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%

– 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

• 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

(Marzluff 2005)

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

Expected Changes

Spatial Changes

Winners

And Losers

Pacific-slope Flycatcher

Approaching a Tipping Point?

(Marzluff 2005 Urban Ecosystems 8:157-177)

Projected Forest Decline

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

• 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

Syrinx

Gill 2005

Syrinx of Suboscine and Oscine

Gill 2005 and Wallace and Mahan 1975

Complex Neural Circuits Involved in Song

Learning

(Reiner et al. 2005)

(Butler and Cotterill 2006)

NOT IN SUBOSCINES(Beecher and Brenowitz 2005)

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

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)

Late Spring

Summer Fall Winter Early Spring

HatchDisperse

Float TerritorialFloat or

semi-territorial

Song Sparrow development and learning

Song LearningSong repertoire

crystallizes

subsong plastic song(better)

Copying and Innovation

Beecher and Brenowitz 2005

1. When song is learned

natal summer throughout

1st yearthroughout

lifetime

2. How many songs bird

learnssingle song

small to mod rep size

> 100 songs

3. Need song tutoring?

song abnormal w/o

song normal w/o

4. Copying fidelity

imitation (faithful copying)

improvisation (using tutor

material)

invention (require song

tutoring?)

5. Degree of canalization

rejection of heterospecific

material

tendency to copy almost anything

(mimicry)

Diversity of song learning programs/strategies in songbirds

Song sparrow

Beecher & Brenowitz TREE 2005

Marler and Peters 1982

Duetting

Farabaugh 1982

Individual Recognition

Marzluff 1988

Motivation of Caller

Morton 1982

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• 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, 3 rd edition. Macmillan Publishing Co. New

York.