Animal Behavior: Learning, Orientation & Biological Rhythms

Non-Associative Learning

• Habituation vs. Sensitization (mentioned as a precursor)
– Habituation = decrease in response after repeated benign stimulus.
– Sensitization = increase in response after repeated strong/aversive stimulus.
– Both vary widely “person-to-person / individual-to-individual,” making them harder to tease apart in field studies.

Filial Imprinting

• Critical-period phenomenon: must occur at a very early developmental stage; afterwards is effectively irreversible.
• Konrad Lorenz (1930s)
– Worked with greylag geese & mallard ducks (goslings).
– Showed that the first large moving object after hatching is accepted as “mother.”
– If Lorenz himself was first seen, chicks followed him permanently.
– Illustrates that the template is broad (“large moving object”) but the time window is narrow.
• Conservation application: Whooping-crane recovery program
– Problem: Cranes were endangered; chicks hand-reared by humans risked imprinting on humans ⇒ loss of wild behaviors.
– Solution: Care-givers wore crane-like puppets while feeding; later guided migration with ultralight aircraft that visually resembled adult cranes.
– Result: Chicks imprinted on aircraft, followed it on first migratory flight, learned the route, then migrated independently in subsequent years.
– Ethical significance: Minimizes human imprint to preserve natural fear of humans, increasing post-release survival.

Associative Learning

General definition: forming a connection between two previously unrelated events.

Classical Conditioning (Pavlovian)

• Involuntary/reflexive linkage between two stimuli.
• Ivan Pavlov’s dogs (textbook archetype):
– Unconditioned stimulus (US): meat powder ⇒ Unconditioned response (UR): salivation.
– Neutral stimulus (NS): bell.
– Repeated pairing: NS + US.
– After sufficient trials, NS becomes Conditioned Stimulus (CS) and elicits Conditioned Response (CR): bell alone → salivation.
• Significance: Demonstrates how animals (including humans) predict biologically important events from neutral cues; underlies modern advertising, phobia therapy, etc.

Operant Conditioning (Instrumental)

• Animal associates one of its own actions with a consequence (reward or punishment). Behavior frequency is modified accordingly.
• Natural example: Coyote bitten by porcupine
– Behavior: Investigating porcupine.
– Consequence: Pain from quills (positive punishment).
– Learning: Future avoidance of porcupines.
• Human-managed example: Marine-mammal training
– Behavior: “Wave fin.”
– Consequence: Fish reward (positive reinforcement).
• BF Skinner’s work
– Skinner box: sound-isolated chamber with lever (rats) or key/peck disk (pigeons).
– Positive reinforcement configuration: lever press → food pellet.
* Acquisition curve: pressing rate rises as P(\text{food}|\text{press}) is learned.
– Punishment configuration: lever press → brief electric shock via floor grid.
* Results: Rapid decline in pressing; illustrates negative contingency.
– Controlled environment prevents extraneous stimuli, permitting precise quantitative analysis (foundation of behaviorism).
– Ethical discussion: trade-off between scientific insight and animal welfare; modern guidelines require minimal shock intensity & enriched housing.

Other Common Behaviors Outside the Above Categories

Play

• Seems purposeless & involves exaggerated, redundant, or incomplete actions.
• Functions: develop motor skills, endurance, social signals, cognition.
• Example: Sibling cheetahs wrestle & chase → hones hunting agility but carries risk of injury (cost–benefit balance).

Kinesis

• Random, undirected changes in activity rate in response to stimulus intensity.
• Example: Snow pill-bugs (woodlice)
– Low humidity → increase walking & turning frequency until moist microhabitat found.
– Movement stops when favorable condition reached.
• Adaptive value: Maintains body water; no need for a “map,” only local feedback.

Taxis

• Directed (vector) movement toward or away from a stimulus source.
• Phototaxis: moths flying toward porch light (positive phototaxis).
• Magnetotaxis: Aquasporillium bacteria swim along Earth’s magnetic field lines toward magnetic north using internal magnetite crystals.

Orientation & Navigation

Homing Pigeons

• Use multimodal cues: sun compass, stellar cues, magnetic field, visual landmarks.
• Magnetic-disruption experiment
– Small magnetic “helmets” placed over beak area (site of magnetoreceptors).
– Cloudy days (no sun): helmeted birds fail to home.
– Clear days: same birds succeed by switching to sun compass — illustrates cue hierarchy & redundancy.

Biological Clocks

• Protein-based cellular oscillators; act at multiple time scales.
• Circadian clock
– Endogenous period ≈ 24\text{ h}; entrained by light/dark cycle.
– Functions: sleep/wake, feeding, hormone secretion.
– Jet lag = mismatch between internal clock and local solar time.
– House sparrows kept in constant darkness still exhibit near-24-h activity rhythm, but free-run gradually out of phase.
• Time-compensated sun compass (pigeons)
– Sun traverses 360^{\circ} per 24 h → 15^{\circ}\text{ h}^{-1}.
– Clock-shift experiment: exposing birds to light cycle shifted 6\text{ h}.
* Upon release, shifted birds flew 90^{\circ} off course (consistent with 6\text{ h} \times 15^{\circ}!! /\text{h}) proving integration of sun position + internal time.
• Lunar & tidal clocks: coastal organisms synchronize foraging/spawning with tides.

Photoperiodism & Seasonal Physiology

Bears and Hibernation

• Photoperiod = day length; reliable seasonal cue.
• Late-summer day shortening triggers hormonal cascade (e.g., leptin, ghrelin) → hyperphagia.
• Hyperphagia → rapid fat storage → entrance into torpor/hibernation when food scarce, temperatures low.
• Captive bears under artificial light cycles still exhibit appetite/metabolic changes, emphasizing endogenous program entrained by light.

Large-Scale Migration (Wildebeest)

• East-African herds (> 1 million individuals) travel hundreds of kilometers following spatio-temporal gradient of rainfall.
• Cues: grass greenness, water scent, atmospheric humidity gradients, photoperiod.
• Adaptive value: maximizes access to high-protein forage, reduces calf mortality.

Integrative Themes & Implications

• Critical periods (imprinting) guide irreversible preferences; mis-imprinting is a conservation risk but can be harnessed (ultralight aircraft).
• Associative learning frameworks (classical vs. operant) underpin modern animal training, pest control, addiction therapy.
• Movement behaviors (kinesis/taxis) show how simple rules yield effective resource tracking without cognition.
• Navigation requires a multimodal sensory “toolkit” + internal time; redundancy ensures robustness when one cue fails.
• Biological clocks maintain synchrony with predictable environmental cycles; human relevance includes shift-work health risks.
• Photoperiod-driven physiology demonstrates anticipatory adaptation: organisms modify behavior before conditions become lethal.
• Ethical & philosophical note: experiments such as Skinner boxes & magnetic disruption raise questions of animal sentience and welfare vs. knowledge gain; current best practice emphasizes the 3 Rs (Replacement, Reduction, Refinement).