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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

Past and Present Threats to Birds

DDT and Persistent Environmental Contaminants


Land Cover Change

changes in land use and land cover
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)

settlement affects native habitat
Settlement Affects Native Habitat
  • Habitat Loss
  • Reduced connection among remaining patches
  • Perforation of large patches
  • Introduction of exotics
  • Degradation of remaining habitat

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)

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.

as urbanization increases and forest is reduced bird diversity increases then decreases
As Urbanization Increases and Forest is Reduced, Bird Diversity Increases, then Decreases

(Marzluff 2005)

Extinction (local extirpation) and colonization determine the pattern of diversity along a gradient of urbanization
and losers
And Losers



approaching a tipping point
Approaching a Tipping Point?

Projected Forest


(Marzluff 2005 Urban Ecosystems 8:157-177)

conservation lessons
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
critical reasoning exercise
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?

Morphology of Voice

Brackenbury 1982 and Gill 2005


Gill 2005

syrinx of suboscine and oscine
Syrinx of Suboscine and Oscine

Gill 2005 and Wallace and Mahan 1975

complex neural circuits involved in song learning
Complex Neural Circuits Involved in Song Learning

(Butler and Cotterill 2006)


(Beecher and Brenowitz 2005)

(Reiner et al. 2005)

learning calls
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

australian magpie alarm calls
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)


Song repertoire


Float or



plastic song


Song Sparrow development and learning

Song Learning












copying and innovation
Copying and Innovation

Beecher and Brenowitz 2005


Song sparrow

Diversity of song learning programs/strategies in songbirds

Beecher & Brenowitz TREE 2005


Farabaugh 1982

full circle
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)

literature cited
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.