Animal Behaviour Notes (Transcript Summary)

Why do birds sing?

Tinbergen's four questions

• What is the Cause?

• What is the Function?

• What is the Development?

• What is the Evolution?

Bird song descriptions (examples by species)

• Common yellowthroat: Slow witchity witchity

• Blackpoll warbler: High tseet

• Mourning warbler: Slurred two-note phrases plus two phrases on a lower note

• Worm-eating warbler: Very fast dry sharp chips

• Yellow-breasted chat: Harsh unmusical chattering clucks

• Northern parula warbler: Rising buzzy trill ending with abrupt lower zip

• Kentucky warbler: Churry, churry, churry

• Magnolia warbler: Weety, weety, weetyeo

• Prairie warbler: Rising buzzy zees

• Nashville warbler: High see-hews, plus low short trill

• Common yellowthroat (repeated): (repeated)

• Cerulean warbler: Short fast accelerating buzzy notes on one pitch plus higher buzzy trill

• Swainson’s warbler: Slurred whistles plus tee-oh

Cause

• Factors that make behaviour happen (in the individual)

• External events, stimuli from the environment

• Other animals (proximity to predator, mates etc.)

• Neural activity in the brain and nervous system

• Hormones

• Information in memory

• and many more

Function

• What behaviour accomplishes in terms of fitness consequences:

• Attract a mate (dominant reason for functional perspective)

• Avoid predation

• Find food

• Maintain a stable body temperature

• Migrate

• Build a nest

• and many more…

Development

• How behaviour emerges over time in an individual: (development does not stop in adulthood…, aging is also development)

• Early experience

• Nutrition, stress

• Learning

• Influence of parents, siblings

• Interaction of genes and environment (dominant topic)

• Epigenetics

Evolution

• How behaviour emerges on an evolutionary time scale

• Effect of natural selection

• Evolutionary descent: Phylogeny

• Change in species in response to selection

• Random and non-selected change in species: Founder effects, drift, pleiotropy

Case study: Migration and wintering in European blackcaps (Berthold et al. 1992)

• In the 1960s, European blackcaps began to spend the winter in Great Britain and became increasingly common there over the next 30 years. (Berthold et al. 1992)

• Migration routes (illustrated on maps): from SW Germany toward Britain; routes also shown in relation to N, S, and E Austria

• Possible origins of wintering blackcaps in Britain (illustrated on the map)

• Mean vectors for three groups of blackcaps:

  • British wintering adults: n = 18, direction = 279°

  • F1 offspring of British adults: n = 41, direction = 273°

  • Young from SW Germany nests: n = 49, direction = 227°

  • Statistical comparison: Groups 1 and 2 do not differ; Group 3 differs from Groups 1 and 2 (P < 0.001)

  • Represented data are summarized as mean vectors in degrees; locations referenced include Radolfzell, Bonn, Oslo

• Interpretation prompt: What does this tell us about the Cause, Function, Development, Evolution of bird migration?

• research lab in germany wanted to see if birds were staying in britain or over wintering in britain

• populations in west part typically go to south of franch and spain

• east skip winter and go to africa

• circles are showing migratory root of birds. arrows where birds are going… longer arrow shows more birds spread of arrows show spread of migration

• how are we tracking the birds?

  • at this time there is radio tracking but they relied on emlen funnel because it was easier

  • migratory restlessness: excited and anticipated to leave so they move around a lot and they move in the direction that they want to go.

  • emlen funnel has paper funnel and bottom of it has black in so what you get is little footprints up the funnel in the direction that they want to go. This allows researchers to visually assess the migratory tendencies of the birds, as the footprints indicate their preferred direction for migration.

• where is the red dot from?

  • are they birds stay there, coming from north or coming from germany

  • they took the birds that are over wintering pack to Germany and placed them in the Emlen funnel to track their migratory patterns and determine their direction of travel.

  • arrow is the mean vector of the direction they would fly… all birds wanted to fly straight west to britain as adults

  • the image on right shows first gen offspring from overwintering adults

    • shows that they also want to go to britain for winter… over wintering

  • compared to young birds that fly to south of france from germany

    • these birds want to go to south of france

Mean vectors of three groups of blackcaps

• Group A: Blackcaps from Britain, showing a preference for wintering in southern France.

• Group B: Young blackcaps migrating from Germany, demonstrating a distinct migratory pattern towards the south.

  • show that they instinctually want to fly to britain and isn’t a learned behaviour

  • not birds that are staying in britain but are birds migrating to britain from germany

  • is this heritable?.. shows change in migratory root and its heritable

• Group C: Resident blackcaps that exhibit varied strategies for winter survival, influenced by environmental conditions.

Data interpretation from Berthold et al. 1992

• Cause: Orientation of migratory behavior shows a population-level pattern and a potential genetic/learned basis for wintering destinations in Britain vs SW Germany; F1 offspring align with British adults, suggesting inherited or culturally transmitted orientation.

