17. Syrinx of Suboscine and Oscine Gill 2005 and Wallace and Mahan 1975

  18. Complex Neural Circuits Involved in Song Learning (Butler and Cotterill 2006) NOT IN SUBOSCINES (Beecher and Brenowitz 2005) (Reiner et al. 2005)

  19. Learning Calls • Songbirds, parrots, hummingbirds, cetacians, bats, and humans learn vocalizations • Avian forebrain has song learning centers (previous slide) • Midbrain may be center of call production (in all birds) • Centers of fear and arousal (nucleus mesencephali lateralis pars dorsalis) may be coordinated with centers of call production (nucleus intercollicularis) Kaplan 2008

  20. Australian Magpie Alarm Calls Complexity of alarm calls in a songbird suggests that learning is involved and forebrain learning centers are recruited, so that the function of various calls can be learned Alarm calls in other non-songbirds may be simple product of midbrain stimulation (no thinking needed)

  21. Song repertoire crystallizes Float or semi-territorial subsong plastic song (better) Song Sparrow development and learning Song Learning Disperse Hatch Float Territorial Early Late Summer Fall Winter Spring Spring

  22. Copying and Innovation Beecher and Brenowitz 2005

  23. Song sparrow Diversity of song learning programs/strategies in songbirds Beecher & Brenowitz TREE 2005

  24. Marler and Peters 1982

  25. Duetting Farabaugh 1982

  26. Individual Recognition Marzluff 1988

  27. Motivation of Caller Morton 1982

  28. Full Circle • Birds sing differently in urban environments • Louder, higher pitched, shorter duration • Possible effects • Cost more to sing loud and high • High pitch doesn’t carry as far • Females or intruders may not respond • Higher pitch suggests less motivation to fight (as per ms rules on earlier slide) (Slabbekoorn et al. 2007; Patricelli and Blickley 2006)

  29. Literature Cited • Beecher, M. D. and E. A. Brenowitz. 2005. Functional aspects of song learning in songbirds. Trends in Ecology and Evolution 20:143-149. • Brackenbury, J. H. 1982. The structural basis of voice production and its relationship to sound characteristics. Pp 53-74 in: Kroodsma, D. E. and E. H. Miller, eds. Acoustic communication in birds, Vol 1. Academic Press.New York. • Farabaugh, S. M. 1982. The ecological and social significance of duetting. Pp 85-124 in: Kroodsma, D. E. and E. H. Miller, eds. Acoustic communication in birds, Vol 2. Academic Press.New York. • Hansen, A. J., R. L. Knight, J. M. Marzluff, S.Powell, K. Brown, P. Hernandez, and K. Jones. 2005. Effects of exurban development on biodiversity: patterns, mechanisms, research needs. Ecological Applications. 15: 1893-1905. • Kaplan, G. 2008. Alarm calls and referntiality in Australian magpies: between midbrain and forebrain, can a case be made for complex cognition? Brain Research Bulletin 76:253-263. • Marler, P. R. and S. Peters. 1982. Subsong and plastic song: their role in the vocal learning process. Pp 25-50 in: Kroodsma, D. E. and E. H. Miller, eds. Acoustic communication in birds, Vol 2. Academic Press.New York. • Marzluff, J. M. 1988. Vocal recognition of mates by breeding pinyon jays. Animal Behaviour 36:296-298. • Marzluff, J.M. 2005. Island biogeography for an urbanizing world: how extinction and colonization may determine biological diversity in human-dominated landscapes. Urban Ecosystems 8: 155-175. • Morton, E. S. 1982. Grading, discreteness, redundancy, and motivation-structural rules. Pp 183-213 in: Kroodsma, D. E. and E. H. Miller, eds. Acoustic communication in birds, Vol 1. Academic Press.New York. • Patricelli, G. L. and J. L Bickley. 2006. Avian communication in urban noise: causes and consequences of vocal adjustment. Auk 123:639-649. • Slabbekoorn, H. Yeh, P., and K .Hunt. 2007. Sound transmission and song divergence: a comparison of urban and forest acoustics. Condor 109:67-78. • Wallace, G. J. and H. D. Mahan. 1975. An introduction to ornithology, 3rd edition. Macmillan Publishing Co. New York.

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