  • birds use earth magnetic field to navigate

  • use the sun

  • use the landscape sometimes, use of these can tell birds where they are

  • birds want to make the migration quickly and back quickly in spring to ensure they can take advantage of the optimal breeding conditions and food availability. …. going to from germany to britain is faster that germany to spain / south of france

  • found a successful root where they can over winter successfully and get back faster to get a hold of resources more easily

• Function: Wintering in Britain likely confers survival/reproductive advantages in that environment; migration direction is part of a strategy to optimize energy use and survival.

• Development: Offspring orientation (Britain- related) resembles parental orientation, indicating a development pattern influenced by parental (and possibly social) cues.

• Evolution: The existence of two distinct migratory orientations within the same species indicates potential evolutionary divergence in migratory behavior; the difference between SW German nest-origin birds and British-origin birds suggests heritable or rapidly adaptable components of migration direction.

Does behaviour evolve?

• Evolutionary theory can be misunderstood; caution against oversimplification. (David Hull, 1995)

• Quote: "Evolutionary theory seems so easy that almost anyone can misunderstand it." Nature 1995, 377, 494

Charles Darwin and the theory of natural selection

• Darwin (1809–1882) identified three unsolved problems in 19th-century biology:

  • Change in life on earth

  • Hierarchical organization of life

  • Adaptation

The theory of natural selection

• Key components:

  • Heritable variation

  • Reproduction is inherently variable

  • Competition

  • Reproductive success varies among members of a population

  • Selection

  • Favourable variation contributes to reproductive success

• Outcome: An increase over time in the frequency of heritable traits that make a positive contribution to reproductive success

Darwin's foundational quotations

• Excerpt from Darwin (1859) On the Origin of Species:

Illustrative example: Harmonia axyridis (ladybird beetle)

• Generation-by-generation changes in allele frequency (illustrative figure):

  • Generation 1: 50% / 50%

  • Generation 2: 40% / 60%

  • Generation 3: 30% / 70%

  • Generation 4: 10% / 90%

  • Generation 5: 0% / 100%

• Source: ANIMAL BEHAVIOR, Eighth Edition, Figure 1.10 (2005 Sinauer Associates, Inc.)

Branching evolution and descent with modification

• Change in life on earth occurs as species change in morphology and behaviour, as new species arise from old, and existing species become extinct

• Hierarchical organization of life results from descent with modification from a common ancestor

• Adaptation results from selection for behaviour and morphology that increase reproductive success by serving a specific function

• Darwin’s notebook (1837) and The Origin of Species (1859) illustrate branching evolution and the concept of descent with modification

• Visual cue on the page: Branching Evolution appears as a schematic from Darwin's notebook; emphasizes gradation and branching from common ancestors

Additional notes and cross-links

• The Berthold et al. study provides a concrete example of Tinbergen's questions in action, particularly illustrating Evolution (changes in migratory behavior over generations) and Development (offspring orientation patterns) tied to population-level Cause (orientation cues) and Function (survival/reproductive success through wintering location)

• The Harmonia axyridis example demonstrates how population genetics can visualize drift/selection across generations, reinforcing the idea of evolutionary change in behavior and morphology

• Across topics, the content ties back to fundamental principles: natural selection, heredity, variation, and adaptation, and how they manifest in real-world animal behavior (song, migration) over ecological and evolutionary timescales

Connections to broader themes

• How environment and learning interact with genetics to shape behavior (Development and Evolution)

• The importance of orientation and navigation in migratory success (Function and Evolution)

• The role of empirical data (mean vectors, sample sizes, P-values) in testing hypotheses about behavior

• Ethical/philosophical considerations (caution about misinterpreting evolutionary theory; need for careful inference about causation and design in nature)

Practical implications

• Understanding migration can inform conservation strategies for birds facing climate change and habitat loss

• Knowledge of heritable vs. learned components of behavior helps predict how species might adapt to new environments

• The integrated Tinbergen framework provides a structured approach to studying any behavior, ensuring consideration of proximate and ultimate causes, development, and evolution

Key equations and numerical references (LaTeX)

• Mean vectors in Berthold et al. 1992 case:

  • British wintering adults: n = 18,\ heta = 279^ ext{o}

  • F1 offspring of British adults: n = 41,\ heta = 273^ ext{o}

  • Young from SW-German nests: n = 49,\ heta = 227^ ext{o}

• Statistical result: P < 0.001

• Additional directional bearings referenced: e.g., Oslo, Bonn, Radolfzell (as cited in Berthold et al. 1992)

Note

• The transcript presents a concise, exam-ready set of notes tying descriptive observations (bird song, migration) to a foundational theoretical framework (Tinbergen, Darwin), while including the empirical data that illustrate these concepts. Use these notes to trace how proximate causes (stimuli, learning) and ultimate causes (survival, reproduction) shape behavior across development and evolution